Author name code: cao
ADS astronomy entries on 2022-09-14
author:"Cao, Wenda" 
------------------------------------------------------------------------  

Title: High-precision Multichannel Solar Image Registration Using
    Image Intensity
Authors: Liang, Bo; Chen, Xi; Yu, Lan; Feng, Song; Guo, Yangfan; Cao,
   Wenda; Dai, Wei; Yang, Yunfei; Yuan, Ding
Bibcode: 2022ApJS..261...10L
Altcode:
  Solar images observed in different channels with different instruments
  are crucial to the study of solar activity. However, the images
  have different fields of view, causing them to be misaligned. It
  is essential to accurately register the images for studying solar
  activity from multiple perspectives. Image registration is described
  as an optimizing problem from an image to be registered to a reference
  image. In this paper, we proposed a novel coarse-to-fine solar image
  registration method to register the multichannel solar images. In the
  coarse registration step, we used the regular step gradient descent
  algorithm as an optimizer to maximize the normalized cross correlation
  metric. The fine registration step uses the Powell-Brent algorithms
  as an optimizer and brings the Mattes mutual information similarity
  metric to the minimum. We selected five pairs of images with different
  resolutions, rotation angles, and shifts to compare and evaluate
  our results to those obtained by scale-invariant feature transform
  and phase correlation. The images are observed by the 1.6 m Goode
  Solar Telescope at Big Bear Solar Observatory and the Helioseismic and
  Magnetic Imager on board the Solar Dynamics Observatory. Furthermore, we
  used the mutual information and registration time criteria to quantify
  the registration results. The results prove that the proposed method
  not only reaches better registration precision but also has better
  robustness. Meanwhile, we want to highlight that the method can also
  work well for the time-series solar image registration.

Title: Solar Chromospheric Network as a Source for Solar Wind
    Switchbacks
Authors: Lee, Jeongwoo; Yurchyshyn, Vasyl; Wang, Haimin; Yang, Xu;
   Cao, Wenda; Carlos Martínez Oliveros, Juan
Bibcode: 2022ApJ...935L..27L
Altcode:
  Recent studies suggest that the magnetic switchbacks (SBs) detected
  by the Parker Solar Probe carry information on the scales of solar
  supergranulation (large scale) and granulation (medium scale). We test
  this claim using high-resolution Hα images obtained with the visible
  spectropolarimeters of the Goode Solar Telescope in Big Bear Solar
  Observatory. As possible solar sources, we count all the spicule-like
  features standing along the chromospheric networks near the coronal
  hole boundary visible in the Hα blue-wing but absent in the red-wing
  images and measure the geometric parameters of dense sections of
  individual flux tubes. Intervals between adjacent spicules located
  along the chromospheric networks are found in the range of 0.4-1.5
  Mm (0.°03-0.°12) tending to be smaller than the medium scale of
  SBs. Interdistances between all pairs of the flux tubes are also counted
  and they appear in a single peak distribution around 0.7 Mm (0.°06)
  unlike the waiting-time distribution of SBs in a scale-free single
  power-law form. The length-to-diameter ratio of the dense section
  of flux tubes is as high as 6-40, similar to the aspect ratio of
  SBs. The number of spicules along a network can be as high as 40-100,
  consistent with numerous SBs within a patch. With these numbers, it is
  argued that the medium scale of SBs can be understood as an equilibrium
  distance resulting from a random walk within each diverging magnetic
  field funnel connected to the chromospheric networks.

Title: Fan-shaped jet close to a light bridge
Authors: Liu, Y.; Ruan, G. P.; Schmieder, B.; Masson, S.; Chen, Y.;
   Su, J. T.; Wang, B.; Bai, X. Y.; Su, Y.; Cao, Wenda
Bibcode: 2022arXiv220713246L
Altcode:
  On the Sun,jets in light bridges are frequently observed with
  high-resolution instruments.The respective roles played by convection
  and the magnetic field in triggering such jets are not yet clear.We
  report a small fan-shaped jet along a LB observed by the 1.6m Goode
  Solar Telescope(GST) with the TiO Broadband Filter Imager(BFI),the
  Visible Imaging Spectrometer(VIS) in H{\alpha},and the Near-InfraRed
  Imaging Spectropolarimeter(NIRIS),along with the Stokes parameters.The
  high spatial and temporal resolution of those instruments allowed us to
  analyze the features identified during the jet event.By constructing
  the H{\alpha} Dopplergrams,we found that the plasma is first moving
  upward,whereas during the second phase of the jet,the plasma is
  flowing back.Working with time slice diagrams,we investigated
  the propagation-projected speed of the fan and its bright base.The
  fan-shaped jet developed within a few minutes,with diverging beams. At
  its base,a bright point was slipping along the LB and ultimately invaded
  the umbra of the sunspot.The H{\alpha} profiles of the bright points
  enhanced the intensity in the wings, similarly to the case of Ellerman
  bombs.Co-temporally,the extreme ultraviolet brightenings developed at
  the front of the dark material jet and moved at the same speed as the
  fan, leading us to propose that the fan-shaped jet material compressed
  and heated the ambient plasma at its extremities in the corona.Our
  multi-wavelength analysis indicates that the fan-shaped jet could result
  from magnetic reconnection across the highly diverging field low in the
  chromosphere,leading to an apparent slipping motion of the jet material
  along the LB.However,we did not find any opposite magnetic polarity at
  the jet base,as would typically be expected in such a configuration.We
  therefore discuss other plausible physical mechanisms,based on waves
  and convection, that may have triggered the event.

Title: Chromospheric Recurrent Jets in a Sunspot Group and Their
    Intergranular Origin
Authors: Zhao, Jie; Su, Jiangtao; Yang, Xu; Li, Hui; Schmieder,
   Brigitte; Ahn, Kwangsu; Cao, Wenda
Bibcode: 2022ApJ...932...95Z
Altcode: 2022arXiv220506981Z
  We report on high-resolution observations of recurrent fan-like jets
  by the Goode Solar Telescope in multiple wavelengths inside a sunspot
  group. The dynamics behavior of the jets is derived from the Hα line
  profiles. Quantitative values for one well-identified event have been
  obtained, showing a maximum projected velocity of 42 km s<SUP>-1</SUP>
  and a Doppler shift of the order of 20 km s<SUP>-1</SUP>. The
  footpoints/roots of the jets have a lifted center on the Hα line
  profile compared to the quiet Sun, suggesting a long-lasting heating at
  these locations. The magnetic field between the small sunspots in the
  group shows a very high resolution pattern with parasitic polarities
  along the intergranular lanes accompanied by high-velocity converging
  flows (4 km s<SUP>-1</SUP>) in the photosphere. Magnetic cancellations
  between the opposite polarities are observed in the vicinity of
  the footpoints of the jets. Along the intergranular lanes horizontal
  magnetic field around 1000 G is generated impulsively. Overall, all the
  kinetic features at the different layers through the photosphere and
  chromosphere favor a convection-driven reconnection scenario for the
  recurrent fan-like jets and evidence a site of reconnection between the
  photosphere and chromosphere corresponding to the intergranular lanes.

Title: Magnetic Field Re-configuration Associated With a Slow Rise
    Eruptive X1.2 Flare in NOAA Active Region 11944
Authors: Yurchyshyn, Vasyl; Yang, Xu; Nita, Gelu; Fleishman, Gregory;
   Abramenko, Valentina; Inoue, Satoshi; Lim, Eun-Kyung; Cao, Wenda
Bibcode: 2022FrASS...916523Y
Altcode:
  Using multi-wavelength observations, we analysed magnetic field
  variations associated with a gradual X1.2 flare that erupted on
  January 7, 2014 in active region (AR) NOAA 11944 located near the disk
  center. A fast coronal mass ejection (CME) was observed following the
  flare, which was noticeably deflected in the south-west direction. A
  chromospheric filament was observed at the eruption site prior to and
  after the flare. We used SDO/HMI data to perform non-linear force-free
  field extrapolation of coronal magnetic fields above the AR and to
  study the evolution of AR magnetic fields prior to the eruption. The
  extrapolated data allowed us to detect signatures of several magnetic
  flux ropes present at the eruption site several hours before the
  event. The eruption site was located under slanted sunspot fields
  with a varying decay index of 1.0-1.5. That might have caused the
  erupting fields to slide along this slanted magnetic boundary rather
  than vertically erupt, thus explaining the slow rise of the flare
  as well as the observed direction of the resulting CME. We employed
  sign-singularity tools to quantify the evolutionary changes in the
  model twist and observed current helicity data, and found rapid and
  coordinated variations of current systems in both data sets prior to
  the event as well as their rapid exhaustion after the event onset.

Title: Design and expected performances of the large acceptance
    calorimeter for the HERD space mission.
Authors: Pacini, L.; Adriani, O.; Bai, Y. l.; Bao, T. w.; Berti, E.;
   Bottai, S.; Cao, W. w.; Casaus, J.; Cui, X. z.; D'Alessandro, R.;
   Formato, V.; Gao, J. r.; Li, R.; Liu, X.; Lorusso, L.; Lyu, L. w.;
   Marín, J.; Martínez, G.; Pizzolotto, C.; Qin, J. j.; Quan, Z.; Shi,
   D. l.; Starodubtsev, O.; Tang, Z. c.; Tiberio, A.; Vagelli, V.; Wang,
   B.; Wang, R. j.; Wang, Z. g.; Xu, M.; Yang, Y.; Zhang, L.; Zheng,
   J. k.; Velasco, M. A.
Bibcode: 2022icrc.confE..66P
Altcode: 2022PoS...395E..66P
  No abstract at ADS

Title: Abyssal Manganese Nodule Recording of Global Cooling and
    Tibetan Plateau Uplift Impacts on Asian Aridification
Authors: Jiang, X. D.; Zhao, X.; Zhao, X. Y.; Chou, Y. -M.; Roberts,
   A. P.; Hein, J. R.; Yu, J. M.; Sun, X. M.; Shi, X. F.; Cao, W.; Liu,
   Q. S.
Bibcode: 2022GeoRL..4996624J
Altcode:
  The impact of central Asian aridification on the low latitude North
  Pacific Ocean since the late Miocene remains unclear. To address this
  question, we systematically studied an abyssal manganese nodule from
  the northwestern Pacific Ocean, which is expected to be sensitive to
  eolian dust sourced from central Asia. Geochemical variations and the
  fossilized remains of magnetotactic bacteria within the studied nodule
  manifest two prominent Asian aridification events at ∼8-7 Ma and 3.6-0
  Ma. These results suggest that central Asian aridification impacted both
  primary productivity and abyssal microbial activity in the NW Pacific
  Ocean via eolian dust inputs. In contrast to the Pliocene aridification
  event, the late Miocene event was associated with a primary productivity
  bloom that is not evident in coeval global primary productivity records,
  which indicates that the ∼8-7 Asian aridification event was likely
  due to NE Tibetan Plateau uplift rather than to global cooling.

Title: A High-resolution Study of Magnetic Field Evolution and
    Spicular Activity around the Boundary of a Coronal Hole
Authors: Wang, Jiasheng; Lee, Jeongwoo; Liu, Chang; Cao, Wenda;
   Wang, Haimin
Bibcode: 2022ApJ...924..137W
Altcode:
  In this study, we analyze high-spatial-resolution (0.″24)
  magnetograms and high-spatial-resolution (0.″10) Hα off-band (±
  0.8 Å) images taken by the 1.6 m Goode Solar Telescope to investigate
  the magnetic properties associated with small-scale ejections in a
  coronal hole boundary region from a statistical perspective. With one
  and a half hours of optical observations under excellent seeing, we
  focus on the magnetic structure and evolution by tracking the magnetic
  features with the Southwest Automatic Magnetic Identification Suite
  (SWAMIS). The magnetic field at the studied coronal hole boundary is
  dominated by negative polarity with flux cancellations at the edges
  of the negative unipolar cluster. In a total of 1250 SWAMIS-detected
  magnetic cancellation events, ~39% are located inside the coronal
  hole with an average flux cancellation rate of 2.0 × 10<SUP>18</SUP>
  Mx Mm<SUP>-2</SUP> hr<SUP>-1</SUP>, and ~49% are located outside
  the coronal hole with an average flux cancellation rate of 8.8 ×
  10<SUP>17</SUP> Mx Mm<SUP>-2</SUP> hr<SUP>-1</SUP>. We estimated
  that the magnetic energy released due to flux cancellation inside the
  coronal hole is six times more than that outside the coronal hole. Flux
  cancellation accounts for ~9.5% of the total disappearance of magnetic
  flux. Other forms of its disappearance are mainly due to fragmentation
  of unipolar clusters or merging with elements of the same polarity. We
  also observed a number of significant small-scale ejections associated
  with magnetic cancellations at the coronal hole boundary that have
  corresponding EUV brightenings.

Title: Multi-passband Observations of a Solar Flare over the He I
    10830 Å line
Authors: Xu, Yan; Yang, Xu; Kerr, Graham S.; Polito, Vanessa; Sadykov,
   Viacheslav M.; Jing, Ju; Cao, Wenda; Wang, Haimin
Bibcode: 2022ApJ...924L..18X
Altcode: 2021arXiv211209949X
  This study presents a C3.0 flare observed by the Big Bear Solar
  Observatory/Goode Solar Telescope (GST) and Interface Region Imaging
  Spectrograph (IRIS) on 2018 May 28 around 17:10 UT. The Near-Infrared
  Imaging Spectropolarimeter of GST was set to spectral imaging mode to
  scan five spectral positions at ±0.8, ±0.4 Å and line center of He I
  10830 Å. At the flare ribbon's leading edge, the line is observed to
  undergo enhanced absorption, while the rest of the ribbon is observed
  to be in emission. When in emission, the contrast compared to the
  preflare ranges from about 30% to nearly 100% at different spectral
  positions. Two types of spectra, "convex" shape with higher intensity at
  line core and "concave" shape with higher emission in the line wings,
  are found at the trailing and peak flaring areas, respectively. On the
  ribbon front, negative contrasts, or enhanced absorption, of about
  ~10%-20% appear in all five wavelengths. This observation strongly
  suggests that the negative flares observed in He I 10830 Å with
  mono-filtergram previously were not caused by pure Doppler shifts of
  this spectral line. Instead, the enhanced absorption appears to be a
  consequence of flare-energy injection, namely nonthermal collisional
  ionization of helium caused by the precipitation of high-energy
  electrons, as found in our recent numerical modeling results. In
  addition, though not strictly simultaneous, observations of Mg II
  from the IRIS spacecraft, show an obvious central reversal pattern
  at the locations where enhanced absorption of He I 10830 Å is seen,
  which is consistent with previous observations.

Title: Stokes Inversion with Stacked Deep Neural Networks
Authors: Jiang, Haodi; Li, Qin; Xu, Yan; Ahn, Kwangsu; Cao, Wenda;
   Wang, Jason T. L.; Wang, Haimin
Bibcode: 2021AGUFMNG45B0583J
Altcode:
  Prediction of solar eruptive events is an important topic in space
  weather research. Acquiring high-quality magnetic and velocity fields
  through Stokes inversion is crucial for accurate solar eruption
  prediction. We present here a new deep learning method, dubbed Stacked
  Deep Neural Networks (SDNN), for Stokes inversion. We apply SDNN to
  inferring line-of-sight (LOS) velocities and Doppler widths in addition
  to vector magnetic fields from Stokes profiles of the Near InfraRed
  Imaging Spectropolarimeter on the 1.6 m Goode Solar Telescope at the Big
  Bear Solar Observatory. Experimental results show that SDNN is faster,
  while producing smoother and cleaner LOS velocity maps and Doppler
  width maps, than the widely used Milne-Eddington method. Furthermore,
  SDNN outperforms three related machine learning algorithms, including
  a convolutional neural network, multiple support vector regression
  model, and multilayer perceptrons model, on different datasets. Thus,
  the proposed deep learning based SDNN tool can be considered as an
  alternative and efficient method for Stokes inversion.

Title: Possible Signature of Sausage Waves in Photospheric Bright
    Points
Authors: Gao, Yuhang; Li, Fuyu; Li, Bo; Cao, Wenda; Song, Yongliang;
   Tian, Hui; Guo, Mingzhe
Bibcode: 2021SoPh..296..184G
Altcode: 2021arXiv211211756G
  Sausage waves have been frequently reported in solar magnetic structures
  such as sunspots, pores, and coronal loops. However, they have not been
  unambiguously identified in photospheric bright points (BPs). Using
  high-resolution TiO image sequences obtained with the Goode Solar
  Telescope at the Big Bear Solar Observatory, we analyzed four isolated
  BPs. It was found that their area and average intensity oscillate
  for several cycles in an in-phase fashion. The oscillation periods
  range from 100 to 200 seconds. We interpreted the phase relation as a
  signature of sausage waves, particularly slow waves, after discussing
  sausage-wave theory and the opacity effect.

Title: Investigations of Sizes and Dynamical Motions of Solar
    Photospheric Granules by a Novel Granular Segmenting Algorithm
Authors: Liu, Yanxiao; Jiang, Chaowei; Yuan, Ding; Zuo, Pingbing;
   Wang, Yi; Cao, Wenda
Bibcode: 2021ApJ...923..133L
Altcode: 2021ApJ...923..133Y; 2021arXiv211003951Y
  Granules observed in the solar photosphere are believed to be
  convective and turbulent, but the physical picture of the granular
  dynamical process remains unclear. Here we performed an investigation
  of granular dynamical motions of full length scales based on data
  obtained by the 1 m New Vacuum Solar Telescope and the 1.6 m Goode
  Solar Telescope. We developed a new granule segmenting method, which
  can detect both small faint and large bright granules. A large number
  of granules were detected, and two critical sizes, 265 and 1420 km,
  were found to separate the granules into three length ranges. The
  granules with sizes above 1420 km follow Gaussian distribution,
  and demonstrate flat in flatness function, which shows that they are
  non-intermittent and thus are dominated by convective motions. Small
  granules with sizes between 265 and 1420 km are fitted by a combination
  of power-law function and Gauss function, and exhibit nonlinearity in
  flatness function, which reveals that they are in the mixing motions
  of convection and turbulence. Mini granules with sizes below 265
  km follow the power-law distribution and demonstrate linearity in
  flatness function, indicating that they are intermittent and strongly
  turbulent. These results suggest that a cascade process occurs: large
  granules break down due to convective instability, which transports
  energy into small ones; then turbulence is induced and grows, which
  competes with convection and further causes the small granules to
  continuously split. Eventually, the motions in even smaller scales
  enter in a turbulence-dominated regime.

Title: A deep learning method to estimate magnetic fields in solar
    active regions from photospheric continuum images
Authors: Bai, Xianyong; Liu, Hui; Deng, Yuanyong; Jiang, Jie; Guo,
   Jingjing; Bi, Yi; Feng, Tao; Jin, Zhenyu; Cao, Wenda; Su, Jiangtao;
   Ji, Kaifan
Bibcode: 2021A&A...652A.143B
Altcode:
  Context. The magnetic field is the underlying cause of solar
  activities. Spectropolarimetric Stokes inversions have been routinely
  used to extract the vector magnetic field from observations for
  about 40 years. In contrast, the photospheric continuum images have
  an observational history of more than 100 years. <BR /> Aims: We
  suggest a new method to quickly estimate the unsigned radial component
  of the magnetic field, |B<SUB>r</SUB>|, and the transverse field,
  B<SUB>t</SUB>, just from photospheric continuum images (I) using deep
  convolutional neural networks (CNN). <BR /> Methods: Two independent
  models, that is, I versus |B<SUB>r</SUB>| and I versus B<SUB>t</SUB>,
  are trained by the CNN with a residual architecture. A total of
  7800 sets of data (I, B<SUB>r</SUB> and B<SUB>t</SUB>) covering 17
  active region patches from 2011 to 2015 from the Helioseismic and
  Magnetic Imager are used to train and validate the models. <BR />
  Results: The CNN models can successfully estimate |B<SUB>r</SUB>|
  as well as B<SUB>t</SUB> maps in sunspot umbra, penumbra, pore, and
  strong network regions based on the evaluation of four active regions
  (test datasets). From a series of continuum images, we can also detect
  the emergence of a transverse magnetic field quantitatively with the
  trained CNN model. The three-day evolution of the averaged value of
  the estimated |B<SUB>r</SUB>| and B<SUB>t</SUB> from continuum images
  follows that from Stokes inversions well. Furthermore, our models can
  reproduce the nonlinear relationships between I and |B<SUB>r</SUB>|
  as well as B<SUB>t</SUB>, explaining why we can estimate these
  relationships just from continuum images. <BR /> Conclusions: Our
  method provides an effective way to quickly estimate |B<SUB>r</SUB>|
  and B<SUB>t</SUB> maps from photospheric continuum images. The
  method can be applied to the reconstruction of the historical
  magnetic fields and to future observations for providing the quick
  look data of the magnetic fields. <P />Movie is available at <A
  href="https://www.aanda.org/10.1051/0004-6361/202140374/olm">https://www.aanda.org</A>

Title: Magneto-acoustic oscillations observed in a solar plage region
Authors: Ji, Haisheng; Hashim, Parida; Hong, Zhenxiang; Xu, Zhe;
   Shen, Jinhua; Ji, Kaifan; Cao, Wenda
Bibcode: 2021RAA....21..179J
Altcode: 2021arXiv210111998J
  We gave an extensive study for the quasi-periodic perturbations on
  the time profiles of the line of sight (LOS) magnetic field in 10
  × 10 sub-areas in a solar plage region (corresponds to a facula
  on the photosphere). The perturbations are found to be associated
  with the enhancement of He I 10830 Å absorption in a moss region,
  which is connected to loops with million-degree plasma. FFT analysis
  to the perturbations gives a kind of spectrum similar to that of
  Doppler velocity: a number of discrete periods around 5 minutes. The
  amplitudes of the magnetic perturbations are found to be proportional
  to magnetic field strength over these sub-areas. In addition, magnetic
  perturbations lag behind a quarter of the cycle in the phase with
  respect to the p-mode Doppler velocity. We show that the relationships
  can be well explained with an MHD solution for the magneto-acoustic
  oscillations in high-β plasma. Observational analysis also shows
  that, for the two regions with the stronger and weaker magnetic field,
  the perturbations are always anti-phased. All findings show that the
  magnetic perturbations are actually magneto-acoustic oscillations on the
  solar surface, the photosphere, powered by p-mode oscillations. The
  findings may provide a new diagnostic tool for exploring the
  relationship between magneto-acoustic oscillations and the heating of
  the solar upper atmosphere, as well as their role in helioseismology.

Title: Multi-passband Observations Of A Negative Flare Near He I
    10830 Å
Authors: Xu, Y.; Yang, X.; Kerr, G.; Polito, V.; Jing, J.; Cao, W.;
   Wang, H.
Bibcode: 2021AAS...23830305X
Altcode:
  This study presents a C3.0 flare observed by the BBSO/GST and
  IRIS, on 2018-May-28 around 17:10 UT. The Near Infrared Imaging
  Spectropolarimeter (NIRIS) was set to spectral imaging mode to scan
  five spectral positions at ±0.8 Å, ±0.4 Å and line center of He I
  10830 Å. Negative contrasts of around 10%, appear in all of the five
  wavelengths, with a weak dependence of these wavelengths. This means
  that the line is undergoing enhanced absorption at these times. The
  observations confirm that the negative flares observed in He I 10830 Å
  with mono-filtergram previously were not caused by pure Doppler shifts
  of this spectral line. Instead, the enhanced absorption is a consequence
  of nonthermal ionization of helium following precipitation of high
  energy electrons, as found in recent numerical modeling results. In
  addition, though not strictly simultaneously, the IRIS observations show
  clear central reversals in Mg II lines and strong Doppler shifts in C
  II and Mg II lines at the locations where enhanced absorption in He I
  10830 Å is occurring, consistent with previous observations and the
  modeling. In other locations the Mg II profiles appear as single peaked.

Title: Magnetic Field Configuration Associated With A Slow Rise
    Eruptive X1.2 Flare In Active Region 11944
Authors: Yang, X.; Yurchyshyn, V.; Nita, G.; Abramenko, V.; Lim, E.;
   Cao, W.
Bibcode: 2021AAS...23812707Y
Altcode:
  Using multi-wavelength observations, we studied a gradual X1.2 flare
  that erupted on January 7, 2014, in active region (AR) NOAA 11944
  located near the disk center. A fast coronal mass ejection (CME) was
  observed following the flare; however, it was strongly deflected in the
  south-west direction. We used SDO/HMI data to perform extrapolation of
  coronal magnetic fields and to study the evolution of AR magnetic fields
  before the eruption. Extrapolated data allowed us to detect a flux rope
  (FR) present at the eruption site several hours before the event. That
  was the only well-defined FR present in the AR. Although the strapping
  and core fields in the model have significantly changed after the flare,
  the model FR did not erupt. We note that a chromospheric filament
  was observed at the eruption site prior to and after the flare. The
  eruption site was located under sunspot canopy fields with a decay
  index of about 0.5, which is not favorable for torus instability to
  develop. That might have caused the erupting fields to slide along the
  canopy rather than vertically erupt, thus explaining the slow rise of
  the flare as well as the observed direction of the resulting CME. We
  employed sign-singularity tools to quantify the evolutionary changes
  in a model twist and observed current helicity data, and found rapid
  enhancements in the current systems in both data sets prior to the
  event as well as their rapid exhaustion after the event onset.

Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope
    (DKIST)
Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio,
   Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart;
   Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa,
   Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez
   Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler,
   Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun,
   Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres,
   Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.;
   Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini,
   Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena;
   Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor;
   Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael;
   Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli,
   Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys,
   Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.;
   Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis,
   Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David
   E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson,
   Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.;
   Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.;
   Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava,
   Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas
   A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas,
   Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST
   Instrument Scientists; DKIST Science Working Group; DKIST Critical
   Science Plan Community
Bibcode: 2021SoPh..296...70R
Altcode: 2020arXiv200808203R
  The National Science Foundation's Daniel K. Inouye Solar Telescope
  (DKIST) will revolutionize our ability to measure, understand,
  and model the basic physical processes that control the structure
  and dynamics of the Sun and its atmosphere. The first-light DKIST
  images, released publicly on 29 January 2020, only hint at the
  extraordinary capabilities that will accompany full commissioning of
  the five facility instruments. With this Critical Science Plan (CSP)
  we attempt to anticipate some of what those capabilities will enable,
  providing a snapshot of some of the scientific pursuits that the DKIST
  hopes to engage as start-of-operations nears. The work builds on the
  combined contributions of the DKIST Science Working Group (SWG) and
  CSP Community members, who generously shared their experiences, plans,
  knowledge, and dreams. Discussion is primarily focused on those issues
  to which DKIST will uniquely contribute.

Title: Research on Multiwavelength Isolated Bright Points Based on
    Deep Learning
Authors: Xu, Li; Yang, Yunfei; Yan, Yihua; Zhang, Yin; Bai, Xianyong;
   Liang, Bo; Dai, Wei; Feng, Song; Cao, Wenda
Bibcode: 2021ApJ...911...32X
Altcode:
  Multiwavelength bright points (BPs) are taken to be cross sections
  of magnetic flux tubes extending from the surface of the photosphere
  upward to the higher photosphere. We aim to study the characteristics
  of isolated multiwavelength BPs using the cotemporal and cospatial
  TiO band and Hα line wings from the Goode Solar Telescope at Big Bear
  Solar Observatory. A deep-learning method, based on Track Region-based
  Convolutional Neural Networks, is proposed to detect, segment, and match
  the BPs across multiple wavelength observations, including the TiO, Hα
  + 1 Å, Hα - 1 Å, Hα + 0.8 Å, and Hα - 0.8 Å line wings. Based on
  the efficient detection and matching result with a precision of 0.98,
  1283 groups of BPs matched in all five wavelengths are selected for
  statistics analysis. The characteristic values of the BPs observed
  at the same red and blue line wings are averaged. For the BPs of the
  TiO, averaged Hα ± 1 Å, and averaged Hα ± 0.8 Å line wings, the
  mean equivalent diameters are 162 ± 32, 254 ± 33, and 284 ± 28 km,
  respectively. The maximum intensity contrasts are 1.11 ± 0.09, 1.05 ±
  0.03, and 1.05 ± 0.02 $\left\langle {I}_{\mathrm{QS}}\right\rangle $
  , respectively. The mean eccentricities are 0.65 ± 0.14, 0.63 ± 0.11,
  and 0.65 ± 0.11, respectively. Moreover, the characteristic ratios of
  each Hα ± 1 Å and Hα ± 0.8 Å BP to its corresponding TiO BP are
  derived. Hα ± 1 Å and Hα ± 0.8 Å line wings BPs show 60% and 80%
  increases compared to TiO BPs, respectively. With increasing height,
  most BPs almost keep their shapes. This work is helpful for modeling
  the three-dimensional structure of flux tubes.

Title: Failed Eruption Caused by Interacting Multi-current System
    in the Solar Corona
Authors: Yang, Kai; Cao, Wenda; Wheatland, Michael S.
Bibcode: 2021cosp...43E1780Y
Altcode:
  Solar flares are one of the most energetic activities of the Sun,
  and are caused by current systems in the solar corona. Sometimes the
  eruption of a current system is confined in the solar corona and fails
  to trigger a coronal mass ejection or jet. A multi-current system
  (multi-flux rope system) makes the confined/failed eruption process
  more complex. To further investigate this phenomenon, we conduct a
  data-driven zero-beta magnetohydrodynamics (MHD) simulation using the
  Message Passing Interface Adaptive Mesh Refinement Versatile Advection
  Code (MPI-AMRVAC). The initial condition is obtained by applying the
  three-dimensional nonlinear force-free model to an observed vector
  magnetogram from HMI. From the force-free magnetic field, three
  flux ropes are identified in the active region, and the results are
  compared with H$\alpha$ observation by the Goode Solar Telescope at
  Big Bear Solar Observatory. The MHD simulation is driven by the time
  series of the observed magnetogram and the inferred photospheric plasma
  velocity. The simulation and observation confirm an interaction between
  the three flux ropes, which leads to the initial eruption. With the
  development of the interaction, magnetic reconnection mixes the flux
  ropes and leads the system to a new stable state.

Title: High-resolution He I 10830 Å Narrowband Imaging for an
    M-class Flare. III. EUV Late Phase
Authors: Wang, Ya; Ji, Haisheng; Warmuth, Alexander; Li, Ying;
   Cao, Wenda
Bibcode: 2020ApJ...905..126W
Altcode:
  In this paper, we report the EUV late phase for the M1.8 class
  flare on 2012 July 5 in the active region (AR) 11515. The late phase
  is shown by the prominent appearance of EUV emission at 131 Å of
  two additional flare loop systems (flare arcades 2 and 3, as named
  in this paper) other than the main flare loop (flare arcade 1), as
  observed by the Atmospheric Imaging Assembly (AIA) on board the Solar
  Dynamic Observatory (SDO). Three sets of flare arcades connect four
  flare ribbons, which forms an asymmetric quadrupole magnetic field
  configuration. While the emission from flare arcade 2, linking the
  pair of secondary flare ribbons, and arcade 3, linking one of the
  main flare ribbons and one of the secondary flare ribbons, conjointly
  contributes to the EUV late phase, their heating mechanisms are quite
  different. While the brightening of flare arcade 2 is the result
  of disturbance created by the eruption of EUV hot channels to the
  overlying coronal magnetic field, the heating of flare arcade 3 was
  closely associated with two rapid contractions of the overlying filament
  threads during the partial eruption of the filament. The contractions
  are discernible in He I 10830 Å images and have signatures in the
  EUV wavelengths of AIA. The two rapid contractions are the result
  of a sudden drop in magnetic pressure after the eruption of two hot
  channels. Clear evidence suggests that magnetic reconnection may
  occur between the contracting filament threads and the low-lying
  magnetic field.

Title: CYRA: the cryogenic infrared spectrograph for the Goode Solar
    Telescope in Big Bear
Authors: Yang, Xu; Cao, Wenda; Gorceix, Nicolas; Plymate, Claude;
   Shumoko, Sergey; Bai, XianYong; Penn, Matt; Ayres, Thomas; Coulter,
   Roy; Goode, Philip R.
Bibcode: 2020SPIE11447E..AGY
Altcode: 2020arXiv200811320Y
  CYRA (CrYogenic solar spectrogRAph) is a facility instrument of the
  1.6-meter Goode Solar Telescope (GST) at the Big Bear Solar Observatory
  (BBSO). CYRA focuses on the study of the near-infrared solar spectrum
  between 1 and 5 microns, an under-explored region which is not only
  fertile ground for photospheric magnetic diagnostics but also allows a
  unique window into the chromosphere lying atop the photosphere. CYRA is
  the first-ever fully cryogenic spectrograph in any solar observatory
  with its two predecessors, on the McMath-Pierce and Mees Telescopes,
  being based on warm optics except for the detectors and order
  sorting filters. CYRA is used to probe magnetic fields in various
  solar features and the quiet photosphere. CYRA measurements will
  allow new and better 3D extrapolations of the solar magnetic field
  and will provide more accurate boundary conditions for solar activity
  models. The superior spectral resolution of 150,000 and better allows
  enhanced observations of the chromosphere in the carbon monoxide (CO)
  spectral bands and will yield a better understanding of energy transport
  in the solar atmosphere. CYRA is divided into two optical sub-systems:
  The Fore-Optics Module and the Spectrograph. The Spectrograph is
  the heart of the instrument and contains the IR detector, grating,
  slits, filters, and imaging optics all in a cryogenically cooled
  Dewar (cryostat). The sensor is a 2048 by 2048 pixel HAWAII 2 array
  produced by Teledyne Scientific and Imaging, LLC. The cryostat interior
  and the readout electronics are maintained at 90 Kelvin by helium
  refrigerant-based cryo-coolers, while the IR array is cooled to 30
  Kelvin. The Fore-Optics Module de-rotates and stabilizes the solar
  image, provides scanning capabilities and transfers the GST image
  to the Spectrograph. CYRA has been installed and is undergoing its
  commissioning phase. This paper reports on the design, implementation,
  and operation of CYRA in detail. The preliminary scientific results
  have been highlighted as well.

Title: Doppler shift oscillations of a sunspot detected by CYRA
    and IRIS
Authors: Li, D.; Yang, X.; Bai, X. Y.; Su, J. T.; Ning, Z. J.; Cao,
   W.; Deng, Y. Y.
Bibcode: 2020A&A...642A.231L
Altcode: 2020arXiv200906942L
  Context. The carbon monoxide (CO) molecular line at around 46655 Å in
  solar infrared spectra is often used to investigate the dynamic behavior
  of the cold heart of the solar atmosphere, i.e., sunspot oscillation,
  especially at the sunspot umbra. <BR /> Aims: We investigated sunspot
  oscillation at Doppler velocities of the CO 7-6 R67 and 3-2 R14 lines
  that were measured by the Cryogenic Infrared Spectrograph (CYRA),
  as well as the line profile of Mg II k line that was detected by the
  Interface Region Imaging Spectrograph (IRIS). <BR /> Methods: A single
  Gaussian function is applied to each CO line profile to extract the
  line shift, while the moment analysis method is used for the Mg II k
  line. Then the sunspot oscillation can be found in the time-distance
  image of Doppler velocities, and the quasi-periodicity at the sunspot
  umbra are determined from the wavelet power spectrum. Finally, the
  cross-correlation method is used to analyze the phase relation between
  different atmospheric levels. <BR /> Results: At the sunspot umbra,
  a periodicity of roughly 5 min is detected at the Doppler velocity
  range of the CO 7-6 R67 line that formed in the photosphere, while a
  periodicity of around 3 min is discovered at the Doppler velocities
  of CO 3-2 R14 and Mg II k lines that formed in the upper photosphere
  or the temperature minimum region and the chromosphere. A time delay
  of about 2 min is measured between the strong CO 3-2 R14 line and
  the Mg II k line. <BR /> Conclusions: Based on the spectroscopic
  observations from the CYRA and IRIS, the 3 min sunspot oscillation
  can be spatially resolved in the Doppler shifts. It may come from the
  upper photosphere or the temperature minimum region and then propagate
  to the chromosphere, which might be regarded as a propagating slow
  magnetoacoustic wave.

Title: Formation of a tiny flux rope in the center of an active region
    driven by magnetic flux emergence, convergence, and cancellation
Authors: Zheng, Ruisheng; Chen, Yao; Wang, Bing; Song, Hongqiang;
   Cao, Wenda
Bibcode: 2020A&A...642A.199Z
Altcode: 2020arXiv200904082Z
  <BR /> Aims: Flux ropes are generally believed to be core structures
  of solar eruptions that are significant for the space weather, but
  their formation mechanism remains intensely debated. We report on
  the formation of a tiny flux rope beneath clusters of active region
  loops on 2018 August 24. <BR /> Methods: Combining the high-quality
  multiwavelength observations from multiple instruments, we studied
  the event in detail in the photosphere, chromosphere, and corona. <BR
  /> Results: In the source region, the continual emergence of two
  positive polarities (P1 and P2) that appeared as two pores (A and
  B) is unambiguous. Interestingly, P2 and Pore B slowly approached
  P1 and Pore A, implying a magnetic flux convergence. During the
  emergence and convergence, P1 and P2 successively interacted with a
  minor negative polarity (N3) that emerged, which led to a continuous
  magnetic flux cancellation. As a result, the overlying loops became
  much sheared and finally evolved into a tiny twisted flux rope
  that was evidenced by a transient inverse S-shaped sigmoid, the
  twisted filament threads with blueshift and redshift signatures,
  and a hot channel. <BR /> Conclusions: All the results show that
  the formation of the tiny flux rope in the center of the active
  region was closely associated with the continuous magnetic flux
  emergence, convergence, and cancellation in the photosphere. Hence,
  we suggest that the magnetic flux emergence, convergence,
  and cancellation are crucial for the formation of the tiny flux
  rope. <P />Movies associated to Figs. 2, 4, and 7 are available at <A
  href="https://www.aanda.org/10.1051/0004-6361/202037475/olm">https://www.aanda.org</A>

Title: High-resolution Observations of Small-scale Flux Emergence
    by GST
Authors: Wang, Jiasheng; Liu, Chang; Cao, Wenda; Wang, Haimin
Bibcode: 2020ApJ...900...84W
Altcode: 2020arXiv200906717W
  Recent observations demonstrated that emerging flux regions, which
  constitute the early stage of solar active regions, consist of
  emergence of numerous small-scale magnetic elements. They in turn
  interact, merge, and form mature sunspots. However, observations of
  fine magnetic structures on photosphere with subarcsecond resolution
  are very rare due to limitations of observing facilities. In this
  work, taking advantage of the high resolution of the 1.6 m Goode Solar
  Telescope, we jointly analyze vector magnetic fields, continuum images,
  and Hα observations of NOAA AR 12665 on 2017 July 13, with the goal
  of understanding the signatures of small-scale flux emergence, as well
  as their atmospheric responses as they emerge through multiple heights
  in the photosphere and chromosphere. Under such a high resolution of
  0"1-0"2, our results confirm two kinds of small-scale flux emergence:
  magnetic flux sheet emergence associated with the newly forming
  granules, and the traditional magnetic flux loop emergence. With
  direct imaging in the broadband TiO, we observe that both types of
  flux emergence are associated with darkening of granular boundaries,
  while only flux sheets elongate granules along the direction of
  emerging magnetic fields and expand laterally. With a life span of
  10 ∼ 15 minutes, the total emerged vertical flux is on the order
  of 10<SUP>18</SUP> Mx for both types of emergence. The magnitudes of
  the vertical and horizontal fields are comparable in the flux sheets,
  while the former is stronger in flux loops. Hα observations reveal
  transient brightenings in the wings in the events of magnetic loop
  emergence, which are most probably the signatures of Ellerman bombs.

Title: Spectral Diagnostics of Solar Photospheric Bright Points
Authors: Hao, Q.; Fang, C.; Ding, M. D.; Li, Z.; Cao, Wenda
Bibcode: 2020ApJ...900..130H
Altcode: 2020arXiv200709675H
  Through the use of the high-resolution spectral data and the broadband
  imaging obtained with the Goode Solar Telescope at the Big Bear Solar
  Observatory on 2013 June 6, the spectra of three typical photospheric
  bright points (PBPs) have been analyzed. Based on the Hα and Ca II
  8542 Å line profiles, as well as the TiO continuum emission, for
  the first time, the non-LTE semiempirical atmospheric models for the
  PBPs are computed. The attractive characteristic is the temperature
  enhancement in the lower photosphere. The temperature enhancement is
  about 200-500 K at the same column mass density as in the atmospheric
  model of the quiet-Sun. The total excess radiative energy of a typical
  PBP is estimated to be 1 × 10<SUP>27</SUP>-2 × 10<SUP>27</SUP> erg,
  which can be regarded as the lower limit energy of the PBPs. The
  radiation flux in the visible continuum for the PBPs is about 5.5
  × 10<SUP>10</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>. Our result
  also indicates that the temperature in the atmosphere above PBPs
  is close to that of a plage. It gives clear evidence that PBPs may
  contribute significantly to the heating of the plage atmosphere. Using
  our semiempirical atmospheric models, we estimate self-consistently
  the average magnetic flux density B in the PBPs. It is shown that the
  maximum value is about 1 kG, and it decreases toward both higher and
  lower layers, reminding us of the structure of a flux tube between
  photospheric granules.

Title: Date Co-alignment for Ground-Based High-Resolution Solar
    Imaging
Authors: Yang, X.; Ji, K.; Cao, W.; Yurchyshyn, V.; Xu, Z.
Bibcode: 2020SPD....5120501Y
Altcode:
  The multi-wavelength analysis is a well-spread method in solar
  physics studies, and the community increasingly relies on coordinated
  observations involving multiple instruments. The calibration of
  heliographic coordinates is therefore vital for the co-alignment
  of such multi-instrument, multi-wavelength data. However, this is
  particularly difficult for ground-based high-resolution observations
  because of the limited field of view. Manually co-aligning data with
  low-contrast features (e.g., photospheric observations of quiet Sun
  regions) between different telescopes requires exceptional efforts
  and patience. Here, we developed a technique to accurately determine
  coordinates of high-resolution images acquired by the Goode Solar
  Telescope (GST) at the Big Bear Solar Observatory. The technique employs
  a scale-invariant feature transform (SIFT) method, which performs
  without human interference. With this new approach, we co-aligned
  multi-wavelength GST data sets to the continuum intensity data from
  the Helioseismic and Magnetic Imager (HMI) precisely. The inferred
  heliographic coordinates are saved in each FITS file header, which
  is compatible with the common mapping methods available in the Solar
  SoftWare (SSW) package. GST data are fully open to the scientific
  community, and a substantial portion of observing time on the GST
  opens to the community as well.

Title: Mare Deposits Identification and Feature Analysis in Mare
    Australe Based on CE-2 CELMS Data
Authors: Meng, Z. G.; Chen, S. B.; Zheng, Y. C.; Cheng, W. M.; Zhu,
   Y. Q.; Cai, Z. C.; Zhang, Y. Z.; Cao, W.; Hou, L. L.
Bibcode: 2020JGRE..12506330M
Altcode:
  The microwave signal has the penetration capability, which provides
  a potential chance to improve understanding of the mare deposits and
  the formation process of Mare Australe, a complex, extensive, and
  poorly understood region on the Moon. In this paper, the Chang'E-2
  microwave radiometer (CELMS) data were selected and processed to
  evaluate the microwave thermal emission features of the mare deposits
  in Mare Australe. After comparison, the dT<SUB>B</SUB> map at 3.0 GHz
  is employed. The results are as follows. (a) The possible cryptomare
  is much more extensive in Australe region than that identified with
  optical data. (b) The basaltic volcanism is re-understood as three
  major episodes. (c) The high dT<SUB>B</SUB> anomaly is interpreted as
  the location of the vent areas in the mare patches. (d) The K-means
  algorithm was first used to process the CELMS data, and the identified
  linear and ring structures indicate some important information about
  the formation processes of Mare Australe. These special findings will be
  of fundamental significance to better understand the basaltic volcanism
  and the evolution of the lunar surface.

Title: Astronomical Massive Data Processing Technology
Authors: Wang, Feng; Cao, Wenda; Bastieri, Denis; Fan, Junhui; Cui,
   Chenzhou
Bibcode: 2020AdAst2020E...5W
Altcode:
  No abstract at ADS

Title: Rapid Evolution of Type II Spicules Observed in Goode Solar
    Telescope On-disk H<SUB>α</SUB> Images
Authors: Yurchyshyn, Vasyl; Cao, Wenda; Abramenko, Valentina; Yang,
   Xu; Cho, Kyung-Suk
Bibcode: 2020ApJ...891L..21Y
Altcode: 2020arXiv200504253Y
  We analyze ground-based chromospheric data acquired at a high temporal
  cadence of 2 s in wings of the H<SUB>α</SUB> spectral line using the
  Goode Solar Telescope operating at the Big Bear Solar Observatory. We
  inspected a 30 minute long H<SUB>α</SUB>-0.08 nm data set to find
  that rapid blueshifted H<SUB>α</SUB> excursions (RBEs), which are a
  cool component of type II spicules, experience very rapid morphological
  changes on timescales of the order of 1 s. Unlike typical reconnection
  jets, RBEs very frequently appear in situ without any clear evidence
  of H<SUB>α</SUB> material being injected from below. Their evolution
  includes inverted "Y," "V," "N," and parallel splitting (doubling)
  patterns as well as sudden formation of a diffuse region followed
  by branching. We also find that the same feature may undergo several
  splitting episodes within about a 1 minute time interval.

Title: Generation of solar spicules and subsequent atmospheric heating
Authors: Samanta, Tanmoy; Tian, Hui; Yurchyshyn, Vasyl; Peter, Hardi;
   Cao, Wenda; Sterling, Alphonse; Erdélyi, Robertus; Ahn, Kwangsu;
   Feng, Song; Utz, Dominik; Banerjee, Dipankar; Chen, Yajie
Bibcode: 2019Sci...366..890S
Altcode: 2020arXiv200602571S
  Spicules are rapidly evolving fine-scale jets of magnetized plasma in
  the solar chromosphere. It remains unclear how these prevalent jets
  originate from the solar surface and what role they play in heating
  the solar atmosphere. Using the Goode Solar Telescope at the Big Bear
  Solar Observatory, we observed spicules emerging within minutes of the
  appearance of opposite-polarity magnetic flux around dominant-polarity
  magnetic field concentrations. Data from the Solar Dynamics Observatory
  showed subsequent heating of the adjacent corona. The dynamic
  interaction of magnetic fields (likely due to magnetic reconnection)
  in the partially ionized lower solar atmosphere appears to generate
  these spicules and heat the upper solar atmosphere.

Title: Light Bridge Brightening and Plasma Ejection Driven by a
    Magnetic Flux Emergence Event
Authors: Yang, Xu; Yurchyshyn, Vasyl; Ahn, Kwangsu; Penn, Matt;
   Cao, Wenda
Bibcode: 2019ApJ...886...64Y
Altcode:
  Observations with the Goode Solar Telescope (GST) are presented
  here showing that the emergence of 1.91 × 10<SUP>18</SUP> Mx of
  new magnetic flux occurred at the edge of a filamentary light bridge
  (LB). This emergence was accompanied by brightness enhancement of a
  photospheric overturning convection cell (OCC) at the endpoints of the
  emerging magnetic structure. We present an analysis of the origin and
  the dynamics of this event using high-resolution GST Fe I 1564.85 nm
  vector magnetic field data, TiO photospheric, and Hα chromospheric
  images. The emerged structure was 1.5 × 0.3 Mm in size at the peak
  of development and lasted for 17 minutes. Doppler observations showed
  presence of systematic upflows before the appearance of the magnetic
  field signal and downflows during the decay phase. Changes in the
  orientation of the associated transverse fields, determined from
  the differential angle, suggest the emergence of a twisted magnetic
  structure. A fan-shaped jet was observed to be spatially and temporally
  correlated with the endpoint of the OCC intruding into the LB. Our data
  suggest that the emerging fields may have reconnected with the magnetic
  fields in the vicinity of the LB, which could lead to the formation of
  the jet. Our observation is the first report of flux emergence within
  a granular LB with evidence in the evolution of vector magnetic field,
  as well as photosphere convection motions, and supports the idea that
  the impulsive jets above the LB are caused by magnetic reconnection.

Title: High-resolution Observations of Dynamics of Superpenumbral
    Hα Fibrils
Authors: Jing, Ju; Li, Qin; Liu, Chang; Lee, Jeongwoo; Xu, Yan; Cao,
   Wenda; Wang, Haimin
Bibcode: 2019ApJ...880..143J
Altcode:
  We present high-resolution Hα observations of a small solar pore in
  NOAA active region 12661, using the 1.6 m Goode Solar Telescope equipped
  with high-order adaptive optics at Big Bear Solar Observatory. The
  observations reveal copious fine-scale chromospheric superpenumbral
  fibrils (with an average cross-sectional width of ∼0.″17 ±
  0.″03), along with associated transit and intermittent flows with
  apparent speeds of 5-14 km s<SUP>-1</SUP>. Wavelet analysis and
  the spatio-temporal pattern of superpenumbral fibrils suggest that
  the observed flows along fibrils are not likely an oscillation/wave
  phenomenon. Based on our pseudo-Dopplergrams, we suggest that the
  observed flows may be a phenomenon similar to inverse Evershed flows in
  the chromosphere. The three-dimensional potential field model indicates
  that the pore and the surrounding fibrils are enclosed by fan-field
  lines forming a separatrix dome configuration. Such a magnetically
  confined configuration may help to maintain the steadfastness of the
  superpenumbral fibril dynamics.

Title: High-resolution Spectroscopic Imaging of Counter-streaming
    Motions in Solar Active Region Magnetic Loops
Authors: Yang, Xu; Cao, Wenda; Ji, Haisheng; Hashim, Parida; Shen,
   Jinhua
Bibcode: 2019ApJ...881L..25Y
Altcode:
  We carried out high-resolution spectroscopic imaging in He I 10830 Å
  and H<SUB> α </SUB> for a set of active region (NOAA 12569) magnetic
  loops of different sizes (classified into short and long loops)
  with the Goode Solar Telescope at the Big Bear Solar Observatory on
  2016 July 18. The long loops take the form of an chromospheric arch
  filament system, yet their extreme ultraviolet (EUV) counterparts
  are observed by the Atmospheric Imaging Assembly on board the Solar
  Dynamics Observatory. Animations of blue- and red-wing images give
  counter-streaming motions; i.e., chromospheric absorption features in
  blue- and red-wing images move in opposite directions at different
  strands. The moving pattern is detected with the local correlation
  tracking method and confirmed by Doppler shifts. We speculate that,
  combined with the results of wavelet analysis that gives obvious 4
  minute oscillation along trailing polarity, counter-streaming motions
  for short loops could be powered by p-mode leakage. However, for
  counter-streaming motions in long loops, we show that unidirectional
  mass flows in two opposite directions are accompanied with simultaneous
  weak EUV brightenings. Heating processes, probably by magnetic
  reconnection at footpoints, may have occurred. In addition, plasma
  flows along the magnetic loops, tracked with absorption features
  in He I 10830 Å, are found to be ejected from and drained out into
  inter-granule lane areas at different ends of the loop system.

Title: Counter-streaming motions in active region magnetic arches
    observed by Helium I 10830Å spectroscopy
Authors: Yang, Xu; Ya, Wang; Ji, Haisheng; Cao, Wenda
Bibcode: 2019AAS...23421706Y
Altcode:
  We report the first high-resolution observations of counter-streaming
  motions in the active region magnetic arches with Helium I 10830
  Å spectroscopy, achieved by the Goode Solar Telescope at Big Bear
  Solar Observatory. Our observations reveal that the counter-streaming
  motions are due to unidirectional mass flows along alternative arches,
  rather than the longitudinal oscillations of filament threads as in some
  solar filaments. Mass flow, rooting in the magnetic network region, are
  pumped up from and down to the inter-granulation lanes. The apparent
  speed of the flow is around 15-50 km s<SUP>-1</SUP> in the He I 10830
  Å blue wing and 5-15 km s<SUP>-1</SUP> in the red wing. Co-spatial
  brightenings in Atmospheric Imaging Assembly 304 Å and 171 Å images
  are witnessed at the same time, indicating the possible corresponding
  heating process. The oscillation power peaks around 4 minutes in the
  roots region of the arches, however, the mass flows inside the long
  arches seem to be continuous.

Title: High-resolution Observations of Dynamics of Superpenumbral
    Hα Fibrils
Authors: Jing, Ju; Li, Qin; Liu, Chang; Lee, Jeongwoo; Xu, Yan; Cao,
   Wenda; Wang, Haimin
Bibcode: 2019AAS...23430502J
Altcode:
  We present unprecedented high-resolution Hα observations of a small
  solar pore in NOAA Active Region 12661, using the 1.6 m Goode Solar
  Telescope (GST) equipped with high-order adaptive optics at Big Bear
  Solar Observatory (BBSO). The observations reveal copious fine-scale
  chromospheric superpenumbral fibrils (with a cross-sectional width of
  0.15") around the pore, along with associated transit and intermittent
  flows with apparent speeds of 5-20 km s<SUP>-1</SUP>. The wavelet
  analysis suggests that the observed flows along fibrils are not likely
  a manifestation of oscillations, but rather collections of actual
  counterstreaming mass motions. The observed flow is interpreted as
  siphon flow. In addition, the three-dimensional potential field model
  indicates that the pore and the surrounding fibrils are enclosed by
  fan field lines forming a separatrix dome configuration. We suggest
  that such a magnetically confined configuration may help to maintain
  the steadfastness of the superpenumbral fibril dynamics.

Title: Multi-wavelength Multi-height Study of Super Strong Surface
    and Coronal Magnetic Fields in Active Region 12673
Authors: Wang, Haimin; Chen, Bin; Jing, Ju; Yu, Sijie; Liu, Chang;
   Yurchyshyn, Vasyl B.; Ahn, Kwangsu; Okamoto, Takenori; Toriumi, Shin;
   Cao, Wenda; Gary, Dale E.
Bibcode: 2019AAS...23440205W
Altcode:
  Using the joint observations of Goode Solar telescope (GST), Expanded
  Owens Valley Solar Array (EOVSA), Solar Dynamics Observatory (SDO)
  and Hinode, we study the Solar Active Region (AR) 12673 in September
  2017, which is the most flare productive AR in the solar cycle 24. GST
  observations show the strong photospheric magnetic fields (nearly
  6000 G) in polarity inversion line (PIL) and apparent photospheric
  twist. Consistent upward flows are also observed in Dopplergrams
  of Hinode, HMI and GST at the center part of that section of PIL,
  while the down flows are observed in two ends, indicating that the
  structure was rising from subsurface. Combining Non-Linear Force Free
  Extrapolation and EOVSA microwave imaging spectroscopy, we also look
  into the coronal structure of magnetic fields in this unusual AR,
  including the evolution before and after the X9.3 flare on September
  6, 2017. Coronal fields between 1000 and 2000 gauss are found above
  the flaring PIL at the height range between 8 and 4Mm, outlining the
  structure of a fluxrope or sheared arcade.

Title: Calibration of the Instrumental Crosstalk for the Near-IR
    Imaging Spectropolarimeter at the NST
Authors: Ahn, K.; Cao, W.
Bibcode: 2019ASPC..526..317A
Altcode: 2019arXiv190912970A
  The Near-IR Imaging Spectropolarimeter (NIRIS) is a polarimeter that is
  installed at the New Solar Telescope at Big Bear Solar Observatory. This
  instrument takes advantage of the highest spatial resolution and
  flux. The primary mirror is an off-axis type, so it was our interest to
  evaluate its contribution to the crosstalk among the Stokes parameters
  since we could not put our calibration optics before the mirror. We
  would like to present our efforts to compensate for the crosstalk among
  Stokes profiles caused by the relay optics from the telescope to the
  detector. The overall data processing pipeline is also introduced.

Title: Flame-like Ellerman Bombs and Their Connection to Solar
    Ultraviolet Bursts
Authors: Chen, Yajie; Tian, Hui; Peter, Hardi; Samanta, Tanmoy;
   Yurchyshyn, Vasyl; Wang, Haimin; Cao, Wenda; Wang, Linghua; He, Jiansen
Bibcode: 2019ApJ...875L..30C
Altcode: 2019arXiv190301981C
  Ellerman bombs (EBs) are small-scale intense brightenings in Hα
  wing images, which are generally believed to be signatures of
  magnetic reconnection around the temperature minimum region of the
  solar atmosphere. They have a flame-like morphology when observed
  near the solar limb. Recent observations from the Interface Region
  Imaging Spectrograph (IRIS) reveal another type of small-scale
  reconnection event called an ultraviolet (UV) burst, in the lower solar
  atmosphere. Though previous observations have shown a clear coincidence
  between the occurrence of some UV bursts and EBs, the exact relationship
  between these two phenomena is still debated. We investigate the spatial
  and temporal relationship between flame-like EBs and UV bursts using
  joint near-limb observations between the 1.6 m Goode Solar Telescope
  (GST) and IRIS. In total, 161 EBs have been identified from the GST
  observations, and ∼20 of them reveal signatures of UV bursts in
  the IRIS images. Interestingly, we find that these UV bursts have a
  tendency to appear at the upper parts of their associated flame-like
  EBs. The intensity variations of most EB-related UV bursts and their
  corresponding EBs match well. Our results suggest that some of these
  UV bursts and EBs likely form at different heights during a common
  reconnection process.

Title: Signatures of Magnetic Reconnection at the Footpoints of
    Fan-shaped Jets on a Light Bridge Driven by Photospheric Convective
    Motions
Authors: Bai, Xianyong; Socas-Navarro, Hector; Nóbrega-Siverio,
   Daniel; Su, Jiangtao; Deng, Yuanyong; Li, Dong; Cao, Wenda; Ji, Kaifan
Bibcode: 2019ApJ...870...90B
Altcode: 2018arXiv181103723B
  Dynamical jets are generally found on light bridges (LBs), which are
  key to studying sunspot decay. So far, their formation mechanism
  is not fully understood. In this paper, we used state-of-the-art
  observations from the Goode Solar Telescope, the Interface Region
  Imaging Spectrograph, the Spectro-polarimeter on board Hinode, and
  the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics
  Observatory to analyze the fan-shaped jets on LBs in detail. A
  continuous upward motion of the jets in the ascending phase is found
  from the Hα velocity that lasts for 12 minutes and is associated
  with the Hα line wing enhancements. Two mini jets appear on the
  bright fronts of the fan-shaped jets visible in the AIA 171 and 193
  Å channels, with a time interval as short as 1 minute. Two kinds of
  small-scale convective motions are identified in the photospheric
  images, along with the Hα line wing enhancements. One seems to be
  associated with the formation of a new convection cell, and the other
  manifests as the motion of a dark lane passing through the convection
  cell. The finding of three-lobe Stokes V profiles and their inversion
  with the NICOLE code indicate that there are magnetic field lines
  with opposite polarities in LBs. From the Hα -0.8 Å images, we found
  ribbon-like brightenings propagating along the LBs, possibly indicating
  slipping reconnection. Our observation supports the idea that the
  fan-shaped jets under study are caused by magnetic reconnection, and
  photospheric convective motions play an important role in triggering
  the magnetic reconnection.

Title: Evolution of Photospheric Vector Magnetic Field Associated
    with Moving Flare Ribbons as Seen by GST
Authors: Liu, Chang; Cao, Wenda; Chae, Jongchul; Ahn, Kwangsu; Prasad
   Choudhary, Debi; Lee, Jeongwoo; Liu, Rui; Deng, Na; Wang, Jiasheng;
   Wang, Haimin
Bibcode: 2018ApJ...869...21L
Altcode: 2018arXiv181011733L
  The photospheric response to solar flares, also known as coronal
  back reaction, is often observed as sudden flare-induced changes in
  the vector magnetic field and sunspot motions. However, it remains
  obscure whether evolving flare ribbons, the flare signature closest to
  the photosphere, are accompanied by changes in vector magnetic field
  therein. Here we explore the relationship between the dynamics of
  flare ribbons in the chromosphere and variations of magnetic fields
  in the underlying photosphere, using high-resolution off-band Hα
  images and near-infrared vector magnetograms of the M6.5 flare on 2015
  June 22 observed with the 1.6 m Goode Solar Telescope. We find that
  changes of photospheric fields occur at the arrival of the flare ribbon
  front, thus propagating analogously to flare ribbons. In general, the
  horizontal field increases and the field lines become more inclined
  to the surface. When ribbons sweep through regions that undergo a
  rotational motion, the fields transiently become more vertical with
  decreased horizontal field and inclination angle, and then restore
  and/or become more horizontal than before the ribbon arrival. The
  ribbon propagation decelerates near the sunspot rotation center,
  where the vertical field becomes permanently enhanced. Similar magnetic
  field changes are discernible in magnetograms from the Helioseismic and
  Magnetic Imager (HMI), and an inward collapse of coronal magnetic fields
  is inferred from the time sequence of nonlinear force-free field models
  extrapolated from HMI magnetograms. We conclude that photospheric fields
  respond nearly instantaneously to magnetic reconnection in the corona.

Title: Roadmap for Reliable Ensemble Forecasting of the Sun-Earth
    System
Authors: Nita, Gelu; Angryk, Rafal; Aydin, Berkay; Banda, Juan;
   Bastian, Tim; Berger, Tom; Bindi, Veronica; Boucheron, Laura; Cao,
   Wenda; Christian, Eric; de Nolfo, Georgia; DeLuca, Edward; DeRosa,
   Marc; Downs, Cooper; Fleishman, Gregory; Fuentes, Olac; Gary, Dale;
   Hill, Frank; Hoeksema, Todd; Hu, Qiang; Ilie, Raluca; Ireland,
   Jack; Kamalabadi, Farzad; Korreck, Kelly; Kosovichev, Alexander;
   Lin, Jessica; Lugaz, Noe; Mannucci, Anthony; Mansour, Nagi; Martens,
   Petrus; Mays, Leila; McAteer, James; McIntosh, Scott W.; Oria, Vincent;
   Pan, David; Panesi, Marco; Pesnell, W. Dean; Pevtsov, Alexei; Pillet,
   Valentin; Rachmeler, Laurel; Ridley, Aaron; Scherliess, Ludger; Toth,
   Gabor; Velli, Marco; White, Stephen; Zhang, Jie; Zou, Shasha
Bibcode: 2018arXiv181008728N
Altcode:
  The authors of this report met on 28-30 March 2018 at the New Jersey
  Institute of Technology, Newark, New Jersey, for a 3-day workshop
  that brought together a group of data providers, expert modelers, and
  computer and data scientists, in the solar discipline. Their objective
  was to identify challenges in the path towards building an effective
  framework to achieve transformative advances in the understanding
  and forecasting of the Sun-Earth system from the upper convection
  zone of the Sun to the Earth's magnetosphere. The workshop aimed to
  develop a research roadmap that targets the scientific challenge
  of coupling observations and modeling with emerging data-science
  research to extract knowledge from the large volumes of data (observed
  and simulated) while stimulating computer science with new research
  applications. The desire among the attendees was to promote future
  trans-disciplinary collaborations and identify areas of convergence
  across disciplines. The workshop combined a set of plenary sessions
  featuring invited introductory talks and workshop progress reports,
  interleaved with a set of breakout sessions focused on specific topics
  of interest. Each breakout group generated short documents, listing
  the challenges identified during their discussions in addition to
  possible ways of attacking them collectively. These documents were
  combined into this report-wherein a list of prioritized activities
  have been collated, shared and endorsed.

Title: Dark Structures in Sunspot Light Bridges
Authors: Zhang, Jingwen; Tian, Hui; Solanki, Sami K.; Wang, Haimin;
   Peter, Hardi; Ahn, Kwangsu; Xu, Yan; Zhu, Yingjie; Cao, Wenda; He,
   Jiansen; Wang, Linghua
Bibcode: 2018ApJ...865...29Z
Altcode: 2018arXiv180900146Z
  We present unprecedented high-resolution TiO images and Fe I 1565
  nm spectropolarimetric data of two light bridges taken by the 1.6
  m Goode Solar Telescope at Big Bear Solar Observatory. In the first
  light bridge (LB1), we find striking knot-like dark structures within
  the central dark lane. Many dark knots show migration away from the
  penumbra along the light bridge. The sizes, intensity depressions,
  and apparent speeds of their proper motion along the light bridges of
  33 dark knots identified from the TiO images are mainly in the ranges
  of 80 ∼ 200 km, 30% ∼ 50%, and 0.3 ∼ 1.2 km s<SUP>-1</SUP>,
  respectively. In the second light bridge (LB2), a faint central dark
  lane and striking transverse intergranular lanes were observed. These
  intergranular lanes have sizes and intensity depressions comparable
  to those of the dark knots in LB1 and also migrate away from the
  penumbra at similar speeds. Our observations reveal that LB2 is made
  up of a chain of evolving convection cells, as indicated by patches of
  blueshift surrounded by narrow lanes of redshift. The central dark lane
  generally corresponds to blueshifts, supporting the previous suggestion
  of central dark lanes being the top parts of convection upflows. In
  contrast, the intergranular lanes are associated with redshifts and
  located at two sides of each convection cell. The magnetic fields are
  stronger in intergranular lanes than in the central dark lane. These
  results suggest that these intergranular lanes are manifestations of
  convergent convective downflows in the light bridge. We also provide
  evidence that the dark knots observed in LB1 may have a similar origin.

Title: Formation of an Active Region Filament Driven By a Series
    of Jets
Authors: Wang, Jincheng; Yan, Xiaoli; Qu, Zhongquan; UeNo, Satoru;
   Ichimoto, Kiyoshi; Deng, Linhua; Cao, Wenda; Liu, Zhong
Bibcode: 2018ApJ...863..180W
Altcode: 2018arXiv180700992W
  We present a formation process of a filament in active region NOAA
  12574 during the period from 2016 August 11 to 12. Combining the
  observations of the Global Oscillation Network Group Hα, the Hida
  spectrum, and the Solar Dynamics Observatory/AIA 304 Å, the formation
  process of the filament is studied. It is found that cool material (T
  ∼ 10<SUP>4</SUP> K) is ejected by a series of jets originating from
  the western footpoint of the filament. Simultaneously, the magnetic flux
  emerged from the photosphere in the vicinity of the western footpoint of
  the filament. These observations suggest that cool material in the low
  atmosphere can be directly injected into the upper atmosphere and the
  jets are triggered by the magnetic reconnection between pre-existing
  magnetic fields and new emerging magnetic fields. A detailed study of
  a jet at 18:02 UT on August 11 with GST/BBSO TiO observations revealed
  that some dark threads appeared in the vicinity of the western footpoint
  after the jet and the projection velocity of plasma along the filament
  axis was about 162.6 ± 5.4 km s<SUP>-1</SUP>. Using these observations
  of the Domeless Solar Telescope/Hida, we find that the injected plasma
  by a jet at 00:42 UT on August 12 was rotating. Therefore, we conclude
  that the jets not only supplied the material for the filament, but also
  injected the helicity into the filament simultaneously. Comparing the
  quantity of mass injection by the jets with the mass of the filament,
  we conclude that the estimated mass loading by the jets is sufficient
  to account for the mass in the filament.

Title: Magnetic Flux Emergence Triggered Light Bridge Brightening
    and Reconnection Jets
Authors: Yang, Xu; Cao, Wenda; Yurchyshyn, Vasyl; Ahn, Kwangsu
Bibcode: 2018cosp...42E3744Y
Altcode:
  Light bridges (LBs) are elongated, bright, granular structures that
  divide the umbra of a large and complex sunspot into two or more umbral
  regions with the same magnetic polarity. Surge-like activities are
  common phenomenon appear above the LBs which always accompanied by the
  magnetic flux emergence process. Former works tried to interpret the
  triggering mechanism for them, however they often lacked the support of
  high spatial and temporal resolution vector magnetic measurement. Our
  recent Observation shows a strong magnetic flux emergence happened
  at the edge of a filamentary Light Bridge (LB) and accompanied by
  brightness enhancement of photospheric granulations at the endpoints
  of the emerged magnetic structure. We study the origin and dynamics of
  this magnetic flux emergence event with high resolution Fe I 1.56 μm
  polarimetry magnetogram, TiO photosphere image and Hα chromosphere
  image from the Goode Solar Telescope. The emerged magnetic structure
  was 1.5 Mm × 0.3 Mm in size at its peak time and lasted for 17
  minutes. Doppler map detected upflows before its formation and downflows
  during the destruction. The magnetic orientation change was obtained by
  calculating the shear angle and plotting the magnetic field vectors. The
  result indicates that the new emerged more transverse magnetic field
  reconnected with the pre-existing more vertical field, which triggered
  the fan-shaped jets. The expanding fields at the endpoints due to the
  flux emergence pushed and compressed the existing granulations and
  led to their enhanced brightness.

Title: Project of a New 2.5m Solar Telescope
Authors: Fang, Cheng; Chen, P. F.; Li, Zhen; Cao, Wenda; Hao, Qi;
   Ding, Mingde; Gu, Baizhong; Yuan, Xiangyan
Bibcode: 2018cosp...42E1042F
Altcode:
  A project of a 2.5m Solar Telescope has been worked out in China. It
  is the first facility in the world with a special innovation design
  and can conduct both high-resolution solar observations and the
  large-field of view (FOV) night survey. Its scientific objectives
  cover solar physics and time-domain astronomy, all of which are recent
  hot topics in astronomy. As a large on-axis solar telescope in the
  world with a larger FOV (7') than all the large solar telescopes
  operating at present, it can provide unprecedented high-resolution
  solar imaging and magnetic field data, which can help us obtain
  breakthrough achievements on the study of solar active regions and
  solar eruptions. The data are also very useful for the study of space
  weather. As a large telescope in China, the telescope is very unique
  in continuously monitoring short-time transient events by filling
  the gap in the specific time-zone. Moreover, the telescope can make
  essential contribution to training the graduate and undergraduate
  students majoring in observational astronomy.

Title: Project of a New 2.5m Solar Telescope
Authors: Fang, Cheng; Chen, P. F.; Li, Zhen; Cao, Wenda; Hao, Qi;
   Ding, Mingde; Gu, Baizhong; Yuan, Xiangyan
Bibcode: 2018cosp...42E1041F
Altcode:
  A project of a 2.5m Solar Telescope has been worked out in China. It
  is the first facility in the world with a special innovation design
  and can conduct both high-resolution solar observations and the
  large-field of view (FOV) night survey. Its scientific objectives
  cover solar physics and time-domain astronomy, all of which are recent
  hot topics in astronomy. As a large on-axis solar telescope in the
  world with a larger FOV (7') than all the large solar telescopes
  operating at present, it can provide unprecedented high-resolution
  solar imaging and magnetic field data, which can help us obtain
  breakthrough achievements on the study of solar active regions and
  solar eruptions. The data are also very useful for the study of space
  weather. As a large telescope in China, the telescope is very unique
  in continuously monitoring short-time transient events by filling
  the gap in the specific time-zone. Moreover, the telescope can make
  essential contribution to training the graduate and undergraduate
  students majoring in observational astronomy.

Title: High-resolution He I 10830 Å Narrowband Imaging for an
M-class Flare. II. Multiple Hot Channels: Their Origin and Destination
Authors: Wang, Ya; Su, Yingna; Shen, Jinhua; Yang, Xu; Cao, Wenda;
   Ji, Haisheng
Bibcode: 2018ApJ...859..148W
Altcode:
  In this paper, we report our second-part result for the M1.8 class
  flare on 2012 July 5, with an emphasis on the initiation process
  for the flare-associated filament eruption. The data set consists
  of high-resolution narrowband images in He I 10830 Å and broadband
  images in TiO 7057 Å taken at Big Bear Solar Observatory with
  the 1.6 m aperture Goode Solar Telescope. EUV images in different
  passbands observed by the Atmospheric Imaging Assembly on board the
  Solar Dynamics Observatory are used to distinguish hot plasma from
  cool plasma structures during the flare process. High-resolution
  10830 Å images clearly show that, below the horizontal fibrils,
  which correspond to the filament’s spine in full-disk Hα images,
  a sheared arch filament system (AFS) lies across the penumbra and
  surrounding satellite sunspots, between which continuous shearing
  motion is observed. Before the eruption, three microflares occurred
  successively and were followed by the appearance of three EUV hot
  channels. Two hot channels erupted, producing two flaring sites and
  two major peaks in GOES soft X-ray light curves; however, one hot
  channel’s eruption failed. The 10830 Å imaging enables us to trace
  the first two hot channels to their very early stage, which is signified
  by the rising of the AFS after the first two precursors. Continuous flux
  emergence and localized flare-associated cancellation are observed under
  the AFS. In addition, EUV ejections were observed during the formation
  of the EUV hot channels. These observations support the fact that the
  hot channels are the result of magnetic reconnections during precursors.

Title: Evolution of Photospheric Magnetic Field Associated with
    Flare Ribbons as Seen by GST
Authors: Liu, Chang; Cao, Wenda; Xu, Yan; Ahn, Kwangsu; Wang, Haimin
Bibcode: 2018tess.conf40803L
Altcode:
  Solar flares produce signatures at various wavelengths and heights,
  among which the response of photospheric magnetic and flow fields
  to flare reconnection has drawn increasing attention recently. Such
  a response has been evidenced as sudden flare-induced photospheric
  structural evolution, especially vector magnetic field changes
  and sunspot rotations. However, previous studies on this coronal
  back-reaction process focused on the magnetic polarity inversion line
  region and/or the overall temporal relationship. Here we present
  high-resolution H-alpha off-band images and near-infrared vector
  magnetograms of a major flare observed with the 1.6 m Goode Solar
  Telescope (GST), which allow us to probe the relationship between
  motions of flare ribbons and variations of the underlying field. It
  is found that changes of photospheric fields occur instantly in a
  largely step-wise fashion at the arrival of the flare ribbon front,
  thus exhibit a propagation analogous to flare ribbons. In general, the
  fields become more inclined to the surface, with enhanced horizontal
  field and magnetic shear. When ribbons sweep through regions that
  undergo an apparent rotational motion, the fields transiently turn
  more vertical with decreased horizontal field and inclination angel,
  and then become more horizontal. Interestingly, the ribbon decelerates
  as approaching the sunspot rotation center, where the vertical field
  becomes persistently enhanced. Overall, NLFFF extrapolation models
  based on HMI vector field data suggest an inward collapse of magnetic
  fields. These results indicate that photospheric fields may respond
  instantaneously and differentially to the coronal field restructuring
  due to reconnection of individual flux bundles.

Title: Observation of Light Bridge Brightening and Plasma Ejection
    Triggered by a Magnetic Flux Emergence Event
Authors: Yang, Xu; Yurchyshyn, Vasyl; Ahn, Kwangsu; Cao, Wenda
Bibcode: 2018tess.conf10906Y
Altcode:
  Light bridges (LBs) are elongated, bright, granular structures that
  divide the umbra of a large and complex sunspot into two or more umbral
  regions with the same magnetic polarity. Surge-like activities are
  common phenomenon appear above the LBs which always accompanied by the
  magnetic flux emergence process. Former works tried to interpret the
  triggering mechanism for them, however they often lacked the support of
  high spatial and temporal resolution vector magnetic measurement. Our
  recent Observation shows a strong magnetic flux emergence happened
  at the edge of a filamentary Light Bridge (LB) and accompanied by
  brightness enhancement of photospheric granulations at the endpoints
  of the emerged magnetic structure. We study the origin and dynamics of
  this magnetic flux emergence event with high resolution Fe I 1.56 μm
  polarimetry magnetogram, TiO photosphere image and Hα chromosphere
  image from the Goode Solar Telescope. The emerged magnetic structure
  was 1.5 Mm × 0.3 Mm in size at its peak time and lasted for 17
  minutes. Doppler map detected upflows before its formation and downflows
  during the destruction. The magnetic orientation change was obtained by
  calculating the shear angle and plotting the magnetic field vectors. The
  result indicates that the new emerged more transverse magnetic field
  reconnected with the pre-existing more vertical field, which triggered
  the fan-shaped jets. The expanding fields at the endpoints due to the
  flux emergence pushed and compressed the existing granulations and
  led to their enhanced brightness.

Title: Study of 3D magnetic Structure Corresponding to Extremely
    Strong Photospheric Magnetic Fields in Active Region 12673
Authors: Wang, Haimin; Yurchyshyn, Vasyl; Liu, Chang; Chen, Bin;
   Jing, Ju; Ahn, Kwangsu; Toriumi, Shin; Cao, Wenda
Bibcode: 2018tess.conf31902W
Altcode:
  Solar Active Region (AR) 12673 is the most flare productive AR in the
  solar cycle 24. It produced four X-class flares including the X9.3 flare
  on 06 September 2017 and the X8.2 limb event on 10 September. Sun and
  Norton (2017) reported that this region had an unusual high rate of
  flux emergence, while Huang et al. (2018) reported that the X9.3 flare
  had extremely strong white-light flare emission. Yang et al. (2017)
  described the detailed morphological evolution of this AR. In this work,
  we first study the unusual behaviors of the light bridge (LB) dividing
  the delta configuration of this AR, namely the strong magnetic fields
  (above 5500 G) in the LB and the apparent photospheric twist as seen in
  observations with a 0.1 arcsec spatial resolution obtained by the 1.6m
  Goode Solar Telescope (GST) at the Big Bear Solar Observatory. Using the
  newly commissioned Expanded Owens Valley Solar Array (EOVSA), we carried
  out diagnoses of magnetic fields in this AR with microwave imaging
  spectroscopy from 2.5 to 18 GHz. Finally, we utilized Non-Linear Force
  Free Field (NLFFF) extrapolation to reveal 3-D magnetic structure to
  gain a physical understanding of GST and EOVSA observations of this AR.

Title: Milne-Eddington Stokes Inversion of the NIRIS Magnetogram
    Data Achieved by Machine Learning Technique
Authors: Ahn, Kwangsu; Cao, Wenda
Bibcode: 2018tess.conf30818A
Altcode:
  The Near InfraRed Imaging Spectrograph (NIRIS) at the Goode Solar
  Telescope produces Stokes I, Q, U, and V polarimetric profiles at
  a spectral resolution of 0.01 nm in 1564.8 nm band, with a typical
  range of -0.25 to +0.25 nm from the line center. This narrow band
  is achieved with a combination of a pre-filter and dual Fabry-Perot
  (F-P) etalon system. Typical line scan takes about 30 seconds. We
  use Milne-Eddington (ME) inversion technique to deduce physical
  parameters of an image pixel - such as total magnetic field strength,
  vertical/horizontal component of the magnetic field, Doppler shift of
  the line center and so on. However, due to many noise factors such
  inversion attempts are not always reasonable, especially when the
  profiles are complicated. Most of the ME fitting errors come from
  the initial guess of the longitudinal field strenghth calcuated from
  the center-of-gravity method. <P />We present our result of a new
  approach of inversion by using machine learning technique. Sagemaker,
  a new platform from Amazon Web Services, was adopted for training and
  modeling of the line profiles. We used principal component analysis
  (PCA) algorithm to deduce several physical parameters out of a trained
  model. This method not only reduces the dimension of the data but also
  enhances the speed of data processing. The result indicates that our
  model well fits into the actual measured line profiles as well as
  saving processing time. We present comparison of our new method to
  the ME inversion method in terms of accuracy and processing time.

Title: The Formation of a Sunspot Penumbra Sector in Active Region
    NOAA 12574
Authors: Li, Qiaoling; Yan, Xiaoli; Wang, Jincheng; Kong, DeFang;
   Xue, Zhike; Yang, Liheng; Cao, Wenda
Bibcode: 2018ApJ...857...21L
Altcode:
  We present a particular case of the formation of a penumbra sector
  around a developing sunspot in the active region NOAA 12574 on 2016
  August 11 by using the high-resolution data observed by the New Solar
  Telescope at the Big Bear Solar Observatory and the data acquired
  by the Helioseismic and Magnetic Imager and the Atmospheric Imaging
  Assembly on board the Solar Dynamics Observatory satellite. Before the
  new penumbra sector formed, the developing sunspot already had two
  umbrae with some penumbral filaments. The penumbra sector gradually
  formed at the junction of two umbrae. We found that the formation of
  the penumbra sector can be divided into two stages. First, during the
  initial stage of penumbral formation, the region where the penumbra
  sector formed always appeared blueshifted in a Dopplergram. The area,
  mean transverse magnetic field strength, and total magnetic flux of
  the umbra and penumbra sector all increased with time. The initial
  penumbral formation was associated with magnetic emergence. Second,
  when the penumbra sector appeared, the magnetic flux and area of the
  penumbra sector increased after the umbra’s magnetic flux and area
  decreased. These results indicate that the umbra provided magnetic flux
  for penumbral development after the penumbra sector appeared. We also
  found that the newly formed penumbra sector was associated with sunspot
  rotation. Based on these findings, we suggest that the penumbra sector
  was the result of the emerging flux that was trapped in the photosphere
  at the initial stage of penumbral formation, and when the rudimentary
  penumbra formed, the penumbra sector developed at the cost of the umbra.

Title: High-resolution Observations of Flares in an Arch Filament
    System
Authors: Su, Yingna; Liu, Rui; Li, Shangwei; Cao, Wenda; Ahn, Kwangsu;
   Ji, Haisheng
Bibcode: 2018ApJ...855...77S
Altcode: 2018arXiv180306085S
  We study five sequential solar flares (SOL2015-08-07) occurring in
  Active Region 12396 observed with the Goode Solar Telescope (GST) at the
  Big Bear Solar Observatory, complemented by Interface Region Imaging
  Spectrograph and SDO observations. The main flaring region is an arch
  filament system (AFS) consisting of multiple bundles of dark filament
  threads enclosed by semicircular flare ribbons. We study the magnetic
  configuration and evolution of the active region by constructing
  coronal magnetic field models based on SDO/HMI magnetograms using
  two independent methods, i.e., the nonlinear force-free field (NLFFF)
  extrapolation and the flux rope insertion method. The models consist
  of multiple flux ropes with mixed signs of helicity, i.e., positive
  (negative) in the northern (southern) region, which is consistent with
  the GST observations of multiple filament bundles. The footprints of
  quasi-separatrix layers (QSLs) derived from the extrapolated NLFFF
  compare favorably with the observed flare ribbons. An interesting
  double-ribbon fine structure located at the east border of the AFS is
  consistent with the fine structure of the QSL’s footprint. Moreover,
  magnetic field lines traced along the semicircular footprint of a
  dome-like QSL surrounding the AFS are connected to the regions of
  significant helicity and Poynting flux injection. The maps of magnetic
  twist show that positive twist became dominant as time progressed,
  which is consistent with the injection of positive helicity before
  the flares. We hence conclude that these circular shaped flares are
  caused by 3D magnetic reconnection at the QSLs associated with the
  AFS possessing mixed signs of helicity.

Title: Frequently Occurring Reconnection Jets from Sunspot Light
    Bridges
Authors: Tian, Hui; Yurchyshyn, Vasyl; Peter, Hardi; Solanki, Sami
   K.; Young, Peter R.; Ni, Lei; Cao, Wenda; Ji, Kaifan; Zhu, Yingjie;
   Zhang, Jingwen; Samanta, Tanmoy; Song, Yongliang; He, Jiansen; Wang,
   Linghua; Chen, Yajie
Bibcode: 2018ApJ...854...92T
Altcode: 2018arXiv180106802T
  Solid evidence of magnetic reconnection is rarely reported within
  sunspots, the darkest regions with the strongest magnetic fields
  and lowest temperatures in the solar atmosphere. Using the world’s
  largest solar telescope, the 1.6 m Goode Solar Telescope, we detect
  prevalent reconnection through frequently occurring fine-scale jets
  in the Hα line wings at light bridges, the bright lanes that may
  divide the dark sunspot core into multiple parts. Many jets have an
  inverted Y-shape, shown by models to be typical of reconnection in a
  unipolar field environment. Simultaneous spectral imaging data from
  the Interface Region Imaging Spectrograph show that the reconnection
  drives bidirectional flows up to 200 km s<SUP>-1</SUP>, and that the
  weakly ionized plasma is heated by at least an order of magnitude up
  to ∼80,000 K. Such highly dynamic reconnection jets and efficient
  heating should be properly accounted for in future modeling efforts
  of sunspots. Our observations also reveal that the surge-like activity
  previously reported above light bridges in some chromospheric passbands
  such as the Hα core has two components: the ever-present short surges
  likely to be related to the upward leakage of magnetoacoustic waves
  from the photosphere, and the occasionally occurring long and fast
  surges that are obviously caused by the intermittent reconnection jets.

Title: Extending Counter-streaming Motion from an Active Region
    Filament to a Sunspot Light Bridge
Authors: Wang, Haimin; Liu, Rui; Li, Qin; Liu, Chang; Deng, Na; Xu,
   Yan; Jing, Ju; Wang, Yuming; Cao, Wenda
Bibcode: 2018ApJ...852L..18W
Altcode: 2017arXiv171206783W
  We analyze high-resolution observations from the 1.6 m telescope
  at Big Bear Solar Observatory that cover an active region
  filament. Counter-streaming motions are clearly observed in the
  filament. The northern end of the counter-streaming motions extends
  to a light bridge, forming a spectacular circulation pattern around a
  sunspot, with clockwise motion in the blue wing and counterclockwise
  motion in the red wing, as observed in the Hα off-bands. The apparent
  speed of the flow is around 10-60 km s<SUP>-1</SUP> in the filament,
  decreasing to 5-20 km s<SUP>-1</SUP> in the light bridge. The most
  intriguing results are the magnetic structure and the counter-streaming
  motions in the light bridge. Similar to those in the filament, the
  magnetic fields show a dominant transverse component in the light
  bridge. However, the filament is located between opposed magnetic
  polarities, while the light bridge is between strong fields of
  the same polarity. We analyze the power of oscillations with the
  image sequences of constructed Dopplergrams, and find that the
  filament’s counter-streaming motion is due to physical mass motion
  along fibrils, while the light bridge’s counter-streaming motion
  is due to oscillation in the direction along the line-of-sight. The
  oscillation power peaks around 4 minutes. However, the section of
  the light bridge next to the filament also contains a component of
  the extension of the filament in combination with the oscillation,
  indicating that some strands of the filament are extended to and rooted
  in that part of the light bridge.

Title: Strong Transverse Photosphere Magnetic Fields and Twist in
    Light Bridge Dividing Delta Sunspot of Active Region 12673
Authors: Wang, Haimin; Yurchyshyn, Vasyl; Liu, Chang; Ahn, Kwangsu;
   Toriumi, Shin; Cao, Wenda
Bibcode: 2018RNAAS...2....8W
Altcode: 2018RNAAS...2a...8W; 2018arXiv180102928W
  Solar Active Region (AR) 12673 is the most flare productive AR in the
  solar cycle 24. It produced four X-class flares including the X9.3 flare
  on 06 September 2017 and the X8.2 limb event on 10 September. Sun and
  Norton (2017) reported that this region had an unusual high rate of
  flux emergence, while Huang et al. (2018) reported that the X9.3 flare
  had extremely strong white-light flare emissions. Yang at al. (2017)
  described the detailed morphological evolution of this AR. In this
  report, we focus on usual behaviors of the light bridge (LB) dividing
  the delta configuration of this AR, namely the strong magnetic fields
  (above 5500 G) in the LB and apparent photospheric twist as shown in
  observations with a 0.1 arcsec spatial resolution obtained by the 1.6m
  telescope at Big Bear Solar Observatory.

Title: Transient rotation of photospheric vector magnetic fields
    associated with a solar flare
Authors: Xu, Yan; Cao, Wenda; Ahn, Kwangsu; Jing, Ju; Liu, Chang;
   Chae, Jongchul; Huang, Nengyi; Deng, Na; Gary, Dale E.; Wang, Haimin
Bibcode: 2018NatCo...9...46X
Altcode: 2018arXiv180103171X
  As one of the most violent eruptions on the Sun, flares are believed to
  be powered by magnetic reconnection. The fundamental physics involving
  the release, transfer, and deposition of energy have been studied
  extensively. Taking advantage of the unprecedented resolution provided
  by the 1.6 m Goode Solar Telescope, here, we show a sudden rotation of
  vector magnetic fields, about 12-20° counterclockwise, associated
  with a flare. Unlike the permanent changes reported previously,
  the azimuth-angle change is transient and cospatial/temporal with
  Hα emission. The measured azimuth angle becomes closer to that in
  potential fields suggesting untwist of flare loops. The magnetograms
  were obtained in the near infrared at 1.56 μm, which is minimally
  affected by flare emission and no intensity profile change was
  detected. We believe that these transient changes are real and discuss
  the possible explanations in which the high-energy electron beams or
  Alfve'n waves play a crucial role.

Title: 1.56 Micron Spectropolarimetry of Umbral Dots and Their
    Evolution Associated with a Major Flare
Authors: Deng, Na; Liu, Chang; Xu, Yan; Ahn, Kwangsu; Jing, Ju; Cao,
   Wenda; Wang, Haimin
Bibcode: 2017SPD....4830003D
Altcode:
  We present unprecedented high-resolution and high magnetic
  sensitivity spectropolarimetric characterization of umbral dots
  (UDs), the prevailing fine scale brightness structure manifesting
  magneto-convection inside sunspot umbrae where the magnetic fields
  are strongest and nearly vertical. This is made available by recent
  development of the Near InfraRed Imaging Spectropolarimeter (NIRIS)
  using the 1.56 micron FeI line at the 1.6 meter New Solar Telescope
  of Big Bear Solar Observatory. Vector magnetograms are obtained after
  Milne-Eddington Stokes inversions, 180-degree azimuthal ambiguity
  resolution, and correction of projection effects. A βγδ spot in NOAA
  AR 12371 was observed for six hours on June 22, 2015 with a cadence of
  87 s, which covered an M6.6 flare. The overall umbra is separated into
  several smaller umbrae by light bridges. The umbrae are close to the
  flaring polarity inversion line and show an average inclination of about
  17° and field strength of about 2100 Gauss. The UDs are resolvable in
  NIRIS vector magnetograms, especially for peripheral UDs. The measured
  field strength is about 3% lower in UDs comparing to umbral cores (UCs)
  where the continuum intensity is below the threshold of UDs. The field
  is more inclined in UDs by 5% ( ≈ 1°) than that in UCs. One of the
  umbrae showed rapid evolution associated with the flare. Its overall
  intensity and the number of UDs decrease by at least 7% within two
  hours after being swept by the flare ribbon. NIRIS vector magnetograms
  indicate that the average field strength of that umbra has a rapid
  stepwise increase for about 100 Gauss while the inclination almost
  has no change. The decreases of the umbral brightness and the number
  of UDs are thus attributed to the increase of the field strength. The
  results suggest that the field strength plays the most important role
  in constraining convective heat transport in umbra.

Title: High-resolution Observations of Photospheric Structural
    Evolution Associated with a Flare
Authors: Liu, Chang; Xu, Yan; Ahn, Kwangsu; Jing, Ju; Deng, Na; Cao,
   Wenda; Wang, Haimin
Bibcode: 2017SPD....4810101L
Altcode:
  The structural evolution of the photosphere not only play an important
  role in contributing to the accumulation of free energy in the corona
  that powers solar flares, but also may response to the restructuring
  of coronal field as a result of flare energy release. A better
  understanding of these issues may be achieved by high-resolution
  observations of the photospheric structure covering the entire
  flaring period, which are, however, still rare. Here we present
  photospheric vector magnetograms and TiO images (at 0.2" and 0.09"
  resolution, respectively) from before to after a major flare, taken
  by the 1.6 m New Solar Telescope at Big Bear Solar Observatory. In the
  pre-flare state, a small-scale magnetic structure of opposite-polarity
  configuration is seen near the footpoints of sheared magnetic loops;
  its magnetic fluxes and currents enhance till the flare start time and
  decline afterwards. During the main phase, as one flare ribbon sweeps
  across a sunspot, its different portions accelerate at different times
  corresponding to peaks of flare hard X-ray emission. We suggest that
  the small-scale flux emergence between the two sheared flux systems
  triggers the flare reconnection, and that the sunspot rotation is driven
  by the surface Lorentz-force change due to the coronal back reaction.

Title: Magnetic vector rotation in response to the energetic electron
    beam during a flare
Authors: Xu, Yan; Cao, Wenda; Kwangsu, Ahn; Jing, Ju; Liu, Chang;
   Chae, Jongchul; Huang, Nengyi; Deng, Na; Gary, Dale E.; Wang, Haimin
Bibcode: 2017SPD....4810001X
Altcode:
  As one of the most violent forms of eruption on the Sun, flares are
  believed to be powered by magnetic reconnection, by which stored
  magnetic energy is released. The fundamental physical processes
  involving the release, transfer and deposition of energy in multiple
  layers of the solar atmosphere have been studied extensively with
  significant progress. Taking advantage of recent developments in
  observing facilities, new phenomena are continually revealed, bringing
  new understanding of solar flares. Here we report the discovery of
  a transient rotation of vector magnetic fields associated with a
  flare observed by the 1.6-m New Solar Telescope at Big Bear Solar
  Observatory. After ruling out the possibility that the rotation is
  caused by line profile changes due to flare heating, our observation
  shows that the transverse field rotateded by about 12-20 degrees
  counterclockwise, and returned quickly to previous values after the
  flare ribbons swept through. More importantly, as a consequence of
  the rotation, the flare loops untwisted and became more potential. The
  vector magnetograms were obtained in the near infrared at 1560 nm, which
  is minimally affected by flare emission and no intensity profile change
  was detected. Therefore, we believe that these transient changes are
  real, and conclude the high energy electron beams play an crucial role
  in the field changes. A straightforward and instructive explanation is
  that the induced magnetic field of the electron beam superimposed on
  the pre-flare field leads to a transient rotation of the overall field.

Title: The Eruption of a Small-scale Emerging Flux Rope as the Driver
    of an M-class Flare and of a Coronal Mass Ejection
Authors: Yan, X. L.; Jiang, C. W.; Xue, Z. K.; Wang, J. C.; Priest,
   E. R.; Yang, L. H.; Kong, D. F.; Cao, W. D.; Ji, H. S.
Bibcode: 2017ApJ...845...18Y
Altcode: 2017arXiv170700073Y
  Solar flares and coronal mass ejections are the most powerful explosions
  in the Sun. They are major sources of potentially destructive space
  weather conditions. However, the possible causes of their initiation
  remain controversial. Using high-resolution data observed by the New
  Solar Telescope of Big Bear Solar Observaotry, supplemented by Solar
  Dynamics Observatory observations, we present unusual observations of
  a small-scale emerging flux rope near a large sunspot, whose eruption
  produced an M-class flare and a coronal mass ejection. The presence of
  the small-scale flux rope was indicated by static nonlinear force-free
  field extrapolation as well as data-driven magnetohydrodynamics modeling
  of the dynamic evolution of the coronal three-dimensional magnetic
  field. During the emergence of the flux rope, rotation of satellite
  sunspots at the footpoints of the flux rope was observed. Meanwhile,
  the Lorentz force, magnetic energy, vertical current, and transverse
  fields were increasing during this phase. The free energy from the
  magnetic flux emergence and twisting magnetic fields is sufficient to
  power the M-class flare. These observations present, for the first time,
  the complete process, from the emergence of the small-scale flux rope,
  to the production of solar eruptions.

Title: Data processing pipeline of the Near-Infrared Imaging
    Spectropolarimeter at the NST
Authors: Ahn, Kwangsu; Cao, Wenda
Bibcode: 2017SPD....4811504A
Altcode:
  The Near-Infrared Imaging Spectropolarimeter (NIRIS) is made for imaging
  magnetic field structures on the Sun. The data acquired undergoes
  extensive post-processing to ensure high resolution, high signal to
  noise ratio, and high accuracy. We would like to introduce how the data
  are processed by demonstrating data processing pipeline. In this manner,
  the capabilities and the limits in data analysis would be evaluated. The
  NIRIS is dedicated to Fe I 15648 band observation for now, while it
  has potential for expanding their choice of bands as well as improving
  data quality. Such upgrade plans should be discussed and prioritized.

Title: Extending Counter-Streaming Motion from an Active Region
    Filament to Sunspot Light Bridge
Authors: Wang, Haimin; Liu, Rui; Deng, Na; Liu, Chang; Xu, Yan; Jing,
   Ju; Wang, Yuming; Cao, Wenda
Bibcode: 2017SPD....4810405W
Altcode:
  In this study, we analyze the high-resolution observations from the 1.6
  m New Solar Telescope at Big Bear Solar Observatory that cover an entire
  active region filament. The southern end of the filament is well defined
  by a narrow lane situated in the negative magnetic polarity, while the
  northern end lies in the positive polarity, extending to a much larger
  area. Counter-streaming motions are clearly seen in the filament. The
  northern end of the counter-streaming motions extends to a light
  bridge, forming a spectacular circulation pattern around a sunspot,
  with clockwise motion in the blue wing and counterclockwise motion in
  the red wing as observed in H-alpha off-band. The apparent speed of the
  flow is around 10 km/s. We show that the southern end of the filament
  is consistent with that of a flux rope in a NLFFF extrapolation model,
  but the northern ends of the modeled flux rope and observed H-alpha
  footpoints have a significant spatial mismatch. The most intriguing
  results are the magnetic structure and the counter-streaming motions
  in the light bridge. Similar to those in the filament, magnetic fields
  show a dominant transverse component in the light bridge. However,
  the filament is located between opposite magnetic polarities, while
  the light bridge is between strong fields of the same polarity. We
  studied the correlation coefficients of image sequences of constructed
  Dopplergrams, and found that the filament and the section of light
  bridge next to it do not show oscillation motions, while a small section
  of light bridge shows a prominent oscillation pattern. Therefore, we
  conclude that the observed circulating counter-streaming motions are
  largely collections of physical mass flows in the transverse direction
  from the filament extending to a large section of the light bridge,
  rather than a form of periodic oscillatory mass motions in line-of-sight
  direction generated by perturbations omnipresent in the chromosphere.

Title: High-Resolution Observations of Flares in an Arch Filament
    System
Authors: Su, Yingna; Liu, Rui; Li, Shangwei; Cao, Wenda; Ji, Haisheng
Bibcode: 2017SPD....4840604S
Altcode:
  We present high-resolution observations of five sequential solar flares
  occurring in NOAA Active Region (AR) 12396 taken with the 1.6-m New
  Solar Telescope at the Big Bear Solar Observatory, complemented by IRIS
  and SDO observations. The main flaring region is an arch filament system
  (AFS) consisting of multiple bundles of dark filament threads enclosed
  by scattered flare brightenings. We study the magnetic configuration and
  evolution of the active region by constructing coronal magnetic field
  models based on SDO/HMI magnetograms using two independent methods,
  i.e., the nonlinear force-free field (NLFFF) extrapolation and the
  flux rope insertion method. We are able to identify multiple flux ropes
  based on magnetic twist derived from the extrapolated NLFFF, which is
  consistent with the NST observations of multiple filaments. Both models
  suggest that the filament bundles may posses mixed signs of helicity,
  i.e., positive (negative) in the north (south). The footprints of
  quasi-separatrix layers (QSLs) derived from the extrapolated NLFFF
  compare favorably with the observed flare ribbons. Moreover, magnetic
  field lines traced along the semi-circular footprint of a dome-like
  QSL surrounding the flaring region are connected to the regions of
  significant helicity and Poynting flux injection. An interesting
  double-ribbon fine structure located at the east border of the AFS is
  consistent with the fine structure of the QSL's footprint. The maps
  of magnetic twist show that positive twist became dominant as time
  progressed, which is consistent with the injection of positive helicity
  during a 26 hour interval before the flares. The trigger mechanisms
  and detailed dynamics of the observed flares are also discussed.

Title: Multi-wavelength Spectral Analysis of Ellerman Bombs Observed
    by FISS and IRIS
Authors: Hong, Jie; Ding, M. D.; Cao, Wenda
Bibcode: 2017ApJ...838..101H
Altcode: 2017arXiv170304268H
  Ellerman bombs (EBs) are a kind of solar activity that is suggested
  to occur in the lower solar atmosphere. Recent observations using the
  Interface Region Imaging Spectrograph (IRIS) show connections between
  EBs and IRIS bombs (IBs), which imply that EBs might be heated to a much
  higher temperature (8 × 10<SUP>4</SUP> K) than previous results. Here
  we perform a spectral analysis of EBs simultaneously observed by the
  Fast Imaging Solar Spectrograph and IRIS. The observational results
  show clear evidence of heating in the lower atmosphere, indicated by
  the wing enhancement in Hα, Ca II 8542 Å, and Mg II triplet lines and
  also by brightenings in images of the 1700 Å and 2832 Å ultraviolet
  continuum channels. Additionally, the intensity of the Mg II triplet
  line is correlated with that of Hα when an EB occurs, suggesting the
  possibility of using the triplet as an alternative way to identify
  EBs. However, we do not find any signal in IRIS hotter lines (C II
  and Si IV). For further analysis, we employ a two-cloud model to fit
  the two chromospheric lines (Hα and Ca II 8542 Å) simultaneously,
  and obtain a temperature enhancement of 2300 K for a strong EB. This
  temperature is among the highest of previous modeling results, albeit
  still insufficient to produce IB signatures at ultraviolet wavelengths.

Title: High-resolution observations of flare precursors in the low
    solar atmosphere
Authors: Wang, Haimin; Liu, Chang; Ahn, Kwangsu; Xu, Yan; Jing, Ju;
   Deng, Na; Huang, Nengyi; Liu, Rui; Kusano, Kanya; Fleishman, Gregory
   D.; Gary, Dale E.; Cao, Wenda
Bibcode: 2017NatAs...1E..85W
Altcode: 2017arXiv170309866W
  Solar flares are generally believed to be powered by free magnetic
  energy stored in the corona<SUP>1</SUP>, but the build up of
  coronal energy alone may be insufficient to trigger the flare to
  occur<SUP>2</SUP>. The flare onset mechanism is a critical but poorly
  understood problem, insights into which could be gained from small-scale
  energy releases known as precursors. These precursors are observed as
  small pre-flare brightenings in various wavelengths<SUP>3-13</SUP>
  and also from certain small-scale magnetic configurations such
  as opposite-polarity fluxes<SUP>14-16</SUP>, where the magnetic
  orientation of small bipoles is opposite to that of the ambient main
  polarities. However, high-resolution observations of flare precursors
  together with the associated photospheric magnetic field dynamics are
  lacking. Here we study precursors of a flare using the unprecedented
  spatiotemporal resolution of the 1.6-m New Solar Telescope, complemented
  by new microwave data. Two episodes of precursor brightenings are
  initiated at a small-scale magnetic channel<SUP>17-20</SUP> (a form of
  opposite-polarity flux) with multiple polarity inversions and enhanced
  magnetic fluxes and currents, lying near the footpoints of sheared
  magnetic loops. Microwave spectra corroborate that these precursor
  emissions originate in the atmosphere. These results provide evidence
  of low-atmospheric small-scale energy release, possibly linked to the
  onset of the main flare.

Title: Magnetic Separatrix as the Source Region of the Plasma Supply
    for an Active-region Filament
Authors: Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Cao, Wenda
Bibcode: 2017ApJ...836..122Z
Altcode: 2017arXiv170101526Z
  Solar filaments can be formed via chromospheric evaporation followed
  by condensation in the corona or by the direct injection of cool
  plasma from the chromosphere to the corona. We here confirm with
  high-resolution Hα data observed by the 1.6 m New Solar Telescope of
  the Big Bear Solar Observatory on 2015 August 21 that an active-region
  filament is maintained by the continuous injection of cold chromospheric
  plasma. We find that the filament is rooted along a bright ridge in Hα,
  which corresponds to the intersection of a magnetic quasi-separatrix
  layer with the solar surface. This bright ridge consists of many
  small patches whose sizes are comparable to the width of the filament
  threads. It is found that upflows originate from the brighter patches
  of the ridge, whereas the downflows move toward the weaker patches of
  the ridge. The whole filament is composed of two opposite-direction
  streams, implying that longitudinal oscillations are not the only
  cause of the counterstreamings, and unidirectional siphon flows with
  alternative directions are another possibility.

Title: A novel 3-D calorimeter for the High Energy cosmic-Radiation
    Detection (HERD) Facility onboard China's Future Space Station
Authors: Dong, Y.; HERD Collaboration; Xu, M.; Wang, Z.; Adriani, O.;
   Albergo, S.; Ambrosi, G.; Azzarello, P.; Bai, Y.; Bao, T.; Bernardini,
   P.; Bertucci, B.; Bi, X.; Bongi, M.; Bottai, S.; Cao, W.; Chai, J.;
   Chen, Z.; D'Alessandro, R.; Santo, M. D.; Duranti, M.; Fang, K.;
   Feng, H.; Formato, V.; Fusco, P.; Gao, J.; Gargano, F.; Giglietto,
   N.; Hu, P.; Li, R.; Li, Y.; Lin, S.; Liu, H.; Liu, X.; Loparco, F.;
   Lyu, J.; Marsella, G.; Mazziottai, M. N.; Mitri, I. D.; Mori, N.;
   Papini, P.; Peng, W.; Pohl, M.; Quan, Z.; Shi, D.; Sun, X.; Surdo,
   A.; Vannuccini, E.; Walter, R.; Wang, B.; Wang, B.; Wang, J.; Wang,
   L.; Wang, R.; Wu, B.; Wu, Q.; Wu, X.; Zhang, L.; Zhang, S. N.
Bibcode: 2017ICRC...35..253D
Altcode: 2017PoS...301..253D
  No abstract at ADS

Title: Introduction to the High Energy cosmic-Radiation Detection
    (HERD) Facility onboard China's Future Space Station
Authors: Zhang, S. N.; Adriani, O.; Consortium, H.; Albergo, S.;
   Ambrosi, G.; An, Q.; Azzarello, P.; Bai, Y.; Bao, T.; Bernardini, P.;
   Bertucci, B.; Bi, X.; Bongi, M.; Bottai, S.; Cao, W.; Cao, Z.; Chai,
   J.; Chang, J.; Chen, G.; Chen, Y.; Chen, Z.; Cui, X. H.; Dai, Z. G.;
   D'Alessandro, R.; Santo, M. D.; Dong, Y.; Duranti, M.; Fan, Y.; Fang,
   K.; Feng, C. Q.; Feng, H.; Formato, V.; Fusco, P.; Gao, J.; Gargano,
   F.; Giglietto, N.; Gou, Q.; Guo, Y. Q.; He, H. H.; Hu, H.; Hu, P.;
   Huang, G. S.; Huang, J.; Huang, Y. F.; Li, H.; Li, R.; Li, Y.; Li,
   Z.; Liang, E. W.; Lin, S.; Liu, H.; Liu, H.; Liu, J. B.; Liu, S. B.;
   Liu, S. M.; Liu, X.; Loparco, F.; Lyu, J.; Marsella, G.; Mazziottai,
   M. N.; Mitri, I. D.; Mori, N.; Papini, P.; Pearce, M.; Peng, W.; Pohl,
   M.; Quan, Z.; Ryde, F.; Shi, D.; Su, M.; Sun, X. L.; Sun, X.; Surdo,
   A.; Tang, Z. C.; Vannuccini, E.; Walter, R.; Wang, B.; Wang, B.; Wang,
   J. C.; Wang, J. M.; Wang, J.; Wang, L.; Wang, R.; Wang, X. L.; Wang,
   X. Y.; Wang, Z.; Wei, D. M.; Wu, B.; Wu, J.; Wu, Q.; Wu, X.; Wu,
   X. F.; Xu, M.; Xu, Z. Z.; Yan, H. R.; Yin, P. F.; Yu, Y. W.; Yuan,
   Q.; Zha, M.; Zhang, L.; Zhang, L.; Yi, Z.; Zhang, Y. L.; Zhao, Z. G.
Bibcode: 2017ICRC...35.1077Z
Altcode: 2017PoS...301.1077Z
  No abstract at ADS

Title: Objective Image Quality Assessment for High Resolution
    Photospheric Images by Median Filter Gradient Similarity
Authors: Deng, Hui; Zhang, Dandan; Wang, Tianyu; Ji, Kaifan; Wang,
   Feng; Liu, Zhong; Xiang, Yongyuan; Jin, Zhenyu; Cao, Wenda
Bibcode: 2017arXiv170105300D
Altcode:
  All next generation ground-based and space-based solar telescopes
  require a good quality assessment metric in order to evaluate their
  imaging performance. In this paper, a new image quality metric, the
  median filter gradient similarity (MFGS) is proposed for photospheric
  images. MFGS is a no-reference/blind objective image quality metric
  (IQM) by a measurement result between 0 and 1 and has been performed
  on short-exposure photospheric images captured by the New Vacuum
  Solar Telescope (NVST) of the Fuxian Solar Observatory and by
  the Solar Optical Telescope (SOT) onboard the Hinode satellite,
  respectively. The results show that: (1)the measured value of MFGS
  changes monotonically from 1 to 0 with degradation of image quality;
  (2)there exists a linear correlation between the measured values of
  MFGS and root-mean-square-contrast (RMS-contrast) of granulation;
  (3)MFGS is less affected by the image contents than the granular
  RMS-contrast. Overall, MFGS is a good alternative for the quality
  assessment of photospheric images.

Title: Unprecedented Fine Structures during a Solar Eruptive
    Event Observed by the 1.6-m New Solar Telescope at Big Bear Solar
    Observatory
Authors: Xu, Y.; Jing, J.; Li, Q.; Cao, W.; Wang, H.
Bibcode: 2016AGUFMSH41E..04X
Altcode:
  A solar eruptive event includes both large-scale and small-scale
  structures. Flares, filament eruptions and CMEs are large-scale features
  and have been studied extensively in the literature. On the other hand,
  fine structures (below 500 km) are rarely observed and are accessible to
  only a fewinstruments world-wide. Using the 1.6-m New Solar Telescope
  (NST) at Big Bear Solar Observatory (BBSO), an M6.5 flare was captured
  on June 22, 2015. This extraordinary observation reveals the process
  of the magnetic energy release in unprecedented detail, including
  the flare ribbon propagating across the sunspots, sunspot rotation,
  magnetic channels (elongated structurescomprising alternating magnetic
  polarity inversion lines), coronal rain (made of condensing plasma)
  streaming down along the post-flare loops, and the chromosphere's
  response to the impact of coronal rain, showing fine-scale brightenings
  at the footpoints of the falling plasma. Here we present our analysis
  of this event in a comprehensive manner covering the above phenomena.

Title: High Resolution He I 10830 AA Narrow-band Imaging of an
    M-class Flare. I - Analysis of Sunspot Dynamics during Flaring
Authors: Wang, Ya; Su, Yingna; Hong, Zhenxiang; Zeng, Zhicheng; Ji,
   Kaifan; Goode, Philip R.; Cao, Wenda; Ji, Haisheng
Bibcode: 2016ApJ...833..250W
Altcode:
  In this paper, we report our first-step results of high resolution
  He I 10830 Å narrow-band imaging (bandpass: 0.5 Å) of an M1.8 class
  two-ribbon flare on 2012 July 5. The flare was observed with the 1.6
  m aperture New Solar Telescope at Big Bear Solar Observatory. For
  this unique data set, sunspot dynamics during flaring were analyzed
  for the first time. By directly imaging the upper chromosphere,
  running penumbral waves are clearly seen as an outward extension
  of umbral flashes; both take the form of absorption in the 10830 Å
  narrow-band images. From a space-time image made of a slit cutting
  across a flare ribbon and the sunspot, we find that the dark lanes
  for umbral flashes and penumbral waves are obviously broadened after
  the flare. The most prominent feature is the sudden appearance of an
  oscillating absorption strip inside the ribbon when it sweeps into the
  sunspot’s penumbral and umbral regions. During each oscillation,
  outwardly propagating umbral flashes and subsequent penumbral waves
  rush out into the inwardly sweeping ribbon, followed by a return
  of the absorption strip with similar speed. We tentatively explain
  the phenomena as the result of a sudden increase in the density
  of ortho-helium atoms in the area of the sunspot being excited by
  the flare’s extreme ultraviolet illumination. This explanation is
  based on the observation that 10830 Å absorption around the sunspot
  area gets enhanced during the flare. Nevertheless, questions are still
  open and we need further well-devised observations to investigate the
  behavior of sunspot dynamics during flares.

Title: Material Supply and Magnetic Configuration of an Active
    Region Filament
Authors: Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q.; Cao, Wenda
Bibcode: 2016ApJ...831..123Z
Altcode: 2017arXiv170102407Z
  It is important to study the fine structures of solar filaments
  with high-resolution observations, since it can help us understand
  the magnetic and thermal structures of the filaments and their
  dynamics. In this paper, we study a newly formed filament located
  inside the active region NOAA 11762, which was observed by the 1.6 m
  New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to
  17:07:58 UT on 2013 June 5. As revealed by the Hα filtergrams, cool
  material is seen to be injected into the filament spine with a speed of
  5-10 km s<SUP>-1</SUP>. At the source of the injection, brightenings
  are identified in the chromosphere, which are accompanied by magnetic
  cancellation in the photosphere, implying the importance of magnetic
  reconnection in replenishing the filament with plasmas from the lower
  atmosphere. Counter-streamings are detected near one endpoint of the
  filament, with the plane-of-the-sky speed being 7-9 km s<SUP>-1</SUP> in
  the Hα red-wing filtergrams and 9-25 km s<SUP>-1</SUP> in the blue-wing
  filtergrams. The observations are indicative that this active region
  filament is supported by a sheared arcade without magnetic dips, and
  the counter-streamings are due to unidirectional flows with alternative
  directions, rather than due to the longitudinal oscillations of filament
  threads as in many other filaments.

Title: Spectropolarimetry of Atomic and Molecular Lines near 4135 nm
Authors: Penn, Matthew James; Uitenbroek, Han; Clark, Alan; Coulter,
   Roy; Goode, Phil; Cao, Wenda
Bibcode: 2016SoPh..291.2243P
Altcode: 2015arXiv151204451P; 2016SoPh..tmp..142P
  New spatially scanned spectropolarimetry sunspot observations are made
  of photospheric atomic and molecular absorption lines near 4135 nm. The
  relative splittings among several atomic lines are measured and shown
  to agree with values calculated with configuration interaction and
  intermediate coupling. Large splitting is seen in a line identified
  with Fe I at 4137 nm, showing multiple Stokes V components and an
  unusual linear polarization. This line will be a sensitive probe of
  quiet-Sun magnetic fields, with a magnetic sensitivity of 2.5 times
  higher than that of the well-known 1565 nm Fe I line.

Title: High resolution He I 10830 angstrom narrow-band imaging of
    an M-class flare.I-analysis of sunspot dynamics during flaring
Authors: Wang, Ya; Su, Yingna; Hong, Zhenxiang; Zeng, Zhicheng; Ji,
   Kaifan; Goode, Philip R.; Cao, Wenda; Ji, Haisheng
Bibcode: 2016usc..confE..38W
Altcode: 2016arXiv161009227W
  We report our first-step results of high resolution He I 1083
  nm narrow-band imaging of an M 1.8 class two-ribbon flare on July
  5,2012. The flare was observed with the 1.6 meter aperture New Solar
  Telescope at Big Bear Solar Observatory. For this unique data set,
  sunspot dynamics during flaring were analyzed for the first time. By
  directly imaging the upper chromosphere, running penumbral waves
  are clearly seen as an outward extention of umbral flashes, both
  take the form of absorption in our 1083 nm narrow-band images. From
  a space-time image made of a slit cutting across the ribbon and the
  sunspot, we find that dark lanes for umbral flashes and penumbral waves
  are obviously broadened after the flare. The most prominent feature
  is the sudden appearance of an oscillating absorption strip inside
  one ribbon of the flare when it sweeps into sunspot's penumbral and
  umbral regions. During each oscillation, outwardly propagating umbral
  flashes and subsequent penumbral waves rush out into the inwardly
  sweeping ribbon, followed by a returning of the absorption strip with
  similar speed. We tentatively explain the phenomenon as the result of
  a sudden increase in the density of ortho-Helium atoms in the area of
  the sunspot area being excited by the flare's EUV illumination. This
  explanation is based on the obsevation that 1083 nm absorption in the
  sunspot area gets enhanced during the flare. Nevertheless, questions are
  still open and we need further well-devised observations to investigate
  the behavior of sunspot dynamics during flares.

Title: Flare differentially rotates sunspot on Sun's surface
Authors: Liu, Chang; Xu, Yan; Cao, Wenda; Deng, Na; Lee, Jeongwoo;
   Hudson, Hugh S.; Gary, Dale E.; Wang, Jiasheng; Jing, Ju; Wang, Haimin
Bibcode: 2016NatCo...713104L
Altcode: 2016arXiv161002969L
  Sunspots are concentrations of magnetic field visible on the solar
  surface (photosphere). It was considered implausible that solar flares,
  as resulted from magnetic reconnection in the tenuous corona, would
  cause a direct perturbation of the dense photosphere involving bulk
  motion. Here we report the sudden flare-induced rotation of a sunspot
  using the unprecedented spatiotemporal resolution of the 1.6 m New
  Solar Telescope, supplemented by magnetic data from the Solar Dynamics
  Observatory. It is clearly observed that the rotation is non-uniform
  over the sunspot: as the flare ribbon sweeps across, its different
  portions accelerate (up to ~50° h<SUP>-1</SUP>) at different times
  corresponding to peaks of flare hard X-ray emission. The rotation may be
  driven by the surface Lorentz-force change due to the back reaction of
  coronal magnetic restructuring and is accompanied by a downward Poynting
  flux. These results have direct consequences for our understanding of
  energy and momentum transportation in the flare-related phenomena.

Title: High-resolution Observations of a Large Fan-shaped Surge
Authors: Li, Zhen; Fang, Cheng; Guo, Yang; Chen, P. F.; Zou, Peng;
   Cao, Wenda
Bibcode: 2016ApJ...826..217L
Altcode:
  We present high-resolution observations of a large fan-shaped
  surge, which was observed on 2013 June 5 with the current largest
  solar telescope, the 1.6 m New Solar Telescope (NST), at the
  Big Bear Solar Observatory. The observations are made at TiO,
  Hα, and 10830 Å wavebands with a spatial resolution better
  than 0\buildrel{\prime\prime}\over{.} 1 and a full-run cadence of
  ∼30 s. The fan-shaped surge consists of many small-scale threads
  with a typical width of 100 km and a length of up to 200 Mm at the
  maximum. The threads come from material ejections, which start with a
  velocity of several km s<SUP>-1</SUP>, and then accelerate up to 60-80
  km s<SUP>-1</SUP> over six to seven minutes with an acceleration of
  up to 0.2-0.3 km s<SUP>-2</SUP>. The threads can be observed in the
  Hα band and in SDO/AIA 171 Å images as absorbed objects, implying
  that they are cool material ejections. The surge is ejected along open
  magnetic field lines in the extrapolated non-linear force-free field,
  which might actually be a part of a large-scale magnetic loop stretching
  back to the solar surface. After 10-20 minutes, the ejections gradually
  decay and the surge eventually vanishes. The total lifetime is about 35
  minutes. The Hα brightening at the root of the fan-shaped surge implies
  that there is heating in the chromosphere, which could be produced
  by low-atmosphere interchange magnetic reconnection. Our observation
  provides evidence of the reconnection model for the fan-shaped surges,
  which was proposed by Jiang et al.

Title: Data Processing of the magnetograms for the Near InfraRed
    Imaging Spectropolarimeter at Big Bear Solar Observatory
Authors: Ahn, Kwangsu; Cao, Wenda; Shumko, Sergiy; Chae, Jongchul
Bibcode: 2016SPD....47.0207A
Altcode:
  We want to present the processing result of the vector magnetograms from
  the Near InfraRed Imaging Spectropolarimeter (NIRIS) at Big Bear Solar
  Observatory. The NIRIS is a successor of an old magnetograph system
  at BBSO, which equips with the new infrared detector and the improved
  Fabry-Perot filter system. While there are several upgrades to the new
  hardware, there are also some challenges as the data acquisition rate
  increases and we deal with the a larger detector array. The overall
  process includes dark and flat correction, image alignment, de-stretch,
  Stokes parameter selection, calibration of instrumental crosstalk,
  and Milne-Eddington inversion.

Title: Ultra-Narrow Negative Flare Front Observed in Helium-10830
    Å Using the1.6m New Solar Telescope
Authors: Xu, Yan; Cao, Wenda; Ding, Mingde; Kleint, Lucia; Su,
   Jiangtao; Liu, Chang; Ji, Haisheng; Chae, Jongchul; Jing, Ju; Cho,
   Kyuhyoun; Cho, Kyung-Suk; Gary, Dale E.; Wang, Haimin
Bibcode: 2016SPD....47.0633X
Altcode:
  Solar flares are sudden flashes of brightness on the Sun and are often
  associated with coronal mass ejections and solar energetic particles
  that have adverse effects on the near-Earth environment. By definition,
  flares are usually referred to as bright features resulting from excess
  emission. Using the newly commissioned 1.6-m New Solar Telescope at
  Big Bear Solar Observatory, we show a striking “negative” flare
  with a narrow but unambiguous “dark” moving front observed in He I
  10830 Å, which is as narrow as 340 km and is associated with distinct
  spectral characteristics in Hα and Mg II lines. Theoretically, such
  negative contrast in He I 10830 Å can be produced under special
  circumstances by nonthermal electron collisions or photoionization
  followed by recombination. Our discovery, made possible due to
  unprecedented spatial resolution, confirms the presence of the required
  plasma conditions and provides unique information in understanding
  the energy release and radiative transfer in solar flares.

Title: BBSO/NST Observations of the Sudden Differential Rotation of
    a Sunspot Caused by a Major Flare
Authors: Liu, Chang; Xu, Yan; Deng, Na; Cao, Wenda; Lee, Jeongwoo;
   Hudson, Hugh S.; Gary, Dale E.; Wang, Jiasheng; Jing, Ju; Wang, Haimin
Bibcode: 2016SPD....47.0615L
Altcode:
  Sunspots are concentrations of magnetic field visible on the solar
  surface (photosphere), from which the field extends high into the
  corona. Complex plasma motions that drag field in the photosphere can
  build up free energy in the corona that powers solar eruptions. It
  is known that solar flares and the often associated coronal ejections
  (CMEs) can produce various radiations in the low atmosphere. However,
  it was considered implausible that disturbances created in the tenuous
  corona would cause a direct perturbation of the dense photosphere
  involving bulk motion. Here we report the sudden rotational motion of
  a sunspot clearly induced by a major solar flare (SOL2015-06-22T18:23
  M6.6), using the unprecedented spatiotemporal resolution of the 1.6 m
  New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO). It is
  particularly striking that the rotation is not uniform over the sunspot:
  as the flare ribbon sweeps across, its different portions accelerate
  (up to ~50 degree per hour) at different times corresponding to peaks
  of flare hard X-ray emission. The intensity and magnetic field of
  the sunspot also change significantly associated with the flare. Our
  results reveal an intrinsic relationship between the photospheric
  plasma bulk motions and coronal energy release, with direct consequences
  for our understanding of energy and momentum balance in the flare/CME
  phenomenon. This work is mainly supported by NASA grants NNX13AF76G
  and NNX13AG13G (LWS), and NNX16AF72G, and NSF grants AGS 1250818
  and 1408703.

Title: Multi-wavelength Observations of a Subarcsecond Penumbral
    Transient Brightening Event
Authors: Bai, X. Y.; Su, J. T.; Cao, W. D.; Liu, S. Q.; Deng, Y. Y.;
   Priya, T. G.
Bibcode: 2016ApJ...823...60B
Altcode:
  We report a subarcsecond penumbral transient brightening event with the
  high-spatial resolution observations from the 1.6 m New Solar Telescope
  (NST), Interface Region Imaging Spectrograph (IRIS), and the Solar
  Dynamics Observatory. The transient brightening, whose thermal energy
  is in the range of nanoflares, has signatures in the chromosphere,
  the transient region, and the corona. NST's Hα channel reveals the
  fine structure of the event with a width as narrow as 101 km (0.″14),
  which is much smaller than the width from the previous observation. The
  transient brightening lasts for about 3 minutes. It is associated with
  a redshift of about 17 km s<SUP>-1</SUP>, found in the Si IV 1402.77
  Å line and exhibits an inward motion to the umbra with a speed of 87
  km s<SUP>-1</SUP>. The small-scale energy released from the event has a
  multi-temperature component. Spectral analysis of the brightening region
  from IRIS shows that not only the transition region lines such as Si
  IV 1402.77 Å and C II 1334.53 Å, but also the chromospheric Mg II k
  2796.35 Å line are significantly enhanced and broadened. In addition,
  the event can be found in all the extreme-ultraviolet passbands of
  the Atmospheric Imaging Assembly and the derived differential emission
  measure profile increases between 4 and 15 MK (or 6.6 ≤ log T ≤ 7.2)
  in the transient brightening phase. It is possible that the penumbral
  transient brightening event is caused by magnetic reconnection.

Title: High-Resolution Observations of Flare Precursors and Their
    Relationship with Magnetic Channels
Authors: Wang, Haimin; Xu, Yan; Ahn, Kwangsu; Jing, Ju; Liu, Chang;
   Deng, Na; Huang, Nengyi; Gary, Dale E.; Cao, Wenda
Bibcode: 2016SPD....4720501W
Altcode:
  The study of precursors of flares is important for understanding
  the basic magnetic instability leading to solar flares, which can
  aid the forecasting of eruptions potentially related to severe
  space weather effects. Although literatures reported many important
  clues, high-resolution observations of pre-flare activities before a
  well-observed solar flare have been rare. Even rarely, the associated
  magnetic structures in fine scale (below 1") were also observed. In
  this study we take advantage of multiwavelength high-resolution
  observations completely covering the 2015 June 22 M6.6 flare, which
  were obtained under excellent seeing condition with the 1.6 m New Solar
  Telescope (NST) at Big Bear Solar Observatory. The NST data includes
  observations of the H-alpha line in five spectral positions at a spatial
  resolution of 0.1" and magnetograms at a resolution of 0.25". These
  are complemented by IRIS UV observations with a resolution of 0.25". We
  find that there are two episodes of pre-flare brightenings (precursors),
  which are spatially associated with magnetic channels, i.e., elongated
  structures comprising alternating magnetic polarity inversion lines
  (Zirin &amp; Wang, 1993, Nature, 363, 426). The pre-flare chromospheric
  and coronal features reflect an extremely sheared magnetic topology,
  while the initiation of main flare brightenings correspond to a much
  less sheared configuration. RHESSI HXR observations reveal that the
  precursors have both thermal and nonthermal components, and the latter
  is further evidenced by the microwave observations of the newly expanded
  Solar Radio Array at Owens Valley.We further investigate the electric
  current system above the magnetic channels using NLFFF extrapolations,
  which show strong current sheets above the channel structure. This is
  consistent with the MHD modeling of Kusano et al (2012, Ap.J., 760, 31),
  who noted the importance of localized small-scale magnetic structure
  in triggering the eruption of the whole active region. We suggest that
  small-scale magnetic reconnection along the channels destabilizes the
  magnetic structure of the active region and subsequently triggers the
  main M6.6 flare and the associated halo CME.

Title: Unprecedented Fine Structure of a Solar Flare Revealed by
    the 1.6~m New Solar Telescope
Authors: Jing, Ju; Xu, Yan; Cao, Wenda; Liu, Chang; Gary, Dale E.;
   Wang, Haimin
Bibcode: 2016SPD....47.0601J
Altcode:
  Solar flares signify the sudden release of magnetic energy and are
  sources of so called space weather. The fine structures (below 500
  km) of flares are rarely observed and are accessible to only a few
  instruments world-wide. Here we present observation of a solar flare
  using exceptionally high resolution images from the 1.6~m New Solar
  Telescope (NST) equipped with high order adaptive optics at Big Bear
  Solar Observatory (BBSO). The observation reveals the process of the
  flare in unprecedented detail, including the flare ribbon propagating
  across the sunspots, coronal rain (made of condensing plasma) streaming
  down along the post-flare loops, and the chromosphere's response to
  the impact of coronal rain, showing fine-scale brightenings at the
  footpoints of the falling plasma. Taking advantage of the resolving
  power of the NST, we measure the cross-sectional widths of flare
  ribbons, post-flare loops and footpoint brighenings, which generally lie
  in the range of 80-200 km, well below the resolution of most current
  instruments used for flare studies. Confining the scale of such fine
  structure provides an essential piece of information in modeling the
  energy transport mechanism of flares, which is an important issue in
  solar and plasma physics.

Title: Unprecedented Fine Structure of a Solar Flare Revealed by
    the 1.6 m New Solar Telescope
Authors: Jing, Ju; Xu, Yan; Cao, Wenda; Liu, Chang; Gary, Dale;
   Wang, Haimin
Bibcode: 2016NatSR...624319J
Altcode: 2016arXiv160408562J
  Solar flares signify the sudden release of magnetic energy and
  are sources of so called space weather. The fine structures (below
  500 km) of flares are rarely observed and are accessible to only a few
  instruments world-wide. Here we present observation of a solar flare
  using exceptionally high resolution images from the 1.6 m New Solar
  Telescope (NST) equipped with high order adaptive optics at Big Bear
  Solar Observatory (BBSO). The observation reveals the process of the
  flare in unprecedented detail, including the flare ribbon propagating
  across the sunspots, coronal rain (made of condensing plasma) streaming
  down along the post-flare loops, and the chromosphere’s response to
  the impact of coronal rain, showing fine-scale brightenings at the
  footpoints of the falling plasma. Taking advantage of the resolving
  power of the NST, we measure the cross-sectional widths of flare
  ribbons, post-flare loops and footpoint brighenings, which generally lie
  in the range of 80-200 km, well below the resolution of most current
  instruments used for flare studies. Confining the scale of such fine
  structure provides an essential piece of information in modeling the
  energy transport mechanism of flares, which is an important issue in
  solar and plasma physics.

Title: Resolving the Fan-spine Reconnection Geometry of a Small-scale
    Chromospheric Jet Event with the New Solar Telescope
Authors: Zeng, Zhicheng; Chen, Bin; Ji, Haisheng; Goode, Philip R.;
   Cao, Wenda
Bibcode: 2016ApJ...819L...3Z
Altcode: 2016arXiv160204237Z
  Jets are ubiquitously present in both quiet and active regions on the
  Sun. They are widely believed to be driven by magnetic reconnection. A
  fan-spine structure has been frequently reported in some coronal jets
  and flares, and has been regarded as a signature of ongoing magnetic
  reconnection in a topology consisting of a magnetic null connected by
  a fan-like separatrix surface and a spine. However, for small-scale
  chromospheric jets, clear evidence of such structures is rather
  rare, although it has been implied in earlier works that showed an
  inverted-Y-shaped feature. Here we report high-resolution (0.″16)
  observations of a small-scale chromospheric jet obtained by the New
  Solar Telescope (NST) using 10830 Å filtergrams. Bi-directional flows
  were observed across the separatrix regions in the 10830 Å images,
  suggesting that the jet was produced due to magnetic reconnection. At
  the base of the jet, a fan-spine structure was clearly resolved by
  the NST, including the spine and the fan-like surface, as well as the
  loops before and after the reconnection. A major part of this fan-spine
  structure, with the exception of its bright footpoints and part of the
  base arc, was invisible in the extreme ultraviolet and soft X-ray images
  (observed by the Atmosphere Imaging Assembly and the X-Ray Telescope,
  respectively), indicating that the reconnection occurred in the upper
  chromosphere. Our observations suggest that the evolution of this
  chromospheric jet is consistent with a two-step reconnection scenario
  proposed by Török et al.

Title: Bidirectional Outflows as Evidence of Magnetic Reconnection
    Leading to a Solar Microflare
Authors: Hong, Jie; Ding, M. D.; Li, Ying; Yang, Kai; Cheng, Xin;
   Chen, Feng; Fang, Cheng; Cao, Wenda
Bibcode: 2016ApJ...820L..17H
Altcode: 2016arXiv160300941H
  Magnetic reconnection is a rapid energy release process that is believed
  to be responsible for flares on the Sun and stars. Nevertheless, such
  flare-related reconnection is mostly detected to occur in the corona,
  while there have been few studies concerning the reconnection in the
  chromosphere or photosphere. Here, we present both spectroscopic and
  imaging observations of magnetic reconnection in the chromosphere
  leading to a microflare. During the flare peak time, chromospheric
  line profiles show significant blueshifted/redshifted components
  on the two sides of the flaring site, corresponding to upflows and
  downflows with velocities of ±(70-80) km s<SUP>-1</SUP>, comparable
  with the local Alfvén speed as expected by the reconnection in
  the chromosphere. The three-dimensional nonlinear force-free field
  configuration further discloses twisted field lines (a flux rope)
  at a low altitude, cospatial with the dark threads in He I 10830 Å
  images. The instability of the flux rope may initiate the flare-related
  reconnection. These observations provide clear evidence of magnetic
  reconnection in the chromosphere and show the similar mechanisms of
  a microflare to those of major flares.

Title: Ultra-narrow Negative Flare Front Observed in Helium-10830
    Å Using the 1.6 m New Solar Telescope
Authors: Xu, Yan; Cao, Wenda; Ding, Mingde; Kleint, Lucia; Su,
   Jiangtao; Liu, Chang; Ji, Haisheng; Chae, Jongchul; Jing, Ju; Cho,
   Kyuhyoun; Cho, Kyungsuk; Gary, Dale; Wang, Haimin
Bibcode: 2016ApJ...819...89X
Altcode: 2016arXiv160104729X
  Solar flares are sudden flashes of brightness on the Sun and are often
  associated with coronal mass ejections and solar energetic particles
  that have adverse effects on the near-Earth environment. By definition,
  flares are usually referred to as bright features resulting from excess
  emission. Using the newly commissioned 1.6 m New Solar Telescope at
  Big Bear Solar Observatory, we show a striking “negative” flare
  with a narrow but unambiguous “dark” moving front observed in He I
  10830 Å, which is as narrow as 340 km and is associated with distinct
  spectral characteristics in Hα and Mg II lines. Theoretically, such
  negative contrast in He I 10830 Å can be produced under special
  circumstances by nonthermal electron collisions or photoionization
  followed by recombination. Our discovery, made possible due to
  unprecedented spatial resolution, confirms the presence of the required
  plasma conditions and provides unique information in understanding
  the energy release and radiative transfer in astronomical objects.

Title: Observations of Oppositely Directed Umbral Wavefronts Rotating
    in Sunspots Obtained from the New Solar Telescope of BBSO
Authors: Su, J. T.; Ji, K. F.; Cao, W.; Banerjee, D.; Priya, T. G.;
   Zhao, J. S.; Bai, X. Y.; Chen, J.; Zhang, M.; Ji, H. S.
Bibcode: 2016ApJ...817..117S
Altcode:
  We study the umbral waves as observed by chromospheric imaging
  observations of two sunspots with the New Solar Telescope at the
  Big Bear Solar Observatory. We find that the wavefronts (WFs) rotate
  clockwise and form a one-armed spiral structure in the first sunspot,
  whereas two- and three-armed structures arise in the second sunspot
  where the WFs rotate anticlockwise and clockwise alternately. All the
  spiral arms display propagation outwards and become running penumbral
  waves once they cross the umbral boundaries, suggesting that the
  umbral and penumbral waves propagate along the same inclined field
  lines. We propose that the one-armed spiral structure may be produced
  by the WF reflections at the chromospheric umbral light bridge, and the
  multi-armed spirals may be related to the twist of the magnetic field
  in the umbra. Additionally, the time lag of the umbral oscillations in
  between the data of He I 10830 Å and {{H}}α -0.4 Å is ∼17 s, and
  it is ∼60 s for that in between the data of 304 Å and {{H}}α -0.4
  Å. This indicates that these disturbances are slow magnetoacoustic
  waves in nature, and that they propagate upward along the inclined
  lines with fast radial expansions causing horizontal velocities of
  the running waves.

Title: Interference of the Running Waves at Light Bridges of a Sunspot
Authors: Su, J. T.; Ji, K. F.; Banerjee, D.; Cao, W. D.; Priya, T. G.;
   Zhao, J. S.; Yu, S. J.; Ji, H. S.; Zhang, M.
Bibcode: 2016ApJ...816...30S
Altcode:
  The observations of chromospheric oscillations of two umbral light
  bridges (LBs) within a sunspot from NOAA Active Region 12127 are
  presented. It was found that the running umbral waves with periods
  of 2.2-2.6 minutes underwent very fast damping before approaching
  umbral boundaries, while those with higher periods (&gt;2.6 minutes)
  could propagate outside umbrae. On two sides of each LB adjacent to
  umbrae, the cross-wavelet spectra displayed that the oscillations on
  them had a common significant power region with dominant frequencies
  of 2-6 minutes and phase differences of ∼90°. A counterstream of
  two running umbral waves in the 2-6 minute frequency range propagated
  toward the LBs, where they encountered each other and gave rise to
  constructive or even destructive interference on the LBs. In addition,
  the velocity and density perturbations on the LBs were found in opposite
  phases suggesting that the perturbations were caused by the downward
  propagating waves.

Title: Statistical Analysis of Filament Features Based on the Hα
    Solar Images from 1988 to 2013 by Computer Automated Detection Method
Authors: Hao, Q.; Fang, C.; Cao, W.; Chen, P. F.
Bibcode: 2015ApJS..221...33H
Altcode: 2015arXiv151104692H
  We improve our filament automated detection method which was proposed
  in our previous works. It is then applied to process the full disk
  Hα data mainly obtained by the Big Bear Solar Observatory from 1988
  to 2013, spanning nearly three solar cycles. The butterfly diagrams
  of the filaments, showing the information of the filament area,
  spine length, tilt angle, and the barb number, are obtained. The
  variations of these features with the calendar year and the latitude
  band are analyzed. The drift velocities of the filaments in different
  latitude bands are calculated and studied. We also investigate the
  north-south (N-S) asymmetries of the filament numbers in total and in
  each subclass classified according to the filament area, spine length,
  and tilt angle. The latitudinal distribution of the filament number
  is found to be bimodal. About 80% of all the filaments have tilt
  angles within [0°, 60°]. For the filaments within latitudes lower
  (higher) than 50°, the northeast (northwest) direction is dominant
  in the northern hemisphere and the southeast (southwest) direction is
  dominant in the southern hemisphere. The latitudinal migrations of the
  filaments experience three stages with declining drift velocities in
  each of solar cycles 22 and 23, and it seems that the drift velocity
  is faster in shorter solar cycles. Most filaments in latitudes lower
  (higher) than 50° migrate toward the equator (polar region). The
  N-S asymmetry indices indicate that the southern hemisphere is the
  dominant hemisphere in solar cycle 22 and the northern hemisphere is
  the dominant one in solar cycle 23.

Title: Detection of a Fine-scale Discontinuity of Photospheric
    Magnetic Fields Associated with Solar Coronal Loop Brightenings
Authors: Song, Donguk; Chae, Jongchul; Park, Soyoung; Cho, Kyung-Suk;
   Lim, Eun-Kyung; Ahn, Kwangsu; Cao, Wenda
Bibcode: 2015ApJ...810L..16S
Altcode:
  We present the transient brightening of a coronal loop and an associated
  fine-scale magnetic discontinuity detected in the photosphere. Utilizing
  the high-resolution data taken with the Fast Imaging Solar Spectrograph
  and InfraRed Imaging Magnetograph of the New Solar Telescope at Big
  Bear Solar Observatory, we detect a narrow lane of intense horizontal
  magnetic field representing a magnetic discontinuity. It was visible
  as a dark lane partially encircling a pore in the continuum image,
  and was located near one of the footpoints of a small coronal loop
  that experienced transient brightenings. The horizontal field strength
  gradually increased before the loop brightening, and then rapidly
  decreased in the impulsive phase of the brightening, suggesting the
  increase of the magnetic non-potentiality at the loop footpoint and the
  sudden release of magnetic energy via magnetic reconnection. Our results
  support the nanoflare theory that coronal heating events are caused
  by magnetic reconnection events at fine-scale magnetic discontinuities.

Title: Objective Image-Quality Assessment for High-Resolution
    Photospheric Images by Median Filter-Gradient Similarity
Authors: Deng, Hui; Zhang, Dandan; Wang, Tianyu; Ji, Kaifan; Wang,
   Feng; Liu, Zhong; Xiang, Yongyuan; Jin, Zhenyu; Cao, Wenda
Bibcode: 2015SoPh..290.1479D
Altcode: 2015SoPh..tmp...34D
  All next-generation ground-based and space-based solar telescopes
  require a good quality-assessment metric to evaluate their imaging
  performance. In this paper, a new image quality metric, the median
  filter-gradient similarity (MFGS) is proposed for photospheric
  images. MFGS is a no-reference/blind objective image-quality
  metric (IQM) by a measurement result between 0 and 1 and has been
  performed on short-exposure photospheric images captured by the New
  Vacuum Solar Telescope (NVST) of the Fuxian Solar Observatory and
  by the Solar Optical Telescope (SOT) onboard the Hinode satellite,
  respectively. The results show that (1) the measured value of the MFGS
  changes monotonically from 1 to 0 with degradation of image quality;
  (2) there exists a linear correlation between the measured values
  of the MFGS and the root-mean-square contrast (RMS-contrast) of the
  granulation; (3) the MFGS is less affected by the image contents than
  the granular RMS-contrast. Overall, the MFGS is a good alternative
  for the quality assessment of photospheric images.

Title: Negative Flare Emissions Observed in Euv By SDO/AIA
Authors: Xu, Y.; Liu, C.; Cao, W.; Jing, J.; Wang, H.
Bibcode: 2014AGUFMSH51C4165X
Altcode:
  In this study, we present a large flare showing negative emissions
  in the EUV passbands observed by SDO/AIA. Contrary to ordinary flare
  emission represented by an increase of intensity, negative flare
  emission refers to as a decrease of intensity during flares. In the
  literature, negative flare emissions were usually reported by stellar
  observations. Only a few negative solar flares were observed in He
  I D3 in 1970s and one event observed in the near Infrared at 8542
  Å in 2001. On 2014-Jan-07, an X1.2 flare occurred near the solar
  disk center with a complex magnetic configuration, showing multiple
  flare ribbons. Among them a remote flare ribbon is located to the
  southwest from the flare core region. A small portion of the remote
  ribbon became darkened from about 18:45 UT, while the rest of the
  ribbon remained bright. This darkening lasted for more than one hour
  and did not show obvious motion. Therefore, we exclude the possibility
  of transient coronal hole associated with EUV waves. By comparing with
  SDO/HMI LOS magnetograms, we find that the negative flare regions are
  associated with weak magnetic fields, lower than 50 Gauss. In contrast,
  the bright flare ribbons are co-spatial with strong magnetic fields
  above 200 Gauss. Furthermore, we investigate the properties of the
  negative emission by examining the temporal evolution of its intensity
  and area. Finally, we discuss the possible mechanisms in generating
  the negative emissions.

Title: Active Region Coronal Rain Event Observed by the Fast Imaging
    Solar Spectrograph on the NST
Authors: Ahn, Kwangsu; Chae, Jongchul; Cho, Kyung-Suk; Song, Donguk;
   Yang, Heesu; Goode, Philip R.; Cao, Wenda; Park, Hyungmin; Nah,
   Jakyung; Jang, Bi-Ho; Park, Young-Deuk
Bibcode: 2014SoPh..289.4117A
Altcode: 2014SoPh..tmp...98A
  The Fast Imaging Solar Spectrograph (FISS) is being operated on the New
  Solar Telescope of the Big Bear Solar Observatory. It simultaneously
  records spectra of Hα and Ca II 8542 Å lines, and this dual-spectra
  measurement provides an estimate of the temperature and nonthermal
  speed components. We observed a loop structure in AR 11305 using the
  FISS, SDO/AIA, and STEREO/EUVI in 304 Å, and found plasma material
  falling along the loop from a coronal height into the umbra of a
  sunspot, which accelerated up to 80 km s<SUP>−1</SUP>. We also
  observed C2 and C7 flare events near the loop. The temperature of the
  downflows was in the range of 10 000 - 33 000 K, increasing toward
  the umbra. The temperature of the flow varied with time, and the
  temperature near the footpoint rose immediately after the C7 flare,
  but the temperature toward the umbra remained the same. There seemed
  to be a temporal correlation between the amount of downflow material
  and the observed C-class flares. The downflows decreased gradually soon
  after the flares and then increased after a few hours. These high-speed
  red-shift events occurred continuously during the observations. The
  flows observed on-disk in Hα and Ca II 8542 Å appeared as fragmented,
  fuzzy condensed material falling from the coronal heights when seen
  off-limb with STEREO/EUVI at 304 Å. Based on these observations,
  we propose that these flows were an on-disk signature of coronal rain.

Title: A Flare Observed in Coronal, Transition Region, and Helium
    I 10830 Å Emissions
Authors: Zeng, Zhicheng; Qiu, Jiong; Cao, Wenda; Judge, Philip G.
Bibcode: 2014ApJ...793...87Z
Altcode: 2014arXiv1408.0236Z
  On 2012 June 17, we observed the evolution of a C-class flare associated
  with the eruption of a filament near a large sunspot in the active
  region NOAA 11504. We obtained high spatial resolution filtergrams
  using the 1.6 m New Solar Telescope at the Big Bear Solar Observatory
  in broadband TiO at 706 nm (bandpass: 10 Å) and He I 10830 Å narrow
  band (bandpass: 0.5 Å, centered 0.25 Å to the blue). We analyze the
  spatio-temporal behavior of the He I 10830 Å data, which were obtained
  over a 90''×90'' field of view with a cadence of 10 s. We also analyze
  simultaneous data from the Atmospheric Imaging Assembly and Extreme
  Ultraviolet Variability Experiment instruments on board the Solar
  Dynamics Observatory spacecraft, and data from the Reuven Ramaty High
  Energy Solar Spectroscopic Imager and GOES spacecrafts. Non-thermal
  effects are ignored in this analysis. Several quantitative aspects
  of the data, as well as models derived using the "0D" enthalpy-based
  thermal evolution of loops model code, indicate that the triplet
  states of the 10830 Å multiplet are populated by photoionization of
  chromospheric plasma followed by radiative recombination. Surprisingly,
  the He II 304 Å line is reasonably well matched by standard emission
  measure calculations, along with the C IV emission which dominates
  the Atmosphere Imaging Assembly 1600 Å channel during flares. This
  work lends support to some of our previous work combining X-ray, EUV,
  and UV data of flares to build models of energy transport from corona
  to chromosphere.

Title: Spectral Observations of Ellerman Bombs and Fitting with a
    Two-cloud Model
Authors: Hong, Jie; Ding, M. D.; Li, Ying; Fang, Cheng; Cao, Wenda
Bibcode: 2014ApJ...792...13H
Altcode: 2014arXiv1407.3048H
  We study the Hα and Ca II 8542 Å line spectra of four typical
  Ellerman bombs (EBs) in the active region NOAA 11765 on 2013 June 6,
  observed with the Fast Imaging Solar Spectrograph installed at the 1.6
  m New Solar Telescope at Big Bear Solar Observatory. Considering that
  EBs may occur in a restricted region in the lower atmosphere, and that
  their spectral lines show particular features, we propose a two-cloud
  model to fit the observed line profiles. The lower cloud can account
  for the wing emission, and the upper cloud is mainly responsible for the
  absorption at line center. After choosing carefully the free parameters,
  we get satisfactory fitting results. As expected, the lower cloud shows
  an increase of the source function, corresponding to a temperature
  increase of 400-1000 K in EBs relative to the quiet Sun. This is
  consistent with previous results deduced from semi-empirical models and
  confirms that local heating occurs in the lower atmosphere during the
  appearance of EBs. We also find that the optical depths can increase
  to some extent in both the lower and upper clouds, which may result
  from either direct heating in the lower cloud, or illumination by an
  enhanced radiation on the upper cloud. The velocities derived from
  this method, however, are different from those obtained using the
  traditional bisector method, implying that one should be cautious when
  interpreting this parameter. The two-cloud model can thus be used as
  an efficient method to deduce the basic physical parameters of EBs.

Title: AO-308: the high-order adaptive optics system at Big Bear
    Solar Observatory
Authors: Shumko, Sergey; Gorceix, Nicolas; Choi, Seonghwan; Kellerer,
   Aglaé; Cao, Wenda; Goode, Philip R.; Abramenko, Volodymyr; Richards,
   Kit; Rimmele, Thomas R.; Marino, Jose
Bibcode: 2014SPIE.9148E..35S
Altcode:
  In this paper we present Big Bear Solar Observatory's (BBSO) newest
  adaptive optics system - AO-308. AO-308 is a result of collaboration
  between BBSO and National Solar Observatory (NSO). AO-308 uses a 357
  actuators deformable mirror (DM) from Xinetics and its wave front sensor
  (WFS) has 308 sub-apertures. The WFS uses a Phantom V7.3 camera which
  runs at 2000 Hz with the region of interest of 416×400 pixels. AO-308
  utilizes digital signal processors (DSPs) for image processing. AO-308
  has been successfully used during the 2013 observing season. The system
  can correct up to 310 modes providing diffraction limited images at
  all wavelengths of interest.

Title: Control and operation of the 1.6 m New Solar Telescope in
    Big Bear
Authors: Varsik, J.; Plymate, C.; Goode, P.; Kosovichev, A.; Cao,
   W.; Coulter, R.; Ahn, K.; Gorceix, N.; Shumko, S.
Bibcode: 2014SPIE.9147E..5DV
Altcode:
  The 1.6m New Solar Telescope (NST) has developed a modern and
  comprehensive suite of instruments which allow high resolution
  observations of the Sun. The current instrument package comprises
  diffraction limited imaging, spectroscopic and polarimetric instruments
  covering the wavelength range from 0.4 to 5.0 microns. The instruments
  include broadband imaging, visible and near-infrared scanning
  Fabry-Perot interferometers, an imaging spectropolarimeter,
  a fast visible-light imaging spectrograph, and a unique new
  scanning cryogenic infrared spectrometer/spectropolarimeter
  that is nearing completion. Most instruments are operated with
  a 308 subaperture adaptive optics system, while the thermal-IR
  spectrometer has a correlation tracker. This paper reports on the
  current observational programs and operational performance of the
  telescope and instrumentation. The current control, data processing,
  and archiving systems are also briefly discussed.

Title: Optical design of the Big Bear Solar Observatory's
    multi-conjugate adaptive optics system
Authors: Zhang, Xianyu; Gorceix, Nicolas; Schmidt, Dirk; Goode,
   Philip R.; Cao, Wenda; Rimmele, Thomas R.; Coulter, Roy
Bibcode: 2014SPIE.9148E..50Z
Altcode:
  A multi-conjugate adaptive optics (MCAO) system is being built for the
  world's largest aperture 1.6m solar telescope, New Solar Telescope,
  at the Big Bear Solar Observatory (BBSO). The BBSO MCAO system employs
  three deformable mirrors to enlarge the corrected field of view. In
  order to characterize the MCAO performance with different optical
  configurations and DM conjugated altitudes, the BBSO MCAO setup also
  needs to be flexible. In this paper, we present the optical design of
  the BBSO MCAO system.

Title: Study of Two Successive Three-ribbon Solar Flares Using
    BBSO/NST Observations
Authors: Wang, Haimin; Liu, Chang; Deng, Na; Zeng, Zhicheng; Xu, Yan;
   Jing, Ju; Cao, Wenda
Bibcode: 2014AAS...22412304W
Altcode:
  We studied two rarely observed three-ribbon flares (M1.9 and C9.2) on
  2012 July 6 in NOAA AR 11515, which we found using Hα observations
  of 0.1 arcsec resolution from the New Solar Telescope and Ca II
  H images from Hinode. The flaring site is characterized by an
  intriguing "fish-bone-like" morphology evidenced by both Halpha
  images and a nonlinear force-free field (NLFFF) extrapolation,
  where two semi-parallel rows of low-lying, sheared loops connect an
  elongated, parasitic negative field with the sandwiching positive
  fields. The NLFFF model also shows that the two rows of loops are
  asymmetric in height and have opposite twists, and are enveloped by
  large-scale field lines including open fields. The two flares occurred
  in succession within half an hour and are located at the two ends of
  the flaring region. The three ribbons of each flare run parallel to
  the magnetic polarity inversion line, with the outer two lying in the
  positive field and the central one in the negative field. Both flares
  show surge-like flows in Halpha apparently toward the remote region,
  while the C9.2 flare is also accompanied by EUV jets possibly along
  the open field lines. Interestingly, the 12-25 keV hard X-ray sources
  of the C9.2 flare first line up with the central ribbon then shift to
  concentrate on the top of the higher branch of loops. These results
  are discussed in favor of reconnection along the coronal null line,
  producing the three flare ribbons and the associated ejections.

Title: A FLARE OBSERVED IN CORONAL, TRANSITION REGION AND HELIUM I
    10830 Å EMISSIONS
Authors: Zeng, Zhicheng; Qiu, Jiong; Cao, Wenda; Judge, Philip G.
Bibcode: 2014AAS...22412309Z
Altcode:
  On June 17, 2012, we observed the evolution of a C-class flare
  associated with the eruption of a filament near a large sunspot in
  the active region NOAA 11504. We obtained high spatial resolution
  filtergrams using the 1.6 m New Solar Telescope at the Big Bear
  Solar Observatory in TiO broad-band (bandpass: 10 Å)and He I 10830
  Å narrow-band (bandpass: 0.5 Å, centered 0.25 Å to the blue). We
  analyze the spatio-temporal behavior of the He I 10830 Å data, which
  were obtained over a 90×90 arcsends field of view with a cadence
  of 10 sec. We also analyze simultaneous data from the Atmospheric
  Imaging Assembly and Extreme Ultraviolet Variability Experiment
  instruments on board the Solar Dynamics Observatoryspacecraft, and
  data from Reuven Ramaty High Energy Solar Spectroscopic Imager and
  GOES spacecrafts. Several quantitative aspects of the data, as well as
  models derived using the “0D” Enthalpy-Based Thermal Evolution of
  Loops model (EBTEL: Klimchuk et al. 2008) code, indicate that the 10830
  Å multiplet is formed primarily by photoionization of chromospheric
  plasma followed by radiative recombination. Surprisingly, the He II
  304 Å line is reasonably well matched by standard emission measure
  calculations, along with the C IV emission which dominates the AIA
  1600 Å channel during flares. This work lends support to some of our
  previous work combining X-ray, EUV and UV data of flares to buildmodels
  of energy transport from corona to chromosphere.

Title: High-resolution Observation of the Smallest Ellerman Bombs
Authors: Fang, Cheng; Tang, Yu-hua; Li, Zhen; Xu, Zhi; Cao, Wenda;
   Guo, Yang
Bibcode: 2014cosp...40E.834F
Altcode:
  By use of the high-resolution spectral data obtained with the largest
  solar telescope NST/BBSO in 2013 June, the characteristics of 3
  well-observed smallest EBs have been analyzed. Their sizes are less
  than 0.5 are second and their durations are only 2-3 minutes. The
  most obvious characteristic of the EB spectra is the two emission
  bumps at the two wings of both Hα and CaII 8542 Å lines. They are
  located near the longitudinal magnetic polarity inversion lines and
  accompanied by mass motions. The semi-empirical atmospheric models
  for the EBs are computed. The common characteristic is the heating in
  the upper photosphere. The temperature enhancement is about 400-500
  K. These imply that the EBs can probably be produced by the magnetic
  reconnection in the solar lower atmosphere. The radiative and kinetic
  energies of the EBs are estimated, and the possible mechanism of
  triggering the EBs is discussed.

Title: Study of Two Successive Three-ribbon Solar Flares on 2012
    July 6
Authors: Wang, Haimin; Liu, Chang; Deng, Na; Zeng, Zhicheng; Xu, Yan;
   Jing, Ju; Cao, Wenda
Bibcode: 2014ApJ...781L..23W
Altcode: 2013arXiv1312.6649W
  This Letter reports two rarely observed three-ribbon flares (M1.9
  and C9.2) on 2012 July 6 in NOAA AR 11515, which we found using Hα
  observations of 0.''1 resolution from the New Solar Telescope and
  Ca II H images from Hinode. The flaring site is characterized by an
  intriguing "fish-bone-like" morphology evidenced by both Hα images
  and a nonlinear force-free field (NLFFF) extrapolation, where two
  semi-parallel rows of low-lying, sheared loops connect an elongated,
  parasitic negative field with the sandwiching positive fields. The
  NLFFF model also shows that the two rows of loops are asymmetric in
  height and have opposite twists, and are enveloped by large-scale field
  lines including open fields. The two flares occurred in succession
  within half an hour and are located at the two ends of the flaring
  region. The three ribbons of each flare run parallel to the magnetic
  polarity inversion line, with the outer two lying in the positive
  field and the central one in the negative field. Both flares show
  surge-like flows in Hα apparently toward the remote region, while
  the C9.2 flare is also accompanied by EUV jets possibly along the
  open field lines. Interestingly, the 12-25 keV hard X-ray sources of
  the C9.2 flare first line up with the central ribbon then shift to
  concentrate on the top of the higher branch of loops. These results
  are discussed in favor of reconnection along the coronal null line,
  producing the three flare ribbons and the associated ejections.

Title: Temperature of Solar Prominences Obtained with the Fast Imaging
    Solar Spectrograph on the 1.6 m New Solar Telescope at the Big Bear
    Solar Observatory
Authors: Park, Hyungmin; Chae, Jongchul; Song, Donguk; Maurya, Ram
   Ajor; Yang, Heesu; Park, Young-Deuk; Jang, Bi-Ho; Nah, Jakyoung; Cho,
   Kyung-Suk; Kim, Yeon-Han; Ahn, Kwangsu; Cao, Wenda; Goode, Philip R.
Bibcode: 2013SoPh..288..105P
Altcode:
  We observed solar prominences with the Fast Imaging Solar Spectrograph
  (FISS) at the Big Bear Solar Observatory on 30 June 2010 and 15 August
  2011. To determine the temperature of the prominence material, we
  applied a nonlinear least-squares fitting of the radiative transfer
  model. From the Doppler broadening of the Hα and Ca II lines, we
  determined the temperature and nonthermal velocity separately. The
  ranges of temperature and nonthermal velocity were 4000 - 20 000 K and
  4 - 11 km s<SUP>−1</SUP>. We also found that the temperature varied
  much from point to point within one prominence.

Title: Fast Imaging Solar Spectrograph of the 1.6 Meter New Solar
    Telescope at Big Bear Solar Observatory
Authors: Chae, Jongchul; Park, Hyung-Min; Ahn, Kwangsu; Yang, Heesu;
   Park, Young-Deuk; Nah, Jakyoung; Jang, Bi Ho; Cho, Kyung-Suk; Cao,
   Wenda; Goode, Philip R.
Bibcode: 2013SoPh..288....1C
Altcode: 2012SoPh..tmp..248C
  For high resolution spectral observations of the Sun - particularly
  its chromosphere, we have developed a dual-band echelle spectrograph
  named Fast Imaging Solar Spectrograph (FISS), and installed it in a
  vertical optical table in the Coudé Lab of the 1.6 meter New Solar
  Telescope at Big Bear Solar Observatory. This instrument can cover any
  part of the visible and near-infrared spectrum, but it usually records
  the Hα band and the Ca II 8542 Å band simultaneously using two CCD
  cameras, producing data well suited for the study of the structure and
  dynamics of the chromosphere and filaments/prominences. The instrument
  does imaging of high quality using a fast scan of the slit across the
  field of view with the aid of adaptive optics. We describe its design,
  specifics, and performance as well as data processing

Title: Doppler Shifts of the Hα Line and the Ca II 854.2 nm Line
    in a Quiet Region of the Sun Observed with the FISS/NST
Authors: Chae, Jongchul; Park, Hyung-Min; Ahn, Kwangsu; Yang, Heesu;
   Park, Young-Deuk; Cho, Kyung-Suk; Cao, Wenda
Bibcode: 2013SoPh..288...89C
Altcode:
  The characteristics of Doppler shifts in a quiet region of the Sun
  are compared between the Hα line and the Ca II infrared line at 854.2
  nm. A small area of 16″×40″ was observed for about half an hour
  with the Fast Imaging Solar Spectrograph (FISS) of the 1.6 meter New
  Solar Telescope (NST) at Big Bear Solar Observatory. The observed area
  contains a network region and an internetwork region, and identified
  in the network region are fibrils and bright points. We infer Doppler
  velocity v<SUB>m</SUB> from each line profile at each individual point
  with the lambdameter method as a function of half wavelength separation
  Δλ. It is confirmed that the bisector of the spatially averaged Ca II
  line profile has an inverse C-shape with a significant peak redshift of
  + 1.8 km s<SUP>−1</SUP>. In contrast, the bisector of the spatially
  averaged Hα line profile has a C-shape with a small peak blueshift of
  − 0.5 km s<SUP>−1</SUP>. In both lines, the bisectors of bright
  network points are significantly redshifted not only at the line
  centers, but also at the wings. The Ca II Doppler shifts are found
  to be correlated with the Hα ones with the strongest correlation
  occurring in the internetwork region. Moreover, we find that here the
  Doppler shifts in the two lines are essentially in phase. We discuss
  the physical implications of our results in view of the formation of
  the Hα line and Ca II 854.2 nm line in the quiet region chromosphere.

Title: Connection Between Chromospheric Events and Photospheric
    Dynamics
Authors: Anđić, A.; Chae, J.; Park, H.; Yang, H.; Ahn, K.; Cao,
   W.; Park, Y. D.
Bibcode: 2013SoPh..288...55A
Altcode: 2012SoPh..tmp..232A
  We analyzed chromospheric events and their connection to oscillation
  phenomena and photospheric dynamics. The observations were done with the
  New Solar Telescope of Big Bear Solar Observatory using a broad-band
  imager at the wavelength of a TiO band and FISS spectrograph scanning
  Ca II and Hα spectral lines. The event in Ca II showed strong plasma
  flows and propagating waves in the chromosphere. The movement of
  the footpoints of flux tubes in the photosphere indicated flux tube
  entanglement and magnetic reconnection as a possible cause of the
  observed brightening and waves propagating in the chromosphere. An
  upward propagating train of waves was observed at the site of the
  downflow event in Hα. There was no clear relationship between
  photospheric waves and the Ca II and Hα events. Our observations
  indicate that chromospheric waves that were previously thought to
  originate from the photosphere may be generated by some events in the
  chromosphere as well.

Title: Infrared Observations from the New Solar Telescope at Big Bear
Authors: Goode, Philip R.; Cao, Wenda
Bibcode: 2013SoPh..287..315G
Altcode:
  The 1.6 m clear aperture solar telescope in Big Bear is operational and
  with its adaptive optics (AO) system it provides diffraction limited
  solar imaging and polarimetry in the near-infrared (NIR). While the AO
  system is being upgraded to provide diffraction limited imaging at bluer
  wavelengths, the instrumentation and observations are concentrated in
  the NIR. The New Solar Telescope (NST) operates in campaigns, making it
  the ideal ground-based telescope to provide complementary/supplementary
  data to SDO and Hinode. The NST makes photometric observations in Hα
  (656.3 nm) and TiO (705.6 nm) among other lines. As well, the NST
  collects vector magnetograms in the 1565 nm lines and is beginning
  such observations in 1083.0 nm. Here we discuss the relevant NST
  instruments, including AO, and present some results that are germane
  to NASA solar missions.

Title: Study of Rapid Formation of a δ Sunspot Associated with the
    2012 July 2 C7.4 Flare Using High-resolution Observations of the
    New Solar Telescope
Authors: Wang, Haimin; Liu, Chang; Wang, Shuo; Deng, Na; Xu, Yan;
   Jing, Ju; Cao, Wenda
Bibcode: 2013ApJ...774L..24W
Altcode: 2013arXiv1308.2639W
  Rapid, irreversible changes of magnetic topology and sunspot
  structure associated with flares have been systematically observed
  in recent years. The most striking features include the increase of
  the horizontal field at the polarity inversion line (PIL) and the
  co-spatial penumbral darkening. A likely explanation of the above
  phenomenon is the back reaction to the coronal restructuring after
  eruptions: a coronal mass ejection carries the upward momentum while
  the downward momentum compresses the field lines near the PIL. Previous
  studies could only use low-resolution (above 1'') magnetograms and
  white-light images. Therefore, the changes are mostly observed for
  X-class flares. Taking advantage of the 0.''1 spatial resolution
  and 15 s temporal cadence of the New Solar Telescope at the Big Bear
  Solar Observatory, we report in detail the rapid formation of sunspot
  penumbra at the PIL associated with the C7.4 flare on 2012 July 2. It
  is unambiguously shown that the solar granulation pattern evolves to
  an alternating dark and bright fibril structure, the typical pattern
  of penumbra. Interestingly, the appearance of such a penumbra creates
  a new δ sunspot. The penumbral formation is also accompanied by the
  enhancement of the horizontal field observed using vector magnetograms
  from the Helioseismic and Magnetic Imager. We explain our observations
  as being due to the eruption of a flux rope following magnetic
  cancellation at the PIL. Subsequently, the re-closed arcade fields
  are pushed down toward the surface to form the new penumbra. NLFFF
  extrapolation clearly shows both the flux rope close to the surface
  and the overlying fields.

Title: Characteristic Length of Energy-containing Structures at the
    Base of a Coronal Hole
Authors: Abramenko, V. I.; Zank, G. P.; Dosch, A.; Yurchyshyn, V. B.;
   Goode, P. R.; Ahn, K.; Cao, W.
Bibcode: 2013ApJ...773..167A
Altcode: 2013arXiv1307.4421A
  An essential parameter for models of coronal heating and fast solar
  wind acceleration that rely on the dissipation of MHD turbulence is
  the characteristic energy-containing length λ<SUB></SUB> of the
  squared velocity and magnetic field fluctuations (u <SUP>2</SUP>
  and b <SUP>2</SUP>) transverse to the mean magnetic field inside a
  coronal hole (CH) at the base of the corona. The characteristic length
  scale directly defines the heating rate. We use a time series analysis
  of solar granulation and magnetic field measurements inside two CHs
  obtained with the New Solar Telescope at Big Bear Solar Observatory. A
  data set for transverse magnetic fields obtained with the Solar Optical
  Telescope/Spectro-Polarimeter on board the Hinode spacecraft was
  utilized to analyze the squared transverse magnetic field fluctuations
  b_t^2. Local correlation tracking was applied to derive the squared
  transverse velocity fluctuations u <SUP>2</SUP>. We find that for u
  <SUP>2</SUP> structures, the Batchelor integral scale λ varies in
  a range of 1800-2100 km, whereas the correlation length sigmav and
  the e-folding length L vary between 660 and 1460 km. Structures for
  b_t^2 yield λ ≈ 1600 km, sigmav ≈ 640 km, and L ≈ 620 km. An
  averaged (over λ, sigmav, and L) value of the characteristic length
  of u <SUP>2</SUP> fluctuations is 1260 ± 500 km, and that of b_t^2
  is 950 ± 560 km. The characteristic length scale in the photosphere
  is approximately 1.5-50 times smaller than that adopted in previous
  models (3-30 × 10<SUP>3</SUP> km). Our results provide a critical
  input parameter for current models of coronal heating and should yield
  an improved understanding of fast solar wind acceleration.

Title: The New Solar Telescope (NST): What’s Next ?
Authors: Cao, Wenda; Goode, P. R.; NST Team
Bibcode: 2013SPD....4440006C
Altcode:
  The 1.6 m, off-axis, clear aperture New Solar Telescope (NST) has been
  in regular operation in Big Bear Solar Observatory since 2009. The
  NST is the first facility class solar telescope built in the U.S. in
  a generation, which already offers a significant improvement in
  ground-based high angular resolution capabilities. This presentation
  reports the up-to-date progress on the NST and its 2nd generation
  instruments including the AO system (AO-308), the Near-InfraRed Imaging
  Spectro-polarimeter (NIRIS), the Visible Imaging Spectrometer (VIS),
  and the Cryogenic Infrared Spectrograph (CYRA).

Title: Observation of Magnetic Reconnection Driven by Granular
    Scale Advection
Authors: Zeng, Zhichen; Cao, W.; Ji, H.
Bibcode: 2013SPD....44...01Z
Altcode:
  We report the first evidence of magnetic reconnection driven by
  advection in a rapidly developing large granule, using high spatial
  resolution observations of a small surge event (base size 4‧‧
  by 4‧‧) with the 1.6 meter aperture New Solar Telescope (NST)
  at Big Bear Solar Observatory. The observations were carried out in
  narrow-band (0.5 Å) Helium I 10830 Å and broad-band (10 Å) TiO
  7057 Å. Since He I 10830 Å triplet has very high excitation level
  and is optically thin, its filtergrams enable us to investigate the
  surge from the photosphere through the chromosphere into the lower
  corona. Simultaneous space data from Atmospheric Imaging Assembly
  (AIA) and Helioseismic and Magnetic Imager (HMI) on board the Solar
  Dynamics Observatory (SDO) were used in the analysis. It is shown that
  the surge is spatio-temporally associated with magnetic flux emergence
  in the rapidly developing large granule. During the development of
  the granule, its advecting flow ( 2 km/ s) squeezed the magnetic flux
  into an intergranular lane area, where a magnetic flux concentration
  was formed and the neighboring flux with opposite magnetic polarity was
  cancelled. During the cancellation, the surge was produced as absorption
  in He I 10830 Å filtergrams while simultaneous EUV brightening occurred
  at its base. The observations clearly indicate evidence of finest-scale
  reconnection process driven by the granule’s motion.

Title: Observation of Magnetic Reconnection Driven by Granular
    Scale Advection
Authors: Zeng, Zhicheng; Cao, Wenda; Ji, Haisheng
Bibcode: 2013ApJ...769L..33Z
Altcode:
  We report the first evidence of magnetic reconnection driven by
  advection in a rapidly developing large granule using high spatial
  resolution observations of a small surge event (base size ~ 4'' ×
  4'') with the 1.6 m aperture New Solar Telescope at the Big Bear Solar
  Observatory. The observations were carried out in narrowband (0.5 Å)
  He I 10830 Å and broadband (10 Å) TiO 7057 Å. Since He I 10830 Å
  triplet has a very high excitation level and is optically thin, its
  filtergrams enable us to investigate the surge from the photosphere
  through the chromosphere into the lower corona. Simultaneous space
  data from the Atmospheric Imaging Assembly and Helioseismic and
  Magnetic Imager on board the Solar Dynamics Observatory were used
  in the analysis. It is shown that the surge is spatio-temporally
  associated with magnetic flux emergence in the rapidly developing large
  granule. During the development of the granule, its advecting flow (~2
  km s<SUP>-1</SUP>) squeezed the magnetic flux into an intergranular
  lane area, where a magnetic flux concentration was formed and the
  neighboring flux with opposite magnetic polarity was canceled. During
  the cancellation, the surge was produced as absorption in He I 10830
  Å filtergrams while simultaneous EUV brightening occurred at its
  base. The observations clearly indicate evidence of a finest-scale
  reconnection process driven by the granule's motion.

Title: NIRIS: The Second Generation Near-Infrared Imaging
    Spectro-polarimeter for the 1.6 Meter New Solar Telescope
Authors: Cao, W.; Goode, P. R.; Ahn, K.; Gorceix, N.; Schmidt, W.;
   Lin, H.
Bibcode: 2012ASPC..463..291C
Altcode:
  The largest aperture solar telescope, the 1.6 m New Solar Telescope
  (NST) has been installed at the Big Bear Solar Observatory
  (BBSO). To take full advantage of the NST's greatest potential, we
  are upgrading the routinely operational InfraRed Imaging Magnetograph
  (IRIM) to its second generation, the NIRIS (Near-InfraRed Imaging
  Spectropolarimeter). NIRIS will offer unprecedented high resolution
  spectroscopic and polarimetric imaging data of the solar atmosphere
  from the deepest photosphere through the base of the corona. With the
  aid of the BBSO adaptive optics (AO) system, the spatial resolution
  will be close to the diffraction limit of the NST. The spectroscopic
  cadence will reach one second, while polarimetric measurements,
  including Stokes I, Q, U, V profiles, remain at a better than 10
  s cadence. Polarization sensitivity is expected to be reach ∼
  10<SUP>-4</SUP>I<SUB>c</SUB>. NIRIS will cover a broad spectral
  range from 1.0 to 1.7μm, with particular attention to two unique
  spectral lines: the Fe I 1565 nm doublet has already proven to be
  the most sensitive to Zeeman effect for probing the magnetic field
  in the deepest photosphere; the He I 1083 nm multiplet is one of the
  best currently available diagnostic of upper chromospheric magnetic
  fields that allows one to map the vector field at the base of the
  corona. NIRIS will be built on dual Fabry-Pérot Interferometers (FPIs),
  each of which has an aperture of 100 mm. The larger aperture of FPIs
  allows the available field-of-view up to one and half minutes with a
  spectral power of ∼ 10<SUP>5</SUP>.

Title: The 1.6 m Off-Axis New Solar Telescope (NST) in Big Bear
Authors: Goode, P. R.; Cao, W.
Bibcode: 2012ASPC..463..357G
Altcode:
  The New Solar Telescope (NST) in Big Bear is the first facility-class
  solar telescope built in the US in a generation, and it has an
  off-axis design as is planned for the Advanced Technology Solar
  Telescope (ATST). The NST is in regular operation with adaptive optics
  (AO) correcting the light currently feeding photometric and near-IR
  polarimetric systems, as well as an imaging spectrograph. Here we show
  the high resolution capabilities of the NST. As well, we sketch our
  plans for, and reasoning behind the next generation NST instrumentation.

Title: The 1.6 m New Solar Telescope (NST) in Big Bear
Authors: Cao, W.
Bibcode: 2012IAUSS...6E.202C
Altcode:
  The 1.6 m clear aperture, off-axis New Solar Telescope (NST) is in
  regular operation in Big Bear Solar Observatory. The NST is the first
  facility-class solar telescope built in the U.S. in a generation. The
  NST provides high resolution and high sensitivity observations of the
  solar photosphere and chromosphere in the visible and near infrared
  (NIR). A high order adaptive optics system delivers corrected light
  to an ensemble of state-of-the-art scientific instruments in the coude
  laboratory including the Broad-band Filter Imagers (BFIs), NIR Imaging
  Spectro-polarimeter (NIRIS), Visible Imaging Spectro-polarimeter (VIS)
  and Fast Imaging Solar Spectrograph (FISS). Some early scientific
  results from the NST will be presented, followed by a progress report
  on NST instrument development projects, as well as upgrades to existing
  instruments.

Title: The 1.6 m off-axis New Solar Telescope (NST) in Big Bear
Authors: Goode, Philip R.; Cao, Wenda
Bibcode: 2012SPIE.8444E..03G
Altcode:
  The 1.6-m New Solar Telescope (NST) has been used to observe the Sun
  for more than three years with ever increasing capabilities as its
  commissioning phase winds down. The NST is the first facility-class
  solar telescope built in the U.S. in a generation, and it has
  an off-axis design as is planned for the 4 m Advanced Technology
  Solar Telescope. Lessons learned will be discussed. Current NST
  post-focus instrumentation includes adaptive optics (AO) feeding
  photometric and near-IR polarimetric sytems, as well as an imaging
  spectrograph. On-going instrumentation projects will be sketched,
  including Multi-Conjugate AO (MCAO), next generation (dual Fabry-
  Perot) visible light and near-IR polarimeters and a fully cryogenic
  spectrograph. Finally, recent observational results illustrating the
  high resolution capabilities of the NST will be shown.

Title: Small Scale Field Emergence and Its Impact on Photospheric
    Granulation
Authors: Yurchyshyn, V.; Ahn, K.; Abramenko, V.; Goode, P.; Cao, W.
Bibcode: 2012arXiv1207.6418Y
Altcode:
  We used photospheric intensity images and magnetic field measurements
  from the New Solar Telescope in Big Bear and Helioseismic Magnetic
  Imager on board Solar Dynamics Observatory (SDO) to study the the effect
  that the new small-scale emerging flux induces on solar granulation. We
  report that emerging flux appears to leave different types of footprint
  on solar granulation: i) diffuse irregular patches of increased
  brightness, ii) well defined filament-like structures and accompanied
  bright points, and iii) bright point-like features that appear inside
  granules. We suggest that the type of the footprint depends on the
  intensity of emerging fields. Stronger fields, emerging as a part of
  large magnetic structure, create on the solar surface a well defined
  filamentary pattern with bright points at the ends of the filaments,
  while weak turbulent fields are associated with bright patches inside
  the host granule.

Title: Profiles of the daytime atmospheric turbulence above Big Bear
    solar observatory
Authors: Kellerer, A.; Gorceix, N.; Marino, J.; Cao, W.; Goode, P. R.
Bibcode: 2012A&A...542A...2K
Altcode:
  Context. Space weather has become acutely critical for today's
  global communication networks. To understand its driving forces we
  need to observe the Sun with high angular-resolution, and within
  large fields-of-view, i.e. with multi-conjugate adaptive optics
  correction. <BR /> Aims: The design of a multi-conjugate adaptive
  optical system requires the knowledge of the altitude distribution of
  atmospheric turbulence. We have therefore measured daytime turbulence
  profiles above the New Solar Telescope (NST), on Big Bear Lake. <BR />
  Methods: To this purpose, a wide-field wavefront sensor was installed
  behind the NST. The variation of the wavefront distortions with
  angular direction allows the reconstruction of the distribution of
  turbulence. <BR /> Results: The turbulence is found to have three
  origins: 1. a ground layer (&lt;500 m) that contains 55-65% of the
  turbulence, 2. a boundary layer between 1-7 km comprises 30-40% of
  the turbulent energy, 3. and the remaining ~5% are generated in the
  tropopause, which is above 12 km in summer and between 8 and 12 km in
  winter. <BR /> Conclusions: A multi-conjugate adaptive optical system
  should thus aim at correcting the ground turbulence, the center of
  the boundary layer at roughly 3 km altitude and, eventually, the upper
  boundary layer around 6 km altitude.

Title: Characteristic Size of Flare Kernels in the Visible and
    Near-infrared Continua
Authors: Xu, Yan; Cao, Wenda; Jing, Ju; Wang, Haimin
Bibcode: 2012ApJ...750L...7X
Altcode:
  In this Letter, we present a new approach to estimate the formation
  height of visible and near-infrared emission of an X10 flare. The sizes
  of flare emission cores in three wavelengths are accurately measured
  during the peak of the flare. The source size is the largest in the
  G band at 4308 Å and shrinks toward longer wavelengths, namely the
  green continuum at 5200 Å and NIR at 15600 Å, where the emission is
  believed to originate from the deeper atmosphere. This size-wavelength
  variation is likely explained by the direct heating model as electrons
  need to move along converging field lines from the corona to the
  photosphere. Therefore, one can observe the smallest source, which in
  our case is 0farcs65 ± 0farcs02 in the bottom layer (represented by
  NIR), and observe relatively larger kernels in upper layers of 1farcs03
  ± 0farcs14 and 1farcs96 ± 0farcs27, using the green continuum and
  G band, respectively. We then compare the source sizes with a simple
  magnetic geometry to derive the formation height of the white-light
  sources and magnetic pressure in different layers inside the flare loop.

Title: Observation of Ultrafine Channels of Solar Corona Heating
Authors: Ji, Haisheng; Cao, Wenda; Goode, Philip R.
Bibcode: 2012ApJ...750L..25J
Altcode:
  We report the first direct observations of dynamical events
  originating in the Sun's photosphere and subsequently lighting up the
  corona. Continuous small-scale, impulsive events have been tracked from
  their origin in the photosphere on through to their brightening of the
  local corona. We achieve this by combining high-resolution ground-based
  data from the 1.6 m aperture New Solar Telescope (NST) at Big Bear Solar
  Observatory (BBSO), and satellite data from the Atmospheric Imaging
  Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The
  NST imaging observations in helium I 10830 Å reveal unexpected
  complexes of ultrafine, hot magnetic loops seen to be reaching from the
  photosphere to the base of the corona. Most of these ultrafine loops
  are characterized by an apparently constant, but surprisingly narrow
  diameter of about 100 km all along each loop, and the loops originate
  on the solar surface from intense, compact magnetic field elements. The
  NST observations detect the signature of upward injections of hot plasma
  that excite the ultrafine loops from the photosphere to the base of the
  corona. The ejecta have their individual footpoints in the intergranular
  lanes between the Sun's ubiquitous, convectively driven granules. In
  many cases, AIA/SDO detects cospatial and cotemporal brightenings
  in the overlying, million degree coronal loops in conjunction with
  the upward injections along the ultrafine loops. Segments of some
  of the more intense upward injections are seen as rapid blueshifted
  events in simultaneous Hα blue wing images observed at BBSO. In sum,
  the observations unambiguously show impulsive coronal heating events
  from upward energy flows originating from intergranular lanes on the
  solar surface accompanied by cospatial mass flows.

Title: Calibration of data from InfraRed Imaging Magnetograph for
    the New Solar Telescope
Authors: Ahn, Kwangsu; Cao, W.; Gorceix, N.; Goode, P. R.
Bibcode: 2012AAS...22020616A
Altcode:
  The InfraRed Imaging Magnetograph (IRIM) takes advantage of the
  high spatial resolution of New Solar Telescope (NST). It adopts a
  rotating birefringent polymer to modulate polarization signals and
  two Wollaston prisms as analyzer. Dual beam setup is used to minimize
  the effect of image motion caused by seeing. Its field of view is 50"
  x 25" and the wavelengths of operation are Fe I 15648 A and He I 10830
  A. Due to the off-axis shape of the NST primary and secondary mirrors,
  multiple calibration techniques should be combined to reconstruct the
  original Stokes parameters. Here, we would like to introduce current
  status of our calibration efforts and discuss how IRIM data can be
  used for scientific purposes.

Title: Characteristic Size Of Flare Kernels In Visible And The
    Near-infrared Continua
Authors: Xu, Yan; Cao, W.; Jing, J.; Wang, H.
Bibcode: 2012AAS...22020413X
Altcode:
  In this study, we present a new approach to estimate the formation
  height of visible and the near-infrared emission during an X10
  flare. The sizes of flare cores in three wavelengths are accurately
  measured during the peak time. The result shows that the source
  size is the largest in G-band at 4308 Å and shrinks towards longer
  wavelengths, namely the green continuum at 5200 Å and NIR at 15600 Å,
  where the emission is believed to originate from deeper atmosphere. This
  size-wavelength variation is likely explained by the direct heating
  model as electrons need to move along converging field lines. In this
  model, energetic electrons are confined by the magnetic field lines,
  which converge from the corona to the photosphere. Therefore one
  can observe the smallest source, which in our case is 0.65 ± 0".02
  (radius by assuming a circular shape) in the bottom layer (represented
  by NIR) and observe relatively large kernels in upper layers of 1".03
  ± 0".14 and 1".96 ± 0".27, using the green continuum and G-band
  respectively. We then compare the source sizes with a simple magnetic
  geometry to derived the formation height of the white-light sources
  and magnetic pressure in different layers inside the flare loop.

Title: Origin of Rapid Blueshifted Events in Coronal Holes
Authors: Yurchyshyn, Vasyl B.; Ahn, K.; Abramenko, V.; Goode, P.;
   Cao, W.
Bibcode: 2012AAS...22042304Y
Altcode:
  Clusters of photospheric bright points are surrounded by chromospheric
  rosette-like structures. These rosettes, when observed in the far
  off-band (-0.1nm) Halpha images often appear to consist of short living,
  narrow rapid blueshifted events (RBEs). RBEs, in turn, are thought to
  be disk counterparts of type II spicules (spicules II), detected in
  Hinode data, which may be playing play an important role in coronal
  heating since they are thought to supply mass to the solar corona. The
  search for the origin of type II spicules was one of the main focus of
  solar physics research in the recent years. <P />Here we present our
  findings on the possible driving mechanism of spicules II, which are
  based on high resolution photospheric, chromospheric and magnetic field
  data from the New Solar Telescope (NST) collected in a coronal hole. We
  report that the majority of RBEs, occurring around a network cluster,
  are associated with appearance of opposite polarity features within
  the unipolar cluster fields, suggesting that magnetic reconnection
  may be the driving mechanism. We will present these observations in
  details and discuss possible implications.

Title: Observation of Hyperfine Channels of Solar Corona Heating
Authors: Cao, Wenda; Ji, H.; Goode, P. R.
Bibcode: 2012AAS...22042301C
Altcode:
  We report here the first direct observations of dynamical events
  originating in the sun’s cool photosphere and subsequently lighting
  up the corona. Continuous impulsive events have been tracked from
  their origin in the photosphere on through to their brightening
  of the local corona. We achieve this by combining high resolution
  ground-based data from the 1.6 meter aperture New Solar Telescope
  (NST) at Big Bear Solar Observatory (BBSO),and satellite data from
  the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics
  Observatory (SDO). The NST observations in a narrow band absorption
  line, Helium I 10830 Å, reveal unexpected complexes of hyperfine,
  hot magnetic loops seen to be reaching from the photosphere to the
  base of the corona. Most of these hyperfine loops are characterized
  by an apparently constant, but surprisingly narrow diameter of about
  100 km all along each loop, and the loops originate on the solar
  surface from intense, small-scale magnetic field elements. The NST
  observations detect upward injections of hot plasma that excite the
  hyperfine loops from the photosphere to the base of the corona. The
  ejecta have their individual footpoints in the intergranular lanes
  between the sun’s ubiquitous, convectively driven granules. In
  many cases, AIA/SDO detects co-spatial and co-temporal brightenings
  in the overlying, million-degree coronal loops in conjunction with
  the upward injections along the hyperfine loops. Segments of some
  of the more intense upward injections are seen as rapid blue-shifted
  events in simultaneous Hα blue wing images observed at BBSO. In sum,
  the observations unambiguously show impulsive coronal heating events
  from upward energy flows originating from intergranular lanes on the
  solar surface accompanied by co-spatial mass flows.

Title: Depth profiling of dopants implanted in Si using the
    synchrotron radiation based high-resolution grazing emission technique
Authors: Kayser, Y.; Banaś, D.; Cao, W.; Dousse, J. -Cl.; Hoszowska,
   J.; Jagodziński, P.; Kavčič, M.; Kubala-Kukuś, A.; Nowak, S.;
   Pajek, M.; Szlachetko, J.
Bibcode: 2012XRS....41...98K
Altcode:
  No abstract at ADS

Title: Properties of Umbral Dots as Measured from the New Solar
    Telescope Data and MHD Simulations
Authors: Kilcik, A.; Yurchyshyn, V. B.; Rempel, M.; Abramenko, V.;
   Kitai, R.; Goode, P. R.; Cao, W.; Watanabe, H.
Bibcode: 2012ApJ...745..163K
Altcode: 2011arXiv1111.3997K
  We studied bright umbral dots (UDs) detected in a moderate size sunspot
  and compared their statistical properties to recent MHD models. The
  study is based on high-resolution data recorded by the New Solar
  Telescope at the Big Bear Solar Observatory and three-dimensional (3D)
  MHD simulations of sunspots. Observed UDs, living longer than 150 s,
  were detected and tracked in a 46 minute long data set, using an
  automatic detection code. A total of 1553 (620) UDs were detected
  in the photospheric (low chromospheric) data. Our main findings
  are (1) none of the analyzed UDs is precisely circular, (2) the
  diameter-intensity relationship only holds in bright umbral areas, and
  (3) UD velocities are inversely related to their lifetime. While nearly
  all photospheric UDs can be identified in the low chromospheric images,
  some small closely spaced UDs appear in the low chromosphere as a single
  cluster. Slow-moving and long-living UDs seem to exist in both the low
  chromosphere and photosphere, while fast-moving and short-living UDs
  are mainly detected in the photospheric images. Comparison to the 3D
  MHD simulations showed that both types of UDs display, on average, very
  similar statistical characteristics. However, (1) the average number
  of observed UDs per unit area is smaller than that of the model UDs,
  and (2) on average, the diameter of model UDs is slightly larger than
  that of observed ones.

Title: Properties of Umbral Dots as Measured from the New Solar
    Telescope Data and MHD Simulations
Authors: Yurchyshyn, V.; Kilcik, A.; Rempel, M.; Abramenko, V.; Kitai,
   R.; Goode, P. R.; Cao, W.; Watanabe, H.
Bibcode: 2011sdmi.confE..86Y
Altcode:
  We studied bright umbral dots (UDs) detected in the main sunspot
  of AR NOAA 11108 and compare their statistical properties to a
  state-of-the-art MHD model of a sunspot. The study is based on
  high resolution data recorded on September 20, 2010 by the New Solar
  Telescope (NST) at Big Bear Solar Observatory and 3D MHD simulations of
  sunspots. The 46 min data set included photospheric (0.3nm TiO filter
  centered at 705.7 nm) and chromospheric (0.025nm Hα Lyot filter)
  adaptive optics corrected and speckle reconstructed images. Bright
  UDs, living longer than 150 s, were detected and tracked using an
  automatic UD detection code. Total 1553 (620) UDs were detected
  in the photospheric (chromospheric) data. Our main findings are:
  i) none of the analyzed UDs is of an exact circular shape, ii) the
  diameter-intensity relationship only works for bright umbral areas, and
  iii) UD velocities inversely related to their life time. Comparison of
  photospheric and chromospheric data showed that nearly all photospheric
  UDs can be identified in the chromospheric images. However, it appears
  that some small closely spaced UDs appear in the chromospheric images
  as a single cluster, which may lead to the underestimation of the total
  number of detected chromospheric UDs. Also, while slow moving and long
  living UDs seem to exist in both chromosphere and photosphere, fast
  moving and short living ones are detected mainly in the photospheric
  images. Comparison of model and observed data shows that both types
  of UDs display very similar statistical characteristics. The main
  difference between parameters of model and observed UDs is that i)
  the average number of observed UDs per unit area is smaller than that
  of the model UDs, and ii) on average, the diameter of model UDs is
  slightly larger than that of observed ones.

Title: High-resolution observations of the solar dynamics and
    magnetism
Authors: Goode, Phil; Cao, Wenda; Yurchyshyn, Vasyl
Bibcode: 2011sdmi.confE..28G
Altcode:
  The NST is the first facility-class solar telescope built in the US
  in a generation. Images and movies illustrating the high resolution
  capabilities of the NST will be shown. In particular, high resolution
  NST observations reveal vortices in the granular field that are
  associated with newly discovered, but ubiquitous small-scale jets,
  which are much smaller-scale than Hinode type-II jets. NST observations
  have been used to probe the nature of the diffusion of magnetic bright
  points, which seems consistent with the operation of small-scale
  dynamos, while seeming to be sufficient on large-scales to support the
  Wang-Sheeley dynamo picture. Other recent NST results correlated with
  satellite observations will be shown and discussed.

Title: Photospheric Signatures of Granular-scale Flux Emergence and
    Cancellation at the Penumbral Boundary
Authors: Lim, Eun-Kyung; Yurchyshyn, Vasyl; Abramenko, Valentyna;
   Ahn, Kwangsu; Cao, Wenda; Goode, Philip
Bibcode: 2011ApJ...740...82L
Altcode: 2011arXiv1107.5254L
  We studied flux emergence events of sub-granular scale in a solar
  active region. The New Solar Telescope (NST) of the Big Bear Solar
  Observatory made it possible to clearly observe the photospheric
  signature of flux emergence with very high spatial (0farcs11 at 7057
  Å) and temporal (15 s) resolution. From TiO observations with the
  pixel scale of 0farcs0375, we found several elongated granule-like
  features (GLFs) stretching from the penumbral filaments of a sunspot
  at a relatively high speed of over 4 km s<SUP>-1</SUP>. After a
  slender arched darkening appeared at the tip of a penumbral filament,
  a bright point (BP) developed and quickly moved away from the filament,
  forming and stretching a GLF. The size of a GLF was approximately
  0farcs5 wide and 3'' long. The moving BP encountered nearby structures
  after several minutes of stretching, and the well-defined elongated
  shape of the GLF faded away. Magnetograms from the Solar Dynamics
  Observatory/Helioseismic and Magnetic Imager and NST/InfraRed Imaging
  Magnetograph revealed that those GLFs are photospheric indicators of
  small-scale flux emergence, and their disappearance is related to
  magnetic cancellation. From two well-observed events, we describe
  detailed development of the sub-structures of GLFs and different
  cancellation processes that each of the two GLFs underwent.

Title: Umbral Dynamics in the Near-infrared Continuum
Authors: Anđić, A.; Cao, W.; Goode, P. R.
Bibcode: 2011ApJ...736...79A
Altcode: 2011arXiv1105.1825A
  We detected peaks of oscillatory power at 3 and ~6.5 minutes in the
  umbra of the central sunspot of the active region NOAA AR 10707 in data
  obtained in the near-infrared (NIR) continuum at 1565.7 nm. The NIR data
  set captured umbral dynamics around 50 km below the τ<SUB>500</SUB> =
  1 level. The umbra does not oscillate as a whole, but rather in distinct
  parts that are distributed over the umbral surface. The most powerful
  oscillations, close to a period of ~6.5, do not propagate upward. We
  noted a plethora of large umbral dots (UDs) that persisted for &gt;=30
  minutes and stayed in the same locations. The peaks of oscillatory
  power above the detected UDs are located at 3 and 5 minute oscillations,
  but are very weak in comparison with the oscillations of ~6.5 minutes.

Title: Near-infrared Imaging Spectropolarimeter For The Nst
Authors: Cao, Wenda; Ahn, K.; Gorceix, N.; Shumko, S.; Coulter, R.;
   Goode, P.
Bibcode: 2011SPD....42.0606C
Altcode: 2011BAAS..43S.0606C
  The NST Near-Infrared Imaging Spectropolarimeter is one of the first
  imaging solar spectro-polarimeters working in the near infrared
  (NIR). It has been installed and commissioned in the Coude Lab of the
  1.6-meter NST at Big Bear Solar Observatory (BBSO). This innovative
  system, which includes a 2.5 nm interference filter, a unique 0.25
  nm birefringent Lyot filter, and a Fabry-Perot etalon, is capable of
  providing a bandpass as low as 0.01 nm over a field-of-view (FOV) of 50"
  in a telecentric configuration. An NIR waveplate rotates ahead of M3
  in the NST as the polarimeter modulator, and ahead of it a calibration
  unit is located to reduce polarization cross-talk induced by subsequent
  oblique mirrors. Dual-beam differential polarimetry is employed to
  minimize seeing-induced spurious polarization. Based on the unique
  advantages in IR window, the very capable NST with adaptive optics, it
  will provide unprecedented solar spectro-polarimetry with high Zeeman
  sensitivity (10<SUP>-3</SUP>I<SUB>c</SUB>), high spatial resolution
  (0.2"), and high cadence (15s). In this presentation, we discuss the
  design, fabrication, and calibration, as well as showing the results
  of the first light observations.

Title: Sunspot Umbral Dots Detected with the New Solar Telescope
Authors: Kilcik, Ali; Yurchyshyn, V.; Abramenko, V.; Goode, P.; Cao, W.
Bibcode: 2011SPD....42.1901K
Altcode: 2011BAAS..43S.1901K
  We present a study of bright umbral dots detected inside a large sunspot
  of NOAA AR 11108. This study is based on high resolution data recorded
  on September 20, 2010 with the New Solar Telescope (NST) at Big Bear
  Solar Observatory. The data set, spanning 46 min, consists of a total
  of 184 adaptive optics corrected and speckle reconstructed images
  obtained with a 0.3 nm passband TiO filter centered on the 705.7 nm
  spectral line. The image cadence is 15 s and the pixel size of 0.0375
  arcsec. <P />Bright umbral dots (UDs) were detected and tracked using
  an automatic routine. Here we only focus on long living UDs (&gt;150
  s in life time) and a total of 513 such features were detected during
  the observed period. We found that the average lifetime of a UD is 7.4
  min and an average size is 0.34 arcsec. There is a tendency for larger
  UDs to be brighter (and more circular). Many UDs are not of circular
  shape. We will also present probability distribution of various physical
  parameters and compare the results to similar earlier studies.

Title: Active Region High Velocity Events Observed by Fast Imaging
    Solar Spectrograph on the NST
Authors: Ahn, Kwangsu; Chae, J.; Nah, J.; Park, H.; Jang, B.; Yang,
   H.; Park, Y.; Cao, W.; Goode, P. R.
Bibcode: 2011SPD....42.1904A
Altcode: 2011BAAS..43S.1904A
  The Fast Imaging Solar Spectrograph (FISS) is the only
  spectrograph-based instrument on the NST that is currently
  operational. With a high spectral resolution of 1.4 x 10<SUP>5</SUP>
  and simultaneous dual spectral band imaging, this instrument can
  accurately determine the physical parameters of chromospheric features
  --- filaments, jets and so on. Initial observations captured several
  peculiar dynamic events that showed high line-of-sight velocities
  of the order of 20 km s<SUP>-1</SUP> in the vicinity of sunspots. We
  expect that FISS will provide a better understanding of the physics
  in the chromosphere with the aid of the unprecedentedly high spatial
  resolution of NST.

Title: Response of Granulation to Small-scale Bright Features in
    the Quiet Sun
Authors: Anđić, A.; Chae, J.; Goode, P. R.; Cao, W.; Ahn, K.;
   Yurchyshyn, V.; Abramenko, V.
Bibcode: 2011ApJ...731...29A
Altcode: 2011arXiv1102.3404A
  We detected 2.8 bright points (BPs) per Mm<SUP>2</SUP> in the quiet
  Sun with the New Solar Telescope at Big Bear Solar Observatory, using
  the TiO 705.68 nm spectral line at an angular resolution ~0farcs1 to
  obtain a 30 minute data sequence. Some BPs formed knots that were
  stable in time and influenced the properties of the granulation
  pattern around them. The observed granulation pattern within ~3''
  of knots presents smaller granules than those observed in a normal
  granulation pattern, i.e., around the knots a suppressed convection
  is detected. Observed BPs covered ~5% of the solar surface and were
  not homogeneously distributed. BPs had an average size of 0farcs22,
  they were detectable for 4.28 minutes on average, and had an averaged
  contrast of 0.1% in the deep red TiO spectral line.

Title: The New Solar Telescope in Big Bear: Polarimetry II
Authors: Cao, W.; Ahn, K.; Goode, P. R.; Shumko, S.; Gorceix, N.;
   Coulter, R.
Bibcode: 2011ASPC..437..345C
Altcode:
  IRIM (Infrared Imaging Magnetograph) is one of the first imaging solar
  spectro-polarimeters working in the near infrared (NIR). IRIM is being
  installed and commissioned in the Coudé Lab of the 1.6-meter New Solar
  Telescope (NST) at Big Bear Solar Observatory (BBSO). This innovative
  system, which includes a 2.5 nm interference filter, a unique 0.25
  nm birefringent Lyot filter, and a Fabry-Pérot etalon, is capable of
  providing a bandpass as low as 0.01 nm over a field-of-view of 50" in a
  telecentric configuration. An NIR waveplate rotates ahead of M3 in the
  NST as the polarimeter modulator, and ahead of it locates a calibration
  unit to reduce polarization cross-talk induced by subsequent oblique
  mirrors. Dual-beam differential polarimetry is employed to minimize
  seeing-induced spurious polarization. Based on the unique advantages
  in IR window, the very capable NST with adaptive optics, IRIM will
  provide unprecedented solar spectro-polarimetry with high Zeeman
  sensitivity (10<SUP>-3</SUP>I<SUB>c</SUB>), high spatial resolution
  (0.2"), and high cadence (15 s). In this paper, we discuss the design,
  fabrication, and calibration of IRIM, as well as the results of the
  first light observations.

Title: Time Distributions of Large and Small Sunspot Groups Over
    Four Solar Cycles
Authors: Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.;
   Ozguc, A.; Rozelot, J. P.; Cao, W.
Bibcode: 2011ApJ...731...30K
Altcode: 2011arXiv1111.3999K
  Here we analyze solar activity by focusing on time variations of
  the number of sunspot groups (SGs) as a function of their modified
  Zurich class. We analyzed data for solar cycles 20-23 by using Rome
  (cycles 20 and 21) and Learmonth Solar Observatory (cycles 22 and 23)
  SG numbers. All SGs recorded during these time intervals were separated
  into two groups. The first group includes small SGs (A, B, C, H, and
  J classes by Zurich classification), and the second group consists
  of large SGs (D, E, F, and G classes). We then calculated small and
  large SG numbers from their daily mean numbers as observed on the
  solar disk during a given month. We report that the time variations
  of small and large SG numbers are asymmetric except for solar cycle
  22. In general, large SG numbers appear to reach their maximum in the
  middle of the solar cycle (phases 0.45-0.5), while the international
  sunspot numbers and the small SG numbers generally peak much earlier
  (solar cycle phases 0.29-0.35). Moreover, the 10.7 cm solar radio
  flux, the facular area, and the maximum coronal mass ejection speed
  show better agreement with the large SG numbers than they do with
  the small SG numbers. Our results suggest that the large SG numbers
  are more likely to shed light on solar activity and its geophysical
  implications. Our findings may also influence our understanding of
  long-term variations of the total solar irradiance, which is thought
  to be an important factor in the Sun-Earth climate relationship.

Title: The New Solar Telescope in Big Bear: Polarimetry I
Authors: Goode, P. R.; Cao, W.; Ahn, K.; Gorceix, N.; Coulter, R.
Bibcode: 2011ASPC..437..341G
Altcode:
  We present here the near-term polarimetry plans for the 1.6 m clear
  aperture, off-axis telescope in Big Bear. The first scientific data
  were taken in the Summer of 2009 at the Nasmyth focus, and first
  observations corrected by adaptive optics were taken in the Summer
  of 2010. The first polarimetry for this telescope will be done in the
  near infrared at 1.56 μm, which is close to the photospheric opacity
  minimum. We show and explain reasons for the general layout of the
  polarimetric hardware for the telescope.

Title: Hard X-ray Source Distributions on EUV Bright Kernels in a
    Solar Flare
Authors: Ning, Zongjun; Cao, Wenda
Bibcode: 2011SoPh..269..283N
Altcode: 2010SoPh..tmp..247N
  We explore the hard X-ray source distributions of an C1.1 flare
  occurred on 14 December 2007. Both Hinode/EIS and RHESSI observations
  are used. One of EIS rasters perfectly covers the double hard X-ray
  footpoints, where the EUV emission appears strong from the cool line
  of He II (log T=4.7) to the hot line of Fe XVI (log T=6.4). We analyze
  RHESSI X-ray images at different energies and different times before
  the hard X-ray maximum. The results show a similar topology for the
  time-dependent source distribution (i.e. at 14:14:35 UT) as that for
  energy-dependent source distribution (i.e. at a given energy band of 6 -
  9 keV) overlapped on EUV bright kernels, which seems to be consistent
  with the evaporation model.

Title: Development of the Fast Imaging Solar Spectrograph for 1.6
    m New Solar Telescope
Authors: Nah, Ja-Kyoung; Chae, Jong-Chul; Park, Young-Deuk; Park,
   Hyung-Min; Jang, Bi-Ho; Ahn, Kwang-Su; Yang, Hee-Su; Cho, Kyung-Suk;
   Kim, Yeon-Han; Kim, Kwang-Dong; Cao, Wenda; Gorceix, Nicolas; Goode,
   Philip. R.
Bibcode: 2011PKAS...26...45N
Altcode:
  No abstract at ADS

Title: Measurement of Sky Brightness and Suppression of Scattering
    in Sky Brightness Monitor
Authors: Liu, N. P.; Liu, Y.; Shen, Y. D.; Zhang, X. F.; Cao, W. D.;
   Arnaud, J.
Bibcode: 2011AcASn..52..160L
Altcode:
  A modern Sky Brightness Monitor (SBM) was developed for the site survey
  in West China for the future large solar equipment installation. The
  performance of this new SBM was tested in the recent preliminary
  experiments. A lot of sky brightness data had been obtained at a few
  sites in Yunnan. The blue channel result shows that the sky brightness
  near the noon time on Jiaozi Snow Mountain is as low as a few millionths
  of the solar center intensity, indicating the low scattering level
  inside our SBM instrument. The scattering is mainly from two parts:
  the diffraction rings from the occulter edges, distributed in the inner
  field of view but outside the occulter region containing the ND4 filter;
  the diffraction from the baffle rings, distributed in the extreme edges
  of the field of view. To suppress the scattering of the latter part,
  experiments with different aperture sizes of baffle rings are made. The
  result shows that, by mounting new baffle rings with proper aperture
  size into the SBM telescope tube, diffraction in the extreme edges of
  the field of view can be effectively reduced.

Title: Ferroelectrics, Thermodynamic Phenomenology of
Authors: Cao, W.
Bibcode: 2011emst.book.3074C
Altcode:
  Phenomenological theories of ferroelectrics, such as the
  Landau-Ginzburg-Devonshire type models, are based on thermodynamic
  principles and the structural symmetry relationship between the
  paraelectric and ferroelectric phases. The primary order parameter for
  describing a ferroelectric system is the electrical polarization, and
  the elastic strain, as a secondary order parameter, almost always plays
  a key role in the phase transition, domain formation, and other related
  physical phenomena. Phenomenological theories are field theories;
  however, they do reflect the discrete atomic displacement patterns and
  the symmetry changes in the unit cell associated with the ferroelectric
  phase transition. &lt;ce:anchor

Title: Chromospheric Signatures of Small-scale Flux Emergence as
    Observed with New Solar Telescope and Hinode Instruments
Authors: Yurchyshyn, V. B.; Goode, P. R.; Abramenko, V. I.; Chae,
   J.; Cao, W.; Andic, A.; Ahn, K.
Bibcode: 2010ApJ...722.1970Y
Altcode: 2011arXiv1102.1034Y
  With the ever-increasing influx of high-resolution images of the solar
  surface obtained at a multitude of wavelengths, various processes
  occurring at small spatial scales have become a greater focus of our
  attention. Complex small-scale magnetic fields have been reported that
  appear to have enough stored energy to heat the chromosphere. While
  significant progress has been made in understanding small-scale
  phenomena, many specifics remain elusive. We present here a detailed
  study of a single event of disappearance of a magnetic dipole and
  associated chromospheric activity. Based on New Solar Telescope Hα
  data and Hinode photospheric line-of-sight magnetograms and Ca II
  H images, we report the following. (1) Our analysis indicates that
  even very small dipoles (elements separated by about 0farcs5 or less)
  may reach the chromosphere and trigger non-negligible chromospheric
  activity. (2) Careful consideration of the magnetic environment where
  the new flux is deposited may shed light on the details of magnetic
  flux removal from the solar surface. We argue that the apparent
  collision and disappearance of two opposite polarity elements may
  not necessarily indicate their cancellation (i.e., reconnection,
  emergence of a "U" tube, or submergence of Ω loops). In our case, the
  magnetic dipole disappeared by reconnecting with overlying large-scale
  inclined plage fields. (3) Bright points (BPs) seen in off-band Hα
  images are very well correlated with the Ca II H BPs, which in turn
  are cospatial with G-band BPs. We further speculate that, in general,
  Hα BPs are expected to be cospatial with photospheric BPs; however,
  a direct comparison is needed to refine their relationship.

Title: Patterns of Flows in an Intermediate Prominence Observed
    by Hinode
Authors: Ahn, Kwangsu; Chae, Jongchul; Cao, Wenda; Goode, Philip R.
Bibcode: 2010ApJ...721...74A
Altcode:
  The investigation of plasma flows in filaments/prominences gives
  us clues to understanding their magnetic structures. We studied
  the patterns of flows in an intermediate prominence observed by
  Hinode/SOT. By examining a time series of Hα images and Ca II H images,
  we have found horizontal flows in the spine and vertical flows in
  the barb. Both of these flows have a characteristic speed of 10-20 km
  s<SUP>-1</SUP>. The horizontal flows displayed counterstreaming. Our
  detailed investigation revealed that most of the moving fragments in
  fact reversed direction at the end point of the spine near a footpoint
  close to the associated active region. These returning flows may be
  one possible explanation of the well-known counterstreaming flows
  in prominences. In contrast, we have found vertical flows—downward
  and upward—in the barb. Most of the horizontal flows in the spine
  seem to switch into vertical flows when they approach the barb,
  and vice versa. We propose that the net force resulting from a small
  deviation from magnetohydrostatic equilibrium, where magnetic fields
  are predominantly horizontal, may drive these patterns of flow. In the
  prominence studied here, the supposed magnetohydrostatic configuration
  is characterized by magnetic field lines sagging with angles of 13°
  and 39° in the spine and the barb, respectively.

Title: Evidence of Filament Upflows Originating from Intensity
    Oscillations on the Solar Surface
Authors: Cao, Wenda; Ning, Zongjun; Goode, Philip R.; Yurchyshyn,
   Vasyl; Ji, Haisheng
Bibcode: 2010ApJ...719L..95C
Altcode:
  A filament footpoint rooted in an active region (NOAA 11032) was well
  observed for about 78 minutes with the 1.6 m New Solar Telescope at the
  Big Bear Solar Observatory on 2009 November 18 in Hα ±0.75 Å. This
  data set had high cadence (~15 s) and high spatial resolution (~0farcs1)
  and offered a unique opportunity to study filament dynamics. As in
  previous findings from space observations, several dark intermittent
  upflows were identified, and they behave in groups at isolated locations
  along the filament. However, we have two new findings. First, we
  find that the dark upflows propagating along the filament channel are
  strongly associated with the intensity oscillations on the solar surface
  around the filament footpoints. The upflows start at the same time as
  the peak in the oscillations, illustrating that the upflow velocities
  are well correlated with the oscillations. Second, the intensity of
  one of the seven upflows detected in our data set exhibits a clear
  periodicity when the upflow propagates along the filament. The periods
  gradually vary from ~10 to ~5 minutes. Our results give observational
  clues on the driving mechanism of the upflows in the filament.

Title: Investigation of Chromospheric Evaporation in a Neupert-type
    Solar Flare
Authors: Ning, Zongjun; Cao, Wenda
Bibcode: 2010ApJ...717.1232N
Altcode:
  The Neupert effect implies a flare model in which the hard X-rays (HXRs)
  are produced by energetic electrons via electron-ion bremsstrahlung as
  they lose their energies in the chromosphere, while the soft X-rays
  (SXRs) are produced by thermal bremsstrahlung from "chromospheric
  evaporation" due to plasma being heated by those same electrons. Based
  on this concept, we investigate the evidence for chromospheric
  evaporation in a Neupert-type flare on 2004 October 30. First, we
  demonstrate that this event is consistent with the Neupert effect. Using
  the RHESSI data, both thermal and nonthermal energies are derived after
  the onset of this flare. The high correlation between the derivative
  of the SXRs and HXRs and between the derivative of the thermal energy
  and nonthermal energy indicates that the 2004 October 30 flare is a
  Neupert-type event. Second, chromospheric evaporation is necessarily
  expected during the flare's rising phase. We analyze RHESSI images at
  different energies and different times around the flare maximum. The
  HXR emission tends to move the footpoints close to each other, finally
  merging them into a single source with the same position as the loop-top
  source. When the projection effect (due to this event being near the
  disk center) is taken into account, this fact can be regarded as the
  signature of chromospheric evaporation in the X-ray observations. RHESSI
  observations show three kinds of evidence that are consistent with
  the evaporation model. First, at a given instant, the higher energy
  X-rays originate from the deeper layers of the atmosphere or further
  away from the loop top. Second, in a given energy band, i.e., at 20-30
  keV, the earlier X-rays originate from the deeper layers or further
  away from the loop top. Third, the X-ray footpoint sources at higher
  energies disappear at later times. Based on these characteristics,
  chromospheric evaporation took about 100 s for the 2004 October 30
  flare. X-rays at all energy bands do not show evidence of evaporation
  probably because measurements are the most sensitive only between 12
  and 30 keV. After measuring the source scale as a function of time,
  we roughly estimate the shrinkage velocities at different energies, for
  instance, 238 km s<SUP>-1</SUP> for 12-15 keV, 285 km s<SUP>-1</SUP> for
  15-20 keV, and 846 km s<SUP>-1</SUP> for 20-30 keV. If the evaporation
  processes primarily contribute to the source shrinkage, these values
  are considered as the evaporation velocities, indicating that the
  evaporation flow would be faster during the latter part of flare.

Title: Oscillatory Behavior in the Quiet Sun Observed with the New
    Solar Telescope
Authors: Anđić, A.; Goode, P. R.; Chae, J.; Cao, W.; Ahn, K.;
   Yurchyshyn, V.; Abramenko, V.
Bibcode: 2010ApJ...717L..79A
Altcode: 2010arXiv1007.0272A
  Surface photometry of the quiet Sun has achieved an angular resolution
  of 0farcs1 with the New Solar Telescope at Big Bear Solar Observatory,
  revealing that a disproportionate fraction of the oscillatory events
  appear above observed bright point-like structures. During the tracking
  of these structures, we noted that the more powerful oscillatory events
  are cospatial with them, indicating that observed flux tubes may be
  the source of many observed oscillatory events.

Title: Repackaging and characterizing of a HgCdTe CMOS infrared
    camera for the New Solar Telescope
Authors: Cao, Wenda; Coulter, Roy; Gorceix, Nicolas; Goode, Philip R.
Bibcode: 2010SPIE.7742E..20C
Altcode: 2010SPIE.7742E..55C
  The 1.6-meter New Solar Telescope (NST) is currently the world's
  largest aperture solar telescope. The NST is newly built at Big Bear
  Solar Observatory (BBSO). Among other instruments, the NST is equipped
  with several focal plane instruments operating in the near infrared
  (NIR). In order to satisfy the diverse observational requirements of
  these scientific instruments, a 1024 × 1024 HgCdTe TCM8600 CMOS camera
  manufactured by Rockwell Scientific Company has been repackaged and
  upgraded at Infrared Laboratories Inc. A new ND-5 dewar was designed to
  house the TCM8600 array with a low background filter wheel, inverted
  operation and at least 12 hours of hold time between fills. The
  repackaged camera will be used for high-resolution NIR photometry
  at the NST Nasmyth focus on the telescope and high-precision NIR
  spectro-polarimetry in the NST Coudé Lab below. In March 2010, this
  repackaged camera was characterized in the Coudé Lab at BBSO. This
  paper presents the design of new dewar, the detailed process of
  repackaging and characterizing the camera, and a series of test results.

Title: Investigation of the Neupert Effect in the Various Intervals
    of Solar Flares
Authors: Ning, Zongjun; Cao, Wenda
Bibcode: 2010SoPh..264..329N
Altcode: 2010SoPh..tmp..124N; 2010SoPh..tmp..112N
  The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
  gives us a chance to investigate the theoretical Neupert effect
  using the correlation between the thermal-energy derivative and
  the nonthermal energy, or the thermal energy and the integral
  nonthermal energy. Based on this concept, we analyze four M-class
  RHESSI flares on 13 November 2003, 4 November 2004, 3 and 25 August
  2005. According to the evolution of the temperature [T], emission
  measure [EM], and thermal energy [E<SUB>th</SUB>], each event is
  divided into three phases during the nonthermal-energy input [\frac
  {dE_{nth}}{dt} in the units of erg s<SUP>−1</SUP>]. Phase 1 is
  identified as the interval before the temperature maximum, while
  after the thermal-energy maximum is phase 3, between them is phase
  2. We find that these four flares show the Neupert effect in phase 1,
  but not in phase 3. The Neupert effect still works well in the second
  phase, although the cooling becomes slightly important. We define
  the parameter μ in the relation of dE_{th}/dt=μdE_{nth}(t)/dt or
  E_{th}(t<SUB>0</SUB>)=μ\int<SUB>0</SUB>^{t<SUB>0</SUB>}dE_{nth}(t)/dt
  dt when the cooling is ignored in phase 1. Considering the uncertainties
  in estimating the energy from the observations, it is not possible to
  precisely determine the fraction of the known energy in the nonthermal
  electrons transformed into the thermal energy of the hottest plasma
  observed by RHESSI. After a rough estimate of the flare volume and the
  assumption of the filling factor, we investigate the parameter μ in
  these four events. Its value ranges from 0.02 to 0.20, indicating that
  a small fraction (2% - 20%) of the nonthermal energy can be efficiently
  transformed into thermal energy, which is traced by the soft X-ray
  emission, and the bulk of the energy is lost possibly due to cooling.

Title: Nasmyth focus instrumentation of the New Solar Telescope at
    Big Bear Solar Observatory
Authors: Cao, Wenda; Gorceix, Nicolas; Coulter, Roy; Wöger, Friedrich;
   Ahn, Kwangsu; Shumko, Sergiy; Varsik, John; Coulter, Aaron; Goode,
   Philip R.
Bibcode: 2010SPIE.7735E..5VC
Altcode: 2010SPIE.7735E.194C
  The largest solar telescope, the 1.6-m New Solar Telescope (NST) has
  been installed and is being commissioned at Big Bear Solar Observatory
  (BBSO). It has an off-axis Gregorian configuration with a focal ratio
  of F/52. Early in 2009, first light scientific observations were
  successfully made at the Nasmyth focus, which is located on the east
  side of the telescope structure. As the first available scientific
  instruments for routine observation, Nasmyth focus instrumentation
  (NFI) consists of several filtergraphs offering high spatial resolution
  photometry in G-band 430 nm, Ha 656 nm, TiO 706 nm, and covering the
  near infrared 1083 nm, 1.6 μm, and 2.2 μm. With the assistance of
  a local correlation tracker system, diffraction limited images were
  obtained frequently over a field-of-view of 70 by 70 after processed
  using a post-facto speckle reconstruction algorithm. These data sets
  not only serve for scientific analysis with an unprecedented spatial
  resolution, but also provide engineering feedback to the NST operation,
  maintenance and optimization. This paper reports on the design and the
  implementation of NFI in detail. First light scientific observations
  are presented and discussed.

Title: First light of the 1.6 meter off-axis New Solar Telescope at
    Big Bear Solar Observatory
Authors: Cao, Wenda; Gorceix, Nicolas; Coulter, Roy; Coulter, Aaron;
   Goode, Philip R.
Bibcode: 2010SPIE.7733E..30C
Altcode: 2010SPIE.7733E..93C
  New Jersey Institute of Technology, in collaboration with the University
  of Hawaii and the Korea Astronomy &amp; Space Science Institute, has
  successfully developed and installed a 1.6 m clear aperture, off-axis
  New Solar Telescope (NST) at the Big Bear Solar Observatory. The NST
  will be the largest aperture solar telescope in the world until the 4
  m Advanced Technology Solar Telescope (ATST) and 4 m European Solar
  Telescope (EST) begin operation in the next decade. Meanwhile, the
  NST will be the largest off-axis telescope before the 8.4 m segmented
  Giant Magellan Telescope (GMT) comes on-line. The NST is configured
  as an off-axis Gregorian system consisting of a parabolic primary,
  prime focus field stop and heat reflector, elliptical secondary and
  diagonal flats. The primary mirror is made of Zerodur from Schott and
  figured to a final residual error of 16 nm rms by Steward Observatory
  Mirror Lab. The final focal ratio is f/52. The 180 circular opening in
  the field stop defines the maximal square field-of-view. The working
  wavelength range will cover 0.4 to 1.7 μm in the CoudÂ´e Lab two
  floors beneath the telescope, and all wavelengths including far infrared
  at the Nasmyth focus on an optical bench attached to the side of the
  telescope structure. First-light scientific observations have been
  attained at the Nasmyth focus and in the CoudÂ´e Lab. This paper
  presents a detailed description of installation and alignment of the
  NST. First-light observational results are also shown to demonstrate
  the validity of the NST optical alignment.

Title: High resolution observations of white-light emissions from
    the opacity minimum during an X-class flare
Authors: Xu, Y.; Cao, W.; Jing, J.; Wang, H.
Bibcode: 2010AN....331..596X
Altcode:
  Using high cadence, high resolution near infrared (NIR) observations of
  the X10 white-light flare (WLF) on 2003 October 29, we investigated
  the evolution of the core-halo structure of white-light emission
  during the two-second period flare peak. We found that size and
  intensity of the halo remained almost constant in the range of 10
  Mm<SUP>2</SUP>. However, the core area was very compact and expanded
  rapidly from about 1 Mm<SUP>2</SUP> to 4 Mm<SUP>2</SUP>. At the same
  time, the total emission of the core increased nearly twenty times. This
  distinct behavior indicates that different heating mechanisms might be
  responsible for core and halo emissions. In addition to the temporal
  analysis, we compared the intensity enhancements of the flare core and
  halo. The result shows that the halo contrast increased by about 8%
  compared to the flare-quiet region, which could be explained by a
  combination of direct-heating and backwarming models.

Title: The NST: First results and some lessons for ATST and EST
Authors: Goode, P. R.; Coulter, R.; Gorceix, N.; Yurchyshyn, V.;
   Cao, W.
Bibcode: 2010AN....331..620G
Altcode:
  In January 2009, first light observations with the NST (New Solar
  Telescope) in Big Bear Solar Observatory (BBSO) were made. NST has a
  1.7 m primary with a 1.6 m clear aperture. First observational results
  in TiO and Hα are shown and discussed. The NST primary mirror is the
  most aspheric telescope mirror deployed to date. The NST is early in its
  commissioning, and the plans for this phase will be sketched. Lessons
  learned in building and implementing the NST are germane for the ATST
  and EST telescopes and will be discussed. The NST has an off-axis
  Gregorian configuration consisting of a parabolic primary, heat-stop,
  elliptical secondary and diagonal flats. The focal ratio of the
  primary mirror is f/2.4. The working wavelength range covers from 0.4
  to 1.7 μm in the Coudé Lab beneath the telescope and all wavelengths
  including the far infrared at the Nasmyth focus on the dome floor.

Title: Scientific instrumentation for the 1.6 m New Solar Telescope
    in Big Bear
Authors: Cao, W.; Gorceix, N.; Coulter, R.; Ahn, K.; Rimmele, T. R.;
   Goode, P. R.
Bibcode: 2010AN....331..636C
Altcode:
  The NST (New Solar Telescope), a 1.6 m clear aperture, off-axis
  telescope, is in its commissioning phase at Big Bear Solar Observatory
  (BBSO). It will be the most capable, largest aperture solar telescope
  in the US until the 4 m ATST (Advanced Technology Solar Telescope)
  comes on-line late in the next decade. The NST will be outfitted with
  state-of-the-art scientific instruments at the Nasmyth focus on the
  telescope floor and in the Coudé Lab beneath the telescope. At the
  Nasmyth focus, several filtergraphs already in routine operation
  have offered high spatial resolution photometry in TiO 706 nm,
  H\alpha 656 nm, G-band 430 nm and the near infrared (NIR), with the
  aid of a correlation tracker and image reconstruction system. Also,
  a Cryogenic Infrared Spectrograph (CYRA) is being developed to supply
  high signal-to-noise-ratio spectrometry and polarimetry spanning
  1.0 to 5.0 μm. The Coudé Lab instrumentation will include Adaptive
  Optics (AO), InfraRed Imaging Magnetograph (IRIM), Visible Imaging
  Magnetograph (VIM), and Fast Imaging Solar Spectrograph (FISS). A 308
  sub-aperture (349-actuator deformable mirror) AO system will enable
  nearly diffraction limited observations over the NST's principal
  operating wavelengths from 0.4 μm through 1.7 μm. IRIM and VIM are
  Fabry-Pérot based narrow-band tunable filters, which provide high
  resolution two-dimensional spectroscopic and polarimetric imaging in
  the NIR and visible respectively. FISS is a collaboration between BBSO
  and Seoul National University focussing on chromosphere dynamics. This
  paper reports the up-to-date progress on these instruments including an
  overview of each instrument and details of the current state of design,
  integration, calibration and setup/testing on the NST.

Title: Highest Resolution Observations of the Quietest Sun
Authors: Goode, Philip R.; Yurchyshyn, Vasyl; Cao, Wenda; Abramenko,
   Valentyna; Andic, Aleksandra; Ahn, Kwangsu; Chae, Jongchul
Bibcode: 2010ApJ...714L..31G
Altcode:
  Highest resolution observations made with the new 1.6 m aperture solar
  telescope in Big Bear Solar Observatory during this time of historic
  inactivity on the Sun reveal new insights into the small-scale dynamics
  of the Sun's photosphere. The telescope's unprecedented resolution
  enabled us to observe that the smallest scale photospheric magnetic
  field seems to come in isolated points in the dark intergranular lanes,
  rather than the predicted continuous sheets confined to the lanes, and
  the unexpected longevity of the bright points implies a deeper anchoring
  than predicted. Further, we demonstrated for the first time that the
  photospheric plasma motion and magnetic fields are in equipartition
  over a wide dynamic range, and both cascade energy to ever-smaller
  scales according to classical Kolmogorov turbulence theory. Finally,
  we discovered tiny jet-like features originating in the dark lanes that
  surround the ubiquitous granules that characterize the solar surface.

Title: New Solar Telescope Observations of Magnetic Reconnection
    Occurring in the Chromosphere of the Quiet Sun
Authors: Chae, Jongchul; Goode, P. R.; Ahn, K.; Yurchysyn, V.;
   Abramenko, V.; Andic, A.; Cao, W.; Park, Y. D.
Bibcode: 2010ApJ...713L...6C
Altcode:
  Magnetic reconnection is a process in which field-line connectivity
  changes in a magnetized plasma. On the solar surface, it often
  occurs with the cancellation of two magnetic fragments of opposite
  polarity. Using the 1.6 m New Solar Telescope, we observed the
  morphology and dynamics of plasma visible in the Hα line, which is
  associated with a canceling magnetic feature (CMF) in the quiet Sun. The
  region can be divided into four magnetic domains: two pre-reconnection
  and two post-reconnection. In one post-reconnection domain, a small
  cloud erupted, with a plane-of-sky speed of 10 km s<SUP>-1</SUP>,
  while in the other one, brightening began at points and then tiny
  bright loops appeared and subsequently shrank. These features support
  the notion that magnetic reconnection taking place in the chromosphere
  is responsible for CMFs.

Title: Dual-Stage Reconnection During Solar Flares Observed in
    Hard X-ray
Authors: Xu, Yan; Jing, Ju; Cao, Wenda; Wang, Haimin
Bibcode: 2010ApJ...709L.142X
Altcode:
  In this Letter, we present hard X-ray (HXR) observation by the Reuven
  Ramaty High Energy Solar Spectroscopic Imager of the 2003 October 29
  X10 flare. Two pairs of HXR conjugate footpoints have been identified
  during the early impulsive phase. This geometric configuration is very
  much in the manner predicted by the "tether-cutting" scenario first
  proposed by Moore &amp; Roumeliotis. The HXR light curves show that
  the outer pair of footpoints disappeared much faster than the other
  pair. This temporal behavior further confirms that this event is a good
  example of the "tether-cutting" model. In addition, we reconstructed
  a three-dimensional magnetic field based on the nonlinear force-free
  extrapolation and found that each pair of HXR footpoints were indeed
  linked by corresponding magnetic field lines.

Title: Scientific Instruments of 1.6 m New Solar Telescope in Big Bear
Authors: Cao, W.
Bibcode: 2009AGUFMSH51A1261C
Altcode:
  The NST (New Solar Telescope) is in its commissioning phase at
  Big Bear Solar Observatory (BBSO). It will be the most capable,
  largest aperture solar telescope in the US until the 4 m ATST
  (Advanced Technology Solar Telescope) comes on-line in the middle
  of the next decade. The NST will be outfitted with state-of-the-art
  post-focus instrumentations at the Nasmyth focus on the dome floor
  and in the Coude Lab beneath the telescope. At the Nasmyth focus,
  several filter-based systems already in routine operation offer high
  spatial resolution photometry in TiO 704 nm, Hα 656 nm, G-band 430
  nm and near infrared 1.56 μm &amp; 2.2 μm, with the assistance
  of local correlation tracking and image reconstruction. As well, a
  Cryogenic InfraRed Spectrograph (CIRS) is being developed to supply
  high signal-to-noise-ratio spectrometry and polarimetry spanning 1.0 to
  5.0 μm. The Coudé-lab instrumentations will include Adaptive Optics
  system (AO), InfraRed Imaging Magnetograph (IRIM), Visible Imaging
  Magnetograph (VIM), Real-time Image Reconstruction System (RIRS), and
  Fast Imaging Solar Spectrograph (FISS) -- most of these instruments
  operated on the old 0.6 m BBSO telescope. AO is being upgraded to a 308
  sub-aperture (349-actuator Deformable Mirror) AO system that will enable
  diffraction limited observations over the NST's principal operating
  wavelengths from 0.4 through 1.7 μm. IRIM and VIM are Fabry-Pérot
  based narrow-band tunable filter, which provide high resolution
  two-dimensional spectroscopic and polarimetric imaging in the near
  infrared and visible respectively. Using a 32-node parallel computing
  system, RIRS is capable of performing real-time image reconstruction
  with one image every minute. FISS is a collaboration between BBSO and
  Seoul National University to focus on chromosphere dynamics. Key tasks
  including optical design, hardware/software integration and subsequent
  setup/testing on the NST, will be presented here. Some preliminary
  observation results in the near infrared will be shown.

Title: A LATE BRITTLE COMPONENT OF MOTION WITHIN THE DUCTILE EASTERN
    SIERRA CREST SHEAR ZONE (ESCSZ) ALONG THE EASTERN BOUNDARY OF THE
    TOLUMNE BATHOLITH IN THE SADDLEBAG LAKE, CA AREA. WHITESIDES, Andrew1,
    ENRIQUEZ, Marcus2 , HARDY, Jill1 , EHRET, Philip1, IANNONE, Monika1,
    CULBERT, Kristan1 GROSS, Ben3, LODEWYK, Jessica3, CAO, Wenrong1 ,
    ZHANG, Tao1, MEMETI, Valbone3, PATERSON, Scott1 SCHMIDT, Keegan4. (1)
    Department of Earth Sciences, University of Southern California,
    Los Angeles, CA 90089-0740, awhitesi@usc.edu , (2) Department of
    Geological Sciences, Cal State L.A., 5151 State University Drive, Los
    Angeles, CA 90032, (3) Department of Earth and Planetary Sciences,
    Washington University, Campus Box 1169, 1 Brookings Dr, Saint
    Louis, MO, 63130, (4) Division of Natural Science and Mathematics,
    Lewis-Clark State College, 500 8th Ave., Lewiston, ID 83501
Authors: Whitesides, A. S.; Enriquez, M.; Hardy, J.; Ehret, P.;
   Iannone, M.; Culbert, K. N.; Gross, M. B.; Lodewyk, J.; Cao, W.;
   Zhang, T.; Memeti, V.; Paterson, S. R.; Schmidt, K. L.
Bibcode: 2009AGUFM.T21D1862W
Altcode:
  During mapping (by the Undergraduate Team Research program, University
  of Southern California) in the Saddlebag Lake pendant just along the
  eastern margin of the Tuolumne batholith we have discovered a brittle
  slip component in the ESCSZ that juxtaposes largely metasedimentary and
  metavolcanic rock packages. The metasedimentary package is dominated
  by bedded sandstones and siltstones and local conglomerates whereas
  the metavolcanics show a large range of volcanic and volcaniclastic
  units. All of the units dip steeply and have an average N-NW
  strike. Dextral oblique ductile shear is distributed in domains in both
  rock packages with varying width from ~2 km in the South to ~1 km in the
  North. Shear sense in planes at high angles to a steep to SW plunging
  mineral lineation include S-C structures, shear bands, asymmetrical
  folding, sigma and delta clasts, and asymmetrical boudins. Partitioning
  of shear is common with the metarhyolites and metasediments showing
  higher non-coaxial strain than in the metaandesite and metadacite
  units. Map-scale “z-shaped” asymmetrical folds within the shear
  zone are also consistent with dextral shearing. Folded and sheared
  dikes of the 88-85 Ma Cathedral Peak phase of the Tuolumne batholith are
  common in the shear zone. A newly discovered brittle slip surface with
  breccias, gouge, and local pseudotachylite and large quartz veins was
  also mapped in the center of the ductile shear zone typically along the
  contact between the western metasedimentary and eastern metavolcanics
  (often a metarhyolite at the contact) on the east. Local slickenlines,
  steps, and offset dikes indicate that the brittle fault also had oblique
  dextral movement, similar to the ductile shear zone. In the mapped area
  no dikes originating from the TB cross the brittle fault and some are
  terminated at the brittle fault surface We interpret these observations
  to indicate northward displacement of the metasedimentary package by
  first ductile then brittle faulting during cooling and possibly uplift
  of this region with the youngest motion post 82 Ma.

Title: Behavior of the Spines in a Quiescent Prominence Observed
    by Hinode/SOT
Authors: Ning, Z.; Cao, W.; Goode, P. R.
Bibcode: 2009ApJ...707.1124N
Altcode:
  We report the behaviors of the spines in a quiescent prominence
  from the observations on 2008 January 15 made with Hinode/SOT in
  Hα +0.076 Å, Hα-0.34 Å, and Ca II H line filters. Two spines (1
  and 2) are visible in this event. In the spacetime plots of the Hα
  and Ca II intensities, the two spines seem to gradually move closer
  together, and finally merge, then separate again. Their behaviors are
  separated into two kinds of typical motions. On the Doppler diagrams,
  the spine 1 has a dominant redshift, and spine 2 favors a blueshift,
  which reveals that the spines 1 and 2 firstly display the drifting
  motions in opposite directions. The former is drifting northward, while
  the latter drifts southward. Second, both spines display large-scale
  oscillating motions. Their oscillating velocities, amplitudes, and
  periods have average values of 3 km s<SUP>-1</SUP>, ±5 Mm, and 98
  minutes, respectively, indicating a small-amplitude oscillation with a
  long period. After the sinusoidal fitting, both spines almost exhibit
  an antiphase oscillating motions. The spine 2 oscillates 135° ahead
  of the spine 1. Such antiphase oscillations would reflect the coupling
  of the transverse oscillations of the spines in this prominence.

Title: Evidence of Chromospheric Evaporation in the 2004 December
    1 Solar Flare
Authors: Ning, Zongjun; Cao, Wenda; Huang, Jing; Huang, Guangli; Yan,
   Yihua; Feng, Hengqiang
Bibcode: 2009ApJ...699...15N
Altcode:
  In this paper, we present the radio and hard X-ray evidence of
  chromospheric evaporation during an M1.0 flare which occurred on 2004
  December 1. The radio emission was observed by the Solar Broadband
  Radio Dynamic Spectrometer in China, which yielded dynamic spectra
  of decimetric emission. The hard X-ray emission was observed by
  RHESSI. In the radio spectra, the burst is characterized by two groups
  of parallel-drifting structures, some of which change their drifting
  rates from positive to negative. Based on the standard flare model,
  we may explain these decimetric bursts in terms of chromospheric
  evaporation. On the other hand, RHESSI observations show that the hard
  X-ray emission in the energy range of 10-15 keV tends to rise from two
  footpoints to the looptop and eventually merges into a single looptop
  source, which is accepted as evidence of hard X-ray chromospheric
  evaporation. Such processes happened twice in this event. The drifting
  radio structures occurred between them, at the same time as the third
  hard X-ray peak was observed at 25-50 keV.

Title: Spatial and Spectral Behaviors of Solar Flares Observed
    in Microwaves
Authors: Ning, Zongjun; Cao, Wenda
Bibcode: 2009SoPh..257..335N
Altcode:
  The spatial and spectral behaviors of two solar flares observed by
  the Nobeyama Radioheliograph (NoRH) on 24 August 2002 and 22 August
  2005 are explored. They were observed with a single loop-top source
  and double footpoint sources at the beginning, then with looplike
  structures for the rest of the event. NoRH has high spatial and temporal
  resolution at the two frequencies of 17 and 34 GHz where a nonthermal
  radio source is often optically thin. Such capabilities give us an
  opportunity to study the spatial and spectral behaviors of different
  microwave sources. The 24 August 2002 flare displayed a soft - hard -
  soft (SHS) spectral pattern in the rising - peak - decay phases at 34
  GHz, which was also observed for the spectral behavior of both loop-top
  and footpoint sources. In contrast, the 22 August 2005 flare showed a
  soft - hard - harder (SHH) spectral pattern for its both loop-top and
  footpoint sources. It is interesting that this event showed a harder
  spectrum in the early rising phase. We found a positive correlation
  between the spectral index and microwave flux in both the loop-top
  source and the footpoint sources in both events. The conclusions drawn
  from the flux index could apply to the electron index as well, because
  of their simple linear relationship under the assumption of nonthermal
  gyrosynchrotron mechanism. Such a property of spatial and spectral
  behaviors of microwave sources gives an observational constraint on
  the electron acceleration mechanism and electron propagation.

Title: Periodicity of Twisting Motions in Sunspot Penumbral Filaments
Authors: Ning, Zongjun; Cao, Wenda; Goode, Philip R.
Bibcode: 2009SoPh..257..251N
Altcode:
  We study the periodicity of twisting motions in sunspot penumbral
  filaments, which were recently discovered from space (Hinode) and
  ground-based (SST) observations. A sunspot was well observed for
  97 minutes by Hinode/SOT in the G-band (4305 Å) on 12 November
  2006. By the use of the time - space gradient applied to intensity
  space - time plots, twisting structures can be identified in the
  penumbral filaments. Consistent with previous findings, we find that
  the twisting is oriented from the solar limb to disk center. Some of
  them show a periodicity. The typical period is about ≈ four minutes,
  and the twisting velocity is roughly 6 km s<SUP>−1</SUP>. However,
  the penumbral filaments do not always show periodic twisting motions
  during the time interval of the observations. Such behavior seems to
  start and stop randomly with various penumbral filaments displaying
  periodic twisting during different intervals. The maximum number of
  periodic twists is 20 in our observations. Studying this periodicity can
  help us to understand the physical nature of the twisting motions. The
  present results enable us to determine observational constraints on
  the twisting mechanism.

Title: Post-focus Instrumentation Of The NST
Authors: Cao, Wenda; Gorceix, N.; Andic, A.; Ahn, K.; Coulter, R.;
   Goode, P.
Bibcode: 2009SPD....40.1803C
Altcode:
  The NST (New Solar Telescope), 1.6 m clear aperture, off-axis
  telescope, is in its commissioning phase at Big Bear Solar Observatory
  (BBSO). It will be the most capable, largest aperture solar telescope
  in the US until the 4 m ATST (Advanced Technology Solar Telescope)
  comes on-line in the middle of the next decade. The NST will be
  outfitted with state-of-the-art post-focus instrumentation, which
  currently include Adaptive Optics system (AO), InfraRed Imaging
  Magnetograph (IRIM), Visible Imaging Magnetograph (VIM), Real-time
  Image Reconstruction System (RIRS), and Fast Imaging Solar Spectrograph
  (FISS). A 308 sub-aperture (349-actuator Deformable Mirror) AO system
  will enable diffraction limited observations over the NST's principal
  operating wavelengths from 0.4 µm through 1.7 µm. IRIM and VIM
  are Fabry-Perot based narrow-band tunable filter, which provide high
  resolution two-dimensional spectroscopic and polarimetric imaging in
  the near infrared and visible respectively. Using a 32-node parallel
  computing system, RIRS is capable of performing real-time image
  reconstruction with one image every minute. FISS is a collaboration
  between NJIT and Seoul National University to focus on chromosphere
  dynamics. This instruments would be installed this Summer as a part
  of the NST commissioning and the implementation of Nysmyth focus
  instrumentation. Key tasks including optical design, hardware/software
  integration and subsequent setup/testing on the NST, will be presented
  in this poster. First light images from the NST will be shown.

Title: Oscillatory Behavior and its Connection to Granulation
Authors: Andic, Aleksandra; Cao, W.; Goode, P. R.; Jess, D. B.
Bibcode: 2009SPD....40.0933A
Altcode:
  Results are presented from two distinct sets of the observations to
  further elucidate origin of, and the role of high frequency oscillations
  in <P />atmospheric dynamics. One set was performed using IBIS that
  Observatorio <P />Astrofisico di Arcetri developed. This 2D spectrograph
  utilized the Fe I 709nm spectral line at the Dunn Solar telescope,
  Sacramento Peak, of National Solar Observatory. This data set was
  first speckle reconstructed. The second data set was obtained from
  the same telescope using BBSO's IRIM with its Rockwell Near Infrared
  Camera measuring the Fe 1565.7nm spectral line. <P />It was determined
  that the magnetic field has a significant role in <P />propagation of
  the oscillations, and our near infrared observations revealed <P />new
  insights into the oscillatory dynamics of the deep photosphere. Detailed
  results will be presented.

Title: Small-scale oscillations in a quiescent prominence observed
    by HINODE/SOT. Prominence oscillations
Authors: Ning, Z.; Cao, W.; Okamoto, T. J.; Ichimoto, K.; Qu, Z. Q.
Bibcode: 2009A&A...499..595N
Altcode:
  Context: Investigations of the behavior of small-scale threads can
  provide an alternative approach to studying prominence dynamics and
  understanding its origin and nature. <BR />Aims: The behavior of
  threads are analyzed in a quiescent prominence, including drifting
  and both the horizontally and vertically oscillating motions. These
  indicate waves in the solar prominence. <BR />Methods: We used the Hα
  images at a setting wavelength of +0.076 Å. A quiescent prominence
  was observed by HINODE/SOT on 2008 January 15 for about 3 h in
  total. <BR />Results: Consistent with previous findings, prominences
  show numerous thread-like structures. Some threads clearly exhibit both
  vertically and horizontally oscillatory motions, while others are only
  drifting. Complicated cases show both drifting and oscillatory motions
  simultaneously. In the upper part of the prominence, the threads are
  oscillating independently of each other. We find that three threads
  oscillate with the same phase for at least two periods. The oscillations
  seem to be strongly damped since they disappear after a few periods. The
  maximum number of observed periods is 8 in our observations. In the
  lower part of the prominence, however, the different threads have a
  mixed character with the individual oscillatory motions unstable for
  one entire period. Most oscillatory motions will disappear after a half
  period or less, while the new oscillatory motions are excited nearby. A
  5-min period is predominant, and the oscillating amplitudes show an
  average value of ±3.5 km s<SUP>-1</SUP>. We find some upflows in the
  spicule layer, and they appear to transport the mass from photosphere
  (or spicules themselves) to the prominence. These upflows have an
  average velocity amplitude of 0.8 km s<SUP>-1</SUP>. <BR />Conclusions:
  The threads exhibit three distinct behaviors. The first is only
  drifting, the second is typically oscillating, and the third shows
  both characteristics. There are no substantial differences between
  the periods of horizontally and vertically oscillating threads in
  this prominence.

Title: Early Abnormal Temperature Structure of X-Ray Loop-Top Source
    of Solar Flares
Authors: Shen, Jinhua; Zhou, Tuanhui; Ji, Haisheng; Wang, Na; Cao,
   Wenda; Wang, Haimin
Bibcode: 2008ApJ...686L..37S
Altcode: 2008arXiv0808.4047S
  This Letter is to investigate the physics of a newly discovered
  phenomenon—contracting flare loops in the early phase of solar
  flares. In classical flare models, which were constructed based on
  the phenomenon of the expansion of flare loops, an energy releasing
  site is put above flare loops. These models can predict that there is
  a vertical temperature gradient in the top of flare loops due to heat
  conduction and cooling effects. Therefore, the centroid of an X-ray
  loop-top source at higher energy bands will be higher in altitude,
  which we can define as the normal temperature distribution. With
  observations made by RHESSI, we analyzed 10 M- or X-class flares (9
  limb flares). For all these flares, the movement of loop-top sources
  shows an obvious U-shaped trajectory, which we take as the signature of
  contraction-to-expansion of flare loops. We find that, for all these
  flares, a normal temperature distribution does exist, but only along
  the path of expansion. The temperature distribution along the path of
  contraction is abnormal, showing no spatial order at all. The result
  suggests that magnetic reconnection processes in the contraction and
  expansion phases of these solar flares are different.

Title: Magnetic Reconnection Rate and RHESSI Hard X-Ray Imaging
    Spectroscopy of Well Resolved X-class Flares
Authors: Xu, Y.; Jing, J.; Cao, W.; Wang, H.
Bibcode: 2008AGUSMSP51C..06X
Altcode:
  Three X-class white-light flares were captured by BBSO observing team
  at NSO in 2003 and the Solar Optical Telescope (SOT) on board HINODE in
  2006. They were all typical two-ribbon flares and the flare ribbons were
  resolved to the diffraction limit in G-band observations. We measure
  the velocities of ribbon-motion Vn for different flaring kernels and
  the corresponding magnetic flux density Bn. We compare the correlation
  between Vn and Bn with previous obtained empirical relationship. In
  addition, we investigate the temporal evolution of shear-angle between
  conjugate foot-points and magnetic neutral line using both Hard X-ray
  (HXR) observation obtained by Ramaty High Energy Solar Spectroscopic
  Imager (RHESSI) and G-band data. The results show clear decrease
  of shear-angles, indicating motion of flare kernels along the flare
  ribbons in early stage of flares. The optical observations including
  G-band show that some isolated HXR flare kernels are actually connected
  by the optical flare ribbons. Using the high resolution cleaned HXR
  images, we also present the spectral information obtained for all
  the HXR kernels and discuss the difference of spectral index in the
  different magnetic field environment.

Title: Multiwavelength Study of Flow Fields in Flaring Super Active
    Region NOAA 10486
Authors: Deng, N.; Xu, Y.; Yang, G.; Cao, W.; Liu, C.; Rimmele, T. R.;
   Wang, H.; Denker, C.
Bibcode: 2006AGUFMSH31B..06D
Altcode:
  We present high resolution observations of horizontal flow fields
  measured by Local Correlation Tracking from intensity images in three
  wavelengths, i.e., G-Band (GB), White-Light (WL), and Near InfraRed
  (NIR). The observations were obtained on 2003 October~29 within
  the flaring super active region NOAA~10486, which was the source of
  several X-class flares, including an X10 flare that occurred near
  the end of the observing run. The data were obtained at National
  Solar Observatory/Sacramento Peak (NSO/SP) using the newly developed
  high-order Adaptive Optics (AO) system. We also use Dopplergrams
  and magnetograms from MDI on board SOHO to study the line-of-sight
  flow and magnetic field. We observe persistent and long-lived (at
  least 5 hours) strong horizontal and vertical shear flows (both in
  the order of 1 km s-1) along the magnetic Neutral Line (NL) until
  the X10 flare occurred. From lower photospheric level (NIR), the
  direction of the flows does not change up to the upper photosphere
  (GB), while the flow speeds in the shear motion regions decrease and
  on the contrary those in regions without shear motions increase with
  increasing altitude. Right after the X10 flare, the magnetic gradient
  decreased, while both horizontal and vertical shear flows dramatically
  enhanced near the flaring NL. Our results suggest that photospheric
  shear flows and local magnetic shear near the NL can increase after
  the flare, which may be the result of shear release in the overlying
  large-scale magnetic system or the reflection of a twisted or sheared
  flux emergence carrying enough energy from subphotosphere.

Title: First Light of the Near-Infrared Narrow-Band Tunable
    Birefringent Filter at Big Bear Solar Observatory
Authors: Cao, Wenda; Hartkorn, Klaus; Ma, Jun; Xu, Yan; Spirock, Tom;
   Wang, Haimin; Goode, Philip R.
Bibcode: 2006SoPh..238..207C
Altcode: 2006SoPh..tmp...53C
  We discuss a near-infrared (NIR) narrow-band tunable birefringent
  filter system newly developed by the Big Bear Solar Observatory
  (BBSO). This is one of the first narrow-bandpass NIR filter systems
  working at 1.56 μm which is used for the observation of the deepest
  solar photosphere. Four stages of calcite were used to obtain a bandpass
  of 2.5 Å along with a free spectral range (FSR) of 40 Å. Some unique
  techniques were implemented in the design, including liquid crystal
  variable retarders (LCVRs) to tune the bandpass in a range of ±100 Å,
  a wide field configuration to provide up to 2° incident angle, and
  oil-free structure to make it more compact and handy. After performing
  calibration and characteristic evaluation at the Evans Facility of
  the National Solar Observatory at Sacramento Peak (NSO/SP), a series
  of high-resolution filtergrams and imaging polarimetry observations
  were carried out with the Dunn Solar Telescope of NSO/SP and the
  65-cm telescope of BBSO, in conjunction with the high-order adaptive
  optics system and the Fabry-Pérot Interferometer (FPI). In this
  paper, we describe the optical design and discuss the calibration
  method. Preliminary observations show that it is capable of serving as
  either a stand-alone narrow-band filter for NIR filtergram observations
  or an order-sorting filter of a FPI applied to NIR two-dimensional
  imaging spectro-polarimetry.

Title: Progress on the 1.6-meter New Solar Telescope at Big Bear
    Solar Observatory
Authors: Denker, C.; Goode, P. R.; Ren, D.; Saadeghvaziri, M. A.;
   Verdoni, A. P.; Wang, H.; Yang, G.; Abramenko, V.; Cao, W.; Coulter,
   R.; Fear, R.; Nenow, J.; Shoumko, S.; Spirock, T. J.; Varsik, J. R.;
   Chae, J.; Kuhn, J. R.; Moon, Y.; Park, Y. D.; Tritschler, A.
Bibcode: 2006SPIE.6267E..0AD
Altcode: 2006SPIE.6267E..10D
  The New Solar Telescope (NST) project at Big Bear Solar Observatory
  (BBSO) now has all major contracts for design and fabrication in place
  and construction of components is well underway. NST is a collaboration
  between BBSO, the Korean Astronomical Observatory (KAO) and Institute
  for Astronomy (IfA) at the University of Hawaii. The project will
  install a 1.6-meter, off-axis telescope at BBSO, replacing a number
  of older solar telescopes. The NST will be located in a recently
  refurbished dome on the BBSO causeway, which projects 300 meters into
  the Big Bear Lake. Recent site surveys have confirmed that BBSO is
  one of the premier solar observing sites in the world. NST will be
  uniquely equipped to take advantage of the long periods of excellent
  seeing common at the lake site. An up-to-date progress report will
  be presented including an overview of the project and details on the
  current state of the design. The report provides a detailed description
  of the optical design, the thermal control of the new dome, the optical
  support structure, the telescope control systems, active and adaptive
  optics systems, and the post-focus instrumentation for high-resolution
  spectro-polarimetry.

Title: Diffraction-limited Polarimetry from the Infrared Imaging
    Magnetograph at Big Bear Solar Observatory
Authors: Cao, Wenda; Jing, Ju; Ma, Jun; Xu, Yan; Wang, Haimin; Goode,
   Philip R.
Bibcode: 2006PASP..118..838C
Altcode:
  The Infrared Imaging Magnetograph (IRIM) system developed by Big Bear
  Solar Observatory (BBSO) has been put into preliminary operation. It is
  one of the first imaging spectropolarimeters working at 1565 nm and is
  used for the observations of the Sun at its opacity minimum, exposing
  the deepest photospheric layers. The tandem system, which includes a
  4.2 nm interference filter, a unique 0.25 nm birefringent Lyot filter,
  and a Fabry-Pérot etalon, is capable of providing a bandpass as low as
  0.01 nm in a telecentric configuration. A fixed quarter-wave plate and
  a nematic liquid crystal variable retarder are employed for analyzing
  the circular polarization of the Zeeman components. The longitudinal
  magnetic field is measured for the highly Zeeman-sensitive Fe I line
  at 1564.85 nm (Landé factor g=3). The polarimetric data were taken
  through a field of view of ~145<SUP>''</SUP>×145<SUP>''</SUP> and
  were recorded by a 1024×1024 pixel, 14 bit HgCdTe CMOS focal plane
  array camera. Benefiting from the correlation tracking system and a
  newly developed adaptive optics system, the first imaging polarimetric
  observations at 1565 nm were made at the diffraction limit on 2005 July
  1 using BBSO's 65 cm telescope. After comparing the magnetograms from
  IRIM with those taken by the Michelson Doppler Imager on board SOHO,
  it was found that all the magnetic features matched very well in both
  sets of magnetograms. In addition, Stokes V profiles obtained from the
  Fabry-Pérot etalon scan data provide access to both the true magnetic
  field strength and the filling factor of the small-scale magnetic
  flux elements. In this paper, we present the design, fabrication, and
  calibration of IRIM, as well as the results of the first scientific
  observations.

Title: High-Resolution Studies of Complex Solar Active Regions
Authors: Deng, Na; Wang, H.; Liu, C.; Yang, G.; Xu, Y.; Tritschler,
   A.; Cao, W.; Rimmele, T. R.; Denker, C.
Bibcode: 2006SPD....37.3401D
Altcode: 2006BAAS...38..258D
  Most Flares and CMEs occur or originate in solar active regions,
  typically in sunspots with complex magnetic fields such as
  delta-spots. Rapid and substantial changes of the sunspot structure have
  been discovered to be associated with flares/CMEs. Rapid penumbral decay
  and umbral enhancements are intensity changes, which are interpreted as
  signatures of magnetic reconnection during the flare. The magnetic field
  lines switch from an inclined to a more vertical orientation. Strong and
  long-lived shear flows near the flaring magnetic inversion line have
  been detected using Local Correlation Tracking (LCT) techniques based
  on multi-wavelength high resolution observations. A newly observed and
  important phenomenon is the increased local shear flow and magnetic
  shear right after the flare in spite of theoretical models requiring
  an overall decrease in the magnetic free energy. The emergence of a
  twisted or pre-sheared flux rope near the neutral line is a possible
  interpretation. Using high-order adaptive optics combined post-facto
  speckle masking image reconstruction, we can obtain time-series with
  highly improved image quality and spatial resolution in the order of
  0.14" or about 100 km on the solar surface. We combine the observed
  longitudinal Dopplergrams obtained with two-dimensional imaging
  spectrometer and transverse LCT flow maps derived from time-series
  of speckle reconstructed images to create real local 3D flow maps
  (view from above). Using these precise 3D flow maps observed in a
  typical sunspot in the course of its center to limb disc passage,
  we observe distinct division line between radially inward and outward
  flow in the penumbra and its evolution during the decaying phase of
  the sunspot. The inclination angles of penumbral flow channels are
  also calculated.Acknowledgments: This work is supported by NSF under
  grant ATM 03-42560, ATM 03-13591, ATM 02-36945, ATM 05-48952, and MRI
  AST 00-79482 and by NASA under grant NAG 5-13661.

Title: Multiwavelength Study of Flow Fields in Flaring Super Active
    Region NOAA 10486
Authors: Deng, Na; Xu, Yan; Yang, Guo; Cao, Wenda; Liu, Chang; Rimmele,
   Thomas R.; Wang, Haimin; Denker, Carsten
Bibcode: 2006ApJ...644.1278D
Altcode:
  We present high-resolution observations of horizontal flow fields
  measured by local correlation tracking from intensity images in three
  wavelengths, i.e., G band (GB), white light (WL), and near-infrared
  (NIR). The observations were obtained on 2003 October 29 within
  the flaring super active region NOAA 10486, which was the source of
  several X-class flares, including an X10 flare that occurred near
  the end of the observing run. The data were obtained at National
  Solar Observatory/Sacramento Peak (NSO/SP) using the newly developed
  high-order adaptive optics (AO) system. We also use Dopplergrams
  and magnetograms from MDI on board SOHO to study the line-of-sight
  flow and magnetic field. We observe persistent and long-lived (at
  least 5 hr) strong horizontal and vertical shear flows (both in the
  order of 1 km s<SUP>-1</SUP>) along the magnetic neutral line (NL)
  until the X10 flare occurred. From lower photospheric level (NIR),
  the direction of the flows does not change up to the upper photosphere
  (GB), while the flow speeds in the shear motion regions decrease and,
  on the contrary, those in regions without shear motions increase with
  increasing altitude. Right after the X10 flare, the magnetic gradient
  decreased, while both horizontal and vertical shear flows dramatically
  enhanced near the flaring NL. Our results suggest that photospheric
  shear flows and local magnetic shear near the NL can increase after
  the flare, which may be the result of shear release in the overlying
  large-scale magnetic system or the reflection of a twisted or sheared
  flux emergence carrying enough energy from the subphotosphere.

Title: The first light of the Infrared Imaging Magnetographat Big
    Bear Solar Observatory
Authors: Cao, Wenda; Ma, J.; Jing, J.; Xu, Y.; Denker, C.; Wang, H.;
   Goode, P.
Bibcode: 2006SPD....37.0612C
Altcode: 2006BAAS...38..227C
  The InfraRed Imaging Magnetograph (IRIM) system developed by Big Bear
  Solar Observatory (BBSO) has been put into preliminary operation. It
  is one of the first imaging spectro-polarimeters working at 1565 nm,
  and is used for the observations of the Sun at its opacity minimum,
  exposing the deepest photospheric layers. The tandem system of a 4.2 nm
  interference filter, an unique 0.25 nm birefringent Lyot filter and a
  Fabry-Perot etalon is capable of providing a bandpass as low as 0.01
  nm in a telecentric configuration. A fixed quarter wave plate and a
  nematic liquid crystal variable retarder are employed for analyzing
  the circular polarization of the Zeeman components. The longitudinal
  magnetic field is measured for highly Zeeman-sensitive Fe I line at
  1564.85 nm (Lande factor g = 3). The polarimetric data, with a field of
  view (FOV) 145" × 145", were recorded by a 1024 × 1024 pixel, 14-bit
  HgCdTe CMOS focal plane array camera. Benefiting from the Correlation
  Tracking system (CT) and newly developed Adaptive Optics (AO) system,
  the first imaging polarimetric observations at 1565 nm were made at the
  diffraction limit on 1 July 2005 using BBSO's 65 cm telescope. After
  comparing the magnetograms from IRIM with those taken by the Michelson
  Doppler Imager (MDI) on board SOHO, it was found that all the magnetic
  features matched very well in both sets of magnetograms. Also, Stokes
  V profiles obtained from the Fabry-Perot etalon scanning data provide
  access to both the true magnetic field strength and filling factor of
  the small-scale magnetic flux elements. In this paper, we present the
  design, fabrication, and calibration of IRIM, as well as the results
  of the first scientific observations.

Title: High-Resolution Observations of Multiwavelength Emissions
    during Two X-Class White-Light Flares
Authors: Xu, Yan; Cao, Wenda; Liu, Chang; Yang, Guo; Jing, Ju; Denker,
   Carsten; Emslie, A. Gordon; Wang, Haimin
Bibcode: 2006ApJ...641.1210X
Altcode:
  We observed two X-class white-light flares (WLFs) on 2003 October 29
  (~20:40 UT) and November 2 (~17:16 UT) using the Dunn Solar Telescope
  (DST) and its High-Order Adaptive Optics (HOAO) system in several
  wavelengths. The spatial resolution was close to the diffraction limit
  of DST's 76 cm aperture, and the cadence was as high as 2 s. This
  is the first time that WLFs have been observed in the near-infrared
  (NIR) wavelength region. We present a detailed study in this paper
  comparing photospheric continuum observations during the two events with
  corresponding line-of-sight magnetograms from the Solar and Heliospheric
  Observatory (SOHO) Michelson Doppler Imager (MDI) and hard X-ray (HXR)
  data from the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). We
  also discuss several models that provide possible mechanisms to explain
  these continuum enhancements, especially in the NIR.

Title: Properties of Small Dark Features Observed in the Pure
    Near-Infrared and Visible Continua
Authors: Xu, Yan; Cao, Wenda; Ma, Jun; Hartkorn, Klaus; Jing, Ju;
   Denker, Carsten; Wang, Haimin
Bibcode: 2005ApJ...628L.167X
Altcode:
  High-resolution images in the visible and near-infrared (NIR) continua
  at around 1560 nm were obtained of solar active regions NOAA AR 10707
  and AR 10486 with the Dunn Solar Telescope (DST) at the National Solar
  Observatory/Sacramento Peak (NSO/SP) on 2004 December 1 and 2 and
  2003 October 29. The images were taken with the high-order adaptive
  optics (HOAO) system, and the spatial resolution was close to the
  diffraction limit of the 76 cm aperture DST in both wavelengths. For
  the 2004 December run, the NIR observations were made with a newly
  developed Lyot filter system, which was designed at the Center for
  Solar-Terrestrial Research (CSTR)/New Jersey Institute of Technology
  (NJIT). The filter has a bandpass of 2.5 Å that allows us to observe
  the pure NIR continuum at the opacity minimum. Our data show that all
  dark features in the NIR are also dark in the visible light. There
  is no evidence showing the existence of so-called dark faculae, i.e.,
  faculae that have negative contrasts in the NIR but positive contrasts
  in the visible. The negative peak contrasts of these small pores are
  about 50% in the visible and 25% in the NIR, and their dimensions are
  in the range of 1"-4".

Title: Near-infrared HeI 1083nm Stokes polarimeter based on liquid
    crystal variable retarders
Authors: Zhang, Zhiyong; Deng, Yuanyong; Wong, Dongguang; Sun, Yingzi;
   Cao, Wenda
Bibcode: 2005SPIE.5901..377Z
Altcode:
  The spectral line of HeI 1083nm is important and potential to measure
  the magnetic field of the solar upper chromosphere. In this paper, we
  present a newly developed Stokes polarimeter for measuring the polarized
  signals at this wavelength. In this device, two Liquid Crystal Variable
  Retarders (LCVRs) were employed as electro-optical modulators and
  a Wollaston prism as analyzer and polarized beam splitter. Compared
  to the commonly used linear-polarized analyzer, the Wollaston prism
  analyzer has main advantage to minimize the seeing-induced contamination
  of earth's atmosphere, as it produces simultaneous images by the
  two perpendicular polarization states. A novel optical design which
  focuses the two beams on different detector areas is described. And
  the accurate calibration methods are introduced too.

Title: 1024 × 1024 HgCdTe CMOS camera for infrared imaging
    magnetograph of Big Bear Solar Observatory
Authors: Cao, W.; Xu, Y.; Denker, C.; Wang, H.
Bibcode: 2005SPIE.5881..245C
Altcode:
  The InfraRed Imaging Magnetograph (IRIM)<SUP>1,2</SUP> is a
  two-dimensional narrow-band solar spectro-polarimeter currently being
  developed at Big Bear Solar Observatory (BBSO). It works in the near
  infrared (NIR) from 1.0 μm to 1.7 μm and possesses high temporal
  resolution, high spatial resolution, high spectral resolving power, high
  magnetic sensitivity. As the detector of IRIM, the 1024 × 1024 HgCdTe
  TCM8600 CMOS camera manufactured by the Rockwell Scientific Company
  plays a very important role in acquiring the high precision solar
  spectropolarimetry data. In order to make the best use of it for solar
  observation, the characteristic evaluation was carried out at BBSO and
  National Solar Observatory (NSO), Sacramento Peak in October 2003. The
  paper presents a series of measured performance parameters including
  linearity, readout noise, gain, full well capacity, hot pixels, dark,
  flat field, frame rate, vacuum, low temperature control, etc., and
  shows some solar infrared narrow band imaging observation results.

Title: Do Dark Faculae Exist?
Authors: Xu, Y.; Cao, W.; Ma, J.; Hartkon, K.; Jing, J.; Denker, C.;
   Wang, H.
Bibcode: 2005AGUSMSP31A..01X
Altcode:
  High-resolution images in visible light and the near infrared
  (NIR) continuum around 1560~nm were obtained in solar active region
  NOAA~10707 with the Dunn Solar Telescope (DST) at the National Solar
  Observatory/Sacramento Peak (NSO/SP) on 2004 December~2 and 7. A
  spatial resolution close to the diffraction limit of the 76~cm DST was
  achieved with high-order adaptive optics system. The observation were
  made with a near infrared tunable Lyot filter system newly developed
  by Big Bear Solar Observatory (BBSO). The filter has a bandpass
  of 2.5~Å. This allows us to observe the pure NIR continuum that
  represents the opacity minimum. Our data show that the contrast of
  faculae has the same sign in the visible and the NIR continua. There
  is no evidence for the existence of so-called "dark faculae", faculae
  that have negative contrasts in the NIR and positive contrasts in
  visible light. We conclude that the previously observed "dark faculae"
  are unresolved pores. <P />This work is supported by NSF under grants
  ATM-0313591, ATM-0236945, ATM-0233931 and AST-0307676, by NASA under
  grants NAG5-10910, NAG5-10212 and NAG5-12733, and by Air Force under
  grant F49620-02-1-0265 and by NSFC-10103004.

Title: The New Solar Telescope at Big Bear Solar Observatory -
    A Progress Report
Authors: Denker, C.; Cao, W.; Chae, J.; Coulter, R.; Kuhn, J. R.;
   Marquette, W. H.; Moon, Y.; Park, Y.; Ren, D.; Tritschler, A.; Varsik,
   J. R.; Wang, H.; Yang, G.; Shoumko, S.; Goode, P. R.
Bibcode: 2005AGUSMSP43A..07D
Altcode:
  The New Solar Telescope (NST) is a new 1.6-meter, off-axis telescope
  for the Big Bear Solar Observatory (BBSO) in California. The NST is
  collaboration between BBSO, the Korean Astronomical Observatory (KAO)
  and Institute for Astronomy (IfA) at the University of Hawaii. BBSO
  is an ideal site for high-spatial resolution observations, since this
  mountain-lake site provides consistent seeing conditions with extended
  periods of excellent seeing from sunrise to sunset. These unique seeing
  characteristics make BBSO ideally suited for combined high-resolution
  campaigns and synoptic observations, which are essential for studies
  of solar activity and space weather. In this progress report, we
  present the latest information on the optical design, the optical
  support structure, the telescope control system and the requisite
  instrumentation for the telescope. Acknowledgements: This work has been
  supported by NSF under grants ATM-0236945, ATM-0342560, MRI-0320540,
  and Air Force DURIP F-49620-03-1-0271.

Title: Dissertation Talk: High Resolution Observations of
    Multi-Wavelength Emissions During Two X-Class White-Light Flares
Authors: Xu, Y.; Cao, W.; Liu, C.; Yang, G.; Jing, J.; Denker, C.;
   Wang, H.
Bibcode: 2005AGUSMSP51C..01X
Altcode:
  We observed two X-class white-light flares (WLF) on 2003 October~29
  (~20:40~UT) and November~2 (~17:16 UT) using the Dunn Solar Telescope
  (DST) and its High-Order Adaptive Optics (HOAO) system in several
  wavelengths. The spatial resolution was close to the diffraction limit
  of DST's 76~cm aperture. The temporal resolution was as high as 2~s. It
  is the first time that WLFs were observed in the Near Infrared (NIR)
  wavelength region. We present a detailed study in this presentation
  by comparing the photospheric continuum observations during these
  two events with corresponding line-of-sight (LOS) magnetograms of the
  Michelson Doppler Imager (MDI) and hard X-ray (HXR) data of the Ramaty
  High Energy Solar Spectroscopic Imager (RHESSI). Our observations show
  that: <P />Significant intensity enhancements were observed in the
  visible and NIR continua and G-band during the impulsive phase of the
  flares. The maximum intensity enhancements were 37% of white-light
  and 25% of the NIR continuum during the first event, and 76% of
  white-light and 66% of the NIR continuum for the second flare. The
  flares were typical two ribbon flares. All ribbons showed a brighter
  core surrounded by a halo structure. The ribbon separation speeds
  were about 28~km/s in the first and 24~km/s in the second event based
  on NIR observations. The derived electric fields in the reconnection
  current sheet Ec are about 23~V~ cm-1 and 22~V~cm-1, respectively. The
  NIR emission and the impulsive HXR emission up to 800~keV were well
  correlated, not considering a small delay of less than two minutes. The
  high resolution and high cadence images gave us the first chance to
  measure the cooling time of flares close to the photosphere. We found
  that the cooling process could be characterized by two steps. A quick
  temperature drop, which is related to the cooling process of the bright
  cores, and a relative slow decay related to the halo structures. The
  fine scale is in the order of less than 30~s and a few minutes for these
  two steps, respectively. <P />Based on these observational results,
  we discuss several models that provide possible mechanisms to explain
  these continuum enhancements, especially in the NIR. This work is
  supported by NSF under grants ATM-0313591, ATM-0236945, ATM-0233931 and
  AST-0307676, by NASA under grants NAG5-10910, NAG5-10212 and NAG5-12733,
  and by Air Force under grant F49620-02-1-0265 and by NSFC-10103004.

Title: First Light for the Near-Infrared Narrow-Band Tunable
    Birefringent Filter of the Big Bear Solar Observatory
Authors: Cao, W.; Hartkorn, K.; Ma, J.; Wang, J.; Xu, Y.; Spirock,
   T.; Denker, C.; Wang, H.
Bibcode: 2005AGUSMSP43A..08C
Altcode:
  A new near-infrared, narrow-band tunable birefringent filter has
  been developed by BBSO/NJIT. This filter, one of the first Lyot
  filters in the near-infrared, has a FWHM of about 2.5 ~Å at the
  design wavelength of 1.5648 μm and is used to observe the deepest
  levels of the photosphere. New techniques were employed in the design,
  including liquid crystal retarders to tune the center wavelength in
  range of ± 100 ~Å. After finishing the calibration and evaluation of
  the filter at the Evans Facility of the NSO at Sacramento Peak, high
  spatial resolution filtergrams and imaging spectroscopy observations
  were carried out at the Dunn Solar Telescope of NSO in December 2004
  with the use of the high-order Adaptive Optics System. For some of
  these observations, the Lyot filter was combined with a Fabry-Perot
  Etalon to achieve a much higher spectral resolution. We discuss the
  calibration methods and present some preliminary observation results.

Title: On the Relation Between Flow Fields and Magnetic Field
    Evolution in Flare Productive NOAA Active Region 10486
Authors: Deng, N.; Xu, Y.; Yang, G.; Cao, W.; Rimmele, T. R.; Wang,
   H.; Denker, C.
Bibcode: 2005AGUSMSP51C..05D
Altcode:
  We present high resolution observations of flow fields within solar NOAA
  active region 10486 before an X10 flare on October 29, 2003. From 2003
  October 28 to November 4, a complex δ-sunspot located in NOAA 10486
  produced dramatic flare activities in the descending phase of the solar
  cycle 23. The flow fields are measured by local correlation tracking
  (LCT) based on speckle masking white-light images, near-infrared (NIR)
  continuum images at 1.56 μm, and G-band images obtained with the Dunn
  Solar Telescope (DST) of the National Solar Observatory/Sacramento Peak
  (NSO/SP). NSO's newly developed high-order adaptive optics system at
  the DST was used to achieve diffraction-limited imaging with a high
  signal-to-noise ratio. The spatial resolution of the images approaches
  the diffraction limit of the 76 cm aperture DST of about 0.14 ″ at
  527 nm. In addtion, we use longitudinal magnetograms from the Michelson
  Doppler Imager (MDI) on board the Solar and Heliospheric Observatory
  (SoHO) to study the evolution of photospheric magnetic field and
  its correlation with flow fields in this flare productive active
  region. We link strong magnetic shear and fast emergence of magnetic
  flux to photospheric flows, which might trigger the flares. Our result
  suggests that the time-series analysis of the photospheric flow fields
  is a critical observational diagnostic for the evolution of magnetic
  fields in solar active regions. This work was supported by NSF under
  grant ATM 03-42560, ATM 03-13591, ATM 02-36945, and MRI AST 00-79482
  and by NASA under grant NAG 5-13661.

Title: Narrow-band Near Infrared Filtergram Observation of Light
    Bridges and Umbral Dots
Authors: Ma, J.; Cao, W.; Denker, C.; Wang, H.
Bibcode: 2005AGUSMSP31A..03M
Altcode:
  We are presenting the observations of the active region NOAA 10709
  on December, 2004 using 0.12Å~narrow band filter centered around
  1.56μm. The observation run was carried out using Dunn Tower
  Telescope of NSO (SacPeak) with high-order AO system. The averaged
  angular resolution of this observation is 0.5" or better. These high
  resolution data in near infrared offer a new view on the photospheric
  structures of sunspot near opacity minimum. By using the tunable near
  infrared narrow band filtergram, we are able to construct magnetic
  field strength map of sunspot. In particular, we will show the magnetic
  structure of light bridges and umbral dots.

Title: Magnetic Helicity Change Rate Associated with an X10
    White-Light Flare
Authors: Yang, G.; Xu, Y.; Cao, W.; Carsten, D.; Wang, H.
Bibcode: 2005AGUSMSP23B..01Y
Altcode:
  Solar active region NOAA 10486 was very active during the descending
  phase of solar cycle 23. Eight X-class flares and a multitude of M-class
  flares were observed in this region from 2003 October 23 to November
  6. In our previous study we presented the high resolution observations
  of the flow fields associated with the X10 white-light flare in this
  active region on 2003 October 29. We linked the strong photospheric
  shear flow with the flare. In this paper, we further our study by
  investigating the magnetic helicity injection rate of the active region
  NOAA 10486 covering the time period of this X10 white-light flare. The
  magnetic helicity injection rate due to horizontal photospheric
  motions is determined by analyzing a set of 1 minute cadence full-disk
  magnetograms taken by the Michelson Doppler Imager on board the Solar
  and Heliospheric Observatory, in addition to the flow fields derived
  previously. The results of this study will aid us to understand the
  process of energy build-up and release associated with the flare.

Title: High-Spatial-Resolution Imaging Combining High-Order Adaptive
    Optics, Frame Selection, and Speckle Masking Reconstruction
Authors: Denker, Carsten; Mascarinas, Dulce; Xu, Yan; Cao, Wenda;
   Yang, Guo; Wang, Haimin; Goode, Philip R.; Rimmele, Thomas
Bibcode: 2005SoPh..227..217D
Altcode:
  We present, for the first time, high-spatial-resolution observations
  combining high-order adaptive optics (AO), frame selection, and
  post-facto image correction via speckle masking. The data analysis is
  based on observations of solar active region NOAA 10486 taken with the
  Dunn Solar Telescope (DST) at the Sacramento Peak Observatory (SPO) of
  the National Solar Observatory (NSO) on 29 October 2003. The high Strehl
  ratio encountered in AO corrected short-exposure images provides highly
  improved signal-to-noise ratios leading to a superior recovery of the
  object's Fourier phases. This allows reliable detection of small-scale
  solar features near the diffraction limit of the telescope. Speckle
  masking imaging provides access to high-order wavefront aberrations,
  which predominantly originate at high atmospheric layers and are only
  partially corrected by the AO system. In addition, the observations
  provided qualitative measures of the image correction away from the
  lock point of the AO system. We further present a brief inspection
  of the underlying imaging theory discussing the limitations and
  prospects of this multi-faceted image reconstruction approach in
  terms of the recovery of spatial information, photometric accuracy,
  and spectroscopic applications.

Title: Photospheric Shear Flows along the Magnetic Neutral Line of
    Active Region 10486 prior to an X10 Flare
Authors: Yang, Guo; Xu, Yan; Cao, Wenda; Wang, Haimin; Denker, Carsten;
   Rimmele, Thomas R.
Bibcode: 2004ApJ...617L.151Y
Altcode:
  We present high spatial resolution observations of proper motions in
  the solar NOAA Active Region 10486 using a high-order adaptive optics
  system, frame selection, and speckle-masking image reconstruction. The
  data were obtained with the Dunn Solar Telescope of the National Solar
  Observatory/Sacramento Peak on 2003 October 29. The resolution of the
  images approaches the diffraction-limited resolution of the Dunn Solar
  Telescope of about 0.14" at 527 nm. We analyzed a 2 hr time series with
  a 1 minute cadence prior to an X10 white-light flare. Local correlation
  tracking was used to measure the photospheric proper motions. We find
  specific evidence of strong shear flows along the magnetic neutral line;
  these shear flows are well defined and correlated with white-light
  flare kernels in the visible and infrared. The speed along the flow
  channels can reach up to 1.6 km s<SUP>-1</SUP>, and the separation of
  channels with head-on flows can be less than 1". Counterstreaming and
  complex flow patterns have been distinguishing characteristics of this
  extraordinarily flare-productive active region.

Title: Near infrared (NIR) achromatic phase retarder
Authors: Ma, Jun; Wang, Jingshan; Cao, W.; Denker, Carsten; Wang,
   Haimin
Bibcode: 2004SPIE.5523..139M
Altcode:
  The tunable near InfraRed Lyot filter (TNIRLF) is one of the focal plane
  instruments for Advanced Technology Solar Telescope (ATST) project of
  the National Solar Observatory (NSO). Achromatic half waveplate and
  quarter waveplates working from 1000 nm to 1700 nm will be used in
  this filter. In this paper, we give a description of the design and
  development for the synthesized achromatic waveplates using quartz
  plates. The retardance variation is within 1% over the full spectral
  range and we discuss the variance of optical axis.

Title: Near infrared waveplate
Authors: Wang, Dongguang; Deng, Yuanyong; Cao, Wenda
Bibcode: 2004SPIE.5492.1786W
Altcode:
  The waveplate made of Polyvinyl Alcohol (PVA) plastic film has several
  advantages compared with that of birefringent crystal in visible region,
  such as its lower cost and insensitivity to temperature and incidence
  angle. What are the performances when they are used in the near infrared
  spectral region? In this paper, we provide some experimental results of
  infrared PVA waveplates. To do this, we make some samples and measure
  their polarization characteristics at several aspects. Firstly, we
  measure the performance of these PVA waveplates by precise instruments
  in laboratory. Secondly, we put the waveplates into a Stokes polarimeter
  to observe the solar magnetic field at near infrared line FeI1.56μm. By
  use of this polarimeter mounted on the vertical spectrograph of 2m
  McMath telescope at Kitt Peak, the two-dimensional Stokes parameters, I,
  Q, U, and V, of a sunspot were observed. From the results of laboratory
  and observation, we get the conclusion that PVA waveplate has the fair
  polarization performance to be used to observe the solar magnetic
  fields in the near infrared spectral region. By these experiments,
  we provide a design of an achromatic waveplate in infrared region,
  which consists of five-element, to illustrate the PVA waveplate is
  the best choice to it.

Title: Near-Infrared Observations at 1.56 Microns of the 2003 October
    29 X10 White-Light Flare
Authors: Xu, Yan; Cao, Wenda; Liu, Chang; Yang, Guo; Qiu, Jiong;
   Jing, Ju; Denker, Carsten; Wang, Haimin
Bibcode: 2004ApJ...607L.131X
Altcode:
  We present high-resolution observations of an X10 white-light flare in
  solar NOAA Active Region 10486 obtained with the Dunn Solar Telescope
  (DST) at the National Solar Observatory/Sacramento Peak on 2003
  October 29. Our investigation focuses on flare dynamics observed
  in the near-infrared (NIR) continuum at 1.56 μm. This is the first
  report of a white-light flare observed at the opacity minimum. The
  spatial resolution was close to the diffraction limit of the 76 cm
  aperture DST. The data benefited from a newly developed high-order
  adaptive optics system and a state-of-the-art NIR complex metal oxide
  semiconductor focal plane array. In addition, we compared hard X-ray
  (HXR) data of RHESSI and magnetograms of the Michelson Doppler Imager on
  board SOHO with the NIR continuum images. Although it is still possible
  that some high-energy electrons penetrate deep to this layer, a more
  likely explanation of the observed emission is back-warming. During
  the impulsive phase of the flare, two major flare ribbons moved apart,
  which were both temporally and spatially correlated with RHESSI HXR
  ribbons. The maximum intensity enhancement of the two flare ribbons is
  18% and 25%, respectively, compared to the quiet-Sun NIR continuum. The
  separation speed of the ribbons is about 38 km s<SUP>-1</SUP> in regions
  with weak magnetic fields and decreases to about 19 km s<SUP>-1</SUP>,
  where stronger magnetic fields are encountered. The derived electric
  field in reconnection current sheet E<SUB>c</SUB> is of the order of
  45 V cm<SUP>-1</SUP> during the flare maximum.

Title: Near Infrared Obsevations at 1.56 μ m of the 2003 October
    29 X10 White-Light Flare
Authors: Xu, Y.; Cao, W.; Liu, C.; Yang, G.; Qiu, J.; Jing, J.;
   Denker, C.; Wang, H.
Bibcode: 2004AAS...204.4712X
Altcode: 2004BAAS...36..738X
  We present high resolution observations of an X10 white-light flare in
  solar active region NOAA 10486 obtained with the Dunn Solar Telescope
  (DST) at the National Solar Observatory/Sacramento Peak (NSO/SP) on 2003
  October 29. Our investigation focusses on flare dynamics observed in the
  near-infrared (NIR) continuum at 1.56 μ m. This is the first report
  of a white-light flare observed in the NIR. The spatial resolution
  was close to the diffraction limit of the 76 cm aperture DST. The data
  benefited from a newly developed high order adaptive optics (AO) system
  and a state-of-the-art NIR complex metal oxide semiconductor (CMOS)
  focal plane array (FPA). In addition, we compared hard X-ray (HXR)
  data of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and
  magnetograms of the Michelson Doppler Imager (MDI) onboard the Solar and
  Heliospheric Observatory (SoHO) with the NIR continuum images. Since the
  NIR data were observed at the opacity minimum, only the most energetic
  electrons can penetrate to this layer in the deep photosphere. As a
  consequence, the flare ribbons appear to be very thin (&lt;2 arcseconds)
  and well defined. During the impulsive phase of the flare, two major
  flare ribbons moved apart, which were both temporally and spatially
  correlated with RHESSI HXR ribbons. The two ribbons ranges are 18%
  to 25% brighter than the quiet sun NIR continuum. The separation speed
  of the ribbons is about 38 km/s in regions with weak magnetic fields
  and decreases to about 19 km/s, where stronger magnetic fields are
  encountered. The derived reconnection electric field E<SUB>c</SUB>
  is of order 50 Vcm<SUP>-1</SUP> at the flare maximum.

Title: The VIsible and InfraRed Imaging Magnetograph (VIM-IRIM)
    at Big Bear Solar Observatory
Authors: Cao, W.; Tritschler, A.; Denker, C.; Wang, H.; Shumko, S.;
   Ma, J.; Wang, J.; Marquette, B.
Bibcode: 2004AAS...204.6907C
Altcode: 2004BAAS...36..795C
  The Visible-light and the InfraRed Imaging Magnetograph (VIM-IRIM) are
  Fabry-Perot based filtergraphs working in a telecentric configuration,
  planned to upgrade the capability for measuring solar magnetic fields
  at BBSO. Both filtergraph instruments are designed to work with
  the combination of a narrow-band prefilter and a single Fabry-Perot
  etalon. VIM and IRIM will provide high temporal resolution, high spatial
  resolution (&lt; 0.2 "/pixel image scale), high spectral resolution
  (&lt; 0.1 Å) simultaneous observation at 600-700 nm and 1.0-1.6 μ
  m with a substantial field of view 170", respectively. Modifications
  in the setup allow also for scanning different spectral lines that
  cover the height range from the solar photosphere up to the solar
  chromopshere. Here we describe the optical setup and present first
  observations to demonstrate the feasibility of the instrument. After
  the instrument has proven to work as a 2D-spectrometer, the upgrade
  to a 2D spectropolarimeter is planned.

Title: Magnetic Helicity Change Rate Associated With X-Class and
    M-Class Flares
Authors: Hartkorn, K.; Wang, H.; Cao, W.; Denker, C.; Xu, Y.
Bibcode: 2004AAS...204.3901H
Altcode: 2004BAAS...36..714H
  We investigate the total helicity change rate of active regions
  during the time period of five X-class and five M-class flares. The
  X-class flares include the X17 flare on October 28 2003 and the X11
  flare on October 29 2003. For the X11 flare we have high-resolution
  IR and G-band data available which allows us to compare flow fields
  derived from this high-resolution data with the flow fields derived
  from MDI full disc magnetograms. <P />Four out of five regions with
  X-class flares show a significant change in the helicity change rate,
  while none of the five active regions with an associated M-class flare
  shows this behavior. We determine the location of the helicity change
  in the active regions and discuss possible causes. We also investigate
  active regions with no flare activity to determine the fluctuations
  of the helicity change rate due to instrumental effects.

Title: High-Spatial Resolution Observations of Flow Fields in Solar
    Active Region NOAA 10486
Authors: Yang, G.; Xu, Y.; Cao, W.; Wang, H.; Denker, C.; Rimmele,
   T. R.
Bibcode: 2004AAS...204.0210Y
Altcode: 2004BAAS...36..669Y
  We present high-spatial resolution observations of proper motions in
  solar active region NOAA 10486 using the newly developed high-order
  adaptive optics (AO) system at the Dunn Solar Telescope (DST) of the
  National Solar Observatory/Sacramento Peak (NSO/SP) on 2003 October
  29. The images were obtained with high-order AO, frame selection, and
  speckle masking image reconstruction. We analyze a two hour time series
  with 1-minute cadence in the context of an X10 white-light flare. Local
  correlation tracking (LCT) was used to measure the horizontal proper
  motions in the photosphere and relate them to the strong shear observed
  in the magnetic field configuration.

Title: Characteristic evaluation of a near-infrared Fabry-Perot
    filter for the InfraRed Imaging Magnetograph (IRIM)
Authors: Cao, Wenda; Denker, Carsten J.; Wang, Haimin; Ma, J.; Qu,
   M.; Wang, Jinshan; Goode, Philip R.
Bibcode: 2004SPIE.5171..307C
Altcode:
  The InfraRed Imaging Magnetograph (IRIM) is a high temporal
  resolution, high spatial resolution, high spectral resolving power,
  and high magnetic sensitivity solar two-dimensional narrow-band
  spectro-polarimeter working in the near infrared from 1.0 μm to
  1.7 μm at Big Bear Solar Observatory (BBSO). It consists of an
  interference filter, a polarization analyzer, a birefringent filter,
  and a Fabry-Perot etalon. As the narrowest filter of IRIM, the infrared
  Fabry-Perot plays a very important role in achieving the narrow band
  transmission of ~ 10 pm and high throughput between 85% and 95% for
  the full wavelength range, maintaining wavelength tuning ability
  from 1.0 to 1.7 μm, and assuring stability and reliability. As
  the third of a series of publications describing IRIM, this paper
  outlines a set of methods to evaluate the near infrared Fabry-Perot
  etalon. Two-dimensional characteristic maps of the near infrared
  Fabry-Perot etalon, including the bandpass ▵λ, effective finesse
  F<SUB>eff</SUB>, peak transmission τ<SUB>max</SUB>, along with a free
  spectral range, flatness, roughness, and stability and repeatability
  were obtained with laboratory equipment. These measured results will
  benefit the optimization of IRIM design and observational mode of
  the future.

Title: Imaging Spectropolarimetry of Ti I 2231 nm in a Sunspot
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
   Livingston, W.
Bibcode: 2003SoPh..215...87P
Altcode:
  Spectro-polarimetric observations at 2231 nm were made of NOAA 10008
  near the west solar limb on 29 June 2002 using the National Solar
  Observatory McMath-Pierce Telescope at Kitt Peak and the California
  State University Northridge - National Solar Observatory infrared
  camera. Scans of spectra in both Stokes I and Stokes V were collected;
  the intensity spectra were processed to remove strong telluric
  absorption lines, and the Stokes V umbral spectra were corrected for
  instrumental polarization. The sunspot temperature is computed using
  the continuum contrast and umbral temperatures down to about 3700 K are
  observed. A strong Ti i line at 2231.0 nm is used to probe the magnetic
  and velocity fields in the spot umbra and penumbra. Measurements of the
  Ti i equivalent width versus plasma temperature in the sunspot agree
  with model predictions. Zeeman splitting measurements of the Stokes I
  and Stokes V profiles show magnetic fields up to 3300 G in the umbra,
  and a dependence of the magnetic field on the plasma temperature
  similar to that which was seen using Fe i 1565 nm observations of the
  same spot two days earlier. The umbral Doppler velocity measurements
  are averaged in 16 azimuthal bins, and no radial flows are revealed to
  a limit of ± 200 m s<SUP>−1</SUP>. A Stokes V magnetogram shows a
  reversal of the line-of-sight magnetic component between the limb and
  disk center sides of the penumbra. Because the Ti i line is weak in
  the penumbra, individual spectra are averaged in azimuthal bins over
  the entire penumbral radial extent. The averaged Stokes V spectra show
  a magnetic reversal as a function of sunspot azimuthal angle. The mean
  penumbral magnetic field as measured with the Stokes V Zeeman component
  splitting is 1400 G. Several weak spectral lines are observed in the
  sunspot and the variation of the equivalent width versus temperature
  for four lines is examined. If these lines are from molecules, it is
  possible that lines at 2230.67, 2230.77, and 2231.70 nm originate from
  OH, while the line at 2232.21 nm may originate from CN.

Title: Weak Infrared Molecular Lines Reveal Rapid Outflow in Cool
    Magnetic Sunspot Penumbral Fibrils
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
   Livingston, W.
Bibcode: 2003ApJ...590L.119P
Altcode:
  New imaging spectropolarimetric observations of the Evershed flow
  in sunspot penumbrae using weak infrared molecular absorption lines
  are presented. A plane-polar coordinate system in the sunspot frame
  is defined, allowing averaging of many raw spectra. Molecular lines
  show Doppler shifts implying typical horizontal outflow speeds of 6
  and up to 9 km s<SUP>-1</SUP>. The Ti I polarimetric spectra show the
  same rapid outflow and suggest an average penumbral magnetic field
  strength of 1400 G. While these observations show Doppler shifts of
  the entire line profile, the velocities are in better agreement with
  previous measurements from spectral line asymmetries.

Title: Weak IR Lines Reveal Rapid Outflow in Cool Magnetic Penumbra
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
   Livingston, W.
Bibcode: 2003SPD....34.1106P
Altcode: 2003BAAS...35..827P
  New imaging spectropolarimetric observations of the Evershed flow in
  sunspot penumbrae using weak infrared molecular absorption lines are
  presented. A plane-polar coordinate system in the sunspot frame is
  defined, allowing averaging of many raw spectra. Molecular lines show
  Doppler shifts implying typical horizontal outflow speeds of 6 to 9
  km/sec. The Ti I polarimetric spectra show the same rapid outflow
  and suggest an average penumbral magnetic field strength of 1400
  Gauss. While these observations show Doppler shifts of the entire
  line profile the velocities are in better agreement with previous
  measurements from spectral line asymmetries.

Title: High-Resolution Infrared Filter System for Solar Spectroscopy
    and Polarimetry
Authors: Cao, W.; Ma, J.; Wang, J.; Goode, P. R.; Wang, H.; Denker, C.
Bibcode: 2003SPD....34.2013C
Altcode: 2003BAAS...35..846C
  We report on the design of an imaging filter system working at the
  near infrared (NIR) of 1.56 μ m to obtain monochromatic images
  and to probe weak magnetic fields in different layers of the deep
  photosphere with high temporal resolution and spatial resolution at
  Big Bear Solar Observatory (BBSO). This filter system consists of
  an interference filter, a birefringent filter, and a Fabry-Pérot
  etalon. As the narrowest filter system, the infrared Fabry-Pérot
  plays an important role in achieving narrow band transmission and
  high throughput, maintaining wavelength tuning ability, and assuring
  stability and reliability. In this poster, we outline a set of methods
  for the evaluation and calibration of the near infrared Fabry-Pérot
  etalon. Two-dimensional characteristic maps of the near infrared
  Fabry-Pérot etalon, including full-width-at-half-maximum (FWHM),
  effective finesse, peak transmission, along with free spectral range,
  flatness, roughness, stability and repeatability were obtained with lab
  equipments. Finally, by utilizing these results, a detailed analysis
  of the filter performance for the Fe I 1.5648 μ m and Fe I 1.5652 μ
  m Zeeman sensitive lines is presented. These results will benefit the
  design of NIR spectro-polarimeter of Advanced Technology Solar Telescope
  (ATST).

Title: Design of Achromatic Waveplates for ATST Near IR Filter System
Authors: Ma, J.; Wang, J.; Cao, W.; Denker, C.; Wang, H.
Bibcode: 2003SPD....34.2024M
Altcode: 2003BAAS...35R.848M
  Achromatic waveplates play one of the central roles in constructing
  universal birefringent filters (UBF). Although it's been developed
  very well by several authors in the last decades, the mechanisms and
  detailed techniques which can realize the achromatism are still not
  clearly categorized. Such waveplates for Infrared do not exist yet. In
  the recent development of a InfraRed High Resolution Magnetograph at
  BBSO, it is realized that a standard approach of designing achromatic
  waveplate is needed not only for the IRHRM, but more importantly, for
  the Near IR Tunable Filter for ATST. <P />There are several theoretical
  methods which are available to describe the behavior of waveplates and
  polarization status of field, including algebraic tools (Jones Algebra,
  Muler Matrix, Stokes Vector), and geometrical approach (Poincere Sphere,
  which is Complex Analysis in fact). By using these methods, it can
  be proved that a combination of waveplates could have much better
  achromatic performance than a single component has. <P />Since the
  simulation of the combination of waveplates gets more and more complex,
  a computer program software package for designing achromatic waveplates
  is developed. Compared to the most popular commercial software package,
  such as ZEMAX which uses ray-tracing approach, the recently developed
  software tools is based on Transfer Functions of Optical Systems,
  which will be more efficient than ray-tracing approach.

Title: Stokes polarimetry at near-infrared 1.56 um for solar
    observation
Authors: Cao, Wenda; Ye, Binxun; Wang, Dongguang; Song, Qian
Bibcode: 2002SPIE.4480..176C
Altcode:
  FeI 1.56 micrometers Zeeman-sensitive lines are very important and
  potential to measure the magnetic field of the deepest layer of the
  solar photosphere. The new generation polarimeter is designed and
  manufactured in this wavelength range. By use of the polarimeter mounted
  on the vertical spectrograph of the 2m solar telescope at Kitt Peak,
  we can observe the Stokes I, Q, U, Vv parameters simultaneously. The
  paper presents the introduction of the near infrared polarimeter and
  the polarmetry of a sunspot group.

Title: The Primary Design of A 1-Meter Infrared Solar Telescope
Authors: Cao, W. D.; Liu, Z.; Ye, B. X.
Bibcode: 2002stma.conf...75C
Altcode:
  No abstract at ADS

Title: Design concepts of EUV telescopes and the detectors boarded
    on the Solar Space Telescope
Authors: Song, Qian; Ye, Binxun; Cao, Jianlin; Chen, Bo; Cao, Wenda
Bibcode: 2001SPIE.4498..335S
Altcode:
  The Solar Space Telescope (SST) is the largest scientific space project
  of China up to now. It engages to observe the transient and steady state
  solar hydrodynamic and magneto-hydrodynamic process over 2-D real time
  polarizing spectrum, UV, X-ray and H(alpha) image, and continuous time
  evolution with high spatial and temporal resolution in order to achieve
  a break through advance in solar physics. The EUV part of SST, the EUV
  telescope (EUT), consists of four telescopes with their detectors, which
  are parallel situated in a single telescope tube. Each telescope of the
  EUT adopts the normal-incidence principle with help of the multilayer
  technology and the primary mirror diameter is 12cm. The detectors of
  the EUT are constructed with EUV sensitive phosphors, fiber tapers,
  image intensifiers, CCDs, camera electronics and cooling blocks. Three
  telescopes of EUT are designed to achieve a spatial resolution of 0.5
  arcsecond with a field of view (FOV) of 8.5'x8.5' in order to get the
  ever high-resolution image of the fine structure of the high temperature
  activities in solar corona and the fourth one is 85'x85' to have the
  full solar disk always in its field of view. In our presentation,
  the scientific objectives and the configuration of EUT are introduced.

Title: The Observation and Study of Two Prominence Events in the
    Infrared
Authors: Cao, W. D.; Ye, B. X.; Livingston, W.
Bibcode: 2001IAUS..203..257C
Altcode:
  This paper reports the infrared observation of two prominence events
  on Jan. 8, 1999 and Feb. 9, 1999 at H Paschen β 12818Å, H Bracket
  α 40512Å, and H Pfund β 46525Å using the McMath Telescope. We
  scanned the spectrograph slit across the prominences parallel to
  the solar limb to obtain three-dimensional data cubes (two spatial
  dimensions and one spectral dimension). By fitting these observed
  lines, we can directly determine some important physical parameters
  such as Doppler width, the optical thickness at line center, and
  the line displacement. Combined with simultaneous observation of
  Balmer H<SUB>α</SUB>, H<SUB>β</SUB>, and K lines, the new results of
  structure and dynamics of limb prominence are presented. These results
  imply that these infrared lines can penetrate through the prominence
  and become the potential probe and tool of them, while H<SUB>α</SUB>
  and H<SUB>β</SUB> sense the prominence skin only.

Title: Simulation and Observation of Solar FeI 1.56 μm Line using
    PtSi Array Camera
Authors: Cao, W.; Song, Q.; Ye, B.
Bibcode: 2001ASPC..236..281C
Altcode: 2001aspt.conf..281C
  No abstract at ADS

Title: PtSi IRFPA camera and its application in infrared solar
    spectrum observation
Authors: Cao, Wenda; Ye, Binxun; Song, Qian; He, J.; Zhou, X. D.;
   Ji, Kaifan
Bibcode: 2000SPIE.4008..806C
Altcode:
  Although the interest in PtSi IR focal pane array has waned due to
  its low quantum efficiency compared with InSb and HgCdTe arrays,
  it is very potential in observing brighter celestial objects. We
  explored the possibility of applying it to the observation of IR solar
  spectrum. In the paper, the methods of the simulation and calibration
  in our observation are introduced and discussed in detail. Using this
  kind of camera, a new observational band is added to the 2D Multi-band
  Solar Spectrograph at Yunnan Observatory. The dispersion for FeI 1.56
  micrometers of the new IR solar spectrograph is 0.0722 angstrom per
  pixel, and each vertical pixel represents 0.51 inch of solar disk. It
  is specially suitable for 2D spectroscopic observation of the deepest
  solar photosphere. Some primary observation results are also presented.

Title: Simultaneous remote observation from six sites organized at
    the 1-m telescope of the Yunnan Observatory
Authors: Cao, Wenda; Song, Qian; Ji, Kaifan
Bibcode: 2000SPIE.4011..117C
Altcode:
  On Mar. 6-7, 1997, a simultaneous remote observation from 6 sites
  was successfully carried out with the cooperation of astronomers
  and hobbyists in China, United States, Canada, and Great Britain. In
  the paper, the process and technical methods in this observation are
  introduced in detail. The present difficulties and brilliant prospects
  in the observational method under the current circumstances of Internet
  in China are shown as well.

Title: A research on the detectors for solar spectrographs.
Authors: Cao, Wenda; Ji, Kaifan; Song, Qian
Bibcode: 2000AcASn..41...93C
Altcode:
  The selection and application of detectors for a solar spectrograph
  described in this paper are more or less different from those in
  other works. For use at the solar spectrograph of Yunnan Observatory,
  the authors have built a model to estimate the spectral fluxes
  of solar spectrograph with computer and confirmed the result with
  observations. The spectral fluxes in visible and near infrared bands
  were calculated for the same spectrograph. Based on these results,
  the authors have discussed the detectors in details and summed up the
  processes in observation where some additional comments are needed.

Title: Simulation and observation of near infrared solar Fe I 1.56
    μm line.
Authors: Cao, Wenda; Song, Qian; Ji, Kaifan
Bibcode: 1999ArBei..34...60C
Altcode:
  The infrared focal plane array (IRFPA) with large size and high
  quantum efficiency is very difficult to acquire. On Jan. 29 - 30,
  1999, the authors utilized PtSi IRFPA to observe the infrared solar
  Fe I 1.56 μm line. The simulation and observation for this experiment
  are introduced in detail.

Title: Radiation damage on CCDs in space environment.
Authors: Song, Qian; Cao, Wenda; Ji, Kaifan
Bibcode: 1999ArBei..34...67S
Altcode:
  The energetic radiation existing in the space natural radiation
  environment may cause damages to charge-coupled devices (CCDs) working
  in space and degrade their performance. In this paper, the mechanism
  of the CCD's radiation damage is reviewed and an interpretation is
  attempted for the radiation-caused performance defects of the Solar-A
  SXT CCD with the flat-band shift resulted from the trapped holes within
  the insulator layer between gates and silicon bulk.

Title: Laboratory evaluation of CCD for astronomical application.
Authors: Song, Qian; Ji, Kaifan; Cao, Wenda
Bibcode: 1999AcApS..19..333S
Altcode:
  The method of evaluating charge-coupled device for astronomical
  application used in Yunnan Observatory CCD-testing Laboratory is
  presented. The parameters evaluated include linearity, noise, gain
  quantum efficiency and transfer efficiency.

Title: Silicon CCD optimized for NIR wavelengths.
Authors: Song, Qian; Ji, Kaifan; Cao, Wenda
Bibcode: 1999PYunO...4...60S
Altcode:
  CCDs processed on typical substrates exhibit low NIR QE. Because
  the relatively thin epitaxial layer allows a high percentage of long
  wavelength photons to pass through and the reflection loss of back
  surface is high. A thick epitaxial layer allows the longer wavelength
  photons to be absorbed into the epitaxial layer where the resultant
  electrons generated will be collected in the potential wells. The
  drawback of processing with this method is a resultant degradation
  of carrier diffusion MTF. Increasing the depleted region under each
  gate, which can be realized by using high resistivity substrates,
  can enhance MTF. A new kind of CCD fabricated on high resisitivity
  silicon at Lick Observatory has superior red performance beyond 800 nm
  wavelength. The application of thin film AR coating directly on to the
  CCD back surface can significantly reduce reflection loss from UV to
  NIR and greatly decrease interference fringing on back illuminated CCDs.

Title: Calculation of spectral fluxes for the solar spectrograph of
    Yunnan Observatory.
Authors: Cao, Wenda; Ji, Kaifan; Song, Qian
Bibcode: 1999PYunO...4...53C
Altcode:
  For the solar spectrograph of Yunnan Observatory, a computer model to
  estimate the spectral fluxes is set up and is verified by the authors'
  observations. The spectral fluxes are calculated. In view of these
  results, the plan of the detectors for the Solar Spectrograph is
  suggested.

Title: An Interpretation of a Radiation Damage Phenomenon of the
    solar-A CCD
Authors: Song, Qian; Cao, Wenda
Bibcode: 1999oaaf.conf..139S
Altcode:
  : The Yohkoh satellite for the Japanese Solar-A Mission was launched
  in 1991. There were some unexpected darkened spots on the recent images
  took by the Soft X-ray Telescope (SXT) boarded on. The images were took
  by a CCD camera utilized a 1024x1024 virtual phase CCD. CCDs used in
  space are subjected to natural radiation environments that may cause
  permanent damages on them and degrade their performance. In this paper,
  an interpretation by CCD radiation damage theory was attempted and a
  computer-simulated result was calculated.

Title: Model of Spectral Fluxes for Solar Spectrograph
Authors: Cao, Wenda; Song, Qian
Bibcode: 1999oaaf.conf..400C
Altcode:
  Taking use of the solar spectrograph in Yunnan Observatory, we built
  a model to estimate the spectral fluxes of solar spectrograph with
  computer and confirmed the result by observations. The spectral
  fluxes in visible and near infrared bands were calculated for the
  solar spectrograph of Yunnan Observatory. Based on the results, we
  made a suggestion of the detectors for solar spectrograph and summed
  out the processes in observation where the additional attention should
  be needed.

Title: Methods for blue enhancement of CCDs.
Authors: Ji, Kaifan; Song, Qian; Cao, Wenda
Bibcode: 1999PYunO...3...50J
Altcode:
  CCDs have become the most important astronomical detector for UV,
  visible and NIR imaging and spectroscopy at most observatories
  throughout the world. But the quantum efficiencies (QE) in the blue
  region of general CCDs are very low. Increasing the sensitivity in
  this region is desirable when the CCDs are used in astronomy. There are
  two ways to improve QEs of frontside illuminated CCDs. Deposition of a
  very thin polysilicon gate allows transmittance of shorter wavelength
  photons, and frontside coating a completed device with lumogen absorbs
  lower wavelength photons and re-emits them near the peak sensitivity
  of the CCD. After optimizing, 100% QE enhancement may be realized at
  UV band.

Title: Easy way to evaluate CCDs for astronomical use
Authors: Song, Qian; Ji, Kaifan; Cao, Wenda
Bibcode: 1998SPIE.3553..291S
Altcode:
  The methods of evaluating the astronomy-using CCDs in Yunnan Observatory
  CCD-testing Lab are introduced, concerning the evaluation of linearity,
  noise, gain, quantum efficiency and transfer efficiency, etc.

Title: Near infrared focal plane arrays for astronomy.
Authors: Cao, Wenda; Ye, Binxun
Bibcode: 1998PABei..16..103C
Altcode:
  Developments in infrared focal plane arrays are summarized. InSb,
  HgCdTe, and PtSi near-infrared focal plane arrays are introduced and
  combined with the plan of the infrared solar tower in China, their
  features are compared in detail.

Title: Two remote-presence observations at the 1-m telescope of the
    Yunnan Observatory in China
Authors: Ji, Kaifan; Cao, Wenda; Ye, Binxun; Song, Q.; Chu, Y.; Chen,
   K.; Sun, J.; Sun, Y. S.
Bibcode: 1998SPIE.3351...25J
Altcode:
  Two remote presence observations on Dec. 25, 1995 and Mar. 7, 1997 were
  achieved at the 1-m telescope of Yunnan Observatory. In this paper,
  the observations are introduced in detail. The technical methods in
  the remote presence observation are also discussed under the current
  circumstances of hardware and software in China. The brilliant prospects
  of the observational method are shown as well.

Title: Evidence for resonant absorption of VLF waves obtained at
    Zhongshan Station, Antarctica
Authors: Tang, K. Y.; Peng, F. L.; Ning, Z. L.; Cao, W. Z.; Meng,
   Q. F.; Yang, Y. H.; Jiao, C. M.
Bibcode: 1998mrat.conf...37T
Altcode:
  Evidence for resonant absorption of VLF waves was obtained at Zhongshan
  Station, Antarctica. The L value for Zhongshan Station is about 14. Due
  to such high geomagnetic latitude, no whistlers were received, but a
  lot of VLF emissions have been recorded since the station was founded
  in 1990. The VLF emission recorded in Zhongshan Station are usually
  wide-band emission, from a few hundred Hz to about 15kHz. In February
  and June of 1993, we recorded two sets of VLF emissions never seen
  before. The main feature for the emission is a blank curve around
  5kHz cut from the wide-band emissions. We explain these observations
  in term of resonant absorption of VLF waves by ions.

Title: The test of the DALSA CA-D7-1024T CCD camera.
Authors: Song, Qian; Liu, Weiwei; Ji, Kaifan; Cao, Wenda
Bibcode: 1998PYunO...2...72S
Altcode:
  From 2nd to 6th, Sep., 1996, the main detector of the balloon-borne
  solar telescope of the Beijing Observatory, DALSA CA-D7-1024T camera,
  was tested in the CCD - Testing Laboratory of Yunnan Observatory. The
  test revealed that despite some problems on the image-collecting system,
  the overall behavior of the camera is superb as a non-cooling detector.

Title: International astronomical remote present observation on IRC.
Authors: Ji, Kaifan; Cao, Wenda; Song, Qian
Bibcode: 1998PYunO...2...67J
Altcode:
  On March 6 - 7, 1997, an international astronomical remote present
  observation (RPO) was made on Internet Relay Chat (IRC) for the first
  time. Seven groups in four countries, China, United States, Canada and
  Great Britain, used the 1 meter telescope of Yunnan observatory together
  by the way of remote present observation. Within minutes, images were
  "On-line" by FTP, and every one was able to get them by anonymous ftp
  and discuss them on IRC from different widely separated sites.

Title: Computer simulation for the observation of the 1.56 μm Fe
    I spectral line of solar magnetic field.
Authors: Cao, Wenda; Ji, Kaifan; Song, Qian
Bibcode: 1998PYunO...4...43C
Altcode:
  It makes an interesting idea and work to use the IRFPA made in China
  and the solar spectrometer at Yunnan Observatory to probe into the
  local magnetic field on solar surface by the observation of NIR Fe I
  line at 1.56 μm. The computer simulation is presented. The influence
  of the apparatus effects and noises in the observation results are
  also discussed in detail.

Title: RVC and Its Effect of Solar-terrestrial Physics
Authors: Ji, S. C.; Wei, F. S.; Cao, W. D.
Bibcode: 1998asct.conf..125J
Altcode:
  No abstract at ADS

Title: A remote-presenting observation at the 1 m telescope of
    Yunnan Observatory.
Authors: Cao, Wenda; Ji, Kaifan; Song, Qian; Liu, Weiwei
Bibcode: 1997PYunO...3...88C
Altcode:
  With the development of techniques of the computer, communication,
  network, and data compress, the technique of remote-presenting
  observation is achieved at the 1 m telescope of Yunnan
  Observatory. Compared with the traditional observation, it has a
  lot of advantages. In this paper, the remote-presenting observation
  during Dec 26 - 27, 1995 is introduced in detail. Under the current
  circumstances of hardware and software in China, the technical methods
  and difficulties in the remote-presenting observation are discussed.

Title: PI 1024 CCD of Yunnan Observatory.
Authors: Ji, Kaifan; Song, Qian; Cao, Wenda
Bibcode: 1997PYunO...4...63J
Altcode:
  No abstract at ADS

Title: WinView software and an application to image processing.
Authors: Cao, Wenda; Huan, Zunxiang; Ji, Kaifan; Song, Qian
Bibcode: 1997PYunO...2...75C
Altcode:
  WinView is a high performance software package written specifically
  for the acquisition and analysis of images. Many sophisticated
  postprocessing options are available. These options are introduced in
  this paper.

Title: Remote Real-Time Astronomical Observations on IRC
Authors: Kaifan, Ji; Cao, W.; Song, Q.; Ye, B.
Bibcode: 1997IAUJD..20E..11K
Altcode:
  On March 6-7, 1997, remote real-time observations were successfully made
  by the cooperation of seven groups in China, the United States, Canada
  and Great Britain. BVy using the medium of FTP and the Internet Relay
  Chat (IRC) network, we were able to make astronomicaal observations,
  from widely separated geographical sites, with the 1m telescope of the
  observatory in China's Yunnan Province. Within minutes, images were
  on the Internet and everyone was able to view them and to communicate
  with each other, discussing the objectives, making decisions and having
  the team member at the observatory operate the controls to obtain the
  images we needed for later study and analysis. The important adavntage
  of this event is that all Internet connections were made through a local
  phone line connection. The long-distance connections were then routed
  through the free Internet communications, thus avoiding the extremely
  high cost of transcontinental long-distance telephone connections.

Title: Laboratory Evaluations of a CCD System For the Balloon-borne
    Solar Telescope
Authors: Song, Q.; Liu, W.; Ji, K.; Cao, W.; Huan, Z.
Bibcode: 1997IAUJD..19E..49S
Altcode:
  The CCD camera, DALSA/CA-D7-1024, which is a commercial CCD system,
  is selected as the main detector for the BAO's Balloon-borne Solar
  Telescope. The principal parameters were tested by the YNAO, CCD-Testing
  Laboratory in the early September, 1996. The equipment of the lab and
  the method of the evaluations are described in the Poster. Evaluations
  show that the overall behavior of the camera is superb among the
  non-cooling commercial CCD systems. Nevertheless, there are some flaws
  in the image-collecting system which must be solved before launch.

Title: Some infared focal panel arrays applying in near infrared
    solar observation.
Authors: Cao, Wenda; Song, Qian; Ji, Kaifan
Bibcode: 1997PYunO...4...73C
Altcode:
  The development course and structure of infrared focal plane arrays
  are summarized. Near-infrared focal plane arrays are introduced
  emphatically, and combined with the infrared solar tower plan at
  present, their features are compared in detail.

Title: The computer network and software system for 1 meter telescope.
Authors: Ji, Kaifan; Song, Qian; Cao, Wenda
Bibcode: 1997PYunO...4...68J
Altcode:
  No abstract at ADS

Title: WinView and its usage on the 1 m telescope at Yunnan
    Observatory.
Authors: Cao, Wenda; Ji, Kaifan; Song, Qian; Huan, Zunxiang
Bibcode: 1997PYunO...1...76C
Altcode:
  The WinView is a highly-efficient software package for image collecting
  and processing in astronomy. The essential functions and the usage of
  this package in astronomy are described in detail.

Title: FITS BMP and SCR image formats and the transformations.
Authors: Ji, Kaifan; Cao, Wenda; Song, Qian
Bibcode: 1996PYunO...2...60J
Altcode:
  The image formats - FITS, BMP and SCR - are introduced in detail. The
  FITS format has become a universal format in astronomy and can
  be supported by almost all the software packages in astronomical
  uses. Meanwhile the BMP format is widely used on personal computers
  and is supported by a large amount of PC softwares in displaying,
  progressing and printing. The SCR format is used in the Yunnan
  Observatory to implement CCD image collection on PCs. Therefore, it
  is important to realize the transformation among the three formats
  so that CCD images head and image data, and the critical part is to
  transform the high and low bits of the data.

Title: The one-dimension centering algorithms of CCD image.
Authors: Kaifan, J.; Song, Qian; Cao, Wenda
Bibcode: 1996PYunO...4...69K
Altcode:
  The digital centering algorithms with high resolution becomes more and
  more important in astrometry. The marginal distribution method is used
  to transform the two-dimensional stellar image to one-dimensional. From
  comparisons among four kinds of one-dimensional centering algorithms
  (Gaussian fit, modified moment, median and derivative search) it is
  shown that Gaussian fit ranks highest in resolution, then the modified
  moment, and derivative the lowest. But the Gaussian fit is too slow in
  the view of calculating speed. Therefore, modified moment is the best
  choise as a centering method which can meet both the high resolution
  and high efficiency demands.

Title: Development and test of an operation gain amplifier with the
    solar radio telescope at 15 cm wavelengths.
Authors: Ghen, Guoqiang; Cao, Wenda; Yang, Kaiping
Bibcode: 1995PYunO...1...47G
Altcode:
  The construction principle of the operation gain amplifier with the
  solar radio telescope at 15 cm wavelengths is introduced. The adjustment
  and the test for measurement results have been obtained.

Title: Approaching to Internet.
Authors: Ji, Kaifan; Song, Qian; Cao, Wenda
Bibcode: 1995PYunO...3...62J
Altcode:
  With help from Computer Network Center of Chinese Academy of Sciences
  (CNC) and Telecommunication Office of Kunming, the authors have built
  their e-mail system. The node computer named ROSE belonging to CNC is
  linked to Internet.

Title: Carbon dioxide interactions with irradiance and temperature
    in potatoes
Authors: Cao, W.; Tibbitts, T. W.; Wheeler, R. M.
Bibcode: 1994AdSpR..14k.243C
Altcode: 1994AdSpR..14..243C
  Separate controlled environment studies were conducted to determine
  the interaction of CO<SUB>2</SUB> with irradiance and interaction of
  CO<SUB>2</SUB> with temperature on growth of three potato cultivars. In
  the first study, an elevated CO<SUB>2</SUB> concentration of 1000
  μmol mol<SUP>-1</SUP> and an ambient CO<SUB>2</SUB> of 350 μmol
  mol<SUP>-1</SUP> were maintained at the photosynthetic photon
  fluxes (PPF) of 17 and 34 mol m<SUP>-2</SUP> d<SUP>-1</SUP> with
  12 h photoperiod, and at the PPF of 34 and 68 mol m<SUP>-2</SUP>
  d<SUP>-1</SUP> with 24 h photoperiod (400 and 800 μmol m<SUP>-2</SUP>
  s<SUP>-1</SUP> PPF at each photoperiod). Tuber and total dry weights of
  90-day old potatoes were significantly increased with CO<SUB>2</SUB>
  enrichment, but the CO<SUB>2</SUB> stimulation was less with higher
  PPF and longer photoperiod. Shoot dry weight was affected more
  by photoperiod than by PPF and CO<SUB>2</SUB> concentrations. The
  elevated CO<SUB>2</SUB> concentration increased leaf CO<SUB>2</SUB>
  assimilation rates and decreased stomatal conductance with 12 h
  photoperiod, but had only a marginal effect with 24 h photoperiod. In
  the second study, four CO<SUB>2</SUB> concentrations of 500, 1000, 1500
  and 2000 μmol mol<SUP>-1</SUP> were combined with two air temperature
  regimes of 16 and 20°C under a 12 h photoperiod. At harvest, 35
  days after transplanting, tuber and total dry weights of potatoes
  reached a maximum with 1000 μmol mol<SUP>-1</SUP> CO<SUB>2</SUB>
  at 16°C, but continued to increase up to 2000 μmol mol<SUP>-1</SUP>
  CO<SUB>2</SUB> at 20°C. Plant growth was greater at 20°C than at 16°C
  under all CO<SUB>2</SUB> concentrations. At 16°C specific leaf weight
  increased substantially with increasing CO<SUB>2</SUB> concentrations
  as compared to 500 μmol mol<SUP>-1</SUP> CO<SUB>2</SUB>, but increased
  only slightly at 20°C. This suggests a carbohydrate build-up in the
  leaves at 16°C temperature that reduces plant response to increased
  CO<SUB>2</SUB> concentrations. The data in the two studies indicate
  that a PPF of 34 mol m<SUP>-2</SUP> d<SUP>-1</SUP>, 20°C temperature,
  and 1000-2000 μmol mol<SUP>-1</SUP> CO<SUB>2</SUB> produces optimal
  tuber yield in potatoes. <P />Current address: MD-RES, Kennedy Space
  Center, FL 32899.

Title: Solid matrix and liquid culture procedures for growth of
    potatoes
Authors: Tibbitts, T. W.; Cao, W.
Bibcode: 1994AdSpR..14k.427T
Altcode: 1994AdSpR..14..427T
  This report discusses the advantages and limitations of several
  different procedures for growth of potatoes for CELSS. Solution culture,
  in which roots and stolons are submerged, and aeroponic culture
  were not found useful for potatoes because stolons did not produce
  tubers unless a severe stress was applied to the plants. In detailed
  comparison studies, three selected culture systems were compared,
  nutrient film technique (NFT), NFT with shallow media, and pot culture
  with deep media. For the NFT and NFT plus shallow media, plants were
  grown in 0.3 m<SUP>2</SUP> trays and for the deep medium culture,
  in 20 liter pots. A 1 cm depth of arcillite, a baked montmorillonite
  clay, was used as shallow media (NFT-arc). Peatvermiculite mixture was
  used to fill the pots for the deep media. Nutrient solution, modified
  half-strength Hoagland's was recirculated among the tray culture plants
  with pH automatically controlled at 5.5, and conductivity maintained
  ~ 1100 μS cm<SUP>-1</SUP> by adding stock nutrients or renewing the
  solution. A separate nutrient solution was used to water the pot plants
  four times daily to excess and the excess was discarded. Plants of
  Norland cv. were utilized and transplanted from sterile-propagated
  stem cutting plantlets. The plants were grown for 66 days under
  12 h photoperiod in a first study and grown for 54 days under 24 h
  photoperiod in a second study. Under both photoperiods, total plant
  growth was greater in NFT-arc than in either NFT or pot culture. Under
  12 h photoperiod, tuber dry weight was 30% higher with NFT-arc, but
  50% lower with NFT, than with pot culture. Under 24 h photoperiod,
  however, tuber dry weight in both NFT and NFT-arc was only 20% of that
  in pot culture. The NFT and NFT-arc produced a greater shoot growth
  and larger number of small tubers than pot culture, especially with 24
  h photoperiod. It is concluded that there are serious limitations to
  the use of NFT alone for growth of potatoes in a CELSS system. These
  limitations can be minimized by using a modified NFT with a shallow
  layer of media, such as arcillite, yet additional work is needed to
  ensure high tuber production with this system under long photoperiods.

Title: Some common characteristics of the basic components of the
    solar radio emission and confirmation of a fourth basic component.
Authors: Ji, S. C.; Cao, W. D.; Chen, G. Q.; Yang, K. P.
Bibcode: 1994A&A...286..588J
Altcode:
  Our high time-resolution data observed with fast sampling radio
  telescopes in three periods were processed. It is found that there
  is a rapidly varying component (RVC) in the radio emission source
  on the Sun. After investigating some common characteristics of the
  basic components of the solar radio emission, we discover that RVC is
  different in nature from the known three basic components: the quiet
  Sun, the slowly varying component (SVC), and the radio burst. It
  has a character superimposed on the radio burst: short duration,
  high brightness temperature and small dimension. For this reason, it
  is presented as a fourth basic component. Up to now, we have observed
  five types of RVC. Among them four types can be confirmed, another
  is yet in dispute. Finally, the five categories of observational
  characteristics of RVC are given.

Title: Solar radio type II burst in the corona and interplanetary
    medium.
Authors: Cao, Wenda; Yang, Kaiping; Ghen, Guoqiang
Bibcode: 1994PYunO...1...49C
Altcode:
  No abstract at ADS

Title: The frequency splitting phenomenon in type II solar radio
    bursts.
Authors: Cao, Wenda; Chen, Guoqing; Yang, Kaiping
Bibcode: 1994PYunO...2...11C
Altcode:
  The frequency splitting phenomenon in type II solar radio bursts is
  introduced and its observational features and theoretical explanation
  are summarized. The numerous existing models on frequency splitting
  are discussed in detail.

Title: Test of the intermediate frequency amplifier of the solar
    radio telescope at 2130 MHz.
Authors: Chen, Guoqing; Cao, Wenda; Yang, Kaiping
Bibcode: 1994PYunO...2...19C
Altcode:
  The construction principle and the technical parameters of the
  intermediate frequency amplifier of the solar radio telescope at 2130
  MHz at Yunnan Observatory are introduced. Some measurement results
  are presented.

Title: Radio and soft X-ray investigation of the solar flares of
    February 4, 1986
Authors: Ji, Shuchen; Ding, Youji; Chen, Guoqiang; Cao, Wenda
Bibcode: 1993Ap&SS.203..241J
Altcode:
  In this paper, the 3B flare of February 4, 1986 is studied
  comprehensively. The escape electrons accelerated to 10 100 keV at the
  top of coronal loop are confirmed by III type bursts. The energetic
  electron beams moved downward trigger the eruptions in the low layer
  of solar atmosphere. The radio and soft X-ray bursts are interpreted,
  respectively, by the maser mechanism and evaporation effect. Finally,
  the important role of energetic electron beams in solar flares is
  pointed out.

Title: Duration of the solar radio spike radiation at decimetric
    waves and milliseconds.
Authors: Cao, Wenda; Ghen, Guoqiang; Yang, Kaiping
Bibcode: 1993PYunO...3...24C
Altcode:
  The duration of the solar radio milliseconds spike radiation is
  shortened with increasing frequency, which has been a puzzling problem
  for a long time. In this paper, according to the electron cyclotron
  maser excited by the electron beams of the hollow beam distribution
  associated with the type III bursts, the relation between the duration
  of the spike radiation and the characteristic frequency ratio with the
  wave growth rate is discussed in detail. It is concluded that at the
  different wavelength of the decimetric wave, the spike radiations are
  the different frequency harmonic waves and the correlative decrease
  of the duration appears with increasing frequency.

Title: Improvement and test of a microwave noise generator.
Authors: Ghen, Guoqiang; Yang, Kaiping; Cao, Wenda
Bibcode: 1993PYunO...3...29G
Altcode:
  The improvement and test of the calibration source (or the noise
  generator) of the solar radio telescope are briefly described. The
  construction principle and measured results are also presented. It is
  known through the operation that the improvement is a success and the
  desired results are achieved.

Title: Solar radio decimetric spike radiation and metric radio bursts.
Authors: Cao, Wenda
Bibcode: 1992PYunO...3....8C
Altcode:
  The millisecond spike events from Jan 1990 to Mar 1991 observed and
  recorded with the fast sampling radio telescopes at four frequencies
  at the Yunnan Observatory are analysed. With the data combined with
  those of the radio outbursts at the metric wave-band published by the
  Solar-Geophysical Data during this time, the various features of the
  millisecond spikes are given. The relation between the millisecond
  spikes and the solar radio bursts of types III, II and IV is also
  summarized.

