Author name code: reardon
ADS astronomy entries on 2022-09-14
author:"Reardon, Kevin P." 
------------------------------------------------------------------------  

Title: Defining the Middle Corona
Authors: West, Matthew J.; Seaton, Daniel B.; Wexler, David B.;
   Raymond, John C.; Del Zanna, Giulio; Rivera, Yeimy J.; Kobelski,
   Adam R.; DeForest, Craig; Golub, Leon; Caspi, Amir; Gilly, Chris R.;
   Kooi, Jason E.; Alterman, Benjamin L.; Alzate, Nathalia; Banerjee,
   Dipankar; Berghmans, David; Chen, Bin; Chitta, Lakshmi Pradeep; Downs,
   Cooper; Giordano, Silvio; Higginson, Aleida; Howard, Russel A.; Mason,
   Emily; Mason, James P.; Meyer, Karen A.; Nykyri, Katariina; Rachmeler,
   Laurel; Reardon, Kevin P.; Reeves, Katharine K.; Savage, Sabrina;
   Thompson, Barbara J.; Van Kooten, Samuel J.; Viall, Nicholeen M.;
   Vourlidas, Angelos
Bibcode: 2022arXiv220804485W
Altcode:
  The middle corona, the region roughly spanning heliocentric altitudes
  from $1.5$ to $6\,R_\odot$, encompasses almost all of the influential
  physical transitions and processes that govern the behavior of
  coronal outflow into the heliosphere. Eruptions that could disrupt
  the near-Earth environment propagate through it. Importantly, it
  modulates inflow from above that can drive dynamic changes at lower
  heights in the inner corona. Consequently, this region is essential
  for comprehensively connecting the corona to the heliosphere and for
  developing corresponding global models. Nonetheless, because it is
  challenging to observe, the middle corona has been poorly studied by
  major solar remote sensing missions and instruments, extending back to
  the Solar and Heliospheric Observatory (SoHO) era. Thanks to recent
  advances in instrumentation, observational processing techniques,
  and a realization of the importance of the region, interest in the
  middle corona has increased. Although the region cannot be intrinsically
  separated from other regions of the solar atmosphere, there has emerged
  a need to define the region in terms of its location and extension
  in the solar atmosphere, its composition, the physical transitions
  it covers, and the underlying physics believed to be encapsulated by
  the region. This paper aims to define the middle corona and give an
  overview of the processes that occur there.

Title: Erratum: "A Study of Sunspot 3 Minute Oscillations Using ALMA
    and GST" (2022, ApJ, 924, 100)
Authors: Chai, Yi; Gary, Dale E.; Reardon, Kevin P.; Yurchyshyn, Vasyl
Bibcode: 2022ApJ...933..247C
Altcode:
  No abstract at ADS

Title: Evaluating Non-LTE Spectral Inversions with ALMA and IBIS
Authors: Hofmann, Ryan A.; Reardon, Kevin P.; Milic, Ivan; Molnar,
   Momchil E.; Chai, Yi; Uitenbroek, Han
Bibcode: 2022ApJ...933..244H
Altcode: 2022arXiv220508760H
  We present observations of a solar magnetic network region in the
  millimeter continuum with the Atacama Large Millimeter/submillimeter
  Array (ALMA) and in the Ca 8542 and Na 5896 Å spectral lines with
  the Interferometric Bidimensional Spectrometer (IBIS). Our goal is
  to compare the measurement of local gas temperatures provided by ALMA
  with the temperature diagnostics provided by non-LTE inversions using
  the STockholm inversion Code (STiC). In performing these inversions,
  we find that using column mass as the reference height scale, rather
  than optical depth, provides more reliable atmospheric profiles above
  the temperature minimum and that the treatment of non-LTE hydrogen
  ionization brings the inferred chromospheric temperatures into better
  agreement with the ALMA measurements. The Band 3 brightness temperatures
  are higher but well correlated spatially with the inversion-derived
  temperatures at the height of formation of the Ca 8542 line core. The
  Band 6 temperatures instead do not show good correlations with the
  temperatures at any specific layer in the inverted atmospheres. We then
  performed inversions that included the millimeter-continuum intensities
  as an additional constraint. Incorporating Band 3 generally resulted in
  atmospheres showing a strong temperature rise in the upper atmosphere,
  while including Band 6 led to significant regions of anomalously low
  temperatures at chromospheric heights. This is consistent with the
  idea that the Band 6 emission can come from a combination of heights
  ranging from the temperature minimum to upper chromosphere. The
  poor constraints on the chromospheric electron density with existing
  inversion codes introduces difficulties in determining the height(s)
  of formation of the millimeter continuum as well as uncertainties in
  the temperatures derived from the spectral lines.

Title: A Spectroscopic Survey of Infrared 1-4 μm Spectra in Regions
    of Prominent Solar Coronal Emission Lines of Fe XIII, Si X, and Si IX
Authors: Ali, Aatiya; Paraschiv, Alin Razvan; Reardon, Kevin; Judge,
   Philip
Bibcode: 2022ApJ...932...22A
Altcode: 2022arXiv220308636A
  The infrared solar spectrum contains a wealth of physical data about
  the Sun and is being explored using modern detectors and technology
  with new ground-based solar telescopes. One such instrument will be
  the ground-based Cryogenic Near-IR Spectro-Polarimeter of the Daniel
  K. Inouye Solar Telescope (DKIST), which will be capable of sensitive
  imaging of the faint infrared solar coronal spectra with full Stokes I,
  Q, U, and V polarization states. Highly ionized magnetic dipole emission
  lines have been observed in galaxies and the solar corona. Quantifying
  the accuracy of spectral inversion procedures requires a precise
  spectroscopic calibration of observations. A careful interpretation
  of the spectra around prominent magnetic dipole lines is essential
  for deriving physical parameters and particularly for quantifying the
  off-limb solar coronal observations from DKIST. In this work, we aim to
  provide an analysis of the spectral regions around the infrared coronal
  emission lines of Fe XIII 1074.68 nm, Fe XIII 1079.79 nm, Si X 1430.10
  nm, and Si IX 3934.34 nm, aligning with the goal of identifying solar
  photospheric and telluric lines that will help facilitate production of
  reliable inversions and data products from four sets of solar coronal
  observations. The outputs can be integrated in processing pipelines
  to produce level 2 science-ready data.

Title: Atmospheric Gravity Waves in the Magnetized Solar Atmosphere
Authors: Vesa, Oana; Jackiewicz, Jason; Reardon, Kevin
Bibcode: 2022AAS...24033203V
Altcode:
  Atmospheric gravity waves (AGWs) are abundantly generated and excited
  in the lower solar atmosphere by turbulent convection along with
  other commonly studied waves, such as acoustic waves. These waves are
  ubiquitous in various stellar and planetary atmospheres. On Earth, they
  play a pivotal role in improving our global weather predictions and
  climate models. On the Sun, AGWs are predicted to reach chromospheric
  heights, where they can deposit substantial amounts of energy to
  compensate for radiative losses. Recent numerical simulations have
  explored how magnetic fields modify the behavior of AGWs and their
  potential as seismic diagnostics for the average magnetic field. <P
  />Using high-resolution, narrowband multi-wavelength ground-based
  observations taken with IBIS at the Dunn Solar Telescope and
  space-based data from the Solar Dynamics Observatory, we investigate
  the behavior of these waves throughout the lower solar atmosphere on
  the quiet Sun. By examining the phase lag from velocity and intensity
  fluctuations measured at different atmospheric heights, we observe the
  signatures of upwardly propagating AGWs at disk center up to around
  the temperature minimum region. We detect unique velocity signatures
  that have not been clearly observed to date. In the regime of AGWs,
  our phase analysis of the intensity and velocity perturbations exhibit
  different overall behavior. Given the weak average magnetic field in our
  field of view, we find that the observed behavior of AGWs is consistent
  with the weak field models reported in numerical simulations. <P />Our
  ultimate goal is to harness their untapped potential as diagnostics
  to probe the average magnetic field structure and atmospheric flows
  in a novel way. In future work, we plan to investigate the behavior
  and energy flux of AGWs away from disk center and around more magnetic
  environments. This study will serve as a pilot for future observations
  of these waves, especially with the 4-meter Daniel K. Inouye Solar
  Telescope.

Title: IBIS-A: The IBIS data Archive. High-resolution observations
    of the solar photosphere and chromosphere with contextual data
Authors: Ermolli, Ilaria; Giorgi, Fabrizio; Murabito, Mariarita;
   Stangalini, Marco; Guido, Vincenzo; Molinaro, Marco; Romano, Paolo;
   Guglielmino, Salvatore L.; Viavattene, Giorgio; Cauzzi, Gianna;
   Criscuoli, Serena; Reardon, Kevin P.; Tritschler, Alexandra
Bibcode: 2022A&A...661A..74E
Altcode: 2022arXiv220209946E
  Context. The IBIS data Archive (IBIS-A) stores data acquired with
  the Interferometric BIdimensional Spectropolarimeter (IBIS), which
  was operated at the Dunn Solar Telescope of the US National Solar
  Observatory from June 2003 to June 2019. The instrument provided series
  of high-resolution narrowband spectropolarimetric imaging observations
  of the photosphere and chromosphere in the range 5800-8600 Å and
  co-temporal broadband observations in the same spectral range and
  with the same field of view as for the polarimetric data. <BR />
  Aims: We present the data currently stored in IBIS-A, as well as the
  interface utilized to explore such data and facilitate its scientific
  exploitation. To this end, we also describe the use of IBIS-A data
  in recent and undergoing studies relevant to solar physics and
  space weather research. <BR /> Methods: IBIS-A includes raw and
  calibrated observations, as well as science-ready data. The latter
  comprise maps of the circular, linear, and net circular polarization,
  and of the magnetic and velocity fields derived for a significant
  fraction of the series available in the archive. IBIS-A furthermore
  contains links to observations complementary to the IBIS data, such
  as co-temporal high-resolution observations of the solar atmosphere
  available from the instruments onboard the Hinode and IRIS satellites,
  and full-disk multi-band images from INAF solar telescopes. <BR />
  Results: IBIS-A currently consists of 30 TB of data taken with IBIS
  during 28 observing campaigns performed in 2008 and from 2012 to 2019
  on 159 days. Of the observations, 29% are released as Level 1 data
  calibrated for instrumental response and compensated for residual seeing
  degradation, while 10% of the calibrated data are also available as
  Level 1.5 format as multi-dimensional arrays of circular, linear, and
  net circular polarization maps, and line-of-sight velocity patterns;
  81% of the photospheric calibrated series present Level 2 data with
  the view of the magnetic and velocity fields of the targets, as derived
  from data inversion with the Very Fast Inversion of the Stokes Vector
  code. Metadata and movies of each calibrated and science-ready series
  are also available to help users evaluate observing conditions. <BR />
  Conclusions: IBIS-A represents a unique resource for investigating
  the plasma processes in the solar atmosphere and the solar origin of
  space weather events. The archive currently contains 454 different
  series of observations. A recently undertaken effort to preserve
  IBIS observations is expected to lead in the future to an increase in
  the raw measurements and the fraction of processed data available in
  IBIS-A. <P />Research supported by the H2020 SOLARNET grant no. 824135.

Title: Subarcsecond Imaging of a Solar Active Region Filament With
    ALMA and IRIS
Authors: da Silva Santos, J. M.; White, S. M.; Reardon, K.; Cauzzi,
   G.; Gunár, S.; Heinzel, P.; Leenaarts, J.
Bibcode: 2022FrASS...9.8115D
Altcode: 2022arXiv220413178D
  Quiescent filaments appear as absorption features on the solar disk
  when observed in chromospheric lines and at continuum wavelengths
  in the millimeter (mm) range. Active region (AR) filaments are their
  small-scale, low-altitude analogues, but they could not be resolved
  in previous mm observations. This spectral diagnostic can provide
  insight into the details of the formation and physical properties of
  their fine threads, which are still not fully understood. Here, we shed
  light on the thermal structure of an AR filament using high-resolution
  brightness temperature (Tb) maps taken with ALMA Band 6 complemented by
  simultaneous IRIS near-UV spectra, Hinode/SOT photospheric magnetograms,
  and SDO/AIA extreme-UV images. Some of the dark threads visible in the
  AIA 304 Å passband and in the core of Mg ii resonance lines have dark
  (Tb &lt; 5,000 K) counterparts in the 1.25 mm maps, but their visibility
  significantly varies across the filament spine and in time. These
  opacity changes are possibly related to variations in temperature and
  electron density in filament fine structures. The coolest Tb values
  (&lt; 5,000 K) coincide with regions of low integrated intensity in the
  Mg ii h and k lines. ALMA Band 3 maps taken after the Band 6 ones do not
  clearly show the filament structure, contrary to the expectation that
  the contrast should increase at longer wavelengths based on previous
  observations of quiescent filaments. The ALMA maps are not consistent
  with isothermal conditions, but the temporal evolution of the filament
  may partly account for this.

Title: Chromospheric Carbon Monoxide Formation around a Solar Pore
Authors: Stauffer, Johnathan R.; Reardon, Kevin P.; Penn, Matt
Bibcode: 2022ApJ...930...87S
Altcode:
  We present observations of NOAA AR 11159, obtained on 2011 February
  14 in the 4.7 μm band of carbon monoxide (CO) and coordinated with
  spectroscopic imaging of three atomic lines (Na I 5896 Å, Fe I 7090 Å,
  and Ca II 8542 Å) which sample heights from the mid-photosphere to the
  chromosphere. Phase-difference spectra between the observed spectral
  lines instead indicate that the CO lines form at z ≍ 530-650 km in
  the quiet Sun. During the two hours of observations, seven long-lived
  cooling events ("cold bubbles") were observed in CO in the region
  surrounding a large pore, but were not visible in the three atomic
  lines. These events show self-similar temporal evolution with time
  scales consistent with the chemical formation rate of CO at z ≍
  1000 km. Due to the lack of such features in the surrounding quiet
  Sun, we hypothesize that the magnetic canopy field surrounding the
  pore, which suppresses the upward propagation of acoustic waves into
  the chromosphere and the subsequent formation of shocks, depresses
  the rate of acoustic heating and allows CO to condense and cool the
  atmosphere at those heights. These "cold bubbles" may be a source of
  the chromospheric CO that produces the unexpectedly high (z ≍ 1000
  km) limb extensions seen in the stronger CO lines, and may provide
  a unique opportunity to study this enigmatic component of the solar
  atmosphere in spatially resolved observations.

Title: Revisiting the Solar Research Cyberinfrastructure Needs:
    A White Paper of Findings and Recommendations
Authors: Nita, Gelu; Ahmadzadeh, Azim; Criscuoli, Serena;
   Davey, Alisdair; Gary, Dale; Georgoulis, Manolis; Hurlburt, Neal;
   Kitiashvili, Irina; Kempton, Dustin; Kosovichev, Alexander; Martens,
   Piet; McGranaghan, Ryan; Oria, Vincent; Reardon, Kevin; Sadykov,
   Viacheslav; Timmons, Ryan; Wang, Haimin; Wang, Jason T. L.
Bibcode: 2022arXiv220309544N
Altcode:
  Solar and Heliosphere physics are areas of remarkable data-driven
  discoveries. Recent advances in high-cadence, high-resolution
  multiwavelength observations, growing amounts of data from realistic
  modeling, and operational needs for uninterrupted science-quality data
  coverage generate the demand for a solar metadata standardization and
  overall healthy data infrastructure. This white paper is prepared as
  an effort of the working group "Uniform Semantics and Syntax of Solar
  Observations and Events" created within the "Towards Integration of
  Heliophysics Data, Modeling, and Analysis Tools" EarthCube Research
  Coordination Network (@HDMIEC RCN), with primary objectives to discuss
  current advances and identify future needs for the solar research
  cyberinfrastructure. The white paper summarizes presentations and
  discussions held during the special working group session at the
  EarthCube Annual Meeting on June 19th, 2020, as well as community
  contribution gathered during a series of preceding workshops and
  subsequent RCN working group sessions. The authors provide examples
  of the current standing of the solar research cyberinfrastructure, and
  describe the problems related to current data handling approaches. The
  list of the top-level recommendations agreed by the authors of the
  current white paper is presented at the beginning of the paper.

Title: A Strategy for a Coherent and Comprehensive Basis for
    Understanding the Middle Corona
Authors: West, M. J.; Seaton, D. B.; Alzate, N.; Caspi, A.; DeForest,
   C. E.; Gilly, C. R.; Golub, L.; Higginson, A. K.; Kooi, J. E.; Mason,
   J. P.; Rachmeler, L. A.; Reeves, K. K.; Reardon, K.; Rivera, Y. J.;
   Savage, S.; Viall, N. M.; Wexler, D. B.
Bibcode: 2022heli.conf.4060W
Altcode:
  We describe a strategy for coherent and comprehensive observations
  needed to achieve a fundamental understanding of the middle solar
  corona.

Title: A Study of Sunspot 3 Minute Oscillations Using ALMA and GST
Authors: Chai, Yi; Gary, Dale E.; Reardon, Kevin P.; Yurchyshyn, Vasyl
Bibcode: 2022ApJ...924..100C
Altcode: 2021arXiv211105812C
  Waves and oscillations are important solar phenomena, not only because
  they can propagate and dissipate energy in the chromosphere, but also
  because they carry information about the structure of the atmosphere
  in which they propagate. The nature of the 3 minute oscillations
  observed in the umbral region of sunspots is considered to be an
  effect of propagation of magnetohydrodynamic waves upward from below
  the photosphere. We present a study of sunspot oscillations and wave
  propagation in NOAA Active Region 12470 using an approximately 1
  hr long data set acquired on 2015 December 17 by the Atacama Large
  Millimeter/submillimeter Array (ALMA), the Goode Solar Telescope
  (GST) operating at the Big Bear Solar Observatory, the Atmospheric
  Imaging Assembly on board the Solar Dynamics Observatory, and the
  Interface Region Imaging Spectrograph. The ALMA data are unique in
  providing a time series of direct temperature measurements in the
  sunspot chromosphere. The 2 s cadence of ALMA images allows us to well
  resolve the 3 minute periods typical of sunspot oscillations in the
  chromosphere. Fourier analysis is applied to ALMA Band 3 (~100 GHz, ~3
  mm) and GST Hα data sets to obtain power spectra as well as oscillation
  phase information. We analyzed properties of the wave propagation by
  combining multiple wavelengths that probe physical parameters of solar
  atmosphere at different heights. We find that the ALMA temperature
  fluctuations are consistent with that expected for a propagating
  acoustic wave, with a slight asymmetry indicating nonlinear steepening.

Title: A Prototype of a Large Tunable Fabry-Pérot Interferometer
    for Solar Spectroscopy
Authors: Greco, V.; Sordini, A.; Cauzzi, G.; Cavallini, F.; Del
   Vecchio, C.; Giovannelli, L.; Berrilli, F.; Del Moro, D.; Reardon,
   K.; Pietraszewski, K. A. R. B.
Bibcode: 2022PASP..134a5007G
Altcode: 2021arXiv211202224G
  Large Fabry-Pérot Interferometers (FPIs) are used in a variety of
  astronomical instrumentation, including spectro-polarimeters for 4 m
  class solar telescopes. In this work we comprehensively characterize
  the cavity of a prototype 150 mm FPI, sporting a novel, fully symmetric
  design. Of particular interest, we define a new method to properly
  assess the gravity effects on the interferometer's cavity when the
  system is used in either the vertical or horizontal configuration,
  both typical of solar observations. We show that the symmetric design
  very effectively limits the combined effects of pre-load and gravity
  forces to only a few nm over a 120 mm diameter illuminated surface,
  with gravity contributing ~2 nm peak-to-valley (~0.3 nm rms) in either
  configuration. We confirm a variation of the tilt between the plates
  of the interferometer during the spectral scan, which can be mitigated
  with appropriate corrections to the spacing commands. Finally, we show
  that the dynamical response of the new system fully satisfies typical
  operational scenarios. We conclude that large, fully symmetric FPIs
  can be safely used within solar instrumentation in both, horizontal
  and vertical position, with the latter better suited to limiting the
  overall volume occupied by such an instrument.

Title: Final Report for SAG 21: The Effect of Stellar Contamination
    on Space-based Transmission Spectroscopy
Authors: Rackham, Benjamin V.; Espinoza, Néstor; Berdyugina, Svetlana
   V.; Korhonen, Heidi; MacDonald, Ryan J.; Montet, Benjamin T.; Morris,
   Brett M.; Oshagh, Mahmoudreza; Shapiro, Alexander I.; Unruh, Yvonne C.;
   Quintana, Elisa V.; Zellem, Robert T.; Apai, Dániel; Barclay, Thomas;
   Barstow, Joanna K.; Bruno, Giovanni; Carone, Ludmila; Casewell, Sarah
   L.; Cegla, Heather M.; Criscuoli, Serena; Fischer, Catherine; Fournier,
   Damien; Giampapa, Mark S.; Giles, Helen; Iyer, Aishwarya; Kopp, Greg;
   Kostogryz, Nadiia M.; Krivova, Natalie; Mallonn, Matthias; McGruder,
   Chima; Molaverdikhani, Karan; Newton, Elisabeth R.; Panja, Mayukh;
   Peacock, Sarah; Reardon, Kevin; Roettenbacher, Rachael M.; Scandariato,
   Gaetano; Solanki, Sami; Stassun, Keivan G.; Steiner, Oskar; Stevenson,
   Kevin B.; Tregloan-Reed, Jeremy; Valio, Adriana; Wedemeyer, Sven;
   Welbanks, Luis; Yu, Jie; Alam, Munazza K.; Davenport, James R. A.;
   Deming, Drake; Dong, Chuanfei; Ducrot, Elsa; Fisher, Chloe; Gilbert,
   Emily; Kostov, Veselin; López-Morales, Mercedes; Line, Mike; Močnik,
   Teo; Mullally, Susan; Paudel, Rishi R.; Ribas, Ignasi; Valenti, Jeff A.
Bibcode: 2022arXiv220109905R
Altcode:
  Study Analysis Group 21 (SAG21) of the Exoplanet Exploration Program
  Analysis Group (ExoPAG) was organized to study the effect of stellar
  contamination on space-based transmission spectroscopy, a method for
  studying exoplanetary atmospheres by measuring the wavelength-dependent
  radius of a planet as it transits its star. Transmission spectroscopy
  relies on a precise understanding of the spectrum of the star being
  occulted. However, stars are not homogeneous, constant light sources
  but have temporally evolving photospheres and chromospheres with
  inhomogeneities like spots, faculae, and plages. This SAG has brought
  together an interdisciplinary team of more than 100 scientists, with
  observers and theorists from the heliophysics, stellar astrophysics,
  planetary science, and exoplanetary atmosphere research communities,
  to study the current needs that can be addressed in this context to
  make the most of transit studies from current NASA facilities like
  HST and JWST. The analysis produced 14 findings, which fall into
  three Science Themes encompassing (1) how the Sun is used as our best
  laboratory to calibrate our understanding of stellar heterogeneities
  ("The Sun as the Stellar Benchmark"), (2) how stars other than the Sun
  extend our knowledge of heterogeneities ("Surface Heterogeneities of
  Other Stars") and (3) how to incorporate information gathered for the
  Sun and other stars into transit studies ("Mapping Stellar Knowledge
  to Transit Studies").

Title: High-frequency Wave Power Observed in the Solar Chromosphere
    with IBIS and ALMA
Authors: Molnar, Momchil E.; Reardon, Kevin P.; Cranmer, Steven R.;
   Kowalski, Adam F.; Chai, Yi; Gary, Dale
Bibcode: 2021ApJ...920..125M
Altcode: 2021arXiv210708952M
  We present observational constraints on the chromospheric heating
  contribution from acoustic waves with frequencies between 5 and 50
  mHz. We use observations from the Dunn Solar Telescope in New Mexico,
  complemented with observations from the Atacama Large Millimeter Array
  collected on 2017 April 23. The properties of the power spectra of the
  various quantities are derived from the spectral lines of Ca II 854.2
  nm, H I 656.3 nm, and the millimeter continuum at 1.25 and 3 mm. At
  the observed frequencies, the diagnostics almost all show a power-law
  behavior, whose particulars (slope, peak, and white-noise floors)
  are correlated with the type of solar feature (internetwork, network,
  and plage). In order to disentangle the vertical versus transverse
  Alfvénic plasma motions, we examine two different fields of view: one
  near disk center, and the other close to the limb. To infer the acoustic
  flux in the middle chromosphere, we compare our observations with
  synthetic observables from the time-dependent radiative hydrodynamic
  RADYN code. Our findings show that acoustic waves carry up to about
  1 kW m<SUP>-2</SUP> of energy flux in the middle chromosphere, which
  is not enough to maintain the quiet chromosphere. This is in contrast
  to previous publications.

Title: Spectroscopic Study Of Wave Propagation In The Quiet Solar
    Chromosphere with IRIS and IBIS
Authors: Molnar, M. E.; Cranmer, S. R.; Reardon, K. P.; Kowalski, A. F.
Bibcode: 2021AAS...23811303M
Altcode:
  In this work, we present constraints on the longitudinal (compressive)
  and transverse (Alfvenic) wave velocity perturbations observed in the
  chromosphere. Better knowledge of the power in these different wave
  modes in different regions of the atmosphere are important inputs into
  models for the heating of the solar corona. By using observations
  at multiple viewing angles (distances from the disc center), the
  relative importance of these two components can be evaluated and
  the power in the local acoustic flux can be explored. This work is
  based on Doppler velocity measurements from IRIS of the ultraviolet
  Mg II h &amp; k and the Mn I 280.19 nm lines. These are compared with
  co-temporal observations from IBIS of the H-alpha and Ca II 854.2 nm
  chromospheric lines in the visible. The observed phase differences
  between the velocity diagnostics in these different lines allows us to
  estimate a formation height of the Mn I 280.19 nm line and compare it
  with recent results from simulations. We can also measure the lowest
  observed frequency at which the phase differences indicate the presence
  of wave propagation in order to calculate the local acoustic-wave
  cutoff. We calculate the coherency of the signals and their phases with
  a cross-wavelet analysis. We further combine the IRIS observations
  with 1D simulations of the lower solar atmosphere from the RADYN
  code to estimate the wave flux inthe upper chromosphere. This study
  provides heating constraints for the middle and upper chromospheres and
  additional estimates of the transverse wave power in the chromosphere
  extending previous work by Molnar et al. (2021).

Title: New Observations Of Chromospheric CO
Authors: Stauffer, J.; Reardon, K.
Bibcode: 2021AAS...23811301S
Altcode:
  The detailed temperature structure of the solar photosphere and
  chromosphere still holds some mysteries. A key example is the challenge
  of trying to reconcile observations of spectral lines from the CO
  molecule into the 1-D models of the solar atmosphere. The line core
  temperatures of this molecular band suggest average temperatures
  around 200 K lower than expected, while observations at the limb
  indicate the presence of CO at what would be considered chromospheric
  heights. Observations at higher resolution and with additional context
  - provided by multi-wavelength datasets - might help resolve some of
  these puzzles. <P />In this work, I present observations of a solar
  pore observed in the CO 4.7 µm band with the McMath Pierce Solar
  Telescope. These observations were coordinated with simultaneous
  IBIS/DST observations in the Fe I 709.0 nm, Na I 589.6 nm, and Ca
  II 854.2 nm lines. These well understood lines, whose regions of
  sensitivity span the base of the photosphere to the middle chromosphere,
  provide a reference against which observations of the CO spectra may
  be compared. <P />Comparisons of the stronger, higher-forming CO lines
  with the atomic spectra suggest that different components of the CO
  spectrum are sensitive to regions of the solar atmosphere spanning the
  temperature minimum (z = 500 km above the surface of the photosphere)
  to chromospheric heights. Velocity phase spectra between the Fe and
  CO lines suggests the CO line core velocity is sensitive to the upper
  photosphere, while comparisons with the calcium line scans suggests
  that the CO line core intensity has significant contributions from
  both photospheric and chromospheric heights. Additionally, a time
  series of the CO line core intensity reveals several intermittent,
  CO-rich features, which appear primarily around the boundary of the
  pore. These "cold bubbles" occur on spatio-temporal scales which are
  distinct from the 5 minute oscillations and solar granulation, but are
  instead consistent with the chemical reaction timescale of CO at z =
  1000 km. <P />A thorough understanding of the height of formation and
  behavior of these lines is particularly valuable in anticipation of
  observations of the 4.7 µm CO band at much better resolution from
  DKIST's Cryo-NIRSP instrument.

Title: On The Interpretation Of H-alpha Filtergrams
Authors: Reardon, K.
Bibcode: 2021AAS...23831314R
Altcode:
  For over 150 years the H-alpha line has been a mainstay of chromospheric
  studies, which have revealed many important aspects of the structure
  and dynamics of the upper solar atmosphere. The strong absorption
  of this line in the visible range has long made it possible to
  isolate its chromospheric contribution in the solar spectrum using
  spectroheliographs, and later using various filter technologies. The
  great bulk of observations in H-alpha, covering decades, have been
  obtained using relatively broad-band filters (0.5-2 Å FWHM). More
  recently, imaging spectroscopy in H-alpha, usually performed with
  Fabry-Perot interferometers, has revealed new information about the
  detailed spectral behavior and characteristics of this line. Using such
  observations, we can now simulate and better interpret observations
  taken through the more widely used, broad filters. <P />In this paper,
  I will evaluate the sensitivity of filter measurements to chromospheric
  temperatures and velocities, depending on the placement and shape of
  the filter passband. In particular, I will discuss how this will aid in
  the interpretation of observations that will be obtained from the Visual
  Broadband Imager (VBI) on the Daniel K. Inouye Solar Telescope (DKIST).

Title: ALMA and IRIS Observations Highlighting the Dynamics and
    Structure of Chromospheric Plage
Authors: Hofmann, R. A.; Reardon, K.; Milic, I.
Bibcode: 2021AAS...23820505H
Altcode:
  Studies of the thermal structure of the solar chromosphere are typically
  hampered by the complexities of non-LTE radiative transfer. This issue
  can be addressed using observations of the millimeter continuum, which
  directly probes the electron temperatures in the chromosphere. In recent
  years, the Atacama Large Millimeter/submillimeter Array (ALMA) has made
  it possible, for the first time, to obtain millimeter observations of
  sufficient spatial resolution to supplement spectral line observations
  and inversions. Here, we present observations of a plage in the 3.0
  mm and 1.2 mm continua with ~2 arcsecond resolution, combined with
  simultaneous imaging spectroscopy observations from the Interferometric
  Bidimensional Spectrometer (IBIS) at the Dunn Solar Telescope. We
  compare the observed ALMA brightness temperatures with temperatures
  inferred from spectral inversions using the Na D1 5896 Å and Ca II 8542
  Å lines, and investigate the wide range of physical heights probed by
  the millimeter continuum. We find that the millimeter emission arises
  from a range of heights both above and below the chromospheric calcium
  line, depending on the local temperature profile and electron densities.

Title: Inferring Plasma Flows In The Solar Photosphere &amp;
    Chromosphere Using Deep Learning And Surface Observations
Authors: Tremblay, B.; Reardon, K.; Attie, R.; Kazachenko, M.;
   Tilipman, D.; Asensio Ramos, A.
Bibcode: 2021AAS...23812301T
Altcode:
  Direct measurements of plasma motions are limited to the line-of-sight
  component at the Sun's surface. Multiple tracking and inversion methods
  were developed to infer the transverse motions from observational
  data. Recently, the fully convolutional DeepVel &amp; DeepVelU neural
  networks were trained in conjunction with detailed magnetohydrodynamics
  (MHD) simulations of the Quiet Sun and sunspots to recover the
  instantaneous depth/height-dependent transverse velocity vector from a
  combination of intensitygrams, magnetograms and/or Dopplergrams of the
  solar surface. Through this supervised learning approach, the neural
  network attempts to emulate the synthetic flows, and by extension the
  physics, from the numerical simulation it was presented during its
  training, i.e. its outputs are model-dependent and may be subjected
  to biases. Although simulations have become increasingly realistic,
  the validity of flows inferred by DeepVel or DeepVelU is subject to
  debate when using real observational data as input. As a test, we use
  white light images of the Quiet Sun photosphere (optical depth tau=1)
  produced by the Interferometric BIdimensional Spectropolarimeter
  (IBIS) installed at the Dunn Solar Telescope to infer plasma motions
  approx. 150-200 km above the surface (i.e., near the transition between
  the photosphere and the chromosphere) using DeepVel. We discuss work
  in progress comparing the neural network estimates to the optical
  flows determined from a time series of observational data formed near
  150-200 km above the surface. Optical flows do not directly track
  actual transverse plasma motions, but are correlated with physical
  flows over certain spatial and temporal scales.

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: Inferring Plasma Flows in the Solar Photosphere &amp;
    Chromosphere using Deep Learning and Surface Observations
Authors: Tremblay, Benoit; Reardon, Kevin; Attié, Raphaël;
   Kazachenko, Maria; Asensio Ramos, Andrés; Tilipman, Dennis
Bibcode: 2021csss.confE.204T
Altcode:
  Direct measurements of plasma motions are limited to the line-of-sight
  component at the Sun's surface. Multiple tracking and inversion methods
  were developed to infer the transverse motions from observational
  data. Recently, the fully convolutional DeepVel &amp; DeepVelU neural
  networks were trained in conjunction with detailed magnetohydrodynamics
  (MHD) simulations of the Quiet Sun and sunspots to recover the
  instantaneous depth/height-dependent transverse velocity vector from a
  combination of intensitygrams, magnetograms and/or Dopplergrams of the
  solar surface. Through this supervised learning approach, the neural
  network attempts to emulate the synthetic flows, and by extension the
  physics, from the numerical simulation it was presented during its
  training, i.e. its outputs are model-dependent and may be subjected
  to biases. Although simulations have become increasingly realistic,
  the validity of flows inferred by DeepVel or DeepVelU is subject to
  debate when using real observational data as input. As a test, we use
  white light images of the Quiet Sun photosphere (optical depth tau=1)
  produced by the Interferometric BIdimensional Spectropolarimeter
  (IBIS) installed at the Dunn Solar Telescope to infer plasma motions
  approx. 150-200 km above the surface (i.e., near the transition between
  the photosphere and the chromosphere) using DeepVel. We discuss work
  in progress comparing the neural network estimates to the optical
  flows determined from a time series of observational data formed near
  150-200 km above the surface. Optical flows do not directly track
  actual transverse plasma motions, but are correlated with physical
  flows over certain spatial and temporal scales.

Title: An overall view of temperature oscillations in the solar
    chromosphere with ALMA
Authors: Jafarzadeh, S.; Wedemeyer, S.; Fleck, B.; Stangalini, M.;
   Jess, D. B.; Morton, R. J.; Szydlarski, M.; Henriques, V. M. J.; Zhu,
   X.; Wiegelmann, T.; Guevara Gómez, J. C.; Grant, S. D. T.; Chen,
   B.; Reardon, K.; White, S. M.
Bibcode: 2021RSPTA.37900174J
Altcode: 2021RSTPA.379..174J; 2020arXiv201001918J
  By direct measurements of the gas temperature, the Atacama Large
  Millimeter/submillimeter Array (ALMA) has yielded a new diagnostic
  tool to study the solar chromosphere. Here, we present an overview
  of the brightness-temperature fluctuations from several high-quality
  and high-temporal-resolution (i.e. 1 and 2 s cadence) time series
  of images obtained during the first 2 years of solar observations
  with ALMA, in Band 3 and Band 6, centred at around 3 mm (100 GHz)
  and 1.25 mm (239 GHz), respectively. The various datasets represent
  solar regions with different levels of magnetic flux. We perform
  fast Fourier and Lomb-Scargle transforms to measure both the spatial
  structuring of dominant frequencies and the average global frequency
  distributions of the oscillations (i.e. averaged over the entire field
  of view). We find that the observed frequencies significantly vary from
  one dataset to another, which is discussed in terms of the solar regions
  captured by the observations (i.e. linked to their underlying magnetic
  topology). While the presence of enhanced power within the frequency
  range 3-5 mHz is found for the most magnetically quiescent datasets,
  lower frequencies dominate when there is significant influence from
  strong underlying magnetic field concentrations (present inside and/or
  in the immediate vicinity of the observed field of view). We discuss
  here a number of reasons which could possibly contribute to the power
  suppression at around 5.5 mHz in the ALMA observations. However,
  it remains unclear how other chromospheric diagnostics (with an
  exception of Hα line-core intensity) are unaffected by similar
  effects, i.e. they show very pronounced 3-min oscillations dominating
  the dynamics of the chromosphere, whereas only a very small fraction
  of all the pixels in the 10 ALMA datasets analysed here show peak power
  near 5.5 mHz. <P />This article is part of the Theo Murphy meeting issue
  `High-resolution wave dynamics in the lower solar atmosphere'.

Title: A Survey of Computational Tools in Solar Physics
Authors: Bobra, M.; Mumford, S.; Hewett, R. J.; Christe, S.; Reardon,
   K.; Savage, S. L.; Ireland, J.; Mendes Domingos Pereira, T.; Chen,
   B.; Pérez-Suárez, D.
Bibcode: 2020AGUFMSH0100001B
Altcode:
  The SunPy project is happy to announce the results of the solar physics
  community survey! <P />For six months last year, between February
  and July 2019, the SunPy Project asked members of the solar physics
  community to fill out a 13-question survey about computational software
  and hardware. A total of 364 community members, across 35 countries,
  took our survey. <P />We found that 99±0.5% of respondents use
  software in their research and 66% use the Python scientific software
  stack. Students are twice as likely as faculty, staff scientists, and
  researchers to use Python. In this respect, the astrophysics and solar
  physics communities differ widely: 78% of solar physics faculty, staff
  scientists, and researchers in our sample uses IDL, compared with 44%
  of astrophysics faculty and scientists sampled by Momcheva and Tollerud
  (2015). <P />We also found that most respondents (63±4%) have not taken
  any computer science courses at an undergraduate or graduate level. We
  found that a small fraction of respondents use the commercial cloud (5%)
  or a regional or national cluster (14%) for their research. Finally,
  we found that 73±4% of respondents cite scientific software in their
  research, although only 42±3% do so routinely. <P />Our survey results
  are published in the journal Solar Physics and available via open
  access at the following URL: https://doi.org/10.1007/s11207-020-01622-2.

Title: Spectroscopic Inversions &amp; Calibrations for DKIST Coronal
    Observations
Authors: Ali, A.; Paraschiv, A.; Reardon, K.; Judge, P. G.
Bibcode: 2020AGUFMSH0280014A
Altcode:
  The Cryo-NIRSP's (Cryogenic Near-IR Spectro-Polarimeter) is one of the
  DKIST instruments capable of sensitive imaging of faint infrared coronal
  solar spectra, and its primary goal is to measure the full polarization
  state (Stokes I, Q, U and V) of spectral lines originating on the Sun
  at different wavelengths. Producing data products from off-limb solar
  coronal observations from the DKIST telescope is essential when trying
  to study its future observations. Quantifying the accuracy of spectral
  inversion procedures based on its spectral comparisons to absorption
  and telluric calibrated spectra will give insight to interpreting
  valid DKIST observations and its ultimate findings. Using simulated
  contaminated data of both pure and noisy data sets has allowed us
  to compare the wavelength shifts and broadening properties to help
  pinpoint where contamination would affect the data set as a whole,
  and by how much. In doing so, we developed code that will eventually
  be integrated in the DKIST Level-2 pipeline. Working to compare
  these findings to absorption and telluric readings will further help
  minimize the uncertainties read in through observations, and give
  direction on how to reduce the original coronal data in hopes to refine
  it. Understanding the origins and magnitude of the contamination would
  therefore help refine the original coronal data and make it compatible
  for data processing, and would assist the automation of processing
  the data observed by the DKIST telescope.

Title: Constraining wave propagation throughout the solar atmosphere
    with IBIS, ALMA and IRIS
Authors: Molnar, M.; Reardon, K.; Cranmer, S. R.; Kowalski, A. F.
Bibcode: 2020AGUFMSH0010003M
Altcode:
  The heating mechanism of the solar chromosphere is still an open
  scientific question. We present observational constraints on the
  high-frequency (acoustic) wave contribution to the chromospheric
  heating. We utilize a unique combination of observations from NSO's
  Dunn Solar Telescope and the Atacama Large Millimeter Array obtained on
  April 23rd 2017 to estimate the high-frequency wave flux in the lower
  solar atmosphere. We extend this study to the upper chromosphere and
  the transition region with archival IRIS data. We infer the wave flux
  through comparison of the observations with synthetic observables
  from the time-dependent hydrodynamic RADYN code. Our findings are
  able to constrain the wave flux at higher altitudes in the solar
  atmosphere than previous works using similar approaches. Furthermore,
  the different diagnostics we use form at different heights, which
  allow us to explore the propagation and dissipation of waves with
  height. We will discuss future plans to extend this work with more
  advanced modeling and additional observations with the upcoming Innoue
  Solar Telescope (DKIST).

Title: The CO Fundamental Band as an LTE Diagnostic of the Temperature
    Minimum
Authors: Stauffer, J.; Reardon, K.
Bibcode: 2020AGUFMSH004..02S
Altcode:
  Spectral and spectro-polarimetric inversion techniques are a powerful
  set of tools capable of inferring the 3-D structure of the solar
  atmosphere from a set of observed atomic spectral lines. However, the
  degree to which an inversion can retrieve the true solar atmospheric
  profiles depends on the formation properties of the observed lines,
  as well as the complexity of the physics involved in the inversion. In
  this work, we invert DST/IBIS observations of several atomic lines (Na
  I 589.6 nm, Fe I 709.0 nm, and Ca II 854.2 nm, which together sample
  the lower photosphere to the mid chromosphere) using the Stockholm
  Inversion Code (STiC) for the temperature and velocity structure in
  the vicinity of a decaying sunspot observed on 02/14/2011. The results
  of these inversions are compared to simultaneous observations of the
  fundamental (Δν=1) ro-vibrational band of CO, which is comprised
  of dozens of individual molecular lines with varying strengths and
  formation properties. These lines form in LTE and can be used to sample
  the properties of the Solar temperature minimum; therefore, by comparing
  the inversion results to maps of CO column density and brightness
  temperature, we can determine the fidelity of the NLTE STiC inversions
  in inferring the qualities of the temperature minimum. Particular focus
  is given to several CO-rich "cold spots" which appear in the vicinity
  of the sunspot remnant during the observing sequence.

Title: ALMA observations and spectral inversions - what can we learn
    about the Sun and our techniques?
Authors: Hofmann, R.; Reardon, K.; Milic, I.
Bibcode: 2020AGUFMSH0010002H
Altcode:
  Studies of the thermal structure of the solar chromosphere are typically
  hampered by the complexities of non-LTE radiative transfer. This issue
  can be addressed using observations of the millimeter continuum, which
  directly probes the electron temperatures in the chromosphere. In recent
  years, the Atacama Large Millimeter/submillimeter Array (ALMA) has made
  it possible, for the first time, to obtain millimeter observations of
  sufficient spatial resolution to supplement spectral line observations
  and inversions. Here, we present observations of a plage in the 3.0
  mm and 1.2 mm continua with ~2 arcsecond resolution, combined with
  simultaneous imaging spectroscopy observations from the Interferometric
  Bidimensional Spectrometer (IBIS) at the Dunn Solar Telescope. We
  compare the observed ALMA brightness temperatures with temperatures
  inferred from spectral inversions using the Na D1 5896 Å and Ca II 8542
  Å lines, and investigate the wide range of physical heights probed by
  the millimeter continuum. We find that the millimeter emission arises
  from a range of heights both above and below the chromospheric calcium
  line, depending on the local temperature profile and electron densities.

Title: Inferring Plasma Flows in the Solar Photosphere &amp;
    Chromosphere using Deep Learning and Surface Observations
Authors: Tremblay, B.; Reardon, K.; Attié, R.; Asensio Ramos, A.;
   Kazachenko, M.; Tilipman, D.
Bibcode: 2020AGUFMSH007..08T
Altcode:
  Direct measurements of plasma motions are limited to the line-of-sight
  component at the Sun's surface. Multiple tracking and inversion methods
  were developed to infer the transverse motions from observational
  data. Optical flows do not directly track actual transverse plasma
  motions, but our most recent results show that unsupervised flow
  tracking performed on simulation data of the solar surface with the
  Ball-tracking method accurately reconstructs the true transverse
  plasma velocity over certain spatial and temporal scales. Recently,
  the fully convolutional DeepVel &amp; DeepVelU neural networks
  were trained in conjunction with detailed magnetohydrodynamics (MHD)
  simulations of the Quiet Sun and sunspots to recover the instantaneous
  depth/height-dependent transverse velocity vector from a combination
  of intensitygrams, magnetograms and/or Dopplergrams of the solar
  surface. Through this supervised learning approach, the neural
  network attempts to emulate the synthetic flows, and by extension the
  physics, from the numerical simulation it was presented during its
  training, i.e. its outputs are model-dependent and may be subjected
  to biases. Although simulations have become increasingly realistic,
  the validity of flows inferred by DeepVel or DeepVelU is subject to
  debate when using real observational data as input. As a test, we use
  white light images of the Quiet Sun photosphere (optical depth τ=1)
  produced by the Interferometric BIdimensional Spectropolarimeter (IBIS)
  installed at the Dunn Solar Telescope to infer plasma motions at optical
  depth τ=0.1 (i.e., near the transition between the photosphere and
  the chromosphere) using DeepVelU. We then compare the results to
  the optical flows determined from a time series of observational
  data formed near τ=0.1, which may not be subjected to the biases
  present in DeepVelU . Finally, we discuss work in progress to infer
  photospheric and chromospheric (optical) flows through unsupervised
  learning, i.e. learning strictly from observational data and thus
  without simulations.

Title: SunPy 2.0: the community-developed open-source solar data
    analysis environment for Python
Authors: Murray, S. A.; Barnes, W.; Bobra, M.; Christe, S.; Freij,
   N.; Hayes, L.; Ireland, J.; Mumford, S.; Pérez-Suárez, D.; Ryan,
   D.; Shih, A. Y.; Chanda, P.; Hewett, R.; Hughitt, V. K.; Hill, A.;
   Hiware, K.; Inglis, A.; Kirk, M. S.; Konge, S.; Mason, J. P.; Maloney,
   S.; Panda, A.; Park, J.; M D Pereira, T.; Reardon, K.; Savage, S. L.;
   Sipocz, B.; Stansby, D.; Jain, Y.; Taylor, G.; Yadav, T.; Kien, H. T.;
   Chen, B.; Glogowski, K.
Bibcode: 2020AGUFMSH0100006M
Altcode:
  The SunPy project facilitates and promotes the use and development
  of several community-led, free, and open-source data analysis
  software packages for solar physics based on the scientific
  Python environment. The project achieves this goal by developing
  and maintaining the SunPy core package and supporting an ecosystem
  of affiliated packages. The SunPy community is pleased to announce
  the release of version 2.0! Some highlights for this release include
  updates to the Fido data search and retrieval tool, various fixes to the
  sunpy.map sub package, and integration of differential rotation into
  the sunpy.coordinates framework. Also new in SunPy 2.0 is the aiapy
  package for analyzing data from SDO/AIA, which replaces aiaprep. Learn
  more about how to install and use the publicly available code at <A
  href="https://sunpy.org">sunpy.org</A> , as well as information about
  how to get involved with the community!

Title: The Propagation of Atmospheric Gravity Waves in the Magnetic
    Solar Atmosphere
Authors: Vesa, O.; Jackiewicz, J.; Reardon, K.
Bibcode: 2020SPD....5120708V
Altcode:
  Atmospheric gravity waves are generated by overshooting convection and
  are thought to propagate throughout the lower solar atmosphere. The
  properties of these waves will be modified by the strength and
  orientation of the magnetic field, resulting in either suppression at
  regions of strong magnetic activity or mode conversion. By combining
  high-resolution, multi-wavelength IBIS observations and co-aligned SDO
  data, we investigate the characteristics of these waves throughout the
  lower solar atmosphere, with the goal of revealing new information about
  the quiet Sun's magnetic field. We have analyzed line core velocities
  and intensities of four spectral lines (Ca II 8542 Å, Fe I 5434 Å,
  Fe I 7090 Å, and K I 7699 Å) along with HMI's Fe I 6173 Å, to
  derive phase differences and construct k-ω diagnostic diagrams at a
  range of heights. We detect the signatures of propagating atmospheric
  gravity waves at disk center. We will ultimately use multiple datasets
  taken at disk center, near the limb, and around active regions to
  also explore their large horizontal velocities and behavior in more
  magnetic environments.

Title: High-frequency Wave Power Observed in the Chromosphere with
    IBIS and ALMA
Authors: Molnar, M. E.; Cranmer, S.; Reardon, K.; Kowalski, A.
Bibcode: 2020SPD....5120106M
Altcode:
  The heating mechanism of the solar chromosphere is still an open
  scientific question. In this work we study observational constraints on
  the contribution to chromospheric heating from high-frequency acoustic
  waves. We utilize a unique combination of observations from NSO's Dunn
  Solar Telescope and from the Atacama Large Millimeter Array obtained
  on April 23rd 2017 to estimate the high-frequency wave flux in the
  lower solar atmosphere. The wave flux is inferred from comparison of
  the observations with synthetic observables from the time-dependent
  hydrodynamic RADYN code. Our findings suggest thatacoustic waves may
  carry up to a few kW/m<SUP>2</SUP> of flux, which is comparable to
  what is required to heat the quiet chromosphere.

Title: Spectral deconvolution with deep learning: removing the
    effects of spectral PSF broadening
Authors: Molnar, Momchil; Reardon, Kevin P.; Osborne, Christopher;
   Milić, Ivan
Bibcode: 2020FrASS...7...29M
Altcode: 2020arXiv200505529M
  We explore novel methods of recovering the original spectral line
  profiles from data obtained by instruments that sample those profiles
  with an extended or multipeaked spectral transmission profile. The
  techniques are tested on data obtained at high spatial resolution from
  the Fast Imaging Solar Spectrograph (FISS) grating spectrograph at the
  Big Bear Solar Observatory and from the Interferometric Bidimensional
  Spectrometer (IBIS) instrument at the Dunn Solar Telescope. The method
  robustly deconvolves wide spectral transmission profiles for fields of
  view sampling a variety of solar structures (granulation, plage and
  pores) with a photometrical precision of less than 1%. The results
  and fidelity of the method are tested on data from IBIS obtained
  using several different spectral resolution modes. The method, based
  on convolutional neural networks (CNN), is extremely fast, performing
  about 10^5 deconvolutions per second on a single CPU for a spectrum with
  40 wavelength samples. This approach is applicable for deconvolving
  large amounts of data from instruments with wide spectral profiles,
  such as the Visible Tunable Filter (VTF) on the DKI Solar Telescope
  (DKIST). We also investigate the application to future instruments
  by recovering spectral line profiles obtained with a theoretical
  multi-peaked spectral transmission profile. We further discuss the
  limitations of this deconvolutional approach through the analysis of
  the dimensionality of the original and multiplexed data.

Title: Solar Disk Center Shows Scattering Polarization in the Sr I
    4607 Å Line
Authors: Zeuner, Franziska; Manso Sainz, Rafael; Feller, Alex; van
   Noort, Michiel; Solanki, Sami K.; Iglesias, Francisco A.; Reardon,
   Kevin; Martínez Pillet, Valentín
Bibcode: 2020ApJ...893L..44Z
Altcode: 2020arXiv200403679Z
  Magnetic fields in turbulent, convective high-β plasma naturally
  develop highly tangled and complex topologies - the solar photosphere
  being the paradigmatic example. These fields are mostly undetectable by
  standard diagnostic techniques with finite spatio-temporal resolution
  due to cancellations of Zeeman polarization signals. Observations of
  resonance scattering polarization have been considered to overcome
  these problems. But up to now, observations of scattering polarization
  lack the necessary combination of high sensitivity and high spatial
  resolution in order to directly infer the turbulent magnetic structure
  at the resolution limit of solar telescopes. Here, we report the
  detection of clear spatial structuring of scattering polarization
  in a magnetically quiet solar region at disk center in the Sr I
  4607 Å spectral line on granular scales, confirming theoretical
  expectations. We find that the linear polarization presents a
  strong spatial correlation with the local quadrupole of the radiation
  field. The result indicates that polarization survives the dynamic and
  turbulent magnetic environment of the middle photosphere and is thereby
  usable for spatially resolved Hanle observations. This is an important
  step toward the long-sought goal of directly observing turbulent
  solar magnetic fields at the resolution limit and investigating their
  spatial structure.

Title: A Survey of Computational Tools in Solar Physics
Authors: Bobra, Monica G.; Mumford, Stuart J.; Hewett, Russell J.;
   Christe, Steven D.; Reardon, Kevin; Savage, Sabrina; Ireland, Jack;
   Pereira, Tiago M. D.; Chen, Bin; Pérez-Suárez, David
Bibcode: 2020SoPh..295...57B
Altcode: 2020arXiv200314186B
  The SunPy Project developed a 13-question survey to understand the
  software and hardware usage of the solar-physics community. Of the
  solar-physics community, 364 members across 35 countries responded
  to our survey. We found that 99 ±0.5 % of respondents use software
  in their research and 66% use the Python scientific-software
  stack. Students are twice as likely as faculty, staff scientists,
  and researchers to use Python rather than Interactive Data Language
  (IDL). In this respect, the astrophysics and solar-physics communities
  differ widely: 78% of solar-physics faculty, staff scientists, and
  researchers in our sample uses IDL, compared with 44% of astrophysics
  faculty and scientists sampled by Momcheva and Tollerud (2015). 63
  ±4 % of respondents have not taken any computer-science courses at an
  undergraduate or graduate level. We also found that most respondents use
  consumer hardware to run software for solar-physics research. Although
  82% of respondents work with data from space-based or ground-based
  missions, some of which (e.g. the Solar Dynamics Observatory and Daniel
  K. Inouye Solar Telescope) produce terabytes of data a day, 14% use
  a regional or national cluster, 5% use a commercial cloud provider,
  and 29% use exclusively a laptop or desktop. Finally, we found that
  73 ±4 % of respondents cite scientific software in their research,
  although only 42 ±3 % do so routinely.

Title: The SunPy Project: Open Source Development and Status of the
    Version 1.0 Core Package
Authors: SunPy Community; Barnes, Will T.; Bobra, Monica G.; Christe,
   Steven D.; Freij, Nabil; Hayes, Laura A.; Ireland, Jack; Mumford,
   Stuart; Perez-Suarez, David; Ryan, Daniel F.; Shih, Albert Y.; Chanda,
   Prateek; Glogowski, Kolja; Hewett, Russell; Hughitt, V. Keith; Hill,
   Andrew; Hiware, Kaustubh; Inglis, Andrew; Kirk, Michael S. F.; Konge,
   Sudarshan; Mason, James Paul; Maloney, Shane Anthony; Murray, Sophie
   A.; Panda, Asish; Park, Jongyeob; Pereira, Tiago M. D.; Reardon,
   Kevin; Savage, Sabrina; Sipőcz, Brigitta M.; Stansby, David; Jain,
   Yash; Taylor, Garrison; Yadav, Tannmay; Rajul; Dang, Trung Kien
Bibcode: 2020ApJ...890...68S
Altcode: 2020ApJ...890...68A
  The goal of the SunPy project is to facilitate and promote the
  use and development of community-led, free, and open source data
  analysis software for solar physics based on the scientific Python
  environment. The project achieves this goal by developing and
  maintaining the sunpy core package and supporting an ecosystem of
  affiliated packages. This paper describes the first official stable
  release (version 1.0) of the core package, as well as the project
  organization and infrastructure. This paper concludes with a discussion
  of the future of the SunPy project.

Title: Hi-C 2.1 Observations of Small-scale
    Miniature-filament-eruption-like Cool Ejections in an Active Region
    Plage
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Panesar, Navdeep
   K.; Reardon, Kevin P.; Molnar, Momchil; Rachmeler, Laurel A.; Savage,
   Sabrina L.; Winebarger, Amy R.
Bibcode: 2020ApJ...889..187S
Altcode: 2019arXiv191202319S
  We examine 172 Å ultra-high-resolution images of a solar plage region
  from the High-Resolution Coronal Imager, version 2.1 (Hi-C 2.1, or Hi-C)
  rocket flight of 2018 May 29. Over its five minute flight, Hi-C resolved
  a plethora of small-scale dynamic features that appear near noise level
  in concurrent Solar Dynamics Observatory (SDO) Atmospheric Imaging
  Assembly (AIA) 171 Å images. For 10 selected events, comparisons with
  AIA images at other wavelengths and with Interface Region Imaging
  Spectrograph (IRIS) images indicate that these features are cool
  (compared to the corona) ejections. Combining Hi-C 172 Å, AIA 171 Å,
  IRIS 1400 Å, and Hα, we see that these 10 cool ejections are similar
  to the Hα "dynamic fibrils" and Ca II "anemone jets" found in earlier
  studies. The front of some of our cool ejections are likely heated,
  showing emission in IRIS 1400 Å. On average, these cool ejections
  have approximate widths 3"2 ± 2"1, (projected) maximum heights and
  velocities 4"3 ± 2"5 and 23 ± 6 km s<SUP>-1</SUP>, and lifetimes 6.5
  ± 2.4 min. We consider whether these Hi-C features might result from
  eruptions of sub-minifilaments (smaller than the minifilaments that
  erupt to produce coronal jets). Comparisons with SDO's Helioseismic and
  Magnetic Imager (HMI) magnetograms do not show magnetic mixed-polarity
  neutral lines at these events' bases, as would be expected for true
  scaled-down versions of solar filaments/minifilaments. But the features'
  bases are all close to single-polarity strong-flux-edge locations,
  suggesting possible local opposite-polarity flux unresolved by HMI. Or
  it may be that our Hi-C ejections instead operate via the shock-wave
  mechanism that is suggested to drive dynamic fibrils and the so-called
  type I spicules.

Title: Early Results from the Solar-Minimum 2019 Total Solar Eclipse
Authors: Pasachoff, J. M.; Lockwood, C. A.; Inoue, J. L.; Meadors,
   E. N.; Voulgaris, A.; Sliski, D.; Sliski, A.; Reardon, K. P.; Seaton,
   D. B.; Caplan, R. M.; Downs, C.; Linker, J. A.; Sterling, A. C.
Bibcode: 2020AAS...23535903P
Altcode:
  We report on first results from our observations in Chile on July
  2, 2019, that revealed the extreme-solar-minimum corona, with only
  equatorial streamers and with visible polar plumes. We have observations
  in clear skies from our three observing sites: (1) The Cerro Tololo
  Inter-American Observatory, 7,240-foot altitude, 2 min 6 sec; (2)
  La Higuera, centerline, 2,500-foot altitude, 2 min 35 sec totality;
  (3) La Serena, sea level, 2 min 15 sec totality. Prominences on the
  limb provided orientation and coordination with spacecraft observations
  from NOAA's GOES-R Solar Ultraviolet Imager (SUVI) and the Atmospheric
  Imaging Assembly (AIA) on NASA's Solar Dynamics Observatory (SDO). The
  double-diamond ring at second contact will extend our determination of
  a new IAU-recommended value of the solar diameter through comparison
  with models taking into account the precise lunar profile. Our coronal
  spectra from slitless spectrographs, from CTIO, showed the Fe XIV 530.3
  nm green line substantially weaker than the Fe X 637.4 nm red line,
  corresponding to the relatively low coronal temperature at this phase
  of the solar-activity cycle. On the spectra we also detected the weak
  coronal emission line of Ar X at 553.3 nm, as we also detected at
  the previous total solar eclipse of August 21, 2017, in the USA. We
  show a comparison of the eclipse observation with a prediction of the
  structure of the corona from an MHD model, carried out by Predictive
  Science Inc. (PSI). We consider the lines of sight to NASA's Parker
  Solar Probe at the times of total eclipses, when we can examine the
  coronal imaging in terms of electron density to compare with the in
  situ measurements. <P />We received major support from grant AGS-903500
  from the Solar Terrestrial Program, Atmospheric and Geospace Sciences
  Division, U.S. National Science Foundation. The CTIO site was courtesy
  of Associated Universities for Research in Astronomy (AURA). We had
  additional student support from the Massachusetts NASA Space Grant
  Consortium; Sigma Xi; the Global Initiatives Fund at Williams College;
  and the University of Pennsylvania. PSI was supported by AFOSR, NASA,
  and NSF. ACS received support from the NASA/HGI program, and from
  the MSFC Hinode project. AV thanks the mathematician Christophoros
  Mouratidis for his help with the data reduction of the spectra.

Title: Early results from the solar-minimum 2019 total solar eclipse
Authors: Pasachoff, Jay M.; Lockwood, Christian A.; Inoue, John L.;
   Meadors, Erin N.; Voulgaris, Aristeidis; Sliski, David; Sliski, Alan;
   Reardon, Kevin P.; Seaton, Daniel B.; Caplan, Ronald M.; Downs, Cooper;
   Linker, Jon A.; Schneider, Glenn; Rojo, Patricio; Sterling, Alphonse C.
Bibcode: 2020IAUS..354....3P
Altcode:
  We observed the 2 July 2019 total solar eclipse with a variety of
  imaging and spectroscopic instruments recording from three sites
  in mainland Chile: on the centerline at La Higuera, from the Cerro
  Tololo Inter-American Observatory, and from La Serena, as well
  as from a chartered flight at peak totality in mid-Pacific. Our
  spectroscopy monitored Fe X, Fe XIV, and Ar X lines, and we imaged Ar
  X with a Lyot filter adjusted from its original H-alpha bandpass. Our
  composite imaging has been compared with predictions based on modeling
  using magnetic-field measurements from the pre-eclipse month. Our
  time-differenced sites will be used to measure motions in coronal
  streamers.

Title: SunPy v1.0, the community-developed, free and open-source
    solar data analysis environment for Python.
Authors: Christe, S.; Barnes, W. T.; Bobra, M.; Freij, N.; Hayes,
   L.; Ireland, J.; Mumford, S.; Pérez-Suárez, D.; Ryan, D.; Shih,
   A. Y.; Chanda, P.; Glogowski, S.; Hewett, R.; Hughitt, V. K.; Hill,
   A.; Hiware, K.; Inglis, A.; Kirk, M. S.; Konge, S.; Mason, J. P.;
   Maloney, S.; Park, J.; Pereira, T. J.; Reardon, K.; Savage, S. L.;
   Yadav, T.; Taylor, G.; Stansby, D.; Jain, Y.; Sipocz, B.; Rajulapati,
   C. R.; Panda, A.
Bibcode: 2019AGUFMSH41C3309C
Altcode:
  The SunPy project facilitates and promotes the use and development
  of several community-led, free, and open source data analysis
  software packages for solar physics based on the scientific Python
  environment. The project achieves this goal by developing and
  maintaining the sunpy core package and supporting an ecosystem of
  affiliated packages. The SunPy project is pleased to announce the 1.0
  release of the sunpy package. This new release is the first stable
  release of the packages and includes several important new features
  such as improved data downloading capabilities, a large enhancement in
  coordinate and coordinate transformations capabilities, new map utility
  functions, and a new logging functionality amongst others. This talk
  will present how the sunpy package can be used for solar data analysis
  and discuss the roadmap for package.

Title: Solar Chromospheric Temperature Diagnostics: A Joint ALMA-Hα
    Analysis
Authors: Molnar, Momchil E.; Reardon, Kevin P.; Chai, Yi; Gary, Dale;
   Uitenbroek, Han; Cauzzi, Gianna; Cranmer, Steven R.
Bibcode: 2019ApJ...881...99M
Altcode: 2019arXiv190608896M
  We present the first high-resolution, simultaneous observations of
  the solar chromosphere in the optical and millimeter wavelength
  ranges, obtained with the Atacama Large Millimeter Array (ALMA)
  and the Interferometric Bidimensional Spectrometer at the Dunn Solar
  Telescope. In this paper we concentrate on the comparison between the
  brightness temperature observed in ALMA Band 3 (3 mm; 100 GHz) and the
  core width of the Hα 6563 Å line, previously identified as a possible
  diagnostic of the chromospheric temperature. We find that in the area
  of plage, network and fibrils covered by our field of view, the two
  diagnostics are well correlated, with similar spatial structures
  observed in both. The strength of the correlation is remarkable,
  given that the source function of the millimeter radiation obeys local
  thermodynamic equilibrium, while the Hα line has a source function that
  deviates significantly from the local Planck function. The observed
  range of ALMA brightness temperatures is sensibly smaller than the
  temperature range that was previously invoked to explain the observed
  width variations in Hα. We employ analysis from forward modeling
  with the Rybicki-Hummer (RH) code to argue that the strong correlation
  between Hα width and ALMA brightness temperature is caused by their
  shared dependence on the population number n <SUB>2</SUB> of the first
  excited level of hydrogen. This population number drives millimeter
  opacity through hydrogen ionization via the Balmer continuum, and
  Hα width through a curve-of-growth-like opacity effect. Ultimately,
  the n <SUB>2</SUB> population is regulated by the enhancement or lack
  of downward Lyα flux, which coherently shifts the formation height
  of both diagnostics to regions with different temperature, respectively.

Title: Disentangling Chromospheric Temperatures and Dynamics with
    ALMA and IBIS
Authors: Reardon, Kevin P.; Molnar, Momchil; Chai, Yi; Hofmann, Ryan
Bibcode: 2019AAS...23431103R
Altcode:
  The chromosphere is highly structured in density, dynamics, and
  temperature. Unfortunately, it can be difficult to disentangle the
  different contributions of these physical conditions to our current
  set of observable diagnostics. With the advent of high-resolution
  observations of the millimeter continuum with the Atacama Large
  Millimeter Array (ALMA), we have a new tool to probe the chromospheric
  temperature structure. By combining these observations with similar
  observations in other visible, infrared, and UV lines, we are
  better able to disentangle the thermal and dynamical behavior of the
  chromosphere. In this talk, we discuss the results of combining ALMA
  images with imaging spectroscopy from the Interferometric Bidimensional
  Spectrometer (IBIS). We find evidence that spectral-line parameters
  of Hα and Ca II are closely correlated with the ALMA brightness
  temperatures. We have performed spectral inversions employing multiple
  diagnostics to retrieve typical atmospheric conditions in our field of
  view. We discuss how this joint analysis changes our understanding of
  chromospheric dynamics and the interpretation of the observed spectral
  intensities. Finally, we explore how these results can guide future
  observations of the chromosphere from both ALMA and DKIST.

Title: New technique to measure the cavity defects of Fabry-Perot
    interferometers
Authors: Greco, V.; Sordini, A.; Cauzzi, G.; Reardon, K.; Cavallini, F.
Bibcode: 2019A&A...626A..43G
Altcode: 2019arXiv190501393G
  Context. Several astronomical instruments, for both nighttime and
  solar use, rely on tunable Fabry-Perot interferometers (FPIs). Knowing
  the exact shape of the etalons' cavity is crucial for assessing the
  overall instrumental transmission profile and its possible variations
  during the tuning process. <BR /> Aims: We aim to define and test
  a technique to accurately measure the cavity defects of air-spaced
  FPIs, including distortions due to the spectral tuning process that
  are typical of astronomical observations. We further aim to develop a
  correction technique to maintain the shape of the cavity as constant as
  possible during the spectral scan. These are necessary steps to optimize
  the spectral transmission profile of a two-dimensional spectrograph
  (polarimeter) using one or more FPIs in series, and to ensure that
  the spectral transmission profile remains constant during typical
  observing conditions. <BR /> Methods: We devised a generalization of the
  techniques developed for the so-called phase-shifting interferometry to
  the case of FPI. This measuring technique is applicable to any given FPI
  that can be tuned via changing the cavity spacing (z-axis), and can be
  used for any etalon regardless of the coating' reflectivity. The major
  strength of our method is the ability to fully characterize the cavity
  during a spectral scan, allowing for the determination of scan-dependent
  modifications of the plates. We have applied the measuring technique to
  three 50 mm diameter interferometers, with cavity gaps ranging between
  600 μm and 3 mm, coated for use in the visible range. <BR /> Results:
  The technique developed in this paper allows us to accurately and
  reliably measure the cavity defects of air-spaced FPIs, and of their
  evolution during the entire spectral scan. Our main, and unexpected,
  result is that the relative tilt between the two FPI plates varies
  significantly during the spectral scan, and can dominate the cavity
  defects; in particular, we observe that the tilt component at the
  extremes of the scan is sensibly larger than that at the center of
  the scan. Exploiting the capability of the electronic controllers to
  set the reference plane at any given spectral step, we then develop
  a correction technique that allows the minimization of the tilt
  during a complete spectral scan. The correction remains highly stable
  over long periods, well beyond the typical duration of astronomical
  observations. <P />Movies attached to Figs. 6 and 13 are available at <A
  href="https://www.aanda.org/10.1051/0004-6361/201935302/olm">https://www.aanda.org</A>

Title: Propagation and Coupling of Waves between the Photosphere
    and Chromosphere in the Presence of Sunspots
Authors: Stauffer, Johnathan; Reardon, Kevin
Bibcode: 2019shin.confE.126S
Altcode:
  Understanding the propagation of plasma waves through the solar
  atmosphere is an important part of constraining the energy budget
  which must give rise to coronal and chromospheric heating. In this
  study, we examine how the behavior of waves traveling between the
  solar phosophere and chromosphere are modulated by the presence of two
  sunspot regions: an isolated sunspot without a penumbra, and a complex,
  multi-spot active region (NOAA AR 11158). Using the Interferometric
  BIdimensional Spectropolarimeter (IBIS) at the Dunn Solar Telescope
  (DST), these regions were observed in the continuum and in three
  spectral lines (Na 5896 Å, Fe 7090 Å, and Ca 8542 Å) chosen to span
  the photosphere and chromosphere. In addition, these regions were
  simultaneously observed in the molecular CO lines at 4.65 µm using
  the by the McMath-Pierce telescope at Kitt Peak Observatory. Together,
  these data mark the first time that these CO molecular lines have
  been observed simultaneously with other chromospheric and photospheric
  spectral lines in high spatial and temporal resolution. These molecular
  lines are indicative of cool plasma in the lower chromosphere, and
  allow us to probe the thermal structure of the atmosphere in the
  presence of these propagating waves. The correspondence of the cool
  pockets observed with CO with other chromospheric structures can also
  be compared with MHD models of similar regions in order to test the
  ability of these models to replicate the temperature structure of
  the solar atmosphere. In the future, the results presented here may
  inform future observations from DKIST, which will be able to observe
  these CO lines in unprecedented spatial and spectral resolution with
  the Cryogenic Near-Infrared Spectro-Polarimeter (Cryo-NIRSP).

Title: High frequency chromospheric observations with IBIS and ALMA
Authors: Molnar, Momchil Emil; Reardon, Kevin; Cranmer, Steven
Bibcode: 2019shin.confE.148M
Altcode:
  The heating mechanism sustaining the quiet chromosphere is still
  unknown and is an area of active research (Kalkofen 2007). A possible
  explanation for the chromospheric heating conundrum is the dissipation
  of high-frequency waves permeating the chromosphere. However, there
  are few studies of this frequency regime (above 30 mHz) with full
  spectral scanning to derive proper Doppler velocity fields in the
  chromosphere. We present observations of the power spectrum of the
  Doppler velocities in the chromosphere from the DST at Sunspot, NM. We
  used the IBIS instrument with a novel reduction technique to derive
  chromospheric Doppler velocities in the spectral lines of H-alpha and Ca
  II 8542 with cadences of about 3.5 seconds for a full spectral scan. We
  find that the power spectrum of the measured velocities follow a power
  law ubiquitous in our field of view up to 60 mHz. The power law index
  is coherent for similar chromospheric regions. We find comparable power
  law in the power spectrum of the temperature variation in simultaneous
  observations with ALMA of the same region. This power law could be a
  signature of turbulent cascade leading to the dissipation of energy of
  these high frequency perturbations at small scales. However, this is
  an unexpected result as the extended formation region of these resonant
  chromospheric lines smears out the spectral signatures produced by short
  wavelength perturbations in the atmosphere. To explain the presence of
  high-frequency energy in the power spectra we study the transmission
  function of the wave perturbations through the solar atmosphere with
  the RH code. This exploratory study could be greatly improved with the
  DKI Solar Telescope, which would enable us to resolve smaller scales
  in the solar atmosphere as well as measure velocities at higher cadence
  and better precision.

Title: The DKI Solar Telescope
Authors: Reardon, Kevin
Bibcode: 2019shin.confE.232R
Altcode:
  The DKI Solar Telescope (DKIST) will begin initial scientific
  operations in the summer of 2020. It is designed to perform, in part,
  as a coronagraph, taking detailed images and spectra of the low solar
  corona. Given the four-meter aperture, excellent coronagraphic site,
  and broad range of diagnostics, it will be a transformational facility,
  permitting detailed studies of the velocities, magnetic field, and
  fine-scale structuring of the off-limb corona. I will describe the
  observational capabilities of DKIST, especially related to coronal
  diagnostics. I will then review some the techniques that can be used
  to process and analyze the DKIST data stream. I will show examples
  of techniques for image reconstruction, used to improve the spatial
  resolution of the recorded data, and for extracting useful information
  from time-series data cubes.

Title: Solar Ultraviolet Bursts
Authors: Young, Peter R.; Tian, Hui; Peter, Hardi; Rutten, Robert J.;
   Nelson, Chris J.; Huang, Zhenghua; Schmieder, Brigitte; Vissers, Gregal
   J. M.; Toriumi, Shin; Rouppe van der Voort, Luc H. M.; Madjarska, Maria
   S.; Danilovic, Sanja; Berlicki, Arkadiusz; Chitta, L. P.; Cheung, Mark
   C. M.; Madsen, Chad; Reardon, Kevin P.; Katsukawa, Yukio; Heinzel, Petr
Bibcode: 2018SSRv..214..120Y
Altcode: 2018arXiv180505850Y
  The term "ultraviolet (UV) burst" is introduced to describe small,
  intense, transient brightenings in ultraviolet images of solar active
  regions. We inventorize their properties and provide a definition
  based on image sequences in transition-region lines. Coronal signatures
  are rare, and most bursts are associated with small-scale, canceling
  opposite-polarity fields in the photosphere that occur in emerging flux
  regions, moving magnetic features in sunspot moats, and sunspot light
  bridges. We also compare UV bursts with similar transition-region
  phenomena found previously in solar ultraviolet spectrometry and
  with similar phenomena at optical wavelengths, in particular Ellerman
  bombs. Akin to the latter, UV bursts are probably small-scale magnetic
  reconnection events occurring in the low atmosphere, at photospheric
  and/or chromospheric heights. Their intense emission in lines with
  optically thin formation gives unique diagnostic opportunities
  for studying the physics of magnetic reconnection in the low solar
  atmosphere. This paper is a review report from an International Space
  Science Institute team that met in 2016-2017.

Title: Modeling wave energy transport using a 3D MHD simulation
    of AR12683
Authors: Tarr, Lucas; Linton, Mark; Reardon, Kevin; Shetye, Juie;
   Verwichte, Erwin
Bibcode: 2018tess.conf20544T
Altcode:
  We use the 3D Magnetohydrodynamic code LARE to model wave transport
  within NOAA Active Region 12683. The simulation extends vertically
  from the photosphere to the low corona and includes gravitational
  stratification and a steep transition region to a high temperature
  corona. AR12683 consists of a leading negative polarity sunspot
  followed by an extended region of plage, and had little X-ray
  activity during the time period we study. Given that, we use a
  potential field, extrapolated from HMI data, for the initial 3D
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  &lt;/use&gt; &lt;/g&gt; &lt;/svg&gt; observations taken with the Goode
  Solar Telescope at Big Bear Solar Observatory revealed interesting
  propagating disturbances near the sunspot, which will be reported
  on elsewhere. In this work, we focus on the general properties of
  wave propagation through the region by introducing compressive wave
  packets at the lower boundary, mimicking convective forcing. We then
  use the techniques developed in Tarr, Linton, &amp; Leake, ApJ 2017,
  to track wave energy, mode conversion, and shock formation as the wave
  packets propagate through the simulation. By varying the wave packet
  injection location, we can isolate photospheric source locations for
  disturbances seen higher up in the chromosphere and low corona, and
  understand the important role of mode conversion in the transfer of
  wave energy throughout the realistically structured atmosphere.

Title: Absorption Spectroscopy of Mercury's Exosphere During the
    2016 Solar Transit
Authors: Schmidt, C. A.; Leblanc, F.; Reardon, K.; Killen, R. M.;
   Gary, D. E.; Ahn, K.
Bibcode: 2018LPICo2047.6022S
Altcode:
  Solar transits of Mercury provide a rare opportunity to study the
  exosphere in absorption and a valuable analog to transiting exoplanet
  studies. This presentation will characterize the sodium exosphere
  during the 2016 transit.

Title: SunPy: Python for Solar Physics
Authors: Bobra, M.; Inglis, A. R.; Mumford, S.; Christe, S.; Freij,
   N.; Hewett, R.; Ireland, J.; Martinez Oliveros, J. C.; Reardon, K.;
   Savage, S. L.; Shih, A. Y.; Pérez-Suárez, D.
Bibcode: 2017AGUFMSH51C2508B
Altcode:
  SunPy is a community-developed open-source software library for
  solar physics. It is written in Python, a free, cross-platform,
  general-purpose, high-level programming language which is being
  increasingly adopted throughout the scientific community. SunPy aims to
  provide the software for obtaining and analyzing solar and heliospheric
  data. This poster introduces a new major release, SunPy version 0.8. The
  first major new feature introduced is Fido, the new primary interface to
  download data. It provides a consistent and powerful search interface
  to all major data providers including the VSO and the JSOC, as well as
  individual data sources such as GOES XRS time series. It is also easy
  to add new data sources as they become available, i.e. DKIST. The
  second major new feature is the SunPy coordinate framework. This
  provides a powerful way of representing coordinates, allowing simple
  and intuitive conversion between coordinate systems and viewpoints of
  different instruments (i.e., Solar Orbiter and the Parker Solar Probe),
  including transformation to astrophysical frames like ICRS. Other new
  features including new timeseries capabilities with better support
  for concatenation and metadata, updated documentation and example
  gallery. SunPy is distributed through pip and conda and all of its
  code is publicly available (sunpy.org).

Title: SunPy 0.8 - Python for Solar Physics
Authors: Inglis, Andrew; Bobra, Monica; Christe, Steven; Hewett,
   Russell; Ireland, Jack; Mumford, Stuart; Martinez Oliveros, Juan
   Carlos; Perez-Suarez, David; Reardon, Kevin P.; Savage, Sabrina;
   Shih, Albert Y.; Ryan, Daniel; Sipocz, Brigitta; Freij, Nabil
Bibcode: 2017SPD....4811506I
Altcode:
  SunPy is a community-developed open-source software library for
  solar physics. It is written in Python, a free, cross-platform,
  general-purpose, high-level programming language which is being
  increasingly adopted throughout the scientific community. Python is
  one of the top ten most often used programming languages, as such
  it provides a wide array of software packages, such as numerical
  computation (NumPy, SciPy), machine learning (scikit-learn), signal
  processing (scikit-image, statsmodels) to visualization and plotting
  (matplotlib, mayavi). SunPy aims to provide the software for obtaining
  and analyzing solar and heliospheric data. This poster introduces
  a new major release of SunPy (0.8). This release includes two major
  new functionalities, as well as a number of bug fixes. It is based on
  1120 contributions from 34 unique contributors. Fido is the new primary
  interface to download data. It provides a consistent and powerful search
  interface to all major data sources provides including VSO, JSOC, as
  well as individual data sources such as GOES XRS time series and and is
  fully pluggable to add new data sources, i.e. DKIST. In anticipation of
  Solar Orbiter and the Parker Solar Probe, SunPy now provides a powerful
  way of representing coordinates, allowing conversion between coordinate
  systems and viewpoints of different instruments, including preliminary
  reprojection capabilities. Other new features including new timeseries
  capabilities with better support for concatenation and metadata, updated
  documentation and example gallery. SunPy is distributed through pip
  and conda and all of its code is publicly available (sunpy.org).

Title: Exploratory study of the chromosphere with ALMA
Authors: Molnar, Momchil E.; Reardon, Kevin
Bibcode: 2017shin.confE.163M
Altcode:
  We will present an exploratory study of the dynamics of the
  chromospheric network and internetwork with the Atacama Large
  Milimeter/submilimeter Array (ALMA). ALMA is an interferometric array
  of sixty six 12-meter and 7-meter dishes in Chile, which recently
  started observing the Sun. The radiation detected with ALMA is formed
  through free-free emission in the chromosphere and can be interpreted
  as brightness temperature. The ALMA observations were conducted on
  the 23rd April 2017 simultaneously with the support of the DST (IBIS,
  ROSA and FIRS instruments), IRIS and Hinode. Using the unprecedented
  high cadence ( 2 seconds) and high angular resolution of the ALMA
  observations we can study in detail the heating mechanisms in the
  chromosphere, including the role of steepening acoustic waves. We will
  present preliminary results from our observations of the shock-driven
  turbulence in the chromosphere, as we extend previous work by Reardon
  et al. (2008) up to higher frequencies and new diagnostics.

Title: Absorption by Mercury's Exosphere During the May 9th, 2016
    Solar Transit.
Authors: Schmidt, C.; Reardon, K.; Killen, R. M.; Gary, D. E.; Ahn, K.;
   Leblanc, F.; Baumgardner, J. L.; Mendillo, M.; Beck, C.; Mangano, V.
Bibcode: 2016AGUFM.P53B2198S
Altcode:
  Observations of Mercury during a solar transit have the unique property
  that line absorption may be used to retrieve the exosphere's column
  density at all points above the terminator simultaneously. We report
  on measurements during the 9 May 2016 transit with the Dunn Solar
  Telescope (Interferometric BIdimensional Spectropolarimeter: IBIS &amp;
  Horizontal Spectrograph: HSG) and the Big Bear Solar Observatory (Fast
  Imaging Solar Spectrograph: FISS). The sodium exosphere was observed
  via Fabry-Perot imaging with IBIS in 9 mA increments, and with FISS at
  a dispersion of 17 mA/pixel by scanning the spectrograph slit over the
  planet's disk. A search for potassium D line absorption was performed
  using slit spectroscopy with HSG at a resolution of R 270,000. In each
  instrument, exposures of 20-40 ms and adaptive optics enable spatial
  structure to be resolved on sub-arcsecond scales. The line profiles at
  every spatial bin are divided by a shifted and scaled reference spectrum
  in order to isolate the exosphere's absorption from line absorption in
  the solar atmosphere and structures inherent to granulation. Analysis
  of these data sets is ongoing, but preliminary findings clearly show
  the densest column of sodium near the poles and the content at dawn
  enhanced several times with respect to dusk. Such is consistent with
  2003 transit results taken at the same Mercury season (Schleicher et
  al., 2004), however the data volumes herein permit a more in-depth
  study in which time-dependence of the exosphere may be considered.

Title: The DKIST Data Center: Meeting the Data Challenges for
    Next-Generation, Ground-Based Solar Physics
Authors: Davey, A. R.; Reardon, K.; Berukoff, S. J.; Hays, T.; Spiess,
   D.; Watson, F. T.; Wiant, S.
Bibcode: 2016AGUFMSH34A..04D
Altcode:
  The Daniel K. Inouye Solar Telescope (DKIST) is under construction
  on the summit of Haleakalā in Maui, and scheduled to start
  science operations in 2020. The DKIST design includes a four-meter
  primary mirror coupled to an adaptive optics system, and a flexible
  instrumentation suite capable of delivering high-resolution optical
  and infrared observations of the solar chromosphere, photosphere, and
  corona. Through investigator-driven science proposals, the facility
  will generate an average of 8 TB of data daily, comprised of millions
  of images and hundreds of millions of metadata elements. The DKIST Data
  Center is responsible for the long-term curation and calibration of data
  received from the DKIST, and for distributing it to the user community
  for scientific use. Two key elements necessary to meet the inherent
  big data challenge are the development of flexible public/private
  cloud computing and coupled relational and non-relational data storage
  mechanisms. We discuss how this infrastructure is being designed to
  meet the significant expectation of automatic and manual calibration of
  ground-based solar physics data, and the maximization the data's utility
  through efficient, long-term data management practices implemented
  with prudent process definition and technology exploitation.

Title: Solar dynamics imaging system a back-end instrument for the
    proposed NLST
Authors: Ramesh, K. B.; Vasantharaju, N.; Pruthvi, H.; Reardon, K.
Bibcode: 2016ExA....42..271R
Altcode: 2016ExA...tmp...24R
  The Solar Dynamics Imaging System (SDIS) will be one of the focal
  plane instruments operated at the National Large Solar Telescope
  (NLST). The prime objective of the instrument is to obtain high
  spatial and temporal resolution images of the region of interest on the
  Sun in the wavelength range from 390 nm to 900 nm. The SDIS provides
  filtergrams using broad-band filters while preserving the Strehl ratio
  provided by the telescope. Furthermore, the SDIS is expected to provide
  observations that allow image reconstruction to extract wave front
  information and achieve a homogenous image quality over the entire FOV.

Title: The 2016 Transit of Mercury Observed from Major Solar
    Telescopes and Satellites
Authors: Pasachoff, Jay M.; Schneider, Glenn; Gary, Dale; Chen, Bin;
   Sterling, Alphonse C.; Reardon, Kevin P.; Dantowitz, Ronald; Kopp,
   Greg A.
Bibcode: 2016DPS....4811705P
Altcode:
  We report observations from the ground and space of the 9 May 2016
  transit of Mercury. We build on our explanation of the black-drop
  effect in transits of Venus based on spacecraft observations of the 1999
  transit of Mercury (Schneider, Pasachoff, and Golub, Icarus 168, 249,
  2004). In 2016, we used the 1.6-m New Solar Telescope at the Big Bear
  Solar Observatory with active optics to observe Mercury's transit at
  high spatial resolution. We again saw a small black-drop effect as 3rd
  contact neared, confirming the data that led to our earlier explanation
  as a confluence of the point-spread function and the extreme solar
  limb darkening (Pasachoff, Schneider, and Golub, in IAU Colloq. 196,
  2004). We again used IBIS on the Dunn Solar Telescope of the Sacramento
  Peak Observatory, as A. Potter continued his observations, previously
  made at the 2006 transit of Mercury, at both telescopes of the sodium
  exosphere of Mercury (Potter, Killen, Reardon, and Bida, Icarus 226,
  172, 2013). We imaged the transit with IBIS as well as with two RED
  Epic IMAX-quality cameras alongside it, one with a narrow passband. We
  show animations of our high-resolution ground-based observations along
  with observations from XRT on JAXA's Hinode and from NASA's Solar
  Dynamics Observatory. Further, we report on the limit of the transit
  change in the Total Solar Irradiance, continuing our interest from
  the transit of Venus TSI (Schneider, Pasachoff, and Willson, ApJ 641,
  565, 2006; Pasachoff, Schneider, and Willson, AAS 2005), using NASA's
  SORCE/TIM and the Air Force's TCTE/TIM. See http://transitofvenus.info
  and http://nicmosis.as.arizona.edu.Acknowledgments: We were glad for
  the collaboration at Big Bear of Claude Plymate and his colleagues of
  the staff of the Big Bear Solar Observatory. We also appreciate the
  collaboration on the transit studies of Robert Lucas (Sydney, Australia)
  and Evan Zucker (San Diego, California). JMP appreciates the sabbatical
  hospitality of the Division of Geosciences and Planetary Sciences of
  the California Institute of Technology, and of Prof. Andrew Ingersoll
  there. The solar observations lead into the 2017 eclipse studies,
  for which JMP is supported by grants from the NSF AGS and National
  Geographic CRE.

Title: Petascale cyberinfrastructure for ground-based solar physics:
    approach of the DKIST data center
Authors: Berukoff, S.; Hays, T.; Reardon, K.; Spiess, DJ; Watson,
   F.; Wiant, S.
Bibcode: 2016SPIE.9913E..1FB
Altcode:
  The Daniel K Inouye Solar Telescope, under construction in Maui,
  is designed to perform high-resolution spectropolarimetric visible
  and infrared measurements of the Sun, and will annually produce 3 PB
  of data, via 5x10<SUP>8</SUP> images and 2x10<SUP>11</SUP> metadata
  elements requiring calibration, long-term data management, and open and
  free distribution. After briefly describing the DKIST and its instrument
  suite, we provide an overview of functions that the DKIST Data Center
  will provide, and focus on major challenges in its development. We
  conclude by discussing approach and mention some technologies that
  the Data Center team is using to develop a petascale computational
  and data storage resource to support this unique world-class DKIST
  facility and support its long-term scientific and operational goals.

Title: Tracing the Chromospheric and Coronal Magnetic Field with AIA,
    IRIS, IBIS, and ROSA Data
Authors: Aschwanden, Markus J.; Reardon, Kevin; Jess, Dave B.
Bibcode: 2016ApJ...826...61A
Altcode: 2016arXiv160202119A
  The aim of this study is to explore the suitability of
  chromospheric images for magnetic modeling of active regions. We
  use high-resolution images (≈ 0\buildrel{\prime\prime}\over{.}
  2{--}0\buildrel{\prime\prime}\over{.} 3), from the Interferometric
  Bidimensional Spectrometer in the Ca II 8542 Å line, the Rapid
  Oscillations in the Solar Atmosphere instrument in the Hα 6563 Å
  line, the Interface Region Imaging Spectrograph in the 2796 Å line,
  and compare non-potential magnetic field models obtained from those
  chromospheric images with those obtained from images of the Atmospheric
  Imaging Assembly in coronal (171 Å, etc.) and in chromospheric (304
  Å) wavelengths. Curvi-linear structures are automatically traced in
  those images with the OCCULT-2 code, to which we forward-fitted magnetic
  field lines computed with the Vertical-current Approximation Nonlinear
  Force Free Field code. We find that the chromospheric images: (1)
  reveal crisp curvi-linear structures (fibrils, loop segments, spicules)
  that are extremely well-suited for constraining magnetic modeling; (2)
  that these curvi-linear structures are field-aligned with the best-fit
  solution by a median misalignment angle of {μ }<SUB>2</SUB>≈ 4^\circ
  -7° (3) the free energy computed from coronal data may underestimate
  that obtained from cromospheric data by a factor of ≈ 2-4, (4) the
  height range of chromospheric features is confined to h≲ 4000 km,
  while coronal features are detected up to h = 35,000 km; and (5) the
  plasma-β parameter is β ≈ {10}<SUP>-5</SUP>{--}{10}<SUP>-1</SUP>
  for all traced features. We conclude that chromospheric images reveal
  important magnetic structures that are complementary to coronal
  images and need to be included in comprehensive magnetic field models,
  something that is currently not accomodated in standard NLFFF codes.

Title: Calibration development strategies for the Daniel K. Inouye
    Solar Telescope (DKIST) data center
Authors: Watson, Fraser T.; Berukoff, Steven J.; Hays, Tony; Reardon,
   Kevin; Speiss, Daniel J.; Wiant, Scott
Bibcode: 2016SPIE.9910E..1GW
Altcode:
  The Daniel K. Inouye Solar Telescope (DKIST), currently under
  construction on Haleakalā, in Maui, Hawai'i will be the largest solar
  telescope in the world and will use adaptive optics to provide the
  highest resolution view of the Sun to date. It is expected that DKIST
  data will enable significant and transformative discoveries that will
  dramatically increase our understanding of the Sun and its effects on
  the Sun-Earth environment. As a result of this, it is a priority of
  the DKIST Data Center team at the National Solar Observatory (NSO)
  to be able to deliver timely and accurately calibrated data to the
  astronomical community for further analysis. This will require a process
  which allows the Data Center to develop calibration pipelines for all of
  the facility instruments, taking advantage of similarities between them,
  as well as similarities to current generation instruments. There will
  also be a challenges which are addressed in this article, such as the
  large volume of data expected, and the importance of supporting both
  manual and automated calibrations. This paper will detail the current
  calibration development strategies being used by the Data Center team at
  the National Solar Observatory to manage this calibration effort, so as
  to ensure delivery of high quality scientific data routinely to users.

Title: Calibration development strategies for the Daniel K. Inouye
    Solar Telescope (DKIST) Data Center
Authors: Watson, Fraser; Reardon, Kevin P.; Berukoff, Steven J.;
   Hays, Tony; Wiant, Scott; Spiess, DJ
Bibcode: 2016SPD....4730902W
Altcode:
  As telescopes have grown larger and data rates have increased, so have
  the challenges in providing reliable and accurate calibration strategies
  for transforming raw data into useful science-ready outputs. The
  Daniel K. Inouye Solar Telescope (DKIST) will be the largest solar
  telescope in the world and will use adaptive optics to provide the
  highest resolution view of the Sun. Its data acquisition rates will
  be in the hundreds of thousands of frames per day, and it will deliver
  an average of 12TB of raw solar data on a daily basis. DKIST data will
  enable significant and transformative discoveries that will dramatically
  increase our understanding of the Sun and its effects on the Sun-Earth
  environment. As such, it is a priority of the DKIST Data Center team at
  the National Solar Observatory (NSO) to be able to deliver timely and
  accurately calibrated data to the astronomical community for further
  analysis.The facility will execute a variety of investigator-driven
  observing programs, which will produce day-to-day variations in
  the types of acquired data. In combination with large data rates
  and limited personnel, this will require some degree of automation
  to be incorporated into the calibration workflows to facilitate
  the generation of scientifically useful data. The heterogeneity of
  the data and the unpredictable variations in the seeing conditions
  (on timescales of seconds or minutes) introduce complexity, which
  requires a self-adapting, extensible calibration pipeline to provide
  sufficient automation to the process. Our knowledge of the instrument
  performance and telescope characteristics will grow as the telescope
  begins operations, and continuously through the facility lifetime. The
  automated calibration pipelines will be capable of modification
  and improvement to incorporate the new information about the DKIST
  system, as well as potential improvements provided by the DKIST user
  community.This poster will detail the calibration development strategies
  being used by the Data Center team at the NSO to manage this calibration
  effort, in order to deliver timely and accurately calibrated data to
  the DKIST user community, with as much scientific value as possible.

Title: Construction Status and Early Science with the Daniel K. Inouye
    Solar Telescope
Authors: McMullin, Joseph P.; Rimmele, Thomas R.; Warner, Mark;
   Martinez Pillet, Valentin; Craig, Simon; Woeger, Friedrich; Tritschler,
   Alexandra; Berukoff, Steven J.; Casini, Roberto; Goode, Philip R.;
   Knoelker, Michael; Kuhn, Jeffrey Richard; Lin, Haosheng; Mathioudakis,
   Mihalis; Reardon, Kevin P.; Rosner, Robert; Schmidt, Wolfgang
Bibcode: 2016SPD....4720101M
Altcode:
  The 4-m Daniel K. Inouye Solar Telescope (DKIST) is in its seventh
  year of overall development and its fourth year of site construction
  on the summit of Haleakala, Maui. The Site Facilities (Utility
  Building and Support &amp; Operations Building) are in place with
  ongoing construction of the Telescope Mount Assembly within. Off-site
  the fabrication of the component systems is completing with early
  integration testing and verification starting.Once complete this
  facility will provide the highest sensitivity and resolution for study
  of solar magnetism and the drivers of key processes impacting Earth
  (solar wind, flares, coronal mass ejections, and variability in solar
  output). The DKIST will be equipped initially with a battery of first
  light instruments which cover a spectral range from the UV (380 nm)
  to the near IR (5000 nm), and capable of providing both imaging and
  spectro-polarimetric measurements throughout the solar atmosphere
  (photosphere, chromosphere, and corona); these instruments are being
  developed by the National Solar Observatory (Visible Broadband Imager),
  High Altitude Observatory (Visible Spectro-Polarimeter), Kiepenheuer
  Institute (Visible Tunable Filter) and the University of Hawaii
  (Cryogenic Near-Infrared Spectro-Polarimeter and the Diffraction-Limited
  Near-Infrared Spectro-Polarimeter). Further, a United Kingdom consortium
  led by Queen's University Belfast is driving the development of high
  speed cameras essential for capturing the highly dynamic processes
  measured by these instruments. Finally, a state-of-the-art adaptive
  optics system will support diffraction limited imaging capable of
  resolving features approximately 20 km in scale on the Sun.We present
  the overall status of the construction phase along with the current
  challenges as well as a review of the planned science testing and the
  transition into early science operations.

Title: Challenges and Rewards in Ground-Based Observing
Authors: Reardon, Kevin P.
Bibcode: 2016SPD....4740802R
Altcode:
  DKIST will be largest ground-based project in solar physics, and
  will offer access and data to the whole community. In pursuit of
  exciting science, many users may have their first encounters with
  high-resolution, ground-based solar observations. New facilities, space
  or ground-based, all bring particular signatures in their data. While
  tools or processed datasets might serve to minimize such non-solar
  signatures, it is nonetheless important for users to understand the
  impacts on observation planning, the nature of the corrections applied,
  and any residual effects on their data.In this talk I will review some
  of the instrumental and atmospheric signatures that are important for
  ground-based observing, in particular in planning for the potential
  capabilities of the DKIST Data Center. These techniques include image
  warping, local PSF deconvolution, atmospheric dispersion correction,
  and scattered light removal. I will present examples of data sets
  afflicted by such problems as well as some of the algorithms used in
  characterizing and removing these contributions. This will demonstrate
  how even with the challenges of observing through a turbulent
  atmosphere, it is possible to achieve dramatic scientific results.

Title: Petascale Computing for Ground-Based Solar Physics with the
    DKIST Data Center
Authors: Berukoff, Steven J.; Hays, Tony; Reardon, Kevin P.; Spiess,
   DJ; Watson, Fraser; Wiant, Scott
Bibcode: 2016SPD....4720502B
Altcode:
  When construction is complete in 2019, the Daniel K. Inouye Solar
  Telescope will be the most-capable large aperture, high-resolution,
  multi-instrument solar physics facility in the world. The telescope
  is designed as a four-meter off-axis Gregorian, with a rotating Coude
  laboratory designed to simultaneously house and support five first-light
  imaging and spectropolarimetric instruments. At current design, the
  facility and its instruments will generate data volumes of 3 PB per
  year, and produce 10<SUP>7</SUP>-10<SUP>9</SUP> metadata elements.The
  DKIST Data Center is being designed to store, curate, and process this
  flood of information, while providing association of science data
  and metadata to its acquisition and processing provenance. The Data
  Center will produce quality-controlled calibrated data sets, and make
  them available freely and openly through modern search interfaces and
  APIs. Documented software and algorithms will also be made available
  through community repositories like Github for further collaboration and
  improvement.We discuss the current design and approach of the DKIST Data
  Center, describing the development cycle, early technology analysis
  and prototyping, and the roadmap ahead. We discuss our iterative
  development approach, the underappreciated challenges of calibrating
  ground-based solar data, the crucial integration of the Data Center
  within the larger Operations lifecycle, and how software and hardware
  support, intelligently deployed, will enable high-caliber solar physics
  research and community growth for the DKIST's 40-year lifespan.

Title: Next-generation solar data and data services from the Daniel
    K. Inouye Solar Telescope
Authors: Berukoff, S.; Reardon, K.; Rimmele, T.
Bibcode: 2015ASPC..495...91B
Altcode: 2015adass..24...91B
  The Daniel K. Inouye Solar Telescope (DKIST), when completed, will
  be the largest, most capable solar telescope in the world. Currently
  under construction on the summit of Haleakala on Maui, the DKIST will
  enable foundational insights into the physics of the Sun's photosphere,
  chromosphere, and corona. Its suite of first-light instruments will
  produce approximately 25TB of raw and processed data per day, with
  bursts up to 50TB. These data rates will require a scalable, flexible
  data and computing architecture that enables and promotes inquiry and
  discovery. We describe the challenges faced by managing DKIST data
  and provide an overview of the proposed data center architecture
  and resources that will allow users to fully exploit this unique
  world-class facility.

Title: Daniel K. Inouye Solar Telescope: Overview and Status
Authors: Rimmele, Thomas; McMullin, Joseph; Warner, Mark; Craig,
   Simon; Woeger, Friedrich; Tritschler, Alexandra; Cassini, Roberto;
   Kuhn, Jeff; Lin, Haosheng; Schmidt, Wolfgang; Berukoff, Steve; Reardon,
   Kevin; Goode, Phil; Knoelker, Michael; Rosner, Robert; Mathioudakis,
   Mihalis; DKIST TEAM
Bibcode: 2015IAUGA..2255176R
Altcode:
  The 4m Daniel K. Inouye Solar Telescope (DKIST) currently under
  construction on Haleakala, Maui will be the world’s largest solar
  telescope. Designed to meet the needs of critical high resolution and
  high sensitivity spectral and polarimetric observations of the sun,
  this facility will perform key observations of our nearest star that
  matters most to humankind. DKIST’s superb resolution and sensitivity
  will enable astronomers to unravel many of the mysteries the Sun
  presents, including the origin of solar magnetism, the mechanisms of
  coronal heating and drivers of the solar wind, flares, coronal mass
  ejections and variability in solar output. The all-reflecting, off-axis
  design allows the facility to observe over a broad wavelength range and
  enables DKIST to operate as a coronagraph. In addition, the photon flux
  provided by its large aperture will be capable of routine and precise
  measurements of the currently elusive coronal magnetic fields. The
  state-of-the-art adaptive optics system provides diffraction limited
  imaging and the ability to resolve features approximately 20 km on
  the Sun. Five first light instruments, representing a broad community
  effort, will be available at the start of operations: Visible Broadband
  Imager (National Solar Observatory), Visible Spectro-Polarimeter (High
  Altitude Observatory), Visible Tunable Filter (Kiepenheuer Institute,
  Germany), Diffraction Limited NIR Spectro-Polarimeter (University
  of Hawaii) and the Cryogenic NIR Spectro-Polarimeter (University of
  Hawaii). High speed cameras for capturing highly dynamic processes
  in the solar atmosphere are being developed by a UK consortium. Site
  construction on Haleakala began in December 2012 and is progressing
  on schedule. Operations are scheduled to begin in 2019. We provide an
  overview of the facility, discuss the construction status, and present
  progress with DKIST operations planning.

Title: Science-Ready Data Production in the DKIST Data Center
Authors: Reardon, Kevin; Berukoff, Steven; Hays, Tony; Spiess, DJ;
   Watson, Fraser
Bibcode: 2015IAUGA..2258326R
Altcode:
  The NSO's new flagship solar observatory, the four-meter Daniel
  K. Inouye Solar Telescope is under construction on Halekalala, Hawaii
  and slated for first light in 2019. The facility will operate an initial
  suite of five complementary spectroscopic and polarimetric instruments,
  with up to 11 detectors running simultaneously at typical cadences of
  5-30 frames per second, or more. The instruments will generate data
  of notable volume, dimensionality, cardinality, and diversity. The
  facility is expected to record several hundred million images per year,
  for a total data volume in excess of 4 petabytes.Beyond the crucial
  informatics infrastructure necessary to transport, store, and curate
  this deluge of data, there are significant challenges in developing the
  robust calibration workflows that can autonomously process the range of
  data to generate science-ready datasets for a heterogeneous and growing
  community. Efforts will be made to improve our ability to compensate for
  the effects of the Earth's atmosphere, to identify and assess instrument
  and facility contributions to the measured signal, and to use of quality
  and fitness-of-use metrics to characterize and advertise datasets.In
  this talk, we will provide an overview of the methods and tools we
  are using to define and evaluate the calibration workflows. We will
  review the type of datasets that may be made available to scientists at
  the time of the initial operations of DKIST, as well as the potential
  mechanisms for the search and delivery of those data products. We will
  also suggest some of the likely secondary data products that could
  possibly be developed successively in collaboration with the community.

Title: Building Petascale Cyberinfrastructure and Science Support
for Solar Physics: Approach of the DKIST Data Center
Authors: Berukoff, Steven; Reardon, Kevin; Hays, Tony; Spiess, DJ;
   Watson, Fraser
Bibcode: 2015IAUGA..2257546B
Altcode:
  When construction is complete in 2019, the Daniel K. Inouye Solar
  Telescope will be the most-capable large aperture, high-resolution,
  multi-instrument solar physics facility in the world. The telescope
  is designed as a four-meter off-axis Gregorian, with a rotating Coude
  laboratory designed to simultaneously house and support five first-light
  imaging and spectropolarimetric instruments. At current design, the
  facility and its instruments will generate data volumes of 5 PB,
  produce 10<SUP>8</SUP> images, and 10<SUP>7</SUP>-10<SUP>9</SUP>
  metadata elements annually. This data will not only forge new
  understanding of solar phenomena at high resolution, but enhance
  participation in solar physics and further grow a small but vibrant
  international community.The DKIST Data Center is being designed to
  store, curate, and process this flood of information, while augmenting
  its value by providing association of science data and metadata to
  its acquisition and processing provenance. In early Operations,
  the Data Center will produce, by autonomous, semi-automatic, and
  manual means, quality-controlled and -assured calibrated data sets,
  closely linked to facility and instrument performance during the
  Operations lifecycle. These data sets will be made available to the
  community openly and freely, and software and algorithms made available
  through community repositories like Github for further collaboration
  and improvement.We discuss the current design and approach of the DKIST
  Data Center, describing the development cycle, early technology analysis
  and prototyping, and the roadmap ahead. In this budget-conscious era,
  a key design criterion is elasticity, the ability of the built system
  to adapt to changing work volumes, types, and the shifting scientific
  landscape, without undue cost or operational impact. We discuss our
  deep iterative development approach, the underappreciated challenges
  of calibrating ground-based solar data, the crucial integration of the
  Data Center within the larger Operations lifecycle, and how software and
  hardware support, intelligently deployed, will enable high-caliber solar
  physics research and community growth for the DKIST's 40-year lifespan.

Title: The Fast Filament Eruption Leading to the X-flare on 2014
    March 29
Authors: Kleint, Lucia; Battaglia, Marina; Reardon, Kevin; Sainz Dalda,
   Alberto; Young, Peter R.; Krucker, Säm
Bibcode: 2015ApJ...806....9K
Altcode: 2015arXiv150400515K
  We investigate the sequence of events leading to the solar X1 flare
  SOL2014-03-29T17:48. Because of the unprecedented joint observations of
  an X-flare with the ground-based Dunn Solar Telescope and the spacecraft
  IRIS, Hinode, RHESSI, STEREO, and the Solar Dynamics Observatory, we can
  sample many solar layers from the photosphere to the corona. A filament
  eruption was observed above a region of previous flux emergence, which
  possibly led to a change in magnetic field configuration, causing
  the X-flare. This was concluded from the timing and location of the
  hard X-ray emission, which started to increase slightly less than a
  minute after the filament accelerated. The filament showed Doppler
  velocities of ∼2-5 km s<SUP>-1</SUP> at chromospheric temperatures
  for at least one hour before the flare occurred, mostly blueshifts,
  but also redshifts near its footpoints. Fifteen minutes before the
  flare, its chromospheric Doppler shifts increased to ∼6-10 km
  s<SUP>-1</SUP> and plasma heating could be observed before it lifted
  off with at least 600 km s<SUP>-1</SUP> as seen in IRIS data. Compared
  to previous studies, this acceleration (∼3-5 km s<SUP>-2</SUP>) is
  very fast, while the velocities are in the common range for coronal
  mass ejections. An interesting feature was a low-lying twisted second
  filament near the erupting filament, which did not seem to participate
  in the eruption. After the flare ribbons started on each of the second
  filament’s sides, it seems to have untangled and vanished during the
  flare. These observations are some of the highest resolution data of
  an X-class flare to date and reveal some small-scale features yet to
  be explained.

Title: The DKIST Data Center: Challenges and Opportunities Ahead
Authors: Berukoff, Steven; Reardon, Kevin; Hays, Tony; Spiess, DJ
Bibcode: 2015TESS....140201B
Altcode:
  The four-meter Daniel K. Inouye Solar Telescope is currently under
  construction on Haleakalā, Hawai´i, with completion planned in
  2019. When fully operational, DKIST will routinely generate 10-20
  TB of data and 10^8 metadata elements per day. These data will be
  transported to the DKIST Data Center at NSO headquarters in Boulder
  for storage, processing, and distribution. The initial output from the
  Data Center is expected to be high-quality calibrated data sets, with
  corrections applied to the level achievable for each acquired dataset
  (with variations due to seeing conditions and experiment design,
  among others). The processed data, along with the software code and
  full data description, will be made openly available to investigators
  and interested users. A key aspect of the design of the DKIST Data
  Center is its scalability, flexibility, and extensibility. Within
  an overview of the status of the Data Center development and plans,
  we will comment on lessons learned thus far in conceiving, designing,
  and prototyping a petascale informatics facility dedicated to generating
  high-quality calibrated data sets.

Title: Chromospheric Rapid Blueshifted Excursions Observed with IBIS
    and their Association with Photospheric Magnetic Field Evolution
Authors: Deng, Na; Chen, Xin; Liu, Chang; Jing, Ju; Tritschler,
   Alexandra; Reardon, Kevin P.; Lamb, Derek A.; Deforest, Craig E.;
   Denker, Carsten; Wang, Shuo; Liu, Rui; Wang, Haimin
Bibcode: 2015ApJ...799..219D
Altcode: 2014arXiv1412.4038D
  Chromospheric rapid blueshifted excursions (RBEs) are suggested to
  be the disk counterparts of type II spicules at the limb and believed
  to contribute to the coronal heating process. Previous identification
  of RBEs was mainly based on feature detection using Dopplergrams. In
  this paper, we study RBEs on 2011 October 21 in a very quiet region at
  the disk center, which were observed with the high-cadence imaging
  spectroscopy of the Ca II 8542 Å line from the Interferometric
  Bidimensional Spectrometer (IBIS). By using an automatic spectral
  analysis algorithm, a total of 98 RBEs are identified during an 11
  minute period. Most of these RBEs have either a round or elongated
  shape, with an average area of 1.2 arcsec<SUP>2</SUP>. The detailed
  temporal evolution of spectra from IBIS makes possible a quantitative
  determination of the velocity (~16 km s<SUP>-1</SUP>) and acceleration
  (~400 m s<SUP>-2</SUP>) of Ca II 8542 RBEs, and reveals an additional
  deceleration (~-160 m s<SUP>-2</SUP>) phase that usually follows the
  initial acceleration. In addition, we also investigate the association
  of RBEs with the concomitant photospheric magnetic field evolution,
  using coordinated high-resolution and high-sensitivity magnetograms
  made by Hinode. Clear examples are found where RBEs appear to be
  associated with the preceding magnetic flux emergence and/or the
  subsequent flux cancellation. However, further analysis with the aid
  of the Southwest Automatic Magnetic Identification Suite does not
  yield a significant statistical association between these RBEs and
  magnetic field evolution. We discuss the implications of our results
  in the context of understanding the driving mechanism of RBEs.

Title: DKIST: Observing the Sun at High Resolution
Authors: Tritschler, A.; Rimmele, T. R.; Berukoff, S.; Casini, R.;
   Craig, S. C.; Elmore, D. F.; Hubbard, R. P.; Kuhn, J. R.; Lin, H.;
   McMullin, J. P.; Reardon, K. P.; Schmidt, W.; Warner, M.; Woger, F.
Bibcode: 2015csss...18..933T
Altcode:
  The 4-m aperture Daniel K. Inouye Solar Telescope (DKIST) formerly
  known as the Advanced Technology Solar Telescope (ATST) and currently
  under construction on Haleakalā (Maui, Hawai'i) will be the largest
  solar ground-based telescope and leading resource for studying the
  dynamic Sun and its phenomena at high spatial, spectral and temporal
  resolution. Accurate and sensitive polarimetric observations at
  high-spatial resolution throughout the solar atmosphere including the
  corona is a high priority and a major science driver. As such the DKIST
  will offer a combination of state-of-the-art instruments with imaging
  and/or spectropolarimetric capabilities covering a broad wavelength
  range. This first-light instrumentation suite will include: a Visible
  Broadband Imager (VBI) for high-spatial and -temporal resolution
  imaging of the solar atmosphere; a Visible Spectro-Polarimeter (ViSP)
  for sensitive and accurate multi-line spectropolarimetry; a double
  Fabry-Pérot based Visible Tunable Filter (VTF) for high-spatial
  resolution spectropolarimetry; a fiber-fed 2D Diffraction-Limited Near
  Infra-Red Spectro-Polarimeter (DL-NIRSP); and a Cryogenic Near Infra-Red
  Spectro-Polarimeter (Cryo-NIRSP) for coronal magnetic field measurements
  and on-disk observations of e.g. the CO lines at 4.7 microns. We
  will provide a brief overview of the DKIST's unique capabilities to
  perform spectroscopic and spectropolarimetric measurements of the solar
  atmosphere using its first-light instrumentation suite, the status of
  the construction project, and how facility and data access is provided
  to the US and international community.

Title: The VAULT2.0 Observing Campaign: A Comprehensive Investigation
    of the Chromosphere-Corona Interface at Sub-arcsecond scales
Authors: Vourlidas, A.; Korendyke, C.; Tun-Beltran, S. D.; Ugarte-Urra,
   I.; Morrill, J. S.; Warren, H. P.; Young, P.; De Pontieu, B.; Gauzzi,
   G.; Reardon, K.
Bibcode: 2014AGUFMSH41C4155V
Altcode:
  We report the first results from an observing campaign in support of
  the VAULT2.0 sounding rocket launch on September 30, 2014. VAULT2.0
  is a Lya (1216Å) spectroheliograph capable of 0.3" (~250 km) spatial
  resolution. The objective of the VAULT2.0 project is the study of
  the chromosphere-corona interface. This interface has acquired renewed
  emphasis over the last few years, thanks to high-resolution observations
  from Hinode/SOT and EIS instruments and the Lya imaging from the two
  VAULT flights. The observations have shown that the upper chromosphere
  may play a more important role in heating the corona and in affecting
  EUV observations that previously thought: (1) by supplying the mass
  via Type-II spicules and, (2) by absorbing coronal emission. Many of
  the required clues for further progress are located in sub-arcsecond
  structures with temperatures between 10000 and 50000 K, a regime not
  accessible by Hinode or SDO. Lyman-alpha observations are, therefore,
  ideal, for filling in this gap. The observing campaign in support of
  the VAULT2.0 is closely coordinated with the Hinode and IRIS missions
  to study the mass/energy flow from the chromosphere to the corona with
  joint observations of type-II spicules, and the magnetic connectivity
  of coronal loops using the full imaging and spectral capabilities of
  IRIS, Hinode and SDO. Several ground-based observatories also provide
  important observations (IBIS, BBSO, SOLIS). The VAULT2.0 project is
  funded by the NASA LCAS program.

Title: High-resolution Observations of the X-flare on 2014-03-29
Authors: Kleint, L.; Battaglia, M.; Krucker, S.; Reardon, K.; Sainz
   Dalda, A.
Bibcode: 2014AGUFMSH31C..06K
Altcode:
  We investigate the sequence of events leading to the X1 flare
  SOL2014-03-29T17:48. Because of the unprecedented joint observations of
  an X-flare with the ground-based Dunn Solar Telescope and the spacecraft
  IRIS, Hinode, RHESSI, STEREO, and SDO, we can sample many solar layers
  from the photosphere to the corona. We find that a filament eruption,
  which was possibly caused by a thermal instability, was the cause of
  this X-flare. The filament was rising in the chromosphere for at least
  one hour before the flare occurred with a velocity of ∼2--5 km/s. 15
  minutes before the flare, its chromospheric rise velocity increased to
  ∼6--10 km/s, before it lifted off with at least 600 km/s, as seen by
  IRIS in the transition region. Doppler velocities from H-alpha images
  reveal intriguing small scale flows along the filament and enable us to
  derive its probable shape. An unusual feature was a low-lying twisted
  flux rope near the filament, which did not participate in the filament
  eruption. After the flare ribbons started on each of its sides, the
  flux rope seems to have untangled and vanished during the flare. We
  present a comprehensive overview of the flare, including polarimetric
  and spectroscopic data at subarcsecond resolution.

Title: Next-generation Solar Data and Data Services from the Daniel
    K. Inouye Solar Telescope
Authors: Berukoff, S. J.; Reardon, K.; Rimmele, T.
Bibcode: 2014AGUFMSH41C4162B
Altcode:
  The Daniel K. Inouye Solar Telescope (DKIST), when completed in
  2019, will be the largest, most capable, solar telescope in the
  world. Currently under construction on the summit of Haleakalā on Maui,
  the DKIST will enable foundational insights into the physics of the
  Sun's photosphere, chromosphere, and corona. Its suite of first-light
  instruments will produce approximately 25 TB of raw data per day,
  with occasional bursts of 50TB per day. These high data rates will
  require a scalable, flexible data and computing architecture that
  enables and promotes scientific inquiry and discovery. We briefly
  describe the DKIST data stream and then provide an overview of the
  proposed data-center architecture and resources that will allow users
  to fully exploit this world-class facility.

Title: Venus' thermospheric temperature field using a refraction
model at terminator : comparison with 2012 transit observations
    using SDO/HMI, VEx/SPICAV/SOIR and NSO/DST/FIRS
Authors: Widemann, Thomas; Jaeggli, Sarah; Reardon, Kevin; Tanga,
   Paolo; Père, Christophe; Pasachoff, Jay M.; Vandaele, Ann Carine;
   Wilquet, Valerie; Mahieux, Arnaud; Wilson, Colin
Bibcode: 2014DPS....4630206W
Altcode:
  The transit of Venus in June 2012 provided a unique case study of the
  Venus' atmosphere transiting in front of the Sun, while at the same time
  ESA's Venus Express orbiter observed the evening terminator at solar
  ingress and solar egress.We report on mesospheric temperature at Venus'
  morning terminator using SDO/HMI aureole photometry and comparison with
  Venus Express. Close to ingress and egress phases, we have shown that
  the aureole photometry reflects the local density scale height and the
  altitude of the refracting layer (Tanga et al. 2012). The lightcurve of
  each spatially resolved aureole element is fit to a two-parameter model
  to constrain the meridional temperature gradient at terminator. Our
  measurements are in agreement with the VEx/SOIR temperatures obtained
  during orbit 2238 at evening terminator during solar ingress (46.75N -
  LST = 6.075PM) and solar egress (31.30N - LST = 6.047PM) captured from
  the Venus Express orbiter at the time Venus transited the Sun.We also
  performed spectroscopy and polarimetry during the transit of Venus
  focusing on extracting signatures of CO2 absorption. Observations were
  taken during the first half of the transit using the Facility InfraRed
  Spectropolarimeter (FIRS) on the Dunn Solar Telescope (DST). Although
  the predicted CO2 transmission spectrum of Venus was not particularly
  strong at 1565 nm, this region of the H-band often used in magnetic
  field studies of the Sun's photosphere provides a particularly flat
  solar continuum with few atmospheric lines. Sun-subtracted Venus limb
  observations show intensity distribution of vibrational CO2 bands 221
  2v+2v2+v3 at 1.571μm and 141 v1+4v2+v3 at 1.606μm.

Title: The Daniel K. Inouye Solar Telescope first light instruments
    and critical science plan
Authors: Elmore, David F.; Rimmele, Thomas; Casini, Roberto; Hegwer,
   Steve; Kuhn, Jeff; Lin, Haosheng; McMullin, Joseph P.; Reardon, Kevin;
   Schmidt, Wolfgang; Tritschler, Alexandra; Wöger, Friedrich
Bibcode: 2014SPIE.9147E..07E
Altcode:
  The Daniel K. Inouye Solar Telescope is a 4-meter-class all-reflecting
  telescope under construction on Haleakalā mountain on the island of
  Maui, Hawai'i. When fully operational in 2019 it will be the world's
  largest solar telescope with wavelength coverage of 380 nm to 28 microns
  and advanced Adaptive Optics enabling the highest spatial resolution
  measurements of the solar atmosphere yet achieved. We review the
  first-generation DKIST instrument designs, select critical science
  program topics, and the operations and data handling and processing
  strategies to accomplish them.

Title: Hα spectroscopy and multiwavelength imaging of a solar flare
    caused by filament eruption
Authors: Huang, Z.; Madjarska, M. S.; Koleva, K.; Doyle, J. G.;
   Duchlev, P.; Dechev, M.; Reardon, K.
Bibcode: 2014A&A...566A.148H
Altcode: 2014arXiv1405.2194H
  Context. We study a sequence of eruptive events including filament
  eruption, a GOES C4.3 flare, and a coronal mass ejection. <BR /> Aims:
  We aim to identify the possible trigger(s) and precursor(s) of the
  filament destabilisation, investigate flare kernel characteristics,
  flare ribbons/kernels formation and evolution, study the interrelation
  of the filament-eruption/flare/coronal-mass-ejection phenomena as
  part of the integral active-region magnetic field configuration, and
  determine Hα line profile evolution during the eruptive phenomena. <BR
  /> Methods: Multi-instrument observations are analysed including Hα
  line profiles, speckle images at Hα - 0.8 Å and Hα + 0.8 Å from
  IBIS at DST/NSO, EUV images and magnetograms from the SDO, coronagraph
  images from STEREO, and the X-ray flux observations from Fermi and
  GOES. <BR /> Results: We establish that the filament destabilisation
  and eruption are the main triggers for the flaring activity. A
  surge-like event with a circular ribbon in one of the filament
  footpoints is determined as the possible trigger of the filament
  destabilisation. Plasma draining in this footpoint is identified as
  the precursor for the filament eruption. A magnetic flux emergence
  prior to the filament destabilisation followed by a high rate of flux
  cancellation of 1.34 × 10<SUP>16</SUP> Mx s<SUP>-1</SUP> is found
  during the flare activity. The flare X-ray lightcurves reveal three
  phases that are found to be associated with three different ribbons
  occurring consecutively. A kernel from each ribbon is selected and
  analysed. The kernel lightcurves and Hα line profiles reveal that the
  emission increase in the line centre is stronger than that in the line
  wings. A delay of around 5-6 min is found between the increase in the
  line centre and the occurrence of red asymmetry. Only red asymmetry is
  observed in the ribbons during the impulsive phases. Blue asymmetry
  is only associated with the dynamic filament. <P />Appendix A and
  movie associated to Fig. A.4 are available in electronic form at <A
  href="http://www.aanda.org/10.1051/0004-6361/201323097/olm">http://www.aanda.org</A>

Title: Chromospheric umbral dynamics
Authors: Reardon, Kevin P.; Vecchio, Antonio; Cauzzi, Gianna;
   Tritschler, Alexandra
Bibcode: 2014AAS...22432304R
Altcode:
  The chromosphere above sunspots is seen to undergo dynamical driving
  from perturbations from lower layers of the atmosphere. Umbral
  flashes have long been understood to be the result of acoustic shocks
  due to the drop in density in the sunspot chromosphere. Detailed
  observations of the umbral waves and flashes may help reveal the
  nature of the sunspot structure in the upper atmosphere. We report
  on high-resolution observations of umbral dynamics observed in the Ca
  II 8542 line by IBIS at the Dunn Solar Telescope. We use a principal
  component decomposition technique (POD) to isolate different components
  of the observed oscillations. We are able to explore temporal and
  spatial evolution of the umbral flashes. We find significant variation
  in the nature of the flashes over the sunspot, indicating that the
  chromospheric magnetic topology can strongly modify the nature of the
  umbral intensity and velocity oscillations.

Title: Chromospheric Diagnostics from IRIS and DST
Authors: Cauzzi, Gianna; Reardon, Kevin P.; Jaeggli, Sarah A.;
   Reid, Aaron
Bibcode: 2014AAS...22430201C
Altcode:
  Using data obtained during a coordinated observing campaign in
  September 2013, we compare the spectral and imaging diagnostics from
  IRIS and the instruments at the Dunn Solar Telescope (DST). We focus
  on a small active region observed for approximately one hour with IRIS
  (NUV, FUV, and SJI) in conjunction with IBIS, FIRS, and ROSA from the
  DST.In particular, we examine the line widths and intensities in the
  different chromospheric lines (H-alpha, Ca II 8542, Mg II) and the
  temporal evolution of these different diagnostics. This allows us to
  better relate the views from new window provided by IRIS to previous
  studies of the chromosphere.

Title: On the Naming and Dscovery of the Solar Chromosphere
Authors: Reardon, Kevin P.
Bibcode: 2014AAS...22420304R
Altcode:
  The chromosphere was discovered by Lockyer and Janssen in 1868,
  and named by Lockyer. It is often stated that his motivation
  for associating this region of the solar atmosphere with "color"
  was because of its bright red appearance at eclipses due to the
  predominance of H-alpha. However, Lockyer had never seen a total
  solar eclipse at the time he gave the name and does not appear to
  have provided this justification himself. It is more likely that the
  "color" refers to the plethora of different colored emission lines
  he saw and identified with his spectrograph.I also discuss the Padre
  Angelo Secchi's observation of the 1860 eclipse in Spain, His accurate
  description of the chromosphere as a complete, theretofore unseen
  layer enveloping the Sun predates Lockyer and Janssen by eight years.

Title: Challenges for the DKIST Data Center
Authors: Reardon, Kevin P.; Rimmele, Thomas R.
Bibcode: 2014AAS...22421843R
Altcode:
  Processing the large volumes of complex, multi-instrument, ground-based
  data generated at the DKIST will require implementation of algorithms
  and tools at a level not previously achieved for high-resolution,
  ground-based solar telescopes. We discuss some the goals of the
  data reduction pipelines for DKIST, including the different types
  of calibrations that would (optimally) be applied to the acquired
  data. We highlight some of the particular challenges for ground-based
  data, including seeing effects, atmospheric dispersion, and rapid
  changes in instrumental calibrations. We will describe a possible
  software framework for the implementation of the pipelines, as well
  as point out some areas for community input or VSO integration in the
  development process.

Title: Venus' thermospheric temperature field using a refraction
model at terminator : comparison with 2012 transit observations
    using SDO/HMI and NSO/DST/FIRS
Authors: Widemann, Thomas; Tanga, Paolo; Père, Christophe; Jaeggli,
   Sarah; Reardon, Kevin; Pasachoff, Jay M.
Bibcode: 2014EGUGA..1612916W
Altcode:
  The transit of Venus in June 2012 provided a unique case study of an
  Earth-size planet's atmosphere transiting in front of its parent star
  at 0.7AU, while at the same time ESA's Venus Express orbiter observed
  the evening terminator at solar ingress and solar egress. We report
  on mesospheric temperature at Venus' morning terminator using SDO/HMI
  aureole photometry and comparison with Venus Express. Close to ingress
  and egress phases, we have shown that the aureole photometry reflects
  the local density scale height and the altitude of the refracting layer
  (Tanga et al. 2012). The lightcurve of each spatial resolution element
  of the aureole is compared to a two-parameter model to constrain the
  meridional temperature gradient along the terminator. Our measurements
  are in agreement with the VEx/SOIR temperatures obtained during
  orbit 2238 at evening terminator during solar ingress (46.75N - LST
  = 6.075PM) and solar egress (31.30N - LST = 6.047PM) captured from
  the Venus Express orbiter at the time Venus transited the Sun for
  Earth-based observers. We also performed spectroscopy and polarimetry
  during the transit of Venus focusing on extracting signatures of
  CO2 absorption. Observations were taken during the first half of the
  transit using the Facility InfraRed Spectropolarimeter on the Dunn
  Solar Telescope. Although the predicted CO2 transmission spectrum
  of Venus was not particularly strong at 1565 nm, this region of the
  H-band often used in magnetic field studies of the Sun's photosphere
  provides a particularly flat solar continuum with few atmospheric and
  molecular lines. Sun-subtracted Venus limb observations show intensity
  distribution of vibrational CO2 bands 221 2v + 2ν2 + ν3 at 1.571um and
  141 ν1 + 4ν2 + ν3 at 1.606um. Data independently allow to constrain
  temperature as well as cross-terminator thermospheric winds.

Title: The Solar Chromosphere Observed at 1 Hz and 0.''2 Resolution
Authors: Lipartito, Isabel; Judge, Philip G.; Reardon, Kevin; Cauzzi,
   Gianna
Bibcode: 2014ApJ...785..109L
Altcode: 2014arXiv1401.4474L
  We recently reported extremely rapid changes in chromospheric fine
  structure observed using the IBIS instrument in the red wing of
  Hα. Here, we examine data obtained during the same observing run
  (2010 August 7), of a mature active region NOAA 11094. We analyze
  more IBIS data including wavelength scans and data from the Solar
  Dynamics Observatory, all from within a 30 minute interval. Using a
  slab radiative transfer model, we investigate the physical nature of
  fibrils in terms of tube-like versus sheet-like structures. Principal
  Component Analysis shows that the very rapid Hα variations in the
  line wings depend mostly on changes of line width and line shift,
  but for Ca II 854.2 the variations are dominated by changes in column
  densities. The tube model must be rejected for a small but significant
  class of fibrils undergoing very rapid changes. If our wing data arise
  from the same structures leading to "type II spicules," our analysis
  calls into question much recent work. Instead, the data do not reject
  the hypothesis that some fibrils are optical superpositions of plasma
  collected into sheets. We review how Parker's theory of tangential
  discontinuities naturally leads to plasma collecting into sheets,
  and show that the sheet picture is falsifiable. Chromospheric fine
  structures seem to be populated by both tubes and sheets. We assess the
  merits of spectral imaging versus slit spectroscopy for future studies.

Title: Observations of the Black-Drop Effect at the 2012 Transit
    of Venus
Authors: Rogoszinski, Zeeve; Pasachoff, J. M.; Babcock, B. A.;
   Schneider, G.; Reardon, K. P.
Bibcode: 2014AAS...22324716R
Altcode:
  We observed the 2012 transit of Venus from several locations,
  including the Mees Solar Observatory of the University of Hawaii on
  Maui; the Dunn Solar Telescope at the Sacramento Peak Observatory of
  the National Solar Observatory in Sunspot, NM; and the Big Bear Solar
  Observatory of the New Jersey Institute of Technology in California. Our
  observations, mainly directed at the study of Venus's atmosphere, also
  included high-resolution views of the black-drop effect. Historically,
  the black-drop effect proved to be a daunting anomaly for measuring
  the path length of Venus across the Sun’s surface with sufficient
  time accuracy to allow satisfactory measurement of the astronomical
  unit. Therefore, this phenomenon set back the accurate calculations
  for centuries of the size and scale of the solar system. In this
  paper, we discuss data taken with the New Solar Telescope at the Big
  Bear Observatory and with the IBIS on the Dunn Solar Telescope. We
  show the evolution of isophotes as a function of time to demonstrate
  various limb effects during second and third contacts. Schneider,
  Pasachoff, and Golub (Icarus 168. 249-256, 2004) have shown that the
  black-drop effect as seen in a transit of Mercury resulted from both the
  point-spread function of the telescope and the extreme limb-darkening
  effect at the region of the solar limb where the black-drop effect is
  demonstrated, and the current paper extends the analysis to the recent
  transit of Venus. As they showed, and as is verified here, Venus's
  atmosphere plays no role in the black-drop effect. ZR (Vassar '14)
  was a Keck Northeast Astronomy Consortium Summer Fellow at Williams
  College, supported by an NSF/REU grant to the Keck Northeast Astronomy
  Consortium. This research used the following tools: IDL/IDP3, ImageJ,
  and DS9. For obtaining the data at the Big Bear Solar Observatory,
  we thank Vasyl Yurchyshyn. Special thanks goes to Dr. Steven Souza
  for his support. The 2012 observations were obtained with a grant from
  the Committee for Research and Exploration of the National Geographic
  Society.

Title: Future Diagnostic Capabilities: The 4-meter Daniel K. Inouye
    Solar Telescope
Authors: Berger, Thomas; Reardon, Kevin; Elmore, David; Woeger,
   Friedrich; Tritschler, Alexandra; Rimmele, Thomas
Bibcode: 2014cosp...40E.294B
Altcode:
  We discuss the observational capabilities of the Daniel K. Inouye
  Solar Telescope (DKSIT), formerly known as the Advanced Technology
  Solar Telescope (ATST), currently under construction on Haleakala
  Mountain on the island of Maui, Hawaii, with first light anticipated
  in mid-2019. The DKIST will be a 4-meter aperture Gregorian telescope
  with advanced environmental control and adaptive optics capable of
  producing diffraction-limited resolution in visible light of 0.03"
  or about 20 km in the solar photosphere. The first light instrument
  suite will include the Visible Broadband Imager (VBI), an interference
  filter-based instrument capable of 30 Hz imaging of photospheric and
  chromospheric magnetic structures in the 380 to 800 nm wavelength
  range. All VBI images will be reconstructed in near-real-time using
  the KISIP speckle reconstruction algorithm adapted to the DKIST
  optical and AO configuration. The Visible Spectropolarimeter (ViSP)
  instrument being fabricated by the High Altitude Observatory (HAO) will
  enable high-precision slit-spectropolarimetery in any three spectral
  regions from 380 to 900 nm. The ViSP instrument will be the highest
  precision spectropolarimeter ever produced with a spatial resolution
  of approximately 40 km at 600 nm and temporal resolution of 10s to
  achieve 1e-03 polarimetric precision. The Visible Tunable Filter (VTF)
  instrument under fabrication at the Kiepenheuer Institute for Solar
  Physics (KIS) is a triple-etalon Fabry-Perot imaging spectropolarimeter
  instrument capable of diffraction limited measurements of the Fe I
  630.2 nm and Ca II 854.2 nm spectral lines for Doppler and magnetic
  measurements in the photosphere and chromosphere, respectively. The
  VTF will also enable the highest spatial and temporal resolution
  observations yet achieved in the H-alpha line for detailed studies of
  chromospheric dynamics in response to photospheric magnetic drivers. The
  Diffraction-Limited Near-IR Spectropolarimeter (DL-NiRSP) and the
  Cryogenic Near-IR Spectropolarimeter (Cryo-NiRSP) instruments, both
  under fabrication at the University of Hawaii, will enable polarimetric
  and spectroscopic investigations in the largely unexplored infra-red
  spectral region. The DL-NiRSP will span 900 nm to 2.5 microns in
  wavelength and include a novel fiber-optic "Integral Field Unit"
  (IFU) for true imaging spectropolarimetry in three simultaneous
  spectral regions over a variable field of view. This instrument
  will enable revolutionary measurements of prominence magnetic fields
  and will also, in the wider field mode, enable coronal polarimetric
  studies. The Cryo-NiRSP instrument spans the 1--5 micron wavelength
  range and will make near-diffraction limited 0.3" resolution slit-scan
  measurements of the coronal magnetic field out to 1.3 solar radii
  with temporal resolution measured in minutes. The DKIST facility
  will undergo extensive polarimetric calibration to ensure that the
  ultimate goal of 5e-04 polarimetic precision is obtainable under the
  best conditions. All of the data from the DKIST will be transmitted
  to the central DKIST data center in Boulder, Colorado where automated
  reduction and calibration pipelines will rapidly provide the community
  with calibrated data products for use in science investigations. The
  DKIST will also be operated in a "Service Mode" access model in which
  investigators will not be required to travel to the telescope to
  accomplish their science observations.

Title: Data integration and analysis using the Heliophysics Event
    Knowledgebase
Authors: Hurlburt, Neal; Reardon, Kevin
Bibcode: 2014cosp...40E1250H
Altcode:
  The Heliophysics Event Knowledgebase (HEK) system provides an integrated
  framework for automated data mining using a variety of feature-detection
  methods; high-performance data systems to cope with over 1TB/day of
  multi-mission data; and web services and clients for searching the
  resulting metadata, reviewing results, and efficiently accessing the
  data products. We have recently enhanced the capabilities of the HEK
  to support the complex datasets being produced by the Interface Region
  Imaging Spectrograph (IRIS). We are also developing the mechanisms to
  incorporate descriptions of coordinated observations from ground-based
  facilities, including the NSO's Dunn Solar Telescope (DST). We will
  discuss the system and its recent evolution and demonstrate its ability
  to support coordinated science investigations.

Title: Comet C/2012 S1 (ISON): Observations of the Dust Grains from
    SOFIA and of the Atomic Gas from NSO Dunn and McMath-Pierce Solar
    Telescopes (Invited)
Authors: Wooden, D. H.; Woodward, C. E.; Harker, D. E.; Kelley, M. S.;
   Sitko, M.; Reach, W. T.; De Pater, I.; Gehrz, R. D.; Kolokolova,
   L.; Cochran, A. L.; McKay, A. J.; Reardon, K.; Cauzzi, G.; Tozzi,
   G.; Christian, D. J.; Jess, D. B.; Mathioudakis, M.; Lisse, C. M.;
   Morgenthaler, J. P.; Knight, M. M.
Bibcode: 2013AGUFM.P24A..07W
Altcode:
  Comet C/2012 S1 (ISON) is unique in that it is a dynamically new comet
  derived from the Oort cloud reservoir of comets with a sun-grazing
  orbit. Infrared (IR) and visible wavelength observing campaigns were
  planned on NASA's Stratospheric Observatory For Infrared Astronomy
  (SOFIA) and on National Solar Observatory Dunn (DST) and McMath-Pierce
  Solar Telescopes, respectively. We highlight our early results. SOFIA
  (+FORCAST [1]) mid- to far-IR images and spectroscopy (~5-35 μm)
  of the dust in the coma of ISON are to be obtained by the ISON-SOFIA
  Team during a flight window 2013 Oct 21-23 UT (r_h≈1.18 AU). Dust
  characteristics, identified through the 10 μm silicate emission
  feature and its strength [2], as well as spectral features from
  cometary crystalline silicates (Forsterite) at 11.05-11.2 μm, and
  near 16, 19, 23.5, 27.5, and 33 μm are compared with other Oort cloud
  comets that span the range of small and/or highly porous grains (e.g.,
  C/1995 O1 (Hale-Bopp) [3,4,5] and C/2001 Q4 (NEAT) [6]) to large and/or
  compact grains (e.g., C/2007 N4 (Lulin) [7] and C/2006 P1 (McNaught)
  [8]). Measurement of the crystalline peaks in contrast to the broad
  10 and 20 μm amorphous silicate features yields the cometary silicate
  crystalline mass fraction [9], which is a benchmark for radial transport
  in our protoplanetary disk [10]. The central wavelength positions,
  relative intensities, and feature asymmetries for the crystalline
  peaks may constrain the shapes of the crystals [11]. Only SOFIA can
  look for cometary organics in the 5-8 μm region. Spatially resolved
  measurements of atoms and simple molecules from when comet ISON is
  near the Sun (r_h&lt; 0.4 AU, near Nov-20--Dec-03 UT) were proposed
  for by the ISON-DST Team. Comet ISON is the first comet since comet
  Ikeya-Seki (1965f) [12,13] suitable for studying the alkalai metals Na
  and K and the atoms specifically attributed to dust grains including
  Mg, Si, Fe, as well as Ca. DST's Horizontal Grating Spectrometer
  (HGS) measures 4 settings: Na I, K, C2 to sample cometary organics
  (along with Mg I), and [O I] as a proxy for activity from water [14]
  (along with Si I and Fe I). State-of-the-art instruments that will also
  be employed include IBIS [15], which is a Fabry-Perot spectral imaging
  system that concurrently measures lines of Na, K, Ca II, or Fe, and ROSA
  (CSUN/QUB) [16], which is a rapid imager that simultaneously monitors Ca
  II or CN. From McMath-Pierce, the Solar-Stellar Spectrograph also will
  target ISON (320-900 nm, R~21,000, r_h&lt;0.3 AU). Assuming survival,
  the intent is to target ISON over r_h&lt;0.4 AU, characteristic of
  prior Na detections [12,13,17,18,19]. References: [1] Adams, J.D., et
  al. 2012, SPIE, 8446, 16; [2] Kelley, M.S., Wooden, D.H. 2009, PSS, 57,
  1133; [3] Harker et al. 2002, ApJ, 580, 579; [4] Hayward et al. 2000,
  ApJ, 538, 428; [5] Hadamcik, E., Levasseur-Regourd, A.C. 2003, JQSRT,
  79-80, 661; [6] Wooden, D.H. 2004, ApJL, 612, L77; [7] Woodward et
  al. 2011, AJ, 141, 181; [8] Kelley et al. 2010, LPSC, 41, #2375;
  [9] Kelley, M.S. et al. 2011, AAS, 211, 560; [10] Wooden, D.H. 2008,
  SSRv, 138, 75; [11] Lindsay et al. 2013, ApJ, 766, 54; [12] Preston,
  G. W. 1967, ApJ, 147, 718; [13] Slaughter, C.D. 1969, AJ, 74, 929;
  [14] McKay et al. 2012, Icarus, 222, 684; [15] Cavallini, F., 2006,
  Solar Phys., 236, 415; [16] Jess et al., 2010, Solar Phys, 261, 363;
  [17] Watanabe, J-I. et al. 2003, ApJ, 585, L159; [18] Leblanc, F. et
  al. 2008, A&amp;A, 482, 293; [19] Fulle, M. et al. 2013, ApJL, 771, L21

Title: Spectral Signatures of Penumbral Transients
Authors: Reardon, K.; Tritschler, A.; Katsukawa, Y.
Bibcode: 2013ApJ...779..143R
Altcode:
  In this work we investigate the properties of penumbral transients
  observed in the upper photospheric and chromospheric region above a
  sunspot penumbra using two-dimensional spectroscopic observations
  of the Ca II 854.21 nm line with a 5 s cadence. In our 30 minutes
  of observations, we identify several penumbral-micro jets (PMJs)
  with cotemporal observations from Dunn Solar Telescope/IBIS and
  Hinode/SOT. We find that the line profiles of these PMJ events
  show emission in the two wings of the line (±0.05 nm), but
  little modification of the line core. These are reminiscent of
  the line profiles of Ellerman bombs observed in plage and network
  regions. Furthermore, we find evidence that some PMJ events have a
  precursor phase starting 1 minute prior to the main brightening that
  might indicate initial heating of the plasma prior to an acoustic or
  bow shock event. With the IBIS data, we also find several other types
  of transient brightenings with timescales of less than 1 minute that
  are not clearly seen in the Hinode/SOT data. The spectral profiles and
  other characteristics of these events are significantly different from
  those of PMJs. The different appearances of all these transients are
  an indicator of the general complexity of the chromospheric magnetic
  field and underscore the highly dynamic behavior above sunspots. It
  also highlights the care that is needed in interpreting broadband
  filter images of chromospheric lines, which may conceal very different
  spectral profiles, and the underlying physical mechanisms at work.

Title: Spatially Resolved Spectroscopic Observations of Na and K in
    the Tail of Comet C/2011 L4 (PanSTARRS)
Authors: Cochran, Anita L.; Wooden, D. H.; McKay, A. J.; Cauzzi, G.;
   Reardon, K.; Tozzi, G.
Bibcode: 2013DPS....4550205C
Altcode:
  We used the Dunn Solar Telescope (DST) of The National Solar Observatory
  to obtain spectroscopic observations of comet C/2011 L4 (PanSTARRS) on
  13 and 14 March 2013. The DST has the advantage for comet observations
  that one can observe the comet when it is close to the Sun. At the
  time of our observations, comet PanSTARRS was at 0.31 and 0.32 AU
  heliocentric distance. We used the Horizontal Spectrograph to observe
  five different spectral regions of the coma. The resolving power was
  50,000 - 60,000. The slit was 0.3 arcsec wide and 171 arcsec long. At
  the comet's geocentric distance, the slit covered 1.43e5 km. The
  comet was approximately centered on the slit. We observed strong
  emissions from sodium (D1@589.592nm and D2@588.995nm) and potassium
  (D1@770.108nm and D2@671.701nm), along with a weak continuum. Lithium
  was not detected. The sodium was visible on the optocenter and the
  tailward side of the comet and extended to the edge of the slit (i.e. at
  least 70,000km tailward). It shifted redward at larger cometocentric
  distances, attributable to the acceleration of sodium by solar radiation
  pressure. The potassium was much weaker than the sodium and does not
  appear to extend as far from the optocenter. In this paper, we will show
  the distribution of these gases and compare their relative strengths. We
  will discuss the effects of the different photodissociative lifetimes
  of sodium and potassium and how they dictate what we observed.

Title: Characterization of a transiting exo-Venus : lessons from
    the 2012 Transit
Authors: Widemann, Thomas; Jaeggli, S. A.; Reardon, K. P.; Tanga,
   P.; Pasachoff, J. M.; Schneider, G.
Bibcode: 2013DPS....4511811W
Altcode:
  The transit of Venus in June 2012 provided a unique chance to
  view a well studied planetary atmosphere as we might see that of a
  transiting exoplanet, through scattered and refracted illumination
  of its parent star. We report on mesospheric temperature at Venus'
  morning terminator using SDO/HMI aureole photometry and comparison with
  Venus Express. Close to ingress and egress phases, we have shown that
  the aureole photometry reflects the local density scale height and the
  altitude of the refracting layer (Tanga et al. 2012). The lightcurve
  of each spatial resolution element of the aureole is compared to a
  two-parameter model to constrain the meridional temperature gradient
  along the terminator. Our measurements are in agreement with the
  VEx/SOIR temperatures obtained during orbit 2238 at evening terminator
  during solar ingress (46.75N - LST = 6.075PM) and solar egress (31.30N -
  LST = 6.047PM) as seen from the orbiter. Imaging data using IBIS/ROSA on
  the Dunn Solar Telescope in the G-band (430 nm) are also presented. We
  also performed spectroscopy and polarimetry during the transit of Venus
  focusing on extracting signatures of CO2 absorption. Observations were
  taken during the first half of the transit using the Facility InfraRed
  Spectropolarimeter on the Dunn Solar Telescope. Although the predicted
  CO2 transmission spectrum of Venus was not particularly strong at 1565
  nm, this region of the H-band often used in magnetic field studies of
  the Sun's photosphere provides a particularly flat solar continuum
  with few atmospheric and molecular lines. Sun-subtracted Venus limb
  observations show intensity distribution of vibro-rotational CO2 band
  221 2ν + 2ν2 + ν3 at 1.571μm allowing for an additional constraint
  on Venus' thermospheric temperature.

Title: Observation of neutral sodium above Mercury during the transit
    of November 8, 2006
Authors: Potter, A. E.; Killen, R. M.; Reardon, Kevin P.; Bida, T. A.
Bibcode: 2013Icar..226..172P
Altcode:
  We mapped the absorption of sunlight by sodium vapor in the exosphere
  of Mercury during the transit of Mercury on November 8, 2006, using
  the IBIS Interferometric BIdimensional Spectrometer at the Dunn Solar
  Telescope operated by the National Solar Observatory at Sunspot, New
  Mexico. The measurements were reduced to line-of-sight equivalent
  widths for absorption at the sodium D<SUB>2</SUB> line around the
  shadow of Mercury. The sodium absorption fell off exponentially with
  altitude up to about 600 km. However there were regions around north
  and south polar-regions where relatively uniform sodium absorptions
  extended above 1000 km. We corrected the 0-600 km altitude profiles
  for seeing blur using the measured point spread function. Analysis of
  the corrected altitude distributions yielded surface densities, zenith
  column densities, temperatures and scale heights for sodium all around
  the planet. Sodium absorption on the dawn side equatorial terminator was
  less than on the dusk side, different from previous observations of the
  relative absorption levels. We also determined Earthward velocities
  for sodium atoms, and line widths for the absorptions. Earthward
  velocities resulting from radiation pressure on sodium averaged 0.8
  km/s, smaller than a prediction of 1.5 km/s. Most line widths were
  in the range of 20 mA after correction for instrumental broadening,
  corresponding to temperatures in the range of 1000 K.

Title: Statistical study of magnetic cancellations and on-disk
    type-II spicules
Authors: Chen, Xin; Deng, N.; Lamb, D.; Jing, J.; Tritschler, A.;
   Reardon, K. P.; Wang, H.
Bibcode: 2013SPD....44...04C
Altcode:
  We present a study using coordinated observations of the Interferometric
  BIdimensional Spectrometer (IBIS) at the Dunn Solar Telescope and
  Hinode / Solar Optical Telescope of a quiet sun (QS) region near
  disk center. Our goal is to analyze the relationship between the
  cancellation of opposite magnetic polarities in the photosphere and
  "Rapid Blueshifted Excursions" (RBEs) by comparing quasi-simultaneous
  magnetograms and chromospheric Hα line profiles. On the one hand,
  the RBEs are considered the on-disk counterpart of the type-II
  spicules observed at the limb that are most likely caused by
  magnetic reconnection on small scales. On the other hand, the
  magnetic cancellation is a signature after small-scale reconnection
  in the QS. We developed an automatic tracking algorithm for detecting
  magnetic cancellation events in the photosphere, based on the existing
  SWAMIS code which is good at tracking magnetic flux emergence. Our
  code can find characteristics of each cancellation event and the
  detected cancellation sites appear to outline the supergranular
  network. Furthermore, another automatic tracking code for RBEs has been
  developed for the spectroscopic observations obtained with IBIS. We
  are able to show a statistical distribution of the properties of RBEs,
  such as lifetime, shape, and line-of-sight velocity. Finally, using the
  spatial and temporal tracking of both magnetic cancellation events and
  RBEs, we find that there is no simple one-to-one correspondence. The
  majority of RBEs are related to magnetic cancellation events, however
  a subset of them are not.

Title: Enabling Science with the ATST Data Stream
Authors: Reardon, Kevin P.
Bibcode: 2013SPD....4440003R
Altcode:
  The ATST will generate a large volume of data simultaneously
  from multiple instruments. These data will have value both to the
  investigators who design specific observational programs, and as
  an archival dataset. The challenges in processing ground-based,
  high-resolution observations are many, and the need to produce
  robust processing pipelines for heterogeneous datasets compound the
  difficulties. I will discuss some approaches for efficiently managing
  these data and generating useful data products. I will also describe
  opportunities for the community to contribute to the planning and
  preparations for the ATST data stream.

Title: Velocity and Magnetic Field Distribution in a Forming Penumbra
Authors: Romano, P.; Frasca, D.; Guglielmino, S. L.; Ermolli, I.;
   Tritschler, A.; Reardon, K. P.; Zuccarello, F.
Bibcode: 2013ApJ...771L...3R
Altcode:
  We present results from the analysis of high-resolution
  spectropolarimetric and spectroscopic observations of the solar
  photosphere and chromosphere, obtained shortly before the formation of a
  penumbra in one of the leading polarity sunspots of NOAA active region
  11490. The observations were performed at the Dunn Solar Telescope of
  the National Solar Observatory on 2012 May 28, using the Interferometric
  Bidimensional Spectrometer. The data set is comprised of a 1 hr time
  sequence of measurements in the Fe I 617.3 nm and Fe I 630.25 nm lines
  (full Stokes polarimetry) and in the Ca II 854.2 nm line (Stokes I
  only). We perform an inversion of the Fe I 630.25 nm Stokes profiles to
  derive magnetic field parameters and the line-of-sight (LOS) velocity
  at the photospheric level. We characterize chromospheric LOS velocities
  by the Doppler shift of the centroid of the Ca II 854.2 nm line. We
  find that, before the formation of the penumbra, an annular zone of
  3''-5'' width is visible around the sunspot. In the photosphere, we
  find that this zone is characterized by an uncombed structure of the
  magnetic field although no visible penumbra has formed yet. We also
  find that the chromospheric LOS velocity field shows several elongated
  structures characterized by downflow and upflow motions in the inner
  and outer parts of the annular zone, respectively.

Title: High-Cadence and High-Resolution Halpha Imaging Spectroscopy
    of a Circular Flare's Remote Ribbon with IBIS
Authors: Deng, Na; Tritschler, A.; Jing, J.; Chen, X.; Liu, C.;
   Reardon, K. P.; Denker, C.; Xu, Y.; Wang, H.
Bibcode: 2013SPD....4440404D
Altcode:
  We present an unprecedented high-resolution halpha imaging
  spectroscopic observation of a C4.1 flare taken with IBIS on 2011
  October 22. The flare consists of a main circular ribbon that occurred
  in a parasitic magnetic configuration and a remote ribbon that was
  observed by the IBIS. Such a circular-ribbon flare with a remote
  brightening is predicted in 3D fan-spine reconnection but so far has
  been rarely reported. During the flare impulsive phase, we define
  "core" and "halo" structures in the observed ribbon. Examining the
  halpha emission spectra averaged in the flare core and halo areas,
  we find that only those from the flare cores show typical nonthermal
  electron beam heating characteristics. These characteristics include:
  broad and centrally reversed emission spectra, excess emission in
  the red wing with regard to the blue wing (i.e., red asymmetry),
  and redshifted bisectors of the emission spectra. We also observe
  rather quick timescales for the heating (30 s) and cooling (14--33
  s) in the flare core locations. Therefore, we suggest that the flare
  cores revealed by IBIS track the sites of electron beam precipitation
  with exceptional spatial and temporal resolution. The flare cores
  show two-stage motion (a parallel motion along the ribbon followed
  by an expansion motion perpendicular to the ribbon) during the two
  impulsive phases of the flare. Some cores jump quickly (30 km/s)
  between discrete magnetic elements implying reconnection involving
  different flux tubes. We observe a very high temporal correlation
  (&gt;0.9) between the integrated halpha and HXR emission during the
  flare impulsive phase. A short time delay (4.6 s) is also found in the
  halpha emission spikes relative to HXR bursts. The ionization timescale
  of the cool chromosphere and the extra time taken for the electrons
  to travel to the remote ribbon site may contribute to this delay.

Title: 1565 nm Observations of the transit of Venus, Proxy for a
    Transiting Exoplanet
Authors: Jaeggli, Sarah A.; Reardon, K. P.; Pasachoff, J. M.;
   Schneider, G.; Widemann, T.; Tanga, P.
Bibcode: 2013SPD....44..150J
Altcode:
  The transit of Venus in June 2012 provided a unique chance to view its
  atmosphere as we might see that of a transiting Cytherean exoplanet,
  through scattered and refracted illumination from its parent star. We
  performed spectroscopy and polarimetry during the transit of Venus
  focusing on extracting signatures of CO2 absorption of Venus from the
  solar spectrum. Although the predicted CO2 transmission spectrum of
  Venus was not particularly strong at 1565 nm, this region of the H-band
  often used in magnetic-field studies of the Sun's photosphere provides
  a particularly flat solar continuum with few atmospheric and molecular
  lines. Observations of Venus were taken throughout first contact
  and on the solar disk using the Facility InfraRed Spectropolarimeter
  on the Dunn Solar Telescope at the National Solar Observatory. The
  transit also provided a unique opportunity to investigate instrumental
  effects. In this poster we discuss initial results from the transit,
  including estimates for an exoplanet detection of this kind, preliminary
  comparison with atmospheric models, and the stray light properties
  of the instrument. This work was performed in collaboration with the
  Williams College Venus transit expedition, which was sponsored by Natl
  Geog/Comm for Research and Exploration.

Title: First Results from the EUNIS 2013 Sounding Rocket Campaign
Authors: Daw, Adrian N.; Rabin, D. M.; Brosius, J. W.; Haas, J. P.;
   Plummer, T.; Cauzzi, G.; Reardon, K. P.; Beck, C.
Bibcode: 2013SPD....4410501D
Altcode:
  The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS)
  sounding rocket launched 23 April 2013 at 17:30 UT, as part of a
  campaign including co-ordinated observations with the Dunn Solar
  Telescope/IBIS, Hinode/EIS, SoHO/CDS, RHESSI and SDO. EUNIS obtained
  the highest-resolution observations of the solar spectrum from 52-63 nm
  observed to date, as well as observations with the previously-flown
  waveband from 30-37 nm. The broad spectral coverage of the EUV
  observations includes emission lines of ionization stages from He I to
  Fe XIX, and thus a wide temperature range of 0.025 to 10 MK. Absolute
  radiometric calibration of EUNIS provides underflight calibration of
  CDS, EIS and AIA. Spectra were obtained with a 1.3 s cadence as the
  660-arcsec long slit was rastered across two different regions. The
  observations captured a B-class flare in active region NOAA 11726 as
  well as active regions 11723, 11724, off-limb, quiet sun and a coronal
  hole. We discuss first results from anaysis of this rich and extensive
  data set.

Title: High-cadence and High-resolution Hα Imaging Spectroscopy of
    a Circular Flare's Remote Ribbon with IBIS
Authors: Deng, Na; Tritschler, Alexandra; Jing, Ju; Chen, Xin; Liu,
   Chang; Reardon, Kevin; Denker, Carsten; Xu, Yan; Wang, Haimin
Bibcode: 2013ApJ...769..112D
Altcode: 2013arXiv1304.4171D
  We present an unprecedented high-resolution Hα imaging spectroscopic
  observation of a C4.1 flare taken with the Interferometric Bidimensional
  Spectrometer (IBIS) in conjunction with the adaptive optics system
  at the 76 cm Dunn Solar Telescope on 2011 October 22 in the active
  region NOAA 11324. Such a two-dimensional spectroscopic observation
  covering the entire evolution of a flare ribbon with high spatial (0.''1
  pixel<SUP>-1</SUP> image scale), cadence (4.8 s), and spectral (0.1 Å
  step size) resolution is rarely reported. The flare consists of a main
  circular ribbon that occurred in a parasitic magnetic configuration and
  a remote ribbon that was observed by the IBIS. Such a circular-ribbon
  flare with a remote brightening is predicted in three-dimensional
  fan-spine reconnection but so far has been rarely studied. During
  the flare impulsive phase, we define "core" and "halo" structures in
  the observed ribbon based on IBIS narrowband images in the Hα line
  wing and line center. Examining the Hα emission spectra averaged in
  the flare core and halo areas, we find that only those from the flare
  cores show typical nonthermal electron beam heating characteristics that
  have been revealed by previous theoretical simulations and observations
  of flaring Hα line profiles. These characteristics include broad and
  centrally reversed emission spectra, excess emission in the red wing
  with regard to the blue wing (i.e., red asymmetry), and redshifted
  bisectors of the emission spectra. We also observe rather quick
  timescales for the heating (~30 s) and cooling (~14-33 s) in the flare
  core locations. Therefore, we suggest that the flare cores revealed by
  IBIS track the sites of electron beam precipitation with exceptional
  spatial and temporal resolution. The flare cores show two-stage
  motion (a parallel motion along the ribbon followed by an expansion
  motion perpendicular to the ribbon) during the two impulsive phases
  of the flare. Some cores jump quickly (30 km s<SUP>-1</SUP>) between
  discrete magnetic elements implying reconnection involving different
  flux tubes. We observe a very high temporal correlation (gsim 0.9)
  between the integrated Hα and hard X-rays (HXR) emission during the
  flare impulsive phase. A short time delay (4.6 s) is also found in the
  Hα emission spikes relative to HXR bursts. The ionization timescale
  of the cool chromosphere and the extra time taken for the electrons
  to travel to the remote ribbon site may contribute to this delay.

Title: Transit Observations of Venus's Atmosphere in 2012 from
    Terrestrial and Space Telescopes as Exoplanet Analogs
Authors: Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.;
   Penn, M. J.; Jaeggli, S. A.; Galayda, E.; Reardon, K. P.; Widemann,
   T.; Tanga, P.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson, P. D.;
   Dantowitz, R.
Bibcode: 2013AAS...22221701P
Altcode:
  We extensively observed the 8 June 2012 transit of Venus from several
  sites on Earth; we provide this interim status report about this and
  about two subsequent ToVs observed from space. From Haleakala Obs., we
  observed the entire June transit over almost 7 h with a coronagraph of
  the Venus Twilight Experiment B filter) and with a RED Epic camera to
  compare with simultaneous data from ESA's Venus Express, to study the
  Cytherean mesosphere; from Kitt Peak, we have near-IR spectropolarimetry
  at 1.6 µm from the aureole and during the disk crossing that compare
  well with carbon dioxide spectral models; from Sac Peak/IBIS we have
  high-resolution imaging of the Cytherean aureole for 22 min, starting
  even before 1st contact; from Big Bear, we have high-resolution imaging
  of Venus's atmosphere and the black-drop effect through 2nd contact;
  and we had 8 other coronagraphs around the world. For the Sept 21 ToV
  as seen from Jupiter, we had 14 orbits of HST to use Jupiter's clouds
  as a reflecting surface to search for an 0.01% diminution in light and a
  differential drop that would result from Venus's atmosphere by observing
  in both IR/UV, for which we have 170 HST exposures. As of this writing,
  preliminary data reduction indicates that variations in Jovian clouds
  and the two periods of Jupiter's rotation will be too great to allow
  extraction of the transit signal. For the December 20 ToV as seen from
  Saturn, we had 22 hours of observing time with VIMS on Cassini, for
  which we are looking for a signal of the 10-hr transit in total solar
  irradiance and of Venus's atmosphere in IR as an exoplanet-transit
  analog. Our Maui &amp; Sac Peak expedition was sponsored by National
  Geographic Society's Committee for Research and Exploration; HST data
  reduction by NASA: HST-GO-13067. Some of the funds for the carbon
  dioxide filter for Sac Peak provided by NASA through AAS's Small
  Research Grant Program. We thank Rob Ratkowski of Haleakala Amateur
  Astronomers; Rob Lucas, Aram Friedman, Eric Pilger, Stan Truitt,
  and Steve Bisque/Software Bisque for Haleakala support/operations;
  Vasyl Yurchyshyn and Joseph Gangestad '06 of The Aerospace Corp. at
  Big Bear Solar Obs; LMSAL and Hinode science/operations team.

Title: Statistical Analysis of Small Ellerman Bomb Events
Authors: Nelson, C. J.; Doyle, J. G.; Erdélyi, R.; Huang, Z.;
   Madjarska, M. S.; Mathioudakis, M.; Mumford, S. J.; Reardon, K.
Bibcode: 2013SoPh..283..307N
Altcode: 2013arXiv1301.1351N
  The properties of Ellerman bombs (EBs), small-scale brightenings in
  the Hα line wings, have proved difficult to establish because their
  size is close to the spatial resolution of even the most advanced
  telescopes. Here, we aim to infer the size and lifetime of EBs using
  high-resolution data of an emerging active region collected using
  the Interferometric BIdimensional Spectrometer (IBIS) and Rapid
  Oscillations of the Solar Atmosphere (ROSA) instruments as well as
  the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics
  Observatory (SDO). We develop an algorithm to track EBs through their
  evolution, finding that EBs can often be much smaller (around 0.3″)
  and shorter-lived (less than one minute) than previous estimates. A
  correlation between G-band magnetic bright points and EBs is also
  found. Combining SDO/HMI and G-band data gives a good proxy of the
  polarity for the vertical magnetic field. It is found that EBs often
  occur both over regions of opposite polarity flux and strong unipolar
  fields, possibly hinting at magnetic reconnection as a driver of these
  events.The energetics of EB events is found to follow a power-law
  distribution in the range of a nanoflare (10<SUP>22−25</SUP> ergs).

Title: Coordinated Observations of On-Disk Type II Spicules with
    IBIS and Hinode
Authors: Chen, Xin; Deng, Na; Jing, Ju; Tritschler, Alexandria;
   Reardon, Kevin; Wang, Haimin
Bibcode: 2013enss.confE.147C
Altcode:
  Ubiquitous small-scale spicules/jets in the chromosphere are believed
  to be an important ingredient contributing to coronal heating and
  solar wind by supplying energy and mass upwards. In particular, type II
  spicules discovered at the solar limb (De Pontieu et al. 2007) and their
  highly probable chromospheric on disk counterpart "Rapid Blueshifted
  Excursions" (RBEs; Langangen et al. 2008) have drawn much attention in
  recent years. Their rapid heating, high speed upflow and association
  with magnetic field indicate that the most possible underlying
  driving mechanism is magnetic reconnection on small scales. In order
  to understand the physical properties of these features, we carried
  out a coordinated high resolution and high cadence observation of
  chromospheric RBEs using the Interferometric BIdimensional Spectrometer
  (IBIS) at the Dunn Solar Telescope and photospheric magnetic fields
  using Hinode SOT/SP and SOT/NFI in October 2011. We identify RBEs based
  on the IBIS observations, study their properties (velocity, density,
  temperature etc.) by statistical analysis and show their relationship
  with signatures of small-scale magnetic reconnection in the Hinode
  magnetograms. Furthermore, we search for coronal counterpart of RBEs
  from observations of the Atmospheric Imaging Assembly (AIA) onboard
  the Solar Dynamics Observatory (SDO). References: De Pontieu, B. et
  al. 2007, PASJ, 59, 655-662 Langangen, O. et al. 2008, ApJ, 679, L167

Title: Three 2012 Transits of Venus: From Earth, Jupiter, and Saturn
Authors: Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.;
   Edelman, E.; Reardon, K.; Widemann, T.; Tanga, P.; Dantowitz, R.;
   Silverstone, M. D.; Ehrenreich, D.; Vidal-Madjar, A.; Nicholson,
   P. D.; Willson, R. C.; Kopp, G. A.; Yurchyshyn, V. B.; Sterling,
   A. C.; Scherrer, P. H.; Schou, J.; Golub, L.; McCauley, P.; Reeves, K.
Bibcode: 2013AAS...22131506P
Altcode:
  We observed the 2012 June 6/5 transit seen from Earth (E/ToV),
  simultaneously with Venus Express and several other spacecraft
  not only to study the Cytherean atmosphere but also to provide an
  exoplanet-transit analog. From Haleakala, the whole transit was visible
  in coronal skies; among our instruments was one of the world-wide Venus
  Twilight Experiment's nine coronagraphs. Venus's atmosphere became
  visible before first contact. SacPeak/IBIS provided high-resolution
  images at Hα/carbon-dioxide. Big Bear's NST also provided
  high-resolution observations of the Cytherean atmosphere and black-drop
  evolution. Our liaison with UH's Mees Solar Observatory scientists
  provided magneto-optical imaging at calcium and potassium. Solar
  Dynamics Observatory's AIA and HMI, and the Solar Optical Telescope
  (SOT) and X-ray Telescope (XRT) on Hinode, and total-solar-irradiance
  measurements with ACRIMSAT and SORCE/TIM, were used to observe the
  event as an exoplanet-transit analog. On September 20, we imaged
  Jupiter for 14 Hubble Space Telescope orbits, centered on a 10-hour
  ToV visible from Jupiter (J/ToV), as an exoplanet-transit analog in
  our own solar system, using Jupiter as an integrating sphere. Imaging
  was good, although much work remains to determine if we can detect
  the expected 0.01% solar irradiance decrease at Jupiter and the even
  slighter differential effect between our violet and near-infrared
  filters caused by Venus's atmosphere. We also give a first report on our
  currently planned December 21 Cassini UVIS observations of a transit of
  Venus from Saturn (S/ToV). Our E/ToV expedition was sponsored by the
  Committee for Research and Exploration/National Geographic Society;
  supplemented: NASA/AAS's Small Research Grant Program. We thank Rob
  Ratkowski, Stan Truitt, Rob Lucas, Aram Friedman, and Eric Pilger
  '82 at Haleakala, and Joseph Gangestad '06 at Big Bear for assistance,
  and Lockheed Martin Solar and Astrophysics Lab and Hinode science and
  operations teams for support for coordinated observations with NASA
  satellites. Our J/ToV observations were based on observations made
  with HST, operated by AURA, Inc., under NASA contract NAS 5-26555;
  these observations are associated with program #13067.

Title: The 2012 Transit of Venus: A Closer Look at the Cytherean
    Aureole
Authors: Edelman, Eric; Pasachoff, J. M.; Schneider, G.; Babcock,
   B. A.; Lu, M.; Reardon, K.; Widemann, T.; Tanga, P.; Dantowitz, R.
Bibcode: 2013AAS...22135304E
Altcode:
  The 2012 Transit of Venus provided a new opportunity to study the
  events that occur during the ingress and egress of transit in greater
  detail. The Venus Twilight Experiment is a group that was formed to
  analyze the twilight phenomena of Venus through close and careful
  observation of planet’s 21st century transits. One particular object
  of interest to this group is the Cytherean aureole, or the arc of light
  caused by refraction of the Sun’s light through Venus’s upper
  atmosphere. A goal associated with the study of this aureole is to
  measure how the brightness of the atmosphere changes over time and as
  a function of latitude on Venus with the use of the multitude of images
  taken of the planet near the beginning and end of the transit. In order
  to further along this goal, I was tasked with sorting, processing,
  and aligning the images taken by the coronagraph used on the 2012
  Williams College Transit of Venus Expedition at Haleakala, Hawaii. Our
  observations through a B filter will be compared with observations
  through VRI-filter observations from other coronagraphs in the set. This
  was research was performed with the support of the Keck Northeast
  Astronomy Consortium, sponsored by the NSF and the Keck foundation. The
  expedition to Haleakala and Sac Peak was sponsored by the Committee
  for Research and Exploration/National Geographic Society. Some funds
  for the IBIS carbon-dioxide filter came from NASA/AAS's Small Research
  Grant Program. We thank Rob Ratkowski, Stan Truitt, Rob Lucas, Aram
  Friedman, and Eric Pilger '82 for assistance with Haleakala observing.

Title: Halpha Imaging Spectroscopy of a C-class flare with IBIS
Authors: Deng, N.; Tritschler, A.; Jing, J.; Chen, X.; Reardon, K.;
   Liu, C.; Xu, Y.; Wang, H.
Bibcode: 2012IAUSS...6E.307D
Altcode:
  We present a rare high cadence and high spatial resolution spectroscopic
  observation of a C4.1 Flare taken with the Interferometric Bidimensional
  Spectrometer (IBIS) in conjunction with the adaptive optics system at
  the 76 cm Dunn Solar Telescope on 2011 October 22 in NOAA AR 11324. The
  IBIS with a round FOV of 90" x 90" and 0.1"/pixel detector image scale
  scanned the Halpha line from 6561.1 to 6563.8 Angstrom with 0.1 Angstrom
  stepsize for 28 steps. Each scan takes about 4.8 s. The flare occurred
  in a mixed polarity region with two parasite configurations. The
  flare shows multiple bright ribbons in the chromosphere spreading
  over a region of 120" x 60". IBIS observed a remote ribbon of the
  flare and fully covered its temporal evolution. The Halpha emission
  integrated over this ribbon area exhibits several bursts over four
  minutes during the flare impulsive phase that are temporally correlated
  with the subpeaks of RHESSI hard X-ray (HXR) light curves. During the
  strong bursts of the Halpha emission, we observe a central reversal
  patten in the Halpha line core, which is believed to be a signature of
  nonthermal process caused by direct electron precipitation. The line
  core shows blueward shift that increases with the Halpha emission,
  which might be related to chromospheric evaporation. The Halpha
  emission is stronger in the red wing than in the blue wing during the
  strong bursts. Substructures within the ribbon are also identified. A
  bright core feature that is 30% brighter than the entire ribbon moves
  at an apparent velocity of about 30 km/s within the ribbon during the
  strongest burst of Halpha emission co-temporal with a strong subpeak of
  HXR. The bright core disappeared in the decay phase of the flare. We
  suggest that this running bright core feature tracks the site of
  electron precipitation.

Title: The IBIS Mosaic
Authors: Cauzzi, G.; Reardon, K.
Bibcode: 2012IAUSS...6E.511C
Altcode:
  Existing and planned instrumentation for large solar telescopes is
  tailored to exploit the high spatial resolution affordable with such
  facilities. However, the typical instrumental tradeoffs restrict the
  field-of-view accessible at once to rather small areas (well below
  100" diameter): this represents a serious impediment for study of
  the active Sun, where large scale magnetic connectivity is of much
  relevance. Mosaicking offers a possibility to obtain high-resolution
  observations over a large FOV, but the technique has been only
  sparsely utilized at ground-based, optical telescopes. In this poster
  we report on an investigation of the feasibility and utility of mosaic
  observations with a state-of-the-art facility, the Interferometric
  BIdimensional Spectrometer instrument (IBIS) installed at the Dunn
  Solar Telescope (NSO). We obtained a 3 x 3 mosaic, covering the full
  AR NOAA 11092 for a total field in excess of 4' x 4', sampling both
  photospheric and chromospheric lines. We report on the methods utilized
  for observation and assembly of the data cubes, and some preliminary
  comparisons with simultaneous observations from other instruments.

Title: The Source of 3 Minute Magnetoacoustic Oscillations in
    Coronal Fans
Authors: Jess, D. B.; De Moortel, I.; Mathioudakis, M.; Christian,
   D. J.; Reardon, K. P.; Keys, P. H.; Keenan, F. P.
Bibcode: 2012ApJ...757..160J
Altcode: 2012arXiv1208.3194J
  We use images of high spatial, spectral, and temporal resolution,
  obtained using both ground- and space-based instrumentation, to
  investigate the coupling between wave phenomena observed at numerous
  heights in the solar atmosphere. Analysis of 4170 Å continuum images
  reveals small-scale umbral intensity enhancements, with diameters
  ~0farcs6, lasting in excess of 30 minutes. Intensity oscillations
  of ≈3 minutes are observed to encompass these photospheric
  structures, with power at least three orders of magnitude higher
  than the surrounding umbra. Simultaneous chromospheric velocity and
  intensity time series reveal an 87° ± 8° out-of-phase behavior,
  implying the presence of standing modes created as a result of
  partial wave reflection at the transition region boundary. We find a
  maximum waveguide inclination angle of ≈40° between photospheric
  and chromospheric heights, combined with a radial expansion factor
  of &lt;76%. An average blueshifted Doppler velocity of ≈1.5 km
  s<SUP>-1</SUP>, in addition to a time lag between photospheric and
  chromospheric oscillatory phenomena, confirms the presence of upwardly
  propagating slow-mode waves in the lower solar atmosphere. Propagating
  oscillations in EUV intensity are detected in simultaneous coronal
  fan structures, with a periodicity of 172 ± 17 s and a propagation
  velocity of 45 ± 7 km s<SUP>-1</SUP>. Numerical simulations reveal that
  the damping of the magnetoacoustic wave trains is dominated by thermal
  conduction. The coronal fans are seen to anchor into the photosphere
  in locations where large-amplitude umbral dot (UD) oscillations
  manifest. Derived kinetic temperature and emission measure time series
  display prominent out-of-phase characteristics, and when combined with
  the previously established sub-sonic wave speeds, we conclude that
  the observed EUV waves are the coronal counterparts of the upwardly
  propagating magnetoacoustic slow modes detected in the lower solar
  atmosphere. Thus, for the first time, we reveal how the propagation
  of 3 minute magnetoacoustic waves in solar coronal structures is a
  direct result of amplitude enhancements occurring in photospheric UDs.

Title: Observation of Neutral Sodium above Mercury During the Transit
    of November 8, 2006
Authors: Potter, Andrew E.; Killen, R. M.; Reardon, K. P.; Bida, T. A.
Bibcode: 2012DPS....4441001P
Altcode:
  We mapped the absorption of sunlight by sodium vapor in the exosphere of
  Mercury during the transit of Mercury on November 8, 2006, using the
  IBIS Interferometric BIdimensional Spectrometer at the Dunn solar
  telescope operated by the National Solar Observatory at Sunspot,
  New Mexico. The measurements were reduced to line-of-sight equivalent
  widths for absorption at the sodium D2 line, and mapped in thirty degree
  increments around the shadow of Mercury. We observed north and south
  polar enhancements of sodium absorption. The sodium absorptions fell
  off exponentially with altitude up to about 600 km, and we analyzed
  the altitude distributions to determine surface densities, zenith
  column densities, temperatures and scale heights for sodium. The
  average surface concentration of sodium atoms was about 900 atoms/cm3,
  and the average zenith column density was 0.8 x 1010 atoms/cm2. The
  average temperature was about 1100 K, with excursions to 1750 and
  700 K. The 2003 transit was observed by Schleicher et al. [2004],
  using instrumentation similar to that employed for this research. They
  reported the appearance of a streamer-like feature extending a thousand
  kilometers above the north polar region, and a similar but smaller
  feature above the south polar region. Our observations did not detect
  similar features. They observed considerably more sodium absorption
  over the dawn terminator than over the dusk terminator. In contrast,
  we observed slightly larger sodium absorption on the dawn relative
  to the dusk side. The difference might be due to the slow advance
  of the dawn terminator at during the 2006 transit (0.13 degrees/day)
  relative to the 2003 transit (3.27 degrees/day). Reference Schleicher,
  H.; Wiedemann, G.; Wöhl, H.; Berkefeld, T.; Soltau, D. (2004),
  Detection of neutral sodium above Mercury during the transit on 2003
  May 7. Astronomy and Astrophysics, 425, 1119-1124

Title: The 2012 Transit of Venus for Cytherean Atmospheric Studies
    and as an Exoplanet Analog
Authors: Pasachoff, Jay M.; Schneider, G.; Babcock, B. A.; Lu, M.;
   Reardon, K. P.; Widemann, T.; Tanga, P.; Dantowitz, R.; Willson,
   R.; Kopp, G.; Yurchyshyn, V.; Sterling, A.; Scherrer, P.; Schou, J.;
   Golub, L.; Reeves, K.
Bibcode: 2012DPS....4450806P
Altcode:
  We worked to assemble as complete a dataset as possible for the
  Cytherean atmosphere in collaboration with Venus Express in situ
  and to provide an analog of spectral and total irradiance exoplanet
  measurements. From Haleakala, the whole transit was visible in
  coronal skies; our B images showed the evolution of the visibility
  of Venus's atmosphere and of the black-drop effect, as part of the
  Venus Twilight Experiment's 9 coronagraphs distributed worldwide
  with BVRI. We imaged the Cytherean atmosphere over two minutes before
  first contact, with subarcsecond resolution, with the coronagraph and
  a separate refractor. The IBIS imaging spectrometer at Sacramento
  Peak Observatory at H-alpha and carbon-dioxide also provided us
  high-resolution imaging. The NST of Big Bear Solar Observatory
  also provided high-resolution vacuum observations of the Cytherean
  atmosphere and black drop evolution. Our liaison with UH's Mees Solar
  Observatory scientists provided magneto-optical imaging at calcium
  and potassium. Spaceborne observations included the Solar Dynamics
  Observatory's AIA and HMI, and the Solar Optical Telescope (SOT)
  and X-ray Telescope (XRT) on Hinode, and total-solar-irradiance
  measurements with ACRIMSAT and SORCE/TIM, to characterize the
  event as an exoplanet-transit analog. Our expedition was sponsored
  by the Committee for Research and Exploration/National Geographic
  Society. Some of the funds for the carbon-dioxide filter for IBIS were
  provided by NASA through AAS's Small Research Grant Program. We thank
  Rob Lucas, Aram Friedman, and Eric Pilger '82 for assistance with
  Haleakala observing, Rob Ratkowski of Haleakala Amateur Astronomers
  for assistance with equipment and with the site, Stan Truitt for the
  loan of his Paramount ME, and Steve Bisque/Software Bisque for TheSky
  X controller. We thank Joseph Gangestad '06 of Aerospace Corp., a
  veteran of our 2004 expedition, for assistance at Big Bear. We thank
  the Lockheed Martin Solar and Astrophysics Laboratory and Hinode
  science and operations teams for planning and support.

Title: Assymetry in the Polar Mesosphere Revealed by the 2012 Venus
    Transit Aureole
Authors: Widemann, Thomas; Tanga, P.; Reardon, K. P.; Limaye, S.;
   Wilson, C.; Vandaele, A.; Wilquet, V.; Mahieux, A.; Robert, S.;
   Pasachoff, J. M.; Schneider, G.
Bibcode: 2012DPS....4450808W
Altcode:
  Close to ingress and egress phases, the fraction of Venus disk projected
  outside the solar photosphere appears outlined by an irregular thin
  arc of light called the "aureole." We have shown that the deviation
  due to refraction and the aureole intensity are related to the local
  density scale height and the altitude of the refraction layer (Tanga
  et al. 2012). Since the aureole brightness is the quantity that can be
  measured during the transit, an appropriate model allows us to determine
  both parameters. We now compare this model developed for the 2004
  data to the first results of 2012 campaign. Ingress pictures of NASA's
  SDO/HMI observations, OP-OCA/VTE coronagraph observations at Haleakala
  and Lowell stations, and Dunn/IBIS observations at Sacramento Peak, NM,
  show latitudinal structure of the aureole during the ingress phase of
  the Venus transit. For the HMI data, the temporal cadence is 3.75 sec
  and the pixel scale is 0.5 arcsec/pixel. The polar region, significantly
  brighter in initial phases due to the larger scale height of the polar
  mesosphere, appears consistently offset toward morning terminator by
  about 15 deg. latitude, peaking at 75N at 6:00 local time. This result
  reflects local latitudinal structure in the polar mesosphere, either in
  temperature or aerosol altitude distribution. Relation with ESA / Venus
  Express / SOIR simultaneous measurements and dynamical interpretation
  will be discussed at the meeting. Tanga et al. 2012, Icarus 218, 207-219

Title: Conceptual design of the data handling system for the European
    Solar Telescope
Authors: Ermolli, Ilaria; Cauzzi, Gianna; Collados, Manuel; Paletou,
   Frederic; Reardon, Kevin; Aboudarham, Jean; Cirami, Roberto; Cosentino,
   Rosario; Del Moro, Dario; Di Marcantonio, Paolo; Giorgi, Fabrizio;
   Lafon, Martine; Pietropaolo, Ermanno; Romano, Paolo
Bibcode: 2012SPIE.8448E..1SE
Altcode:
  We present an overview of the conceptual design of the data handling
  unit of the ECS, the Control System for the European Solar Telescope
  (EST). We will focus on describing the critical requirements for this
  unit resulting from the overall design of the telescope, together with
  its architecture and the results of the feasibility analysis carried
  out to date.

Title: Evidence for Sheet-like Elementary Structures in the Sun's
    Atmosphere?
Authors: Judge, Philip G.; Reardon, Kevin; Cauzzi, Gianna
Bibcode: 2012ApJ...755L..11J
Altcode:
  Narrow, thread-like structures in the Sun's chromosphere are currently
  understood to be plasma guided along narrow tubes of magnetic flux. We
  report on 1 s cadence imaging spectroscopic measurements of the Hα
  line with the IBIS Fabry-Pérot instrument at the Dunn Solar Telescope,
  obtained +0.11 nm from line center. Rapid changes grossly exceeding
  the Alfvén speed are commonly seen along the full extent of many
  chromospheric threads. We argue that only an optical superposition
  effect can reasonably explain the data, analogous to striations of
  curtains blowing in the wind. Other explanations appear to require
  significant contrivances to avoid contradicting various aspects of
  the data. We infer that the absorbing plasma exists in two-dimensional
  sheet-like structures within the three-dimensional magnetofluid, related
  perhaps to magnetic tangential discontinuities. This interpretation
  demands a re-evaluation of basic assumptions about low-β solar plasmas,
  as advocated by Parker, with broader implications in astrophysics
  and plasma physics. Diverse, high-cadence observations are needed to
  further define the relationship between magnetic field and thermal
  fine structure.

Title: Helium D3 at High Resolution
Authors: Reardon, Kevin P.
Bibcode: 2012AAS...22020301R
Altcode:
  We present high-resolution observations of the Helium D3 (587.6 nm)
  line obtained with the IBIS imaging spectrometer at the Dunn Solar
  Telescope. The D3 line is observed both on-disk and off-limb in a
  variety of solar features. These observations reveal that structures
  in this line are both finely structured (at our resolution limit of
  0.2 arcsec) and highly dynamic. We use the observed spectral profiles
  to derive information on the local atmospheric properties. We compare
  the appearance of the D3 line with features seen in simultaneous Hα
  and Ca II 854.2 nm chromospheric observations, as well as SDO/AIA
  images of the transition region and corona. The fibrils observed in
  the He D3 line provide useful information on connectivity from the
  chromospheric layers up into the corona.

Title: The IBIS Mosaic - A Broad View Of The Solar Atmosphere
Authors: Reardon, Kevin P.; Cauzzi, G.
Bibcode: 2012AAS...22020111R
Altcode:
  We present a unique set of observations spanning the photosphere and
  chromosphere with a large field-of-view (4 x 4 arcminutes) ,high-spatial
  resolution (0.1"/pixel), and full spectral profiles (R ∼ 200,000). The
  data were obtained with the IBIS imaging spectrometer at the NSO/Dunn
  Solar Telescope on August 3, 2010 using a mosaic technique to tile an
  active region and surrounding areas. Spectral profiles were obtained
  in the chromospheric Hα, CaII 854.2 nm, and He I D3 lines, as well as
  photospheric FeI 543.4 nm. Combining this dataset with simultaneous
  SDO/AIA and SDO/HMI images and magnetic field measurements allow a
  highly comprehensive view of an entire volume of the solar atmosphere
  from photosphere to corona. The wealth of information is used to
  explore the nature of the chromospheric fibrillar structures and their
  relationship with the overlying corona.

Title: Evidence for Two Separate But Interlaced Components of the
    Chromospheric Magnetic Field
Authors: Muglach, Karin; Reardon, K.; Wang, Y.; Warren, H.
Bibcode: 2012AAS...22012403M
Altcode:
  Chromospheric fibrils are generally thought to trace out horizontal
  magnetic fields that fan out from flux concentrations in the
  photosphere. A high-resolution (0.2") image taken in the core of the
  Ca II 854.2 nm line shows the dark fibrils within an active region
  remnant as fine, looplike features that are aligned parallel to each
  other and have lengths on the order of a supergranular diameter ( 30
  Mm). Comparison with a line-of-sight magnetogram confirms that the
  fibrils are centered above intranetwork areas, with one end rooted
  just inside <P />the neighboring plage or strong unipolar network
  but the other endpoint less clearly defined. Focusing on a particular
  arcade-like structure lying entirely on one side of a filament channel
  (large-scale polarity inversion), we find that the total amount of
  positive-polarity flux underlying this ``fibril arcade'' is 50 times
  greater than the total amount of negative-polarity flux. Thus, if the
  fibrils represent closed loops, they must consist of very weak fields
  (in terms of flux density), which are interpenetrated by a more vertical
  field that contains most of the flux. This surprising result suggests
  that the fibrils in unipolar regions connect the network to the nearby
  intranetwork flux, while the bulk of the network flux is diverted
  upward into the corona and connects to remote regions of the opposite
  polarity. We conclude that the chromospheric field near the edge of
  the network has an interlaced structure resembling that in sunspot
  penumbrae, with the fibrils representing the low-lying horizontal flux
  that remains trapped within the highly nonpotential chromospheric layer.

Title: ATST Data Distribution and Analysis
Authors: Reardon, Kevin P.
Bibcode: 2012AAS...22032305R
Altcode:
  The Advanced Technology Solar Telescope will be a key research
  facility for solar physics in the coming decade. ATST will produce
  large volumes of data covering the full solar atmosphere. The objective
  is to turn this stream of images and spectra into well-calibrated data
  products useful for the broad solar physics community. Some of the data
  processing challenges include managing the tens of terabytes of data
  that can be produced on a daily basis, the correction of distortions
  produced by the terrestrial atmosphere, and the extraction of physical
  parameters from the high-resolution observations. We will describe
  the approaches we will take in addressing these issues, as well as
  the ways in which the ATST data can be integrated with other data
  resources and made available through the VSO.

Title: X-Ray Searches for Solar Axions
Authors: Hudson, H. S.; Acton, L. W.; DeLuca, E. E.; Hannah, I. G.;
   Reardon, K.; Van Bibber, K.
Bibcode: 2012ASPC..455...25H
Altcode: 2012arXiv1201.4607H
  Axions generated thermally in the solar core can convert nearly directly
  to X-rays as they pass through the solar atmosphere via interaction with
  the magnetic field. The result of this conversion process would be a
  diffuse centrally-concentrated source of few-keV X-rays at disk center;
  it would have a known dimension, of order 10% of the solar diameter, and
  a spectral distribution resembling the blackbody spectrum of the solar
  core. Its spatial structure in detail would depend on the distribution
  of mass and field in the solar atmosphere. The brightness of the source
  depends upon these factors as well as the unknown coupling constant
  and the unknown mass of the axion; this particle is hypothetical and
  no firm evidence for its existence has been found yet. We describe the
  solar magnetic environment as an axion/photon converter and discuss
  the upper limits obtained by existing and dedicated observations from
  three solar X-ray observatories: Yohkoh, RHESSI, and Hinode.

Title: High Cadence and High Resolution Halpha Imaging Spectroscopy
    of a C4.1 Flare with IBIS
Authors: Deng, Na; Tritschler, A.; Jing, J.; Chen, X.; Reardon, K.;
   Liu, C.; Xu, Y.; Wang, H.
Bibcode: 2012AAS...22020449D
Altcode:
  We present a rare high cadence and high spatial resolution spectroscopic
  observation of a C4.1 Flare taken with the Interferometric Bidimensional
  Spectrometer (IBIS) in conjunction with the adaptive optics system at
  the 76cm Dunn Solar Telescope on 2011 October 22 in NOAA AR11324. The
  IBIS with a round FOV of 90"X90" and 0.1"/pix detector image scale
  scanned the Halpha line from 6561.1 to 6563.8 A with 0.1 A stepsize for
  28 steps. Each scan takes about 4.8s. The flare occurred in a mixed
  polarity region with two parasite configurations. The flare shows
  multiple bright ribbons in the chromosphere spreading over a region
  of 120"X60". IBIS observed a remote ribbon of the flare and fully
  covered its temporal evolution. The Halpha emission integrated over
  this ribbon area exhibits several bursts over four minutes during the
  flare impulsive phase that are temporally correlated with the subpeaks
  of RHESSI hard X-ray (HXR) light curves. During the strongest burst of
  the Halpha emission, we observe a central reversal patten in the Halpha
  line core, which is believed to be a signature of nonthermal process
  caused by direct electron precipitation. The line core shows blueward
  shift that increases with the Halpha emission, which might be related
  to chromospheric evaporation. The line width also increases with the
  emission. The Halpha emission is stronger in the red wing than in the
  blue wing during the strong bursts. Substructures within the ribbon are
  also identified. A bright core feature that is 30% brighter than the
  entire ribbon moves at an apparent velocity of about 30 km/s within
  the ribbon during the strongest burst of Halpha emission co-temporal
  with a strong subpeak of HXR. The bright core disappeared in the decay
  phase of the flare. We suggest that this running bright core feature
  tracks the site of electron precipitation.

Title: Coordinated Observations Of On-disk Type II Spicules With
    IBIS And Hinode
Authors: Chen, Xin; Na, D.; Jing, J.; Tritschler, A.; Reardon, K.;
   Wang, H.
Bibcode: 2012AAS...22020310C
Altcode:
  Ubiquitous small-scale spicules/jets in the chromosphere are believed
  to be an important ingredient contributing to coronal heating and
  solar wind by supplying energy and mass upwards. In particular, type II
  spicules discovered at the solar limb (De Pontieu et al. 2007) and their
  highly probable chromospheric on disk counterpart "Rapid Blueshifted
  Excursions" (RBEs; Langangen et al. 2008) have drawn much attention in
  recent years. Their rapid heating, high speed upflow and association
  with magnetic field indicate that the most possible underlying
  driving mechanism is magnetic reconnection on small scales. In order
  to understand the physical properties of these features, we carried
  out a coordinated high resolution and high cadence observation of
  chromospheric RBEs using the Interferometric BIdimensional Spectrometer
  (IBIS) at the Dunn Solar Telescope and photospheric magnetic fields
  using Hinode SOT/SP and SOT/NFI in October 2011. Different targets near
  disk center were observed, such as quite sun and active regions. For
  each target region, both Halpha and Ca II 854.2 nm lines were scanned
  by IBIS with high-spatial ( 0.1 arcsec/pixel, with adaptive optics),
  high-temporal ( 6s) and moderate-spectral ( 0.1 angstrom) resolution. At
  the same time Hinode/SP and NFI pointing at the same area providing the
  geometry and time evolution of photospheric magnetic fields, such as
  flux emergence, convergence and cancellation on small spatial scales. We
  identify RBEs based on the IBIS observations, study their properties
  (velocity, density, temperature and statistical distribution) and search
  for signatures of small-scale magnetic reconnection in the Hinode
  magnetograms. The poster will show the details of the temporal and
  spatial relation between chromospheric RBEs and photospheric magnetic
  field activities. <P />References: <P />De Pontieu, B. et al. 2007,
  PASJ, 59, 655-662 <P />Langangen, O. et al. 2008, ApJ, 679, L167

Title: New insight on the coupling of the solar atmosphere from
    imaging spectroscopy
Authors: Reardon, K.; Cauzzi, G.
Bibcode: 2012decs.confE..20R
Altcode:
  We present spectrally resolved, high-resolution observations of
  chromospheric diagnostics obtained with IBIS covering a full active
  region. In particular, the data includes the first high-resolution
  observations of the He I D3 line (587.6 nm), a subordinate of the more
  famous HeI 1083.0 nm line, showing loops and other structures on the
  solar disk at the 150 km diffraction limit. The large FOV of our data
  allows a meaningfully comparison with the SDO full disk observations
  to investigate the coupling between different portions of the solar
  atmosphere and the topology of the chromospheric magnetic field. The
  relationship between the chromospheric signatures and the SDO 304 Å and
  171 Å emission provides intriguing hints to the existence of low-lying
  loops at TR temperatures effectively disconnected from the corona.

Title: Data handling and control  of the European Solar Telescope
Authors: Ermolli, I.; Bettonvil, F.; Cauzzi, G.; Cavaller, L.;
   Collados, M.; Di Marcantonio, P.; Grivel, C.; Paletou, F.; Romano,
   P.; Aboudarham, J.; Cirami, R.; Cosentino, R.; Giorgi, F.; Lafon,
   M.; Laforgue, D.; Reardon, K.; Sliepen, G.
Bibcode: 2012MSAIS..19..380E
Altcode:
  We describe some aspects of the facility operation that have been
  considered for the design of the data handling and control of the
  European Solar Telescope. The main sub-systems of the EST relevant for
  the control are summarized, together with some information on current
  solar data models.

Title: Evidence for Two Separate but Interlaced Components of the
    Chromospheric Magnetic Field
Authors: Reardon, K. P.; Wang, Y. -M.; Muglach, K.; Warren, H. P.
Bibcode: 2011ApJ...742..119R
Altcode:
  Chromospheric fibrils are generally thought to trace out low-lying,
  mainly horizontal magnetic fields that fan out from flux concentrations
  in the photosphere. A high-resolution (~0farcs1 pixel<SUP>-1</SUP>)
  image, taken in the core of the Ca II 854.2 nm line and covering
  an unusually large area, shows the dark fibrils within an active
  region remnant as fine, looplike features that are aligned parallel
  to each other and have lengths comparable to a supergranular
  diameter. Comparison with simultaneous line-of-sight magnetograms
  confirms that the fibrils are centered above intranetwork areas
  (supergranular cell interiors), with one end rooted just inside the
  neighboring plage or strong unipolar network but the other endpoint
  less clearly defined. Focusing on a particular arcade-like structure
  lying entirely on one side of a filament channel (large-scale polarity
  inversion), we find that the total amount of positive-polarity flux
  underlying this "fibril arcade" is ~50 times greater than the total
  amount of negative-polarity flux. Thus, if the fibrils represent closed
  loops, they must consist of very weak fields (in terms of total magnetic
  flux), which are interpenetrated by a more vertical field that contains
  most of the flux. This surprising result suggests that the fibrils in
  unipolar regions connect the network to the nearby intranetwork flux,
  while the bulk of the network flux links to remote regions of the
  opposite polarity, forming a second, higher canopy above the fibril
  canopy. The chromospheric field near the edge of the network thus has
  an interlaced structure resembling that in sunspot penumbrae.

Title: Nonpotentiality of Chromospheric Fibrils in NOAA Active
    Regions 11092 and 9661
Authors: Jing, Ju; Yuan, Yuan; Reardon, Kevin; Wiegelmann, Thomas;
   Xu, Yan; Wang, Haimin
Bibcode: 2011ApJ...739...67J
Altcode:
  In this paper, we present a method to automatically segment
  chromospheric fibrils from Hα observations and further identify their
  orientation. We assume that chromospheric fibrils are aligned with the
  magnetic field. By comparing the orientation of the fibrils with the
  azimuth of the embedding chromospheric magnetic field extrapolated from
  a potential field model, the shear angle, a measure of nonpotentiality,
  along the fibrils is readily deduced. Following this approach, we make
  a quantitative assessment of the nonpotentiality of fibrils in two NOAA
  active regions (ARs): (1) the relatively simple AR 11092, observed with
  very high resolution by Interferometric Bidimensional Spectrometer,
  and (2) a β-γ-δ AR 9661, observed with median resolution by Big
  Bear Solar Observatory before and after an X1.6 flare.

Title: Nonpotentiality of Chromospheric Fibrils in the Active Regions
    NOAA 9661 and NOAA 11092
Authors: Jing, Ju; Yuan, Y.; Reardon, K.; Wiegelmann, T.; Deng, N.;
   Xu, Y.; Wang, H.
Bibcode: 2011SPD....42.1738J
Altcode: 2011BAAS..43S.1738J
  We have developed a method to automatically segment chromospheric
  fibrils from Halpha observations and further identify their
  orientation. We assume that chromospheric fibrils are magnetic
  field-aligned. By comparing the orientation of the fibrils with the
  azimuth of the embedding chromospheric magnetic field extrapolated
  from the photosphere or chromosphere with the help of a potential
  field model, the shear angle, a measure of nonpotentiality, along
  the fibrils is readily deduced. Following this approach, we make
  a quantitative assessment of the nonpotentiality of fibrils in the
  active region NOAA 9661 and NOAA 11092. The spatial distribution and
  the histogram of the shear angle along fibrils are presented.

Title: Turbulence in the solar chromosphere and its role in small
    scale energy deposition
Authors: Lepreti, F.; Carbone, V.; Vecchio, A.; Reardon, K.;
   Capparelli, V.; Rossi, C.
Bibcode: 2010AGUFMSH11B1650L
Altcode:
  The line-of-sight velocity fluctuations in the solar chromosphere are
  studied. The velocities are obtained from imaging spectral scans in the
  chromospheric line Ca II 854.2 nm, acquired at high spatial resolution
  with the Interferometric BIdimensional Spectrometer (IBIS) in the
  quiet Sun. Nearly power law tails above the acoustic cutoff frequency
  in the chromospheric velocity power spectra are found. The probability
  density function of chromospheric velocity increments are non-Gaussian
  and asymmetric. Intermittency is much larger in the network than in
  fibril and internetwork regions. These results suggest that the small
  scale velocity fluctuations in the solar chromosphere are the result
  of a turbulent cascade generated from acoustic oscillations near the
  cutoff frequency. An estimate of the energy flux towards small scales
  is given on the basis of third order structure functions of velocity
  increments and the possible role of the turbulent cascade for small
  scale energy deposition and chromospheric heating is discussed.

Title: Data handling and control for the European Solar Telescope
Authors: Ermolli, Ilaria; Bettonvil, Felix; Cauzzi, Gianna; Cavaller,
   Lluis; Collados, Manuel; Di Marcantonio, Paolo; Paletou, Frederic;
   Romano, Paolo; Aboudarham, Jean; Cirami, Roberto; Cosentino, Rosario;
   Giorgi, Fabrizio; Lafon, Martine; Laforgue, Didier; Reardon, Kevin;
   Sliepen, Guus
Bibcode: 2010SPIE.7740E..0GE
Altcode: 2010SPIE.7740E..13E
  We introduce the concepts for the control and data handling systems of
  the European Solar Telescope (EST), the main functional and technical
  requirements for the definition of these systems, and the outcomes
  from the trade-off analysis to date. Concerning the telescope control,
  EST will have performance requirements similar to those of current
  medium-sized night-time telescopes. On the other hand, the science
  goals of EST require the simultaneous operation of three instruments
  and of a large number of detectors. This leads to a projected data
  flux that will be technologically challenging and exceeds that of
  most other astronomical projects. We give an overview of the reference
  design of the control and data handling systems for the EST to date,
  focusing on the more critical and innovative aspects resulting from
  the overall design of the telescope.

Title: Imaging performance of multi-etalon bidimensional spectrometers
Authors: Righini, A.; Cavallini, F.; Reardon, K. P.
Bibcode: 2010A&A...515A..85R
Altcode:
  <BR /> Aims: In recent years, several new solar and nighttime
  panoramic spectrometers based on Fabry-Perot interferometers have
  been successfully developed. In this paper we evaluate the imaging
  performance of the two types of mountings that have been adopted,
  telecentric and classic, in particular trying to understand which one
  might be more suitable for future large-aperture solar telescopes. <BR
  /> Methods: Numerical code was written to simulate the behavior of such
  spectrometers, on the basis of the theory of Fourier optics. This code
  was used to simulate different instrument configurations and was tested
  on previous results obtained either analytically or numerically by
  other authors. <BR /> Results: Calculations of the system MTF and Strehl
  ratios show that both mountings may perform very close to theoretical
  expectations. However, gap irregularities in the interferometers
  may alter the optical quality of the monochromatic images. In the
  case of the classical mounting in a collimated beam, it is possible
  to partially compensate for the resulting errors in the wavefront
  emerging from the interferometers with a suitable phase plate. We also
  performed an observational test of the optical quality delivered by
  the IBIS interferometer installed at the Dunn Solar Telescope of the
  National Solar Observatory, with the results substantially confirming
  the calculations. <BR /> Conclusions: It follows from our results
  that both mountings may be efficiently used for solar bidimensional
  spectroscopy. The final choice depends on the tradeoff between factors
  such as image quality, field of view, and acceptable wavelength shift.

Title: Delving into the Chromosphere: New Observational Tools
Authors: Reardon, Kevin P.; Cauzzi, G.; Tritschler, A.; Uitenbroek, H.
Bibcode: 2010AAS...21630503R
Altcode:
  The chromosphere lies at the boundary between the near-equilibrium
  photosphere and the hot, expanding corona. This region combines both
  large interconnecting magnetic structures, and fine-scaled dynamics into
  an intriguingly complex whole. Studying this behavior is a significant
  observational challenge, requiring sizable fields of view (60-90")
  sampled at high spatial (&lt; 0.3") and temporal resolution (&lt; 30
  seconds), with full spectral information in multiple lines. We will
  describe how instruments based on Fabry-Perot interferometers have
  recently begun to routinely deliver such observations. We will review
  some of the most exciting results obtained and the deeper insights
  they have provided into the characteristics of the solar chromosphere.

Title: SDO Data Access Via The Virtual Solar Observatory
Authors: Hill, Frank; Gurman, J.; Martens, P.; Bogart, R.; Davey, A.;
   Hourcle, J.; Suarez Sola, F.; Hughitt, K.; Spencer, J.; Reardon, K.;
   Amezcua, A.
Bibcode: 2010AAS...21640218H
Altcode: 2010BAAS...41Q.876H
  The launch of SDO brings not only the prospect of new solar physics
  discoveries, but also a flood of data. The sustained data rate of
  150 Mbs (about 1.6 TB per day) is the highest yet produced by a
  solar physics observatory, and the handling of the data requires new
  methods. One approach is to distribute the data storage and request
  system over a number of distinct sites to reduce the bandwidth
  requirements at a single location. The VSO, in conjunction with the
  Joint Science and Operations Center (JSOC) at Stanford and a network of
  partial archive sites currently at CfA, NSO, ROB, and MPIS, is now able
  to provide metadata search and data retrieval services for the SDO AIA
  and HMI instruments. EVE data will also be included in the future. This
  talk will describe how SDO data can be accessed via the VSO.

Title: The Quiet Solar Atmosphere Observed and Simulated in Na
    I D<SUB>1</SUB>
Authors: Leenaarts, J.; Rutten, R. J.; Reardon, K.; Carlsson, M.;
   Hansteen, V.
Bibcode: 2010ApJ...709.1362L
Altcode: 2009arXiv0912.2206L
  The Na I D<SUB>1</SUB> line in the solar spectrum is sometimes
  attributed to the solar chromosphere. We study its formation in
  quiet-Sun network and internetwork. We first present high-resolution
  profile-resolved images taken in this line with the imaging
  spectrometer Interferometric Bidimensional Spectrometer at the Dunn
  Solar Telescope and compare these to simultaneous chromospheric images
  taken in Ca II 8542 Å and Hα. We then model Na I D<SUB>1</SUB>
  formation by performing three-dimensional (3D) non-local
  thermodynamic equilibrium profile synthesis for a snapshot from a
  3D radiation-magnetohydrodynamics simulation. We find that most Na I
  D<SUB>1</SUB> brightness is not chromospheric but samples the magnetic
  concentrations that make up the quiet-Sun network in the photosphere,
  well below the height where they merge into chromospheric canopies,
  with aureoles from 3D resonance scattering. The line core is sensitive
  to magneto-acoustic shocks in and near magnetic concentrations, where
  shocks occur deeper than elsewhere, and may provide evidence of heating
  deep within magnetic concentrations.

Title: Fabry-Pérot Versus Slit Spectropolarimetry of Pores and
Active Network: Analysis of IBIS and Hinode Data
Authors: Judge, Philip G.; Tritschler, Alexandra; Uitenbroek, Han;
   Reardon, Kevin; Cauzzi, Gianna; de Wijn, Alfred
Bibcode: 2010ApJ...710.1486J
Altcode: 2010arXiv1001.0561J
  We discuss spectropolarimetric measurements of photospheric (Fe I
  630.25 nm) and chromospheric (Ca II 854.21 nm) spectral lines in and
  around small magnetic flux concentrations, including a pore. Our
  long-term goal is to diagnose properties of the magnetic field
  near the base of the corona. We compare ground-based two-dimensional
  spectropolarimetric measurements with (almost) simultaneous space-based
  slit spectropolarimetry. We address the question of noise and crosstalk
  in the measurements and attempt to determine the suitability of Ca II
  measurements with imaging spectropolarimeters for the determination
  of chromospheric magnetic fields. The ground-based observations
  were obtained 2008 May 20, with the Interferometric Bidimensional
  Spectrometer (IBIS) in spectropolarimetric mode operated at the Dunn
  Solar Telescope at Sunspot, NM. The space observations were obtained
  with the Spectro-Polarimeter of the Solar Optical Telescope aboard the
  Japanese Hinode satellite. The agreement between the near-simultaneous
  co-spatial IBIS and Hinode Stokes-V profiles at 630.25 nm is
  excellent, with V/I amplitudes compatible to within 1%. The IBIS QU
  measurements are affected by residual crosstalk from V, arising from
  calibration inaccuracies, not from any inherent limitation of imaging
  spectroscopy. We use a Principal Component Analysis to quantify the
  detected crosstalk. QU profiles with V crosstalk subtracted are in
  good agreement with the Hinode measurements, but are noisier owing to
  fewer collected photons. Chromospheric magnetic fields are notoriously
  difficult to constrain by polarization of Ca II lines alone. However,
  we demonstrate that high cadence, high angular resolution monochromatic
  images of fibrils in Ca II and Hα, seen clearly in IBIS observations,
  can be used to improve the magnetic field constraints, under conditions
  of high electrical conductivity. Such work is possible only with time
  series data sets from two-dimensional spectroscopic instruments such
  as IBIS, under conditions of good seeing.

Title: Chromospheric Structure and Dynamics.  From Old Wisdom to
    New Insights
Authors: Tritschler, A.; Reardon, K.; Uitenbroek, H.
Bibcode: 2010MmSAI..81..533T
Altcode: 2010MmSAI..81..533R
  No abstract at ADS

Title: Dual-Line Spectral Imaging of the Chromosphere
Authors: Cauzzi, G.; Reardon, K.; Rutten, R. J.; Tritschler, A.;
   Uitenbroek, H.
Bibcode: 2010ASSP...19..513C
Altcode: 2010mcia.conf..513C
  Hα filtergrams are notoriously difficult to interpret, "beautiful
  to view but not fit for analysis." We try to remedy this by using
  the IBIS bi-dimensional spectrometer at the Dunn Solar Telescope at
  NSO/Sacramento Peak to compare the quiet-sun chromosphere observed in
  Hα to what is observed simultaneously in Ca II 854.2 nm, sampling both
  lines with high angular and spectral resolution and extended coverage
  of space, time, and wavelength. Per (x, y, t) pixel we measured the
  intensity and Dopplershift of the minimum of each line's profile at
  that pixel, as well as the width of their inner chromospheric cores. A
  paper submitted to A&amp;A (December 2008) compares these measurements
  in detail.

Title: Service-Mode Observations for Ground-Based Solar Physics
Authors: Reardon, K. P.; Rimmele, T.; Tritschler, A.; Cauzzi, G.;
   Wöger, F.; Uitenbroek, H.; Tsuneta, S.; Berger, T.
Bibcode: 2009ASPC..415..332R
Altcode: 2009arXiv0909.1522R
  There are significant advantages in combining Hinode observations
  with ground-based instruments that can observe additional spectral
  diagnostics at higher data rates and with greater flexibility. However,
  ground-based observations, because of the random effects of weather
  and seeing as well as the complexities data analysis due to changing
  instrumental configurations, have traditionally been less efficient
  than satellite observations in producing useful datasets. Future large
  ground-based telescopes will need to find new ways to optimize both
  their operational efficiency and scientific output. <P />We have begun
  experimenting with service-mode or queue-mode observations at the Dunn
  Solar Telescope using the Interferometric Bidimensional Spectrometer
  (IBIS) as part of joint Hinode campaigns. We describe our experiences
  and the advantag es of such an observing mode for solar physics.

Title: Turbulence and Intermittency in the Solar Chromosphere
Authors: Lepreti, F.; Reardon, K. P.; Carbone, V.; Vecchio, A.
Bibcode: 2009AGUFMSH41B1649L
Altcode:
  We study the line-of-sight velocity fluctuations measured simultaneously
  in a photospheric (Fe I 709.0 nm) and a chromospheric line (Ca II 854.2
  nm). The velocities were obtained from imaging spectral scans acquired
  at high spatial resolution with the Interferometric BIdimensional
  Spectrometer (IBIS) covering an 80" diameter field in the quiet Sun. We
  find nearly power law tails above the acoustic cutoff frequency in
  the chromospheric velocity power spectra. The probability density
  functions (PDFs) of chromospheric velocity increments are non-Gaussian
  and asymmetric. Intermittency is much larger in the network than in
  fibril and internetwork regions. These results suggest that the small
  scale velocity fluctuations in the solar chromosphere are the result
  of a turbulent cascade generated from acoustic oscillations near the
  cutoff frequency. The role of this turbulent cascade for chromospheric
  heating is also discussed.

Title: The solar chromosphere at high resolution with
    IBIS. IV. Dual-line evidence of heating in chromospheric network
Authors: Cauzzi, G.; Reardon, K.; Rutten, R. J.; Tritschler, A.;
   Uitenbroek, H.
Bibcode: 2009A&A...503..577C
Altcode: 2009arXiv0906.2083C
  The structure and energy balance of the solar chromosphere remain
  poorly known. We used the imaging spectrometer IBIS at the Dunn Solar
  Telescope to obtain fast-cadence, multi-wavelength profile sampling
  of Hα and Ca ii 854.2 nm over a sizable two-dimensional field of view
  encompassing quiet-Sun network. We provide a first inventory of how the
  quiet chromosphere appears in these two lines by comparing basic profile
  measurements in the form of image displays, temporal-average displays,
  time slices, and pixel-by-pixel correlations. We find that the two lines
  can be markedly dissimilar in their rendering of the chromosphere,
  but that, nevertheless, both show evidence of chromospheric heating,
  particularly in and around network: Hα in its core width and Ca ii
  854.2 nm in its brightness. We discuss venues for improved modeling.

Title: Spectropolarimetry of Ca II 8542: Probing the Chromospheric
    Magnetic Field
Authors: Kleint, L.; Reardon, K.; Stenflo, J. O.; Uitenbroek, H.;
   Tritschler, A.
Bibcode: 2009ASPC..405..247K
Altcode:
  We present spectropolarimetric observations of the chromospheric Ca II
  8542 and photospheric Fe I 6302 lines obtained with the Interferometric
  Bidimensional Spectrometer (IBIS) at the Dunn Solar Telescope. The
  high spatial resolution over a large field of view (FOV) allows us to
  connect the observed profiles to the overall topology of the target
  region. After suitable calibrations we can extract Stokes profiles
  for each point in the FOV. The Stokes V profiles observed in the Ca II
  line show a large variety of shapes, indicating widely varying vertical
  behavior of the field strength, velocity, and temperature. We examine
  the center-of-gravity method for determining a representative field
  strength from the observed profiles and use it to directly compare
  photospheric and chromospheric magnetic fields.

Title: The solar chromosphere at high resolution with
    IBIS. III. Comparison of Ca II K and Ca II 854.2 nm imaging
Authors: Reardon, K. P.; Uitenbroek, H.; Cauzzi, G.
Bibcode: 2009A&A...500.1239R
Altcode: 2008arXiv0810.5260R
  Aims: Filtergrams obtained in Ca II H, Ca II K, and Hα are often
  employed as diagnostics of the solar chromosphere. The vastly disparate
  appearance between the typical filtergrams in these different lines
  calls into question the nature of what is actually being observed. We
  investigate the lack of obvious structures of magnetic origin such as
  fibrils and mottles in on-disk Ca II H and K images. <BR />Methods: We
  directly compare a temporal sequence of classical Ca II K filtergrams
  with a co-spatial and co-temporal sequence of spectrally resolved
  Ca II 854.2 images obtained with the Interferometric Bidimensional
  Spectrometer (IBIS), considering the effect of both the spectral and
  spatial smearing. We analyze the temporal behavior of the two series
  by means of Fourier analysis. <BR />Results: The lack of fine magnetic
  structuring in Ca II K filtergrams, even with the narrowest available
  filters, is due to observational effects, primarily contributions from
  the bright, photospheric wings of the line that swamp the small and
  dark chromospheric structures. Signatures of fibrils remain, however,
  in the temporal evolution of the filtergrams, in particular with
  the evidence of magnetic shadows around the network elements. The
  Ca II K filtergrams do not appear, however, to properly reflect the
  high-frequency behavior of the chromosphere. Using the same analysis,
  we find no significant chromospheric signature in the Hinode/SOT Ca II
  H quiet-Sun filtergrams. <BR />Conclusions: The picture provided by Hα
  and Ca II 854.2, which show significant portions of the chromosphere
  dominated by magnetic structuring, appears to reflect the true and
  essential nature of the solar chromosphere. Data that do not resolve
  this aspect, whether spatially or spectrally, may misrepresent the
  behavior the chromosphere.

Title: The Virtual Solar Observatory: Where Do We Go from Here?
Authors: Gurman, Joseph B.; Bogart, R.; Spencer, J.; Hill, F.; Suarez
   Sola, I.; Reardon, K.; Hourcle, J.; Hughitt, K.; Martens, P.; Davey, A.
Bibcode: 2009SPD....40.1508G
Altcode:
  The Virtual Solar Observatory (VSO) continues to add features in an
  effort to broaden the ways in which it can be used to aid research. We
  describe and demonstrate plans for SDO data access (see also the poster
  Suarez-Sola et al.), multiple catalog access (Hourclé et al.), and
  new capabilities of the IDL VSO_SEARCH function, as well as describing
  future capabilities in development and under consideration. <P />Since
  the VSO is funded by the Solar Data Analysis Center (SDAC), which will
  be undergoing a NASA Senior Review in July, we solicit community input
  to help us prioritize this new work: what should we do with the limited
  resources available?

Title: The Virtual Solar Observatory—A Resource for International
    Heliophysics Research
Authors: Hill, Frank; Martens, Piet; Yoshimura, Keji; Gurman, Joseph;
   Hourclé, Joseph; Dimitoglou, George; Suárez-Solá, Igor; Wampler,
   Steve; Reardon, Kevin; Davey, Alisdair; Bogart, Richard S.; Tian,
   Karen Q.
Bibcode: 2009EM&P..104..315H
Altcode: 2008EM&P..tmp...47H
  The Virtual Solar Observatory (VSO) has been developed to allow
  researchers, educators, and the general public to access data
  and images from the major sources of on-line solar data. The VSO
  substantially reduces the effort required to locate disparate data
  sets, and removes the need for the user to locate the data and
  learn multiple interfaces. The VSO provides a single interface to
  about 60 geographically distributed data sets including space- and
  ground-based sources. These data sets incorporate several physical
  variables including magnetic field, intensity, Doppler velocity, etc.,
  and all wavelengths from X-ray to radio. All layers of the sun, from
  the interior to the corona, are included. In this paper we describe
  the system and present the interface that the user will encounter. We
  also discuss future enhancements planned for the system.

Title: The solar chromosphere at high resolution with
    IBIS. II. Acoustic shocks in the quiet internetwork and the role of
    magnetic fields
Authors: Vecchio, A.; Cauzzi, G.; Reardon, K. P.
Bibcode: 2009A&A...494..269V
Altcode: 2008arXiv0807.4966V
  Context: The exact nature of the quiet solar chromosphere and
  especially its temporal variation, are still subjects of intense
  debate. One of the contentious issues is the possible role of the
  magnetic field in structuring the quieter solar regions. <BR />Aims:
  We characterize the dynamics of the quiet inter-network chromosphere
  by studying the occurrence of acoustic shocks and their relation with
  the concomitant photospheric structure and dynamics, including small
  scale magnetic structures. <BR />Methods: We analyze a comprehensive
  data set that includes high-resolution chromospheric (Ca ii 854.2
  nm) and photospheric (Fe i 709.0 nm) spectra obtained with the IBIS
  imaging spectrometer in two quiet-Sun regions. This is complemented by
  high-resolution sequences of MDI magnetograms of the same targets. From
  the chromospheric spectra we identify the spatio-temporal occurrence of
  the acoustic shocks. We compare it with the photospheric dynamics by
  means of both Fourier and wavelet analysis and study the influence of
  magnetic structures on the phenomenon. <BR />Results: Mid-chromospheric
  shocks occur within the general chromospheric dynamics pattern of
  acoustic waves propagating from the photosphere. In particular, they
  appear as a response to underlying powerful photospheric motions
  at periodicities nearing the acoustic cut-off, consistent with 1-D
  hydrodynamical modeling. However, their spatial distribution within
  the supergranular cells is highly dependent on the local magnetic
  topology, both at the network and internetwork scale. We find that
  large portions of the internetwork regions undergo very few shocks,
  since they are “shadowed” by the horizontal component of the
  magnetic field. The latter is betrayed by the presence of chromospheric
  fibrils, observed in the core of the Ca ii line as slanted structures
  with distinct dynamical properties. The shadow mechanism also appears
  to operate on the very small scales of inter-network magnetic elements,
  and provides for a very pervasive influence of the magnetic field even
  in the quietest region analyzed. <BR />Conclusions: The magnetic field
  might play a larger role in structuring the quiet solar chromosphere
  than normally assumed. The presence of fibrils highlights a clear
  disconnection between the photospheric dynamics and the response of
  the geometrically overlaying chromosphere. As these results hold for
  a mid-chromospheric indicator such as the Ca ii 854.2 line, it is
  expected that diagnostics formed in higher layers, such as UV lines
  and continua, will be affected to a greater extent by the presence
  of magnetic fields, even in quiet regions. This is relevant for the
  chromospheric models that make use of such diagnostics.

Title: The Solar Chromosphere: Old Challenges, New Frontiers
Authors: Ayres, T.; Uitenbroek, H.; Cauzzi, G.; Reardon, K.; Berger,
   T.; Schrijver, C.; de Pontieu, B.; Judge, P.; McIntosh, S.; White,
   S.; Solanki, S.
Bibcode: 2009astro2010S...9A
Altcode:
  No abstract at ADS

Title: Evidence for a Current Sheet above a Sunspot Umbra
Authors: Tritschler, A.; Uitenbroek, H.; Reardon, K.
Bibcode: 2008ApJ...686L..45T
Altcode:
  We present observational evidence for the existence of a current
  sheet in the chromosphere above a sunspot umbra based on high angular
  resolution two-dimensional spectroscopic observations in the Ca II
  854.21 nm line. In the core of this line we observe a very stable bright
  ribbon-like structure separating magnetic field configurations that
  connect to different parts of the active region. We make plausible
  that the structure is a string of sheets carrying vertical currents
  that result from dissipation when the different parts of the active
  region are moved around in the photosphere. To our knowledge this is
  the first direct observation of the heating caused by the dissipation
  in such a current sheet in the chromosphere.

Title: Imaging Spectropolarimetry of the Photosphere and Chromosphere
    with IBIS
Authors: Reardon, K.; Tritschler, A.; Uitenbroek, H.; et al.
Bibcode: 2008ESPM...12.2.31R
Altcode:
  We present recent results based on high-resolution spectropolarimetry
  using IBIS, a dual Fabry-Perot imaging spectrometer. We describe
  the characteristics of the instrument and its capability to measure
  the full Stokes vector in a range of photospheric and chromospheric
  spectral lines. <P />Since late 2006 IBIS has been regularly used in
  spectropolarimetric mode and observations have included solar pores,
  quiet sun network and internetwork areas, and the disk passage of active
  regions NOAA 10941 and 10940. Measurements are primarily performed in
  the Fe I 630.2 and the Ca II 854.2 nm lines to provide information on
  both photospheric to chromospheric heights. We present results on the
  highly dynamical nature of both the vertical and horizontal components
  of quiet Sun magnetic fields. We also show the fine structure and
  height variation of the magnetic field in a large sunspot.

Title: Speckle interferometry with adaptive optics corrected
    solar data
Authors: Wöger, F.; von der Lühe, O.; Reardon, K.
Bibcode: 2008A&A...488..375W
Altcode:
  Context: Adaptive optics systems are used on several advanced solar
  telescopes to enhance the spatial resolution of the recorded data. In
  all cases, the correction remains only partial, requiring post-facto
  image reconstruction techniques such as speckle interferometry
  to achieve consistent, near-diffraction limited resolution. <BR
  />Aims: This study investigates the reconstruction properties of
  the Kiepenheuer-Institut Speckle Interferometry Package (KISIP)
  code, with focus on its phase reconstruction capabilities and
  photometric accuracy. In addition, we analyze its suitability for
  real-time reconstruction. <BR />Methods: We evaluate the KISIP
  program with respect to its scalability and the convergence of
  the implemented algorithms with dependence on several parameters,
  such as atmospheric conditions. To test the photometric accuracy of
  the final reconstruction, comparisons are made between simultaneous
  observations of the Sun using the ground-based Dunn Solar Telescope and
  the space-based Hinode/SOT telescope. <BR />Results: The analysis shows
  that near real-time image reconstruction with high photometric accuracy
  of ground-based solar observations is possible, even for observations in
  which an adaptive optics system was utilized to obtain the speckle data.

Title: Acoustic Shocks in the Quiet Internetwork and the Role of
    Magnetic Fields
Authors: Cauzzi, G.; Vecchio, A.; Reardon, K.
Bibcode: 2008ESPM...12.2.37C
Altcode:
  By using imaging spectroscopy in the CaII 854.2 nm line obtained with
  IBIS over several quiet Sun regions, we present compelling evidence of
  acoustic shocks occurring in the quiet chromosphere at the dominant
  3-minute periodicity. The shocks present many of the characteristics
  prescribed in 1-D hydrodynamics models, including a mostly vertical
  propagation of the disturbance from regions of enhanced photospheric
  velocity at periodicities close to the acoustic cut-off. <P />Our most
  interesting result, however, is the large influence that magnetic
  structures exert on the development of chromospheric shocks. In
  particular, shocks are essentially absent from extended regions
  around magnetic network elements, creating the so-called "magnetic
  shadows". These areas coincide with the presence of chromospheric
  fibrils rooted in the network itself, that apparently absorb or
  otherwise modify the upward propagating acoustic waves, inhibiting
  the formation of shocks. <P />Intriguingly, we also find a clear
  reduction in the number of shocks observed in quiet internetwork areas
  whenever small magnetic structures are seen in MDI HR maps. This is
  true even when strong photospheric motions at the relevant periods
  are present. This might imply the need to reevaluate the acoustic
  contribution to the observed chromospheric "basal" flux.

Title: Chromospheric Counterparts of UV Explosive Events
Authors: Reardon, K.; Cauzzi, G.; Teriaca, L.; Pitterle, M.; Curdt, W.
Bibcode: 2008ESPM...12.2.17R
Altcode:
  We present a study of a unique, multi-wavelength dataset of a quiet
  sun region with the primary goal of studying explosive events at
  chromospheric and transition region heights. Several hypotheses
  have been made about the nature of the explosive events, however the
  underlying mechanisms remain elusive due to their small spatial and
  temporal scales. Several theoretical models predict an important
  role for the chromosphere in the triggering of these events. <P
  />To shed light on this issue, we have obtained a comprehensive
  set of simultaneous high spatial, spectral, and temporal resolution
  observations on April 18, 2007, combining both ground- and space-based
  observatories. Most importantly, we carried out coordinated observations
  with SUMER in the transition region Si IV 140.2 nm line together
  with high-cadence IBIS imaging spectroscopy of the chromospheric CaII
  854.2 nm line. This allows us to examine the chromospheric dynamics
  and acoustic shocks that underlie the transition region events. We
  also use SOT/NFI magnetograms to examine the relation of the explosive
  events to the changes in the magnetic topology. The combined dataset
  also includes Hinode/EIS rasters and Hinode/XRT images that provide
  information on the higher-temperature coronal response.

Title: On the Role of Acoustic-gravity Waves in the Energetics of
    the Solar Atmosphere
Authors: Straus, T.; Fleck, B.; Jefferies, S. M.; Cauzzi, G.; McIntosh,
   S. W.; Reardon, K.; Severino, G.; Steffen, M.; Suter, M.; Tarbell,
   T. D.
Bibcode: 2008ESPM...12.2.11S
Altcode:
  We revisit the dynamics and energetics of the solar atmosphere, using a
  combination of high-quality observations and 3D numerical simulations
  of the overshoot region of compressible convection into the stable
  photosphere. We discuss the contribution of acoustic-gravity waves
  to the energy balance of the photosphere and low chromosphere. We
  demonstrate the presence of propagating internal gravity waves at
  low frequencies (&lt; 5mHz). Surprisingly, these waves are found
  to be the dominant phenomenon in the quiet middle/upper photosphere
  and to transport a significant amount of mechanical energy into the
  atmosphere outweighing the contribution of high-frequency (&gt; 5mHz)
  acoustic waves by more than an order of magnitude. We compare the
  properties of high-frequency waves in the simulations with results
  of recent high cadence, high resolution Doppler velocity measurements
  obtained with SOT/SP and SOT/NFI on Hinode. Our results seem to be in
  conflict with the simple picture of upward propagating sound waves. We
  discuss the implications of our findings on the energy flux estimate
  at high-frequencies.

Title: Physical Properties of Chromospheric Structures in H-alpha
    and and CaII 854.2 nm
Authors: Bostanci, Z. F.; Rutten, R., R. Jtenbroek, H.; Reardon, K.;
   Cauzzi, G.
Bibcode: 2008ESPM...12.2.45B
Altcode:
  Comprehensive studies of chromospheric structures are the key to
  understanding their dynamics in different solar regimes and their
  contribution in heating of the solar atmosphere. High spatial and
  spectral resolution observations of a quiet chromospheric region
  were obtained with the Interferometric BIdimensional Spectrometer
  (IBIS) installed at the Dunn Solar Telescope (DST) of the National
  Solar Observatory (NSO) on Sacramento Peak, USA. Chromospheric fibrils
  that were observed simultaneously in the Balmer H? and CaII 854.2 nm
  line are analysed using the cloud model technique to derive numerical
  values for the standard cloud model parameters; optical thickness,
  source function, Dopplerwidth and Dopplershift for the two lines,
  enabling detailed comparison between these.

Title: Evidence of Shock-driven Turbulence in the Solar Chromosphere
Authors: Reardon, K. P.; Lepreti, F.; Carbone, V.; Vecchio, A.
Bibcode: 2008ApJ...683L.207R
Altcode: 2008arXiv0809.4243R
  We study the acoustic properties of the solar chromosphere in the
  high-frequency regime using a time sequence of velocity measurements
  in the chromospheric Ca II 854.2 nm line taken with the Interferometric
  Bidimensional Spectrometer (IBIS). We concentrate on quiet-Sun behavior,
  apply Fourier analysis, and characterize the observations in terms of
  the probability density functions (PDFs) of velocity increments. We
  confirm the presence of significant oscillatory fluctuation power above
  the cutoff frequency and find that it obeys a power-law distribution
  with frequency up to our 25 mHz Nyquist limit. The chromospheric PDFs
  are non-Gaussian and asymmetric, and they differ among the network,
  fibril, and internetwork regions. This suggests that the chromospheric
  high-frequency power is not simply the result of short-period waves
  propagating upward from the photosphere but rather is the signature of
  turbulence generated within the chromosphere from shock oscillations
  near the cutoff frequency. The presence of this pervasive and broad
  spectrum of motions in the chromosphere is likely to have implications
  for the excitation of coronal loop oscillations.

Title: The Energy Flux of Internal Gravity Waves in the Lower Solar
    Atmosphere
Authors: Straus, Thomas; Fleck, Bernhard; Jefferies, Stuart M.;
   Cauzzi, Gianna; McIntosh, Scott W.; Reardon, Kevin; Severino, Giuseppe;
   Steffen, Matthias
Bibcode: 2008ApJ...681L.125S
Altcode:
  Stably stratified fluids, such as stellar and planetary atmospheres,
  can support and propagate gravity waves. On Earth these waves,
  which can transport energy and momentum over large distances and can
  trigger convection, contribute to the formation of our weather and
  global climate. Gravity waves also play a pivotal role in planetary
  sciences and modern stellar physics. They have also been proposed
  as an agent for the heating of stellar atmospheres and coronae, the
  exact mechanism behind which is one of the outstanding puzzles in solar
  and stellar physics. Using a combination of high-quality observations
  and 3D numerical simulations we have the first unambiguous detection
  of propagating gravity waves in the Sun's (and hence a stellar)
  atmosphere. Moreover, we are able to determine the height dependence of
  their energy flux and find that at the base of the Sun's chromosphere it
  is around 5 kW m<SUP>-2</SUP>. This amount of energy is comparable to
  the radiative losses of the entire chromosphere and points to internal
  gravity waves as a key mediator of energy into the solar atmosphere.

Title: Search for High Velocities in the Disk Counterpart of Type
    II Spicules
Authors: Langangen, Ø.; De Pontieu, B.; Carlsson, M.; Hansteen,
   V. H.; Cauzzi, G.; Reardon, K.
Bibcode: 2008ApJ...679L.167L
Altcode: 2008arXiv0804.3256L
  Recently, De Pontieu and coworkers discovered a class of spicules
  that evolve more rapidly than previously known spicules, with rapid
  apparent motions of 50-150 km s<SUP>-1</SUP>, thickness of a few 100
  km, and lifetimes of order 10-60 s. These so-called type II spicules
  have been difficult to study because of limited spatiotemporal and
  thermal resolution. Here we use the IBIS instrument to search for the
  high velocities in the disk counterpart of type II spicules. We have
  detected rapidly evolving events, with lifetimes that are less than a
  minute and often equal to the cadence of the instrument (19 s). These
  events are characterized by a Doppler shift that only appears in the
  blue wing of the Ca II IR line. Furthermore, the spatial extent,
  lifetime, and location near network all suggest a link to type II
  spicules. However, the magnitude of the measured Doppler velocity is
  significantly lower than the apparent motions seen at the limb. We
  use Monte Carlo simulations to show that this discrepancy can be
  explained by a forward model in which the visibility on the disk of
  the high-velocity flows in these events is limited by a combination
  of line-of-sight projection and reduced opacity in upward propelled
  plasma, especially in reconnection driven jets that are powered by a
  roughly constant energy supply.

Title: Solar Chromospheric Dynamics: Onwards and Upwards
Authors: Cauzzi, G.; Reardon, K.; Rimmele, T.; Rutten, R.; Tritschler,
   A.; Uitenbroek, H.; Woeger, F.
Bibcode: 2008AGUSMSP41B..03C
Altcode:
  We present a study of chromospheric dynamics and its relation with the
  driving photospheric magneto-convection in a variety of solar targets,
  from quiet Sun to more active regions. To this end high resolution
  observations were obtained in CaII 854.2 nm, Hα, and photospheric
  FeI lines with the Interferometric BIdimensional Spectrometer (IBIS)
  installed at the Dunn Solar Telescope of the NSO. The availability of
  full spectroscopic information on extended fields of view allows us
  to derive a comprehensive view of the intrinsically 3-D chromospheric
  scene. A coherent picture is emerging that involves the propagation
  and dissipation of photospheric acoustic waves into the chromospheric
  layers, but selected and guided by the local and highly variable
  magnetic topology. In particular, ubiquitous fibrilar structures,
  apparently originating from even the smallest magnetic elements,
  appear an integral part of the dynamic chromosphere.

Title: WHI Targeted Campaigns on Coronal Holes and Quiet Sun: High
    Resolution Observations of the Lower Atmosphere With IBIS
Authors: Cauzzi, G.; Reardon, K. P.; Rimmele, T.; Tritschler, A.;
   Uitebroek, H.; Woeger, F.; Deforest, C.; McIntosh, S.
Bibcode: 2008AGUSMSH51A..02C
Altcode:
  The Interferometric BIdimensional Spectrometer (IBIS) is a dual
  Fabry-Perot instrument installed at the Dunn Solar Telescope that allows
  two-dimensional spectroscopic observations in a variety of spectral
  lines. The IBIS/DST will participate in the WHI targeted campaigns
  on coronal holes (April 3-9) and quiet Sun dynamics (April 10-16)
  performing simultaneous high-resolution observations of the dynamics of
  the photosphere and chromosphere in the coordinated targets. The aim is
  to obtain insights on the role of the lower atmosphere's dynamics and
  energetics into the structuring of the coronal plasma and, possibly,
  into the origin of the solar wind. In this paper we will present the
  observations obtained as well as first results, and attempt to relate
  them with recent work performed on quiet Sun chromospheric dynamics.

Title: Evidence of Shock-Driven Turbulence in the Solar Chromosphere
Authors: Reardon, K.; Lepreti, F.; Carbone, V.; Vecchio, A.
Bibcode: 2008AGUSMSP21B..03R
Altcode:
  We present observations of photospheric and chromospheric velocities
  at high spatial resolution using the Interferometric Bidimensional
  Spectrometer (IBIS). We study an area of quiet Sun and apply Fourier
  analysis to the velocity time series. We confirm the presence of
  significant power in the chromosphere above the cutoff frequency
  and find that it obeys power-law distribution with frequency up to
  our 25 mHz Nyquist limit. We further characterize the observations
  in terms of Probability Density Functions (PDFs) and find that the
  chromospheric PDFs are non-Gaussian and asymmetric. This suggests
  that the chromospheric high-frequency power is probably not made up
  of short-period waves propagating upward from the photosphere, but
  rather is the signature of turbulence generated within the chromosphere
  from shock oscillations near the cutoff frequency. The presence of
  this pervasive and broad spectrum of motions in the chromosphere is
  important for atmospheric modeling and is likely to have implications
  for the excitation of coronal loop oscillations.

Title: Searching the X-ray Sun For Solar Axions
Authors: Hudson, Hugh S.; Acton, L. W.; DeLuca, E. E.; Hannah, I. G.;
   Hurford, G. J.; Lin, R. P.; Reardon, K. P.; van Bibber, K.
Bibcode: 2008AAS...212.0402H
Altcode: 2008BAAS...40..193H
  The axion is a hypothetical weakly-interacting elementary particle. The
  solar core may produce a copious axion flux via the Primakoff
  effect. This same process can also convert a tiny fraction of the
  axions back into photons via interaction with the magnetic field
  threading the solar atmosphere. The spectral signature of the emitted
  X-rays is determined mainly by the temperature of the solar core, and
  the spatial distribution also depends strongly on the solar magnetic
  field in the back-conversion process. The X-ray intensity thus varies as
  G<SUB>a</SUB><SUB>γγ</SUB>(&amp;#8747B<SUB>perp</SUB>dL)<SUP>2</SUP>,
  where B<SUB>perp</SUB> is the perpendicular component of the
  chromospheric and coronal magnetic field in the appropriate zone
  for interaction and photon escape, and G<SUB>a</SUB><SUB>γγ</SUB>
  is the (unknown) coupling constant, dependent on the (unknown) mass
  of the axion. We describe observational tests suitable for solar
  X-ray imagers and discuss projects now under way with Yohkoh/SXT,
  RHESSI, and Hinode/XRT. The successful detection of axions would have
  implications for basic physics and for cosmological dark matter. It
  would also help us to characterize the ill-understood extension of the
  solar magnetic field into the chromosphere and corona. We specifically
  focus on applying the existing understanding of solar (and stellar)
  magnetism to this problem.

Title: Characterization of Fabry-Perot interferometers and
    multi-etalon transmission profiles. The IBIS instrumental profile
Authors: Reardon, K. P.; Cavallini, F.
Bibcode: 2008A&A...481..897R
Altcode:
  Aims: Properly characterizing Fabry-Perot interferometers (FPI) is
  essential for determining their effective properties and evaluating
  the performance of the astronomical instruments in which they are
  employed. Furthermore, in two-dimensional spectrographs where multiple
  FPI are used in series, the actual distribution of plate separation
  errors will be crucial for determining the resulting transmission
  profiles. We describe techniques that address these issues utilizing
  the FPI of IBIS, a solar bidimensional spectrometer installed at the
  Dunn Solar Telescope. <BR />Methods: A frequency-stabilized He-Ne
  laser was used in three different optical layouts to measure the
  spatially-resolved transmission of the FPI. Analyzing the shape and
  wavelength shift of the observed profiles allows the characteristics of
  the cavity errors and the interferometer coating to be determined. <BR
  />Results: We have measured the spatial distribution of the large-scale
  plate defects, which shows a steep radial trend, as well as the
  magnitude of the small-scale microroughness. We also extracted
  the effective reflectivity and absorption of the coating at the
  laser line wavelength for both interferometers. <BR />Conclusions:
  These techniques, which are generally applicable to any Fabry-Perot
  interferometer, provide the necessary information for calculating
  the overall instrumental profile for any illuminated area of the
  interferometer plates. Accurate knowledge of the spectral transmission
  profile is important, in particular when using inversion techniques
  or in comparing observations with simulated data.

Title: The solar chromosphere at high resolution with IBIS. I. New
    insights from the Ca II 854.2 nm line
Authors: Cauzzi, G.; Reardon, K. P.; Uitenbroek, H.; Cavallini, F.;
   Falchi, A.; Falciani, R.; Janssen, K.; Rimmele, T.; Vecchio, A.;
   Wöger, F.
Bibcode: 2008A&A...480..515C
Altcode: 2007arXiv0709.2417C
  Context: The chromosphere remains a poorly understood part of the solar
  atmosphere, as current modeling and observing capabilities are still
  ill-suited to investigating its fully 3-dimensional nature in depth. In
  particular, chromospheric observations that can preserve high spatial
  and temporal resolution while providing spectral information over
  extended fields of view are still very scarce. <BR />Aims: In this
  paper, we seek to establish the suitability of imaging spectroscopy
  performed in the Ca II 854.2 nm line as a means of investigating
  the solar chromosphere at high resolution. <BR />Methods: We utilize
  monochromatic images obtained with the Interferometric BIdimensional
  Spectrometer (IBIS) at multiple wavelengths within the Ca II 854.2 nm
  line and over several quiet areas. We analyze both the morphological
  properties derived from narrow-band monochromatic images and the
  average spectral properties of distinct solar features such as network
  points, internetwork areas, and fibrils. <BR />Results: The spectral
  properties derived over quiet-Sun targets are in full agreement with
  earlier results obtained with fixed-slit spectrographic observations,
  highlighting the reliability of the spectral information obtained
  with IBIS. Furthermore, the very narrowband IBIS imaging reveals very
  clearly the dual nature of the Ca II 854.2 nm line. Its outer wings
  gradually sample the solar photosphere, while the core is a purely
  chromospheric indicator. The latter displays a wealth of fine structures
  including bright points akin to the Ca II H{2V} and K{2V} grains, and
  as fibrils originating from even the smallest magnetic elements. The
  fibrils occupy a large fraction of the observed field of view, even
  in the quiet regions, and clearly outline atmospheric volumes with
  different dynamical properties, strongly dependent on the local magnetic
  topology. This highlights how 1D models stratified along the vertical
  direction can provide only a very limited representation of the actual
  chromospheric physics. <BR />Conclusions: Imaging spectroscopy in the
  Ca II 854.2 nm line currently represents one of the best observational
  tools for investigating the highly structured and highly dynamical
  chromospheric environment. A high-performance instrument such as IBIS
  is crucial in achieving the necessary spectral purity and stability,
  spatial resolution, and temporal cadence. <P />Two movies are only
  available in electronic form at http://www.aanda.org

Title: Two-dimensional Spectropolarimetry At The Dunn Solar Tower
Authors: Uitenbroek, Han; Tritshler, A.; Reardon, K.; Kleint, L.
Bibcode: 2007AAS...210.2605U
Altcode: 2007BAAS...39..324U
  Measurement of the solar magnetic field within individual atmospheric
  structures is a desirable, but persistently challenging goal, in
  particular in chromospheric layers. Successful measurements over
  different heights would provide an important contribution to our
  understanding of the solar atmosphere and would provide valuable
  input for theoretical modeling. We provide a short description of the
  capabilities of the Interferometric BIdimensional Spectrometer (IBIS),
  which has recently been upgraded to full Stokes capabilities. IBIS
  is installed at the Dunn Solar Tower (DST) at the Sacramento Peak
  observatory operated by NSO. Using IBIS we achieve high spatial
  resolution over a large field of view in both the photosphere and
  the chromosphere, which allows us to connect the observed profiles
  to the overall topology of the target region. After performing
  suitable calibrations for the telescope and instrument polarization
  properties, we can extract Stokes profiles for each point in the
  field of view. Stokes V profiles observed in the Ca II 854.2 nm line
  show a large variety of forms, indicating widely varying vertical
  behavior of the field strength, velocity, and temperature. We examine
  the center-of-gravity method for determining a representative field
  strength from the observed profiles looking at observations and
  comparing with simulated profiles.

Title: Comparison of spatially and spectrally resolved solar data
    with numerical simulations
Authors: Cauzzi, G.; Asensio Ramos, A.; Reardon, K. P.; Janssen, K.
Bibcode: 2007IAUS..239..138C
Altcode:
  No abstract at ADS

Title: Acoustic Shocks in the Quiet Solar Chromosphere
Authors: Cauzzi, G.; Reardon, K. P.; Vecchio, A.; Janssen, K.;
   Rimmele, T.
Bibcode: 2007ASPC..368..127C
Altcode:
  We exploit the two-dimensional spectroscopic capabilities of the
  Interferometric BIdimensional Spectrometer (IBIS) to study the
  chromospheric Ca II 854.2 nm line and its temporal evolution in a quiet
  region at the center of the solar disk. The Ca II 854.2 profiles in the
  internetwork portion of the field of view clearly indicate the presence
  of hydrodynamic shocks, occurring at frequencies above the acoustic
  cut-off. <P />The location and strength of such shocks perfectly map
  the areas where large velocity power is found at frequencies of 5.5-8
  mHz in a standard Fourier analysis. The shocks locations evidence a
  sharp partition of the quiet area in regions of very distinct dynamical
  behavior, highlighting the role of the local magnetic topology in
  structuring the lower chromosphere. The portions of the field of view
  where the photospheric field is very weak, and that are presumably
  connected to distant magnetic structures (or open to the interplanetary
  field), are the site of frequent shock occurrence. On the contrary, in
  regions neighboring the magnetic network and harboring a more horizontal
  configuration of the chromospheric magnetic field, shocks are heavily
  suppressed, even if the photospheric field is essentially absent in
  these areas as well. These latter regions, with much reduced velocity
  power at frequencies of 5.5-8 mHz \citep[the ``magnetic shadows'' first
  described in][]{gc-judge_01}, are spatially coincident with fibrilar
  structures visible in the Ca II 854.2 line core intensity maps. <P />We
  finally argue that areas within and immediately surrounding the magnetic
  network also display evidence of chromospheric shocks, but occurring at
  periodicities of 4-6 minutes. Such slow shocks are stronger than those
  occurring in field-free areas, as evidenced by the strong emission
  in the inner blue-wing of the line. This is in agreement with recent
  results claiming that magneto-acoustic shocks can develop in inclined
  magnetic structures, acting as `portals' through which the powerful
  low-frequency photospheric oscillations can leak into the chromosphere.

Title: Comparison of Ca II K and Ca II 8542 Å Images
Authors: Reardon, K. P.; Cauzzi, G.; Rimmele, T.
Bibcode: 2007ASPC..368..151R
Altcode:
  We compare a time sequence of filtergrams obtained in the Ca II K line
  with a series of spectrally resolved images obtained simultaneously
  with the IBIS instrument in the Ca II 8542 Å line. Using the
  narrowband IBIS images and a synthetic filter profile, we construct
  simulated 8542 filtergrams that mimic the observed K<SUB>2V</SUB>
  filtergrams. We observe that these filtergrams appear to contain
  elements corresponding to both photospheric and chromospheric
  structures. Intermediate scale patterns seen in the filtergrams may
  simply be the result of the combination of a variety of structures
  from different atmospheric levels. We analyze the Fourier power
  spectra of the filtergrams and note that at frequencies well above
  the acoustic cut-off value the observed power in the K<SUB>2V</SUB>
  filtergrams seems to be predominantly photospheric in origin. The use
  of Ca II H and K filtergrams to study the chromospheric behavior thus
  may be inherently problematic. Narrowband images in the Ca II 8542 Å
  line might provide a better source of information about chromospheric
  behavior with little loss in spatial or temporal resolution.

Title: Photon Spectroscopy with Imaging X-Ray Instruments
Authors: Labonte, B. J.; Reardon, K. P.
Bibcode: 2007SoPh..240..387L
Altcode:
  Individual X-ray photons in the keV energy range produce hundreds of
  photoelectrons in a single pixel of a CCD array detector. The number
  of photoelectrons produced is a linear function of the photon energy,
  allowing the measurement of spectral information with an imaging
  detector system. Most solar X-ray telescopes, such as Yohkoh/SXT and
  Hinode/XRT, use CCD detectors in an integrating mode and are designed to
  make temperature estimates from multiband filter photometry. We show how
  such instruments can be used in a new way to perform a limited type of
  this photon spectroscopy. By measuring the variance in intensity of a
  series of repeated images through a single filter of an X-ray source,
  the mean energy per detected photon can be determined. This energy
  is related to the underlying coronal spectrum, and hence it can be
  used to deduce the mean plasma temperature. We apply this technique to
  data from the Yohkoh Soft X-Ray Telescope and compare the temperatures
  obtained with this technique with the temperatures derived using the
  standard filter ratio method for a postflare loop system. Given the
  large dynamic range of the soft X-ray flux observed from the Sun,
  we describe the requirements for a future instrument that would be
  better suited to performing photon spectroscopy.

Title: Solar atmospheric oscillations and the chromospheric magnetic
    topology
Authors: Vecchio, A.; Cauzzi, G.; Reardon, K. P.; Janssen, K.;
   Rimmele, T.
Bibcode: 2007A&A...461L...1V
Altcode: 2006astro.ph.11206V
  Aims:We investigate the oscillatory properties of the quiet solar
  chromosphere in relation to the underlying photosphere, with particular
  regard to the effects of the magnetic topology. <BR />Methods: For the
  first time we perform a Fourier analysis on a sequence of line-of-sight
  velocities measured simultaneously in a photospheric (Fe I 709.0 nm)
  and a chromospheric line (Ca II 854.2 nm). The velocities were obtained
  from full spectroscopic data acquired at high spatial resolution with
  the Interferometric BIdimensional Spectrometer (IBIS). The field of
  view encompasses a full supergranular cell, allowing us to discriminate
  between areas with different magnetic characteristics. <BR />Results: We
  show that waves with frequencies above the acoustic cut-off propagate
  from the photosphere to upper layers only in restricted areas of
  the quiet Sun. A large fraction of the quiet chromosphere is in fact
  occupied by “magnetic shadows”, surrounding network regions, that
  we identify as originating from fibril-like structures observed in
  the core intensity of the Ca II line. We show that a large fraction
  of the chromospheric acoustic power at frequencies below the acoustic
  cut-off, residing in the proximity of the magnetic network elements,
  directly propagates from the underlying photosphere. This supports
  recent results arguing that network magnetic elements can channel
  low-frequency photospheric oscillations into the chromosphere, thus
  providing a way to input mechanical energy in the upper layers.

Title: High-resolution IBIS Observations and Comparison with 3D
    Simulations
Authors: Cauzzi, G.; Asensio Ramos, A.; Reardon, K.; Janssen, K.
Bibcode: 2006ASPC..354...26C
Altcode:
  We present first comparisons between high resolution observations of
  the quiet photosphere, obtained with the Interferometric BIdimensional
  Spectrometer (IBIS) in the non-magnetic Fe I 7090.4 Å spectral
  line, and the synthetic spectrum calculated for a 3D snapshot of a
  radiation-hydrodynamical simulation of the solar atmosphere. Together
  with morphological comparisons between the synthetic images and the
  observed ones at different wavelengths, we have carried out comparisons
  between several observables. The simulations reproduce quite well
  many of the observational properties of the high resolution IBIS data,
  apart from the velocity distribution, that contains values quite larger
  than observed.

Title: 3-D Structure of Sunspots Using Imaging Spectroscopy
Authors: Balasubramaniam, K. S.; Gary, G. A.; Reardon, K.
Bibcode: 2006ASPC..354..237B
Altcode:
  We use the Interferometric BIdimensional Spectrometer (IBIS) of the
  INAF/Arcetri Astrophysical Observatory and installed at the National
  Solar Observatory (NSO) Dunn Solar Telescope, to understand the
  structure of sunspots. Using the spectral lines Fe I 6301.5 Å, Fe II
  7224.4 Å, and Ca II 8542.6 Å, we examine the spectroscopic variation
  of sunspot penumbral and umbral structures at the heights of formation
  of these lines. These high resolution observations were acquired on
  2004 July 30 -- 31, of active region NOAA 10654, using the high order
  NSO adaptive optics system. We map the spatio-temporal variation of
  Doppler signatures in these spectral lines, from the photosphere to
  the chromosphere. From a 70-minute temporal average of individual
  32-second cadence Doppler observations we find that the averaged
  velocities decrease with height. They are about 3.5 times larger in the
  deeper photosphere (Fe II 7224.4 Å; height-of-formation ≈ 50 km)
  than in the upper photosphere Fe I 6301.5 Å; height-of-formation
  ≈ 350 km), There is a remarkable coherence of Doppler signals
  over the height difference of 300 km. From a high-speed animation
  of the Doppler sequence we find evidence for what appears to be
  ejection of high speed gas concentrations from edges of penumbral
  filaments into the surrounding granular photosphere. The Evershed
  flow persists a few arcseconds beyond the traditionally demarcated
  penumbra-granulation boundary. We present these and other results and
  discuss the implications of these measurements for sunspot models.

Title: The Effects of Atmospheric Dispersion on High-Resolution
    Solar Spectroscopy
Authors: Reardon, Kevin P.
Bibcode: 2006SoPh..239..503R
Altcode: 2007astro.ph..1303R; 2006SoPh..tmp...89R
  We investigate the effects of atmospheric dispersion on observations
  of the Sun at the ever-higher spatial resolutions afforded by increased
  apertures and improved techniques. The problems induced by atmospheric
  refraction are particularly significant for solar physics because
  the Sun is often best observed at low elevations, and the effect of
  the image displacement is not merely a loss of efficiency, but the
  mixing of information originating from different points on the solar
  surface. We calculate the magnitude of the atmospheric dispersion
  for the Sun during the year and examine the problems produced by this
  dispersion in both spectrographic and filter observations. We describe
  an observing technique for scanning spectrograph observations that
  minimizes the effects of the atmospheric dispersion while maintaining
  a regular scanning geometry. Such an approach could be useful for
  the new class of high-resolution solar spectrographs, such as SPINOR,
  POLIS, TRIPPEL, and ViSP.

Title: The Interferometric Bidimensional Spectrometer (IBIS)
Authors: Cauzzi, Gianna; Cavallini, F.; Reardon, K.; Berrilli, F.;
   Rimmele, T.; IBIS Team
Bibcode: 2006SPD....37.0608C
Altcode: 2006BAAS...38..226C
  The Interferometric Bidimensional Spectrometer (IBIS) is an advanced
  instrument for imaging spectroscopy installed at the Dunn Solar
  Telescope at NSO/Sacramento Peak. The instrument has been constructed by
  a consortium of italian institutes and allows for observations of the
  photosphere and chromosphere at high spatial, spectral, and temporal
  resolution. Such observations are essential for performing spatial
  and spectral comparisons with numerical simulations. We will present
  some of the performance characteristics of the instrument and show some
  examples of the IBIS data. We will also show some initial results of the
  recently tested polarimetric mode. IBIS is available for community use
  as a facility instrument of NSO.IBIS has been funded by the Italian
  Research Ministry (MIUR), the Italian Institute for Astrophysics
  (INAF), and the Universities of Florence and Rome. Additional support
  is provided by the National Solar Observatory.

Title: High Resolution Spectropolarimetry of Penumbral Formation
    with IBIS
Authors: Reardon, Kevin; Casini, R.; Cavallini, F.; Tomczyk, S.;
   Rouppe van der Voort, L.; Van Noort, M.; Woeger, F.; Socas Navarro,
   H.; IBIS Team
Bibcode: 2006SPD....37.3503R
Altcode: 2006BAAS...38..260R
  We present the results of first spectropolarimetric observations
  made with the Interferometric Bidimensional Spectrometer (IBIS)
  at the NSO/Dunn Solar Telescope. The use of narrowband imaging and
  post-facto reconstruction techniques allows for observations close
  to the diffraction limit of the vector magnetic field. We will show
  observations of the the formation of an individual penumbral filament
  around a small pore. We measure the magnetic field and velocity field
  of the forming penumbral filament. The spectropolarimetric mode of
  IBIS will be available to the community in the fall of 2006.

Title: Imaging Spectroscopy Of Sunspots Using IBIS
Authors: Balasubramaniam, K. S.; Gary, G. A.; Reardon, K.
Bibcode: 2006SPD....37.0712B
Altcode: 2006BAAS...38..229B
  We use the Interferometric BIdimensional Spectrometer (IBIS) of
  the INAF/Arcetri Astrophysical Observatory and installed at the
  National Solar Observatory (NSO) Dunn Solar Telescope, to understand
  the structure of sunspots. These high resolution observations were
  acquired on 2004 July 30-31, of active region NOAA 10654, using the
  high order NSO adaptive optics system. We map the spatio-temporal
  variation of the penumbral Doppler signatures in three spectral
  lines, FeI 6301.5 Å, FeII 7224.4 Å, and CaII 8542.6 Å, from the
  photosphere to the chromosphere. From a 70-minute temporal average
  of individual 32-second cadence Doppler observations we find that
  the averaged velocities decrease with height, about 3.5 times larger
  in the deeper photosphere (FeII 7224.4 Å height-of-formation ≈50
  km) than in the upper photosphere FeI 6301.5 Å height-of-formation
  ≈350 km), There is a remarkable coherence of Doppler signals over
  the height difference of 300 km. From a high-speed animation of the
  Doppler sequence we find evidence for what appears to be ejection of
  high speed gas concentrations from edges of penumbral filaments into
  the surrounding granular photosphere. The Evershed flow persists a few
  arcseconds beyond the traditionally demarcated penumbra-granulation
  boundary. We present these and other results and discuss implications
  of these measurements for sunspot models.

Title: High-resolution IBIS Observations and Comparison with 3D
    Simulations .
Authors: Asensio Ramos, A.; Janssen, K.; Cauzzi, G.; Reardon, K.
Bibcode: 2006MSAIS...9...59A
Altcode:
  High resolution observations of a very quiet region of the solar
  surface have been obtained with IBIS (Interferometric BIdimensional
  Spectrometer) in the non-magnetic Fe I 7090.4 Å spectral line. We
  present a first comparison between the observed, spatially resolved,
  spectral data and the simulated spectra in a 3D snapshot of a
  radiation-hydrodynamical simulation of the solar atmosphere. Preliminary
  results indicate that the simulations reproduce quite well many of
  the observational properties of the high resolution IBIS data, even
  though the simulations present a velocity distribution that contains
  values quite larger than the observed ones.

Title: IBIS instrumental characteristics and first results
Authors: Cavallini, F.; Reardon, K.
Bibcode: 2006MSAIS...9...55C
Altcode:
  The Interferometric BIdimensional Spectrometer (IBIS) was installed in
  June 2003 at the DST/NSO, where it is used in conjuction with a high
  order AO system. IBIS has since proved to be a reliable and versatile
  instrument for performing high resolution observations in both the
  photosphere and chromosphere. We describe here the instrument and its
  performance characteristics especially with respect to the obtainable
  spectral, temporal and spatial resolutions, providing examples of the
  actual observations.

Title: Quiet Solar Photosphere: Comparisons of High Resolution
    Observations with 3-D Simulations
Authors: Cauzzi, G.; Asensio Ramos, A.; Reardon, K.; Janssen, K.
Bibcode: 2005ESASP.600E..12C
Altcode: 2005dysu.confE..12C; 2005ESPM...11...12C
  No abstract at ADS

Title: Photospheric and Chromospheric structure of Sunspots using
    IBIS.
Authors: Balasubramaniam, K. S.; Gary, G. A.; Reardon, K.
Bibcode: 2005AGUSMSP11A..04B
Altcode:
  We use the Interferometric BIdimensional Spectrometer (IBIS) of the
  INAF/Arcetri Astrophysical Observatory and installed at the National
  Solar Observatory's (NSO) Dunn Solar Telescope, to understand the
  structure of sunspots. Using the spectral lines FeI 6301.5Å, FeII
  7224.4Å and CaII 8542.6Å, we examine the spectroscopic variation of
  sunspot penumbral and umbral structures about the heights of formation
  of these lines. Simultaneous white-light imaging data helps us to
  register and track the images. We map the spatio-temporal variation
  of Doppler signatures in these spectral lines, from the photosphere
  to the chromosphere, and discuss the implication of these variations
  for sunspot models. These high resolution observations were acquired
  on 2004 July 30-31, on a sunspot NOAA 10654, using the higher order
  NSO adaptive optics system.

Title: A Solar Data Model for Use in Virtual Observatories
Authors: Reardon, K. P.; Bentley, R. D.; Messerotti, M.; Giordano, S.
Bibcode: 2004AAS...204.7003R
Altcode: 2004BAAS...36Q.796R
  The creation of a virtual solar observatories relies heavily on the
  merging of the metadata describing different datasets into a common
  form so that it can be handled in a standard way for all associated
  resources. In order to bring together the varied data descriptions
  that already exist, it is necessary to have a common framework on
  which all the different datasets can be represented. The definition of
  this framework is done through a data model which attempts to provide
  a simplified but realistic description of the various entities that
  make up a data set or solar resource. <P />We present the solar data
  model which has been developed as part of the European Grid of Solar
  Observations (EGSO) project. This model attempts to include many of
  the different elements in the field of solar physics, including data
  producers, data sets, event lists, and data providers. This global
  picture can then be used to focus on the particular elements required
  for a specific implementation. We present the different aspects of
  the model and describe some systems in which portions of this model
  have been implemented.

Title: IBIS Observations of Quiet Sun Photosphere - Velocity Structure
    from Fe I 7090.4 Å
Authors: Janßen, Katja; Cauzzi, Gianna; Falchi, Ambretta; Cavallini,
   Fabio; Reardon, Kevin
Bibcode: 2004IAUS..223..631J
Altcode: 2005IAUS..223..631J
  In our contribution we introduce the new Interferometric BIdimensional
  Spectrometer (IBIS) and present the first results on bisector velocities
  of two dimensional spectral scans in FeI 7090.4 Å comparing granules
  and intergranular regions.

Title: Recent results from IBIS
Authors: Cavallini, F.; Baffa, C.; Reardon, K.; Berrilli, F.;
   Cantarano, S.; Egidi, A.
Bibcode: 2003MmSAI..74..796C
Altcode:
  IBIS (Interferometric BIdimensional Spectrometer) is a new instrument
  for solar bidimensional spectroscopy. It essentially consists
  of two Fabry-Perot interferometers, piezo-scanned and capacity
  servo-controlled, used in classic mount and in axial-mode, in series
  with a set of narrow-band interference filters. This instrument will
  operate on a large field of view (80") and on a large wavelength
  range (580 - 860 nm), with high spectral, spatial and temporal
  resolution. IBIS, developed to become one of the focal plane instruments
  of THEMIS, has been completed in its essential form and some tests have
  been already performed. It is now possible therefore to compare expected
  with measured values of the more relevant instrumental parameters.

Title: The Italian solar data archives: national and European
    perspectives
Authors: Messerotti, M.; Coretti, I.; Padovan, S.; Zlobec, P.;
   Antonucci, E.; Cora, A.; Volpicelli, C. A.; Dimitoglou, G.; Reardon,
   K.; Tripicchio, A.; Severino, G.; EGSO Team
Bibcode: 2003MmSAI..74..391M
Altcode:
  We discuss the present status of the solar data archives geographically
  distributed in the Italian Astronomical Observatories of the National
  Institute for Astrophysics (INAF). In particular, we describe the
  national project SOLARNET (SOLAR NETwork) aimed at federating all the
  Italian solar archives as a distributed database, the first step toward
  an Italian Virtual Solar Observatory (IVSO), and the European Grid
  for Solar Observations (EGSO) project, which is under implementation
  to construct the basis for a large solar archive federation based on
  the Grid architecture to provide the scientific user with advanced
  resources such as a solar feature catalogue.

Title: EGSO - The European Grid of Solar Observations
Authors: Reardon, K.; Antonucci, E.; Giordano, S.; Severino, G.;
   Messerotti, M.; EGSO Team
Bibcode: 2003MmSAI..74..823R
Altcode:
  The European Grid of Solar Observations (EGSO) project aims to
  produce the framework for a coordinated community-wide resource for
  obtaining and reducing solar observations. The EGSO will be capable of
  sharing resources coming from all types of providers, while ensuring
  scalability, security, and compatibility among all datasets. The user
  will be provided with a customizable search interface from which to
  simultaneously browse or data mine a range of solar and heliospheric
  data archives. In essence, the EGSO will create the fabric of a virtual
  solar observatory.

Title: Characterization of the IBIS Transmission Profile
Authors: Reardon, K.; Cavallini, F.
Bibcode: 2003MmSAI..74..815R
Altcode:
  We describe the techniques used to characterize the components of
  the IBIS instrument in the laboratory in order to determine the
  operational performance of the completed instrument. In particular,
  we have measured the surface and coating irregularities of the two
  Fabry-Perot interferometers at the heart of IBIS. From this we construct
  a theoretical transmission profile for the instrument and relate that
  to the accuracy that can be obtained in measurements of the Sun.

Title: In-flight Calibration of the UVCS White Light Channel
Authors: Romoli, M.; Frazin, R. A.; Kohl, J. L.; Gardner, L. D.;
   Cranmer, S. R.; Reardon, K.; Fineschi, S.
Bibcode: 2002ISSIR...2..181R
Altcode: 2002ESASR...2..181R; 2002rcs..conf..181R
  The UVCS White Light Channel (WLC) is designed to measure the linearly
  polarized radiance (pB) of the corona, in the wavelength band from 450
  nm to 600 nm, in order to derive one of the fundamental parameters of
  the solar corona: the electron density. This paper gives a thorough
  description of the in-flight radiometric calibration of the WLC, which
  uses the star α Leo and the planet Jupiter as transfer standards
  and is based on calibrations of ground-based instruments. The
  method for computing the polarized radiance from the measurements
  is also described, together with the stray light and polarization
  characterizations obtained from dedicated, in-flight measurements.

Title: Simultaneous Hα and X-ray Observations of Prominence Eruption
    and Disappearance
Authors: Tonooka, H.; Matsumoto, R.; Miyaji, S.; Martin, S. F.;
   Canfield, R. C.; Reardon, K.; McAllister, A.; Shibata, K.
Bibcode: 2000AdSpR..26..473T
Altcode:
  Prominence eruptions or disappearances observed with an Hα limb
  filtergraph can be classified into 3 categories, the eruptive
  prominence, the quasi-eruptive prominence, and the disappearing
  prominence. We investigated their mechanism by comparing the results
  of simultaneous observations by Yohkoh SXT and Hα. We found that soft
  X-ray features change in both eruptive prominences and quasieruptive
  prominences, whereas no significant change takes place in disappearing
  prominences.In one prominence eruption event soft X-ray cusp structure
  suggests that the reconnection point is just below the Hα prominence

Title: The Eruptive Flare of 15 November 1991: Preflare Phenomena
Authors: Canfield, Richard C.; Reardon, Kevin P.
Bibcode: 1998SoPh..182..145C
Altcode:
  We present and interpret observations of the preflare phase of the
  eruptive flare of 15 November, 1991 in NOAA AR 6919. New flux emerged
  in this region, indicated by arch filaments in Hα and increasing
  vertical flux in vector magnetograms. With increasing frequency
  before the eruption, transient dark Hα fibrils were observed that
  crossed Hα bright plage and the magnetic inversion line to extend
  from the region of flux emergence to the filament, whose eruption was
  associated with the flare. These crossing fibrils were dynamic, and
  were often associated with sites of propagating torsional motion. These
  sites propagated from the region of flux emergence into the filament
  flux system. We interpret these morphological and dynamic features in
  terms of relaxation after magnetic reconnection episodes which create
  longer field lines within the filament flux system, as envisioned in
  the tether cutting model, and transfer twist to it, as well.

Title: Design Issues for HTML-Based Solar Archive Interfaces
Authors: Reardon, Kevin
Bibcode: 1998ASPC..155..292R
Altcode: 1998sasp.conf..292R
  No abstract at ADS

Title: Whole Sun Catalog: Design and Implementation
Authors: Dimitoglou, G.; Mendiboure, C.; Reardon, K.; Sanchèz-Duarte,
   L.
Bibcode: 1998ASPC..155..297D
Altcode: 1998sasp.conf..297D
  No abstract at ADS

Title: The RISE-PSPT telescope operative at the OAR
Authors: Ermolli, I.; Fofi, M.; Torelli, M.; Reardon, K.
Bibcode: 1998MmSAI..69..631E
Altcode:
  No abstract at ADS

Title: SXR Coronal Polar Jets and Recurrent Flashes
Authors: Koutchmy, S.; Hara, H.; Shibata, K.; Suematsu, Y.; Reardon, K.
Bibcode: 1998ASSL..229...87K
Altcode: 1998opaf.conf...87K
  No abstract at ADS

Title: Soft X-Ray Features of Prominence Eruption and Disappearance
Authors: Tonooka, H.; Matsumoto, R.; Miyaji, S.; Martin, S. F.;
   Canfield, R. C.; Reardon, K.; McAllister, A.; Shibata, K.
Bibcode: 1998ASSL..229..371T
Altcode: 1998opaf.conf..371T
  No abstract at ADS

Title: Variation of the Solar Granulation Over the Cycle: Previous
    Results and Future Observations
Authors: Roudier, Th.; Reardon, K.
Bibcode: 1998ASPC..140..455R
Altcode: 1998ssp..conf..455R
  No abstract at ADS

Title: The Role of Data Archives in Synoptic Solar Physics
Authors: Reardon, Kevin
Bibcode: 1998ASPC..140..467R
Altcode: 1998ssp..conf..467R
  The detailed study of solar cycle variations requires analysis of
  recorded datasets spanning many years of observations, that is,
  a data archive. The use of digital data, combined with powerful
  database server software, gives such archives new capabilities
  to provide, quickly and flexibly, selected pieces of information
  to scientists. Use of standardized protocols will allow multiple
  databases, independently maintained, to be seamlessly joined, allowing
  complex searches spanning multiple archives. These data archives also
  benefit from being developed in parallel with the telescope itself,
  which helps to assure data integrity and to provide close integration
  between the telescope and archive. Development of archives that can
  guarantee long-term data availability and strong compatibility with
  other projects makes solar-cycle studies easier to plan and realize.

Title: The Magneto-Optical Filter in Napoli: Perspectives and Test
    Observations
Authors: Moretti, P. F.; Severino, G.; Cauzzi, G.; Reardon, K.;
   Straus, T.; Cacciani, A.; Marmolino, C.; Oliviero, M.; Smaldone, L. A.
Bibcode: 1997ASSL..225..293M
Altcode: 1997scor.proc..293M
  An observing station based on the Magneto-Optical-Filter (MOF)
  technology is being installed at Osservatorio Astronomico di
  Capodimonte, in Napoli. In this paper, the main characteristics and
  goals of this new instrument are discussed, and several velocity and
  magnetic observations from a test campaign are shown.

Title: X-ray photon spectroscopy with the YOHKOH Soft X-ray telescope
Authors: Labonte, B.; Reardon, K.
Bibcode: 1997SPD....28.0140L
Altcode: 1997BAAS...29..886L
  Individual X-ray photons in the keV energy range produce hundreds of
  photoelectrons in a single pixel of a CCD array detector. The number
  of photoelectrons produced is a linear function of the photon energy,
  allowing the measurement of spectral information with an imaging
  detector system. The Yohkoh Soft X-ray Telescope uses a CCD in an
  integrating mode and makes temperature estimates from multiband filter
  photometry. We show how the SXT can be used in a new way to perform
  a limited type of photon spectroscopy. By measuring the variance in
  intensity through a single filter of an x-ray source on repeated SXT
  images, the mean energy per detected photon can be determined. This
  value is related to the underlying coronal spectrum, and hence can
  be used to deduce the plasma temperature. We compare the results
  of the temperatures derived using this new technique on a series of
  SXT images of a post-flare loop system with the temperatures derived
  using the standard flux-ratio method. We demonstrate that the bright
  postflare loops really are cooler than the surrounding material, as
  shown by Tsuneta et al. (1992). Given the large dynamic range of the
  soft x-ray flux observed from the Sun, we describe the requirements for
  a future instrument that would take advantage of photon spectroscopy.

Title: SXR Coronal Flashes.
Authors: Koutchmy, S.; Hara, H.; Suematsu, Y.; Reardon, K.
Bibcode: 1997A&A...320L..33K
Altcode:
  We provide evidence for the existence of a new type of soft X-ray
  (SXR) brightening event that we call coronal flashes. The phenomenon
  was observed on deep time series taken with the SXT of Yohkoh in the
  north polar coronal hole, near the sunspot minimum. Events last as
  short as 1.5 mn and the corresponding SXR flux span the range of
  energies, from single pixel brightenings corresponding to fluxes
  of about 10^24^erg but barely surpassing the level of the noise,
  to higher and more smeared multiple px brightenings still orders
  of magnitude smaller than the known small SXR bright points and/or
  transient brightenings. The typical occurrence rate of flashes is
  1-event/arcmin^2^/5mn with a 1/2mn integration time. At least part of
  the coronal flashes are recurrent and some of them could be associated
  with a SXR jet; it is not clear what is their optical counterpart.

Title: ARTHEMIS: The Archive Project for the IPM and THEMIS
Authors: Reardon, K.; Severino, G.; Cauzzi, G.; Gomez, M. T.; Straus,
   T.; Russo, G.; Smaldone, G.; Marmolino, C.
Bibcode: 1997ASPC..118..398R
Altcode: 1997fasp.conf..398R
  We describe the plan for ARTHEMIS, the italian archive for THEMIS, from
  the point of view of the prospective users of the archive. This archive
  is designed to store the data from the Italian Panoramic Monochromator
  (IPM) instrument installed on THEMIS as well as the full-disk images
  obtained by the telescope. We break the expected users down into
  seven categories: a) prospective IPM users; b) campaign planners; c)
  data analysts, d) external collaborators; e) instrument monitors, f)
  archival observers; and g) the general public.

Title: ARTHEMIS: The archive project for the Italian Panoramic
    Monochromator
Authors: Reardon, K.; Severino, G.; Cauzzi, G.; Gomez, M. T.; Straus,
   T.; Russo, G.; Smaldone, L. A.; Marmolino, C.
Bibcode: 1997MmSAI..68..499R
Altcode:
  No abstract at ADS

Title: Coronal heating experiments of the Williams College Group at
    Mukandgarh Fort, Rajasthan.
Authors: Pasachoff, J. M.; Babcock, B. A.; Diaz, S.; Reardon, K. P.;
   Kutner, E. R.
Bibcode: 1997KodOB..13...75P
Altcode:
  The authors report on the Williams College expedition to Mukandgarh
  Fort, Rajasthan, for the total solar eclipse of 24 October 1995. The
  main experiments were a search for 1 Hz oscillations in coronal loops
  as an indication of magnetohydrodynamic theories of coronal heating
  and a mapping of the coronal temperature through comparison of images
  at specific ultraviolet wavelengths, measuring the difference between
  the photospheric and coronal continuum. The authors also obtained a
  variety of coronal images.

Title: H alpha Surges and X-Ray Jets in AR 7260
Authors: Canfield, Richard C.; Reardon, Kevin P.; Leka, K. D.; Shibata,
   K.; Yokoyama, T.; Shimojo, M.
Bibcode: 1996ApJ...464.1016C
Altcode:
  We discuss nine events, observed simultaneously as jets in X-rays and
  surges in Hα, which are associated with moving magnetic bipoles. The
  X-ray jets share many features with those discovered by Yohkoh in active
  regions, emerging flux regions, and X-ray bright points (see paper by
  Shibata et al.); in particular, they originate near one end of a pair of
  small flaring loops. The Hα surges are adjacent to the X-ray jets. At
  the bases of these surges we observe both blueshifts (initially) and
  redshifts (1-2 minutes later). All the observed surges spin in a sense
  consistent with the relaxation of the twist stored in the magnetic
  fields of the moving magnetic bipoles. Newly discovered phenomena
  include footpoint convergence and moving-blueshift features. <P
  />We develop a model of the role of magnetic reconnection in these
  events. This model explains the temporal and spatial relationship
  between the jets and surges, the role of the moving bipoles, the
  flaring X-ray loops and their converging Hα footpoints, the Hα
  moving-blueshift features, the direction and amount of spin of the
  surges, and the relative temporal development of the Hα redshifts
  and blueshifts.

Title: H alpha Surges and X-ray Jets in AR7260
Authors: Canfield, R. C.; Reardon, K. P.; Leka, K. D.; Shibata, K.;
   Yokoyama, T.; Shimojo, M.
Bibcode: 1996mpsa.conf...49C
Altcode: 1996IAUCo.153...49C
  No abstract at ADS

Title: YOHKOH SXT Observations of Prominence Eruption and
    Disappearance
Authors: Tonooka, H.; Matsumoto, R.; Miyaji, S.; Martin, S. F.;
   Canfield, R. C.; Reardon, K.; McAllister, A.; Shibata, K.
Bibcode: 1996mpsa.conf..493T
Altcode: 1996IAUCo.153..493T
  No abstract at ADS

Title: Study of the High-Frequency Coronal-Loop Oscillation Spectrum
    at the 1994 Total Solar Eclipse
Authors: Pasachoff, J. M.; Babcock, B.; Diaz, J. S.; Reardon, K.;
   Nichols-Kiley, R.
Bibcode: 1995AAS...18710106P
Altcode: 1995BAAS...27.1427P
  We summarize results from observations made at the November 3, 1994,
  total solar eclipse from the International Astronomical Union site
  in Putre, Chile, through partly cloudy skies. We discuss the image
  reduction and analysis of two simultaneous series of coronal images with
  a cadence of 10 frames per second for a total time of 160 seconds. One
  series of images was taken through a filter isolating the 530.3 nm
  [Fe XIV] coronal green line and the other through a 10 nm filter in
  the nearby K-corona continuum. After standard calibrations and image
  alignment, we use Fourier analysis to search in the [Fe XIV] channel
  for high-frequency ( 1 Hz) intensity oscillations in loops at the base
  of the corona. Such oscillations are predicted as a result of density
  fluctuations from the resonant absorption of high-frequency Alfven
  waves. The dissipation of a significant amount of mechanical energy from
  the photosphere into the corona through this mechanism could provide
  sufficient energy to heat the corona. The observations were supported by
  NSF ATM-9005194 and Education Division DUE-9351279 grants; the National
  Geographic Society through their Committee on Research and Explorations
  (grant: 5190-94), and the Keck Northeastern Astronomy Consortium.

Title: Coronal Heating Studies at the 1994 Total Eclipse
Authors: Pasachoff, J. M.; Babcock, B.; Reardon, K.
Bibcode: 1995pist.conf...18P
Altcode:
  No abstract at ADS

Title: Coronal Loop Interaction Observed at Visible Wavelengths
Authors: Smartt, R. N.; Zhang, Z.; Kim, I. S.; Reardon, K. P.
Bibcode: 1994scs..conf..219S
Altcode: 1994IAUCo.144..219S
  Brightening is observed to occur in regions where two loops come
  into contact, with resultant heating of the common plasma volume,
  and subsequent cooling. The observations show systematically that a
  brightness maximum in the cooler (634 Å) line lags that of the hotter
  (5303 Å) line. Coalescence is evident in that the brightness can extend
  away from the overlapping region along the adjacent parts of the loops.

Title: Filament Tether Cutting Before a Major Eruptive Flare
Authors: Canfield, R. C.; Blais, K. A.; Reardon, K. P.; Acton, Loren;
   Kurokawa, H.
Bibcode: 1994ASPC...68..411C
Altcode: 1994sare.conf..411C
  No abstract at ADS

Title: The X Flare of 15 November, 1991: Preflare Flux Emergence,
    Heating and Filament Eruption
Authors: Canfield, R. C.; Blais, K. A.; McClymont, A. N.; Metcalf,
   T. R.; Reardon, K. P.; Wülser, J. -P.; Acton, L. W.; Kurokawa, H.;
   Hirayama, T.
Bibcode: 1994xspy.conf..153C
Altcode:
  No abstract at ADS

Title: Simultaneous IR and Visible Light Measurements of the Solar
    Granulation
Authors: Keil, S.; Kuhn, J.; Lin, H.; Reardon, K.
Bibcode: 1994IAUS..154..251K
Altcode:
  No abstract at ADS

Title: Coronal Images from the 1984 Solar Eclipse
Authors: Pasachoff, Jay M.; Reardon, Kevin P.; MacKenty, John W.
Bibcode: 1993SoPh..146..405P
Altcode:
  We present digitized photographs of the white-light solar corona
  taken during the total solar eclipse of 22-23 November, 1984, on both
  calibrated black-and-white film and on color film. Conditions on site
  in Hula, Papua New Guinea, were exceptionally clear. The color image
  was used to produce an isophotal map of the inner corona, from which
  a flattening coefficient of 0.23 was measured. The black-and-white
  image was enhanced through a digital radial filter. Our images are the
  best processed images available from the 1984 eclipse and so provide
  important data for synoptic observations.

Title: Filament Tether Cutting Before a Major Eruptive Flare
Authors: Canfield, R. C.; Blais, K. A.; McClymont, A. N.; Metcalf,
   T. R.; Reardon, K. P.; Wuelser, J. -P.; Acton, L. W.; Kurokawa, H.
Bibcode: 1993BAAS...25.1188C
Altcode:
  No abstract at ADS

Title: High-Frequency Acoustic Waves in the Solar Atmosphere
Authors: Reardon, Kevin
Bibcode: 1991usra.conf..100R
Altcode:
  No abstract at ADS

