Author name code: kobelski
ADS astronomy entries on 2022-09-14
author:"Kobelski, Adam" 
------------------------------------------------------------------------  

Title: Quiet Sun Center to Limb Variation of the Linear Polarization
    Observed by CLASP2 Across the Mg II h and k Lines
Authors: Rachmeler, L. A.; Bueno, J. Trujillo; McKenzie, D. E.;
   Ishikawa, R.; Auchère, F.; Kobayashi, K.; Kano, R.; Okamoto,
   T. J.; Bethge, C. W.; Song, D.; Ballester, E. Alsina; Belluzzi,
   L.; Pino Alemán, T. del; Ramos, A. Asensio; Yoshida, M.; Shimizu,
   T.; Winebarger, A.; Kobelski, A. R.; Vigil, G. D.; Pontieu, B. De;
   Narukage, N.; Kubo, M.; Sakao, T.; Hara, H.; Suematsu, Y.; Štěpán,
   J.; Carlsson, M.; Leenaarts, J.
Bibcode: 2022ApJ...936...67R
Altcode: 2022arXiv220701788R
  The CLASP2 (Chromospheric LAyer Spectro-Polarimeter 2) sounding rocket
  mission was launched on 2019 April 11. CLASP2 measured the four Stokes
  parameters of the Mg II h and k spectral region around 2800 Å along a
  200″ slit at three locations on the solar disk, achieving the first
  spatially and spectrally resolved observations of the solar polarization
  in this near-ultraviolet region. The focus of the work presented here
  is the center-to-limb variation of the linear polarization across these
  resonance lines, which is produced by the scattering of anisotropic
  radiation in the solar atmosphere. The linear polarization signals of
  the Mg II h and k lines are sensitive to the magnetic field from the
  low to the upper chromosphere through the Hanle and magneto-optical
  effects. We compare the observations to theoretical predictions
  from radiative transfer calculations in unmagnetized semiempirical
  models, arguing that magnetic fields and horizontal inhomogeneities
  are needed to explain the observed polarization signals and spatial
  variations. This comparison is an important step in both validating and
  refining our understanding of the physical origin of these polarization
  signatures, and also in paving the way toward future space telescopes
  for probing the magnetic fields of the solar upper atmosphere via
  ultraviolet spectropolarimetry.

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: A Publicly Available Multiobservatory Data Set of an Enhanced
    Network Patch from the Photosphere to the Corona
Authors: Kobelski, Adam R.; Tarr, Lucas A.; Jaeggli, Sarah A.; Luber,
   Nicholas; Warren, Harry P.; Savage, Sabrina
Bibcode: 2022ApJS..261...15K
Altcode: 2022arXiv220501766K
  New instruments sensitive to chromospheric radiation at X-ray, UV,
  visible, IR, and submillimeter wavelengths have become available that
  significantly enhance our ability to understand the bidirectional
  flow of energy through the chromosphere. We describe the calibration,
  coalignment, initial results, and public release of a new data set
  combining a large number of these instruments to obtain multiwavelength
  photospheric, chromospheric, and coronal observations capable of
  improving our understanding of the connectivity between the photosphere
  and the corona via transient brightenings and wave signatures. The
  observations center on a bipolar region of enhanced-network
  magnetic flux near disk center on SOL2017-03-17T14:00-17:00. The
  comprehensive data set provides one of the most complete views to
  date of chromospheric activity related to small-scale brightenings
  in the corona and chromosphere. Our initial analysis shows a strong
  spatial correspondence between the areas of broadest width of the
  hydrogen-α spectral line and the hottest temperatures observed in
  Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 radio
  data, with a linear coefficient of 6.12 × 10<SUP>-5</SUP>Å/K. The
  correspondence persists for the duration of cotemporal observations
  (≍60 m). Numerous transient brightenings were observed in multiple
  data series. We highlight a single, well-observed transient brightening
  in a set of thin filamentary features with a duration of 20 minutes. The
  timing of the peak intensity transitions from the cooler (ALMA, 7000 K)
  to the hotter (XRT, 3 MK) data series.

Title: Radar observations and characterization of (436724) 2011 UW158
Authors: Naidu, Shantanu; Benner, Lance; Brozovic, Marina; Giorgini,
   Jon; Busch, Michael; Taylor, Patrick; Richardson, James; Ghigo, Frank;
   Kobelski, Adam; Ford, Linda
Bibcode: 2019EPSC...13..737N
Altcode:
  Near-Earth asteroid (436724) 2011 UW158 made a close approach to the
  Earth on 2015 July 19 at a distance of 0.016 au (6.4 lunar distances),
  which provided an outstanding opportunity for ground-based radar
  imaging. We observed it using the Goldstone X-band (8560 MHz, 3.5 cm)
  radar, the Green Bank Telescope (GBT), and Arecibo S-band (2380 MHz,
  12.6 cm) radar, between July 13-26. The radar dataset allowed us
  to estimate the shape, spin state, and other physical properties of
  the object.

Title: Frequency Agile Solar Radiotelescope
Authors: Bastian, Tim; Bain, H.; Bradley, R.; Chen, B.; Dahlin, J.;
   DeLuca, E.; Drake, J.; Fleishman, G.; Gary, D.; Glesener, L.; Guo,
   Fan; Hallinan, G.; Hurford, G.; Kasper, J.; Ji, Hantao; Klimchuk,
   J.; Kobelski, A.; Krucker, S.; Kuroda, N.; Loncope, D.; Lonsdale,
   C.; McTiernan, J.; Nita, G.; Qiu, J.; Reeves, K.; Saint-Hilaire, P.;
   Schonfeld, S.; Shen, Chengcai; Tun, S.; Wertheimer, D.; White, S.
Bibcode: 2019astro2020U..56B
Altcode:
  We describe the science objectives and technical requirements for a
  re-scoped Frequency Agile Solar Radiotelescope (FASR). FASR fulfills
  a long term community need for a ground-based, solar-dedicated, radio
  telescope - a next-generation radioheliograph - designed to perform
  ultra-broadband imaging spectropolarimetry.

Title: Transient dynamics and energy transfer from the photosphere
to the low corona: initial results from a coordinated ALMA, DST,
    Hinode, IRIS, and SDO observation campaign
Authors: Kobelski, Adam; Tarr, Lucas A.; Jaeggli, Sarah A.; Savage,
   Sabrina
Bibcode: 2019AAS...23430702K
Altcode:
  We present initial results from a coordinated observation campaign
  to study transient dynamics and energy transfer in the low solar
  atmosphere. The observations ran from approximately 2017-03-21 from
  13UT to 19UT, and include data from Hinode, IRIS, DST, and ALMA. The
  target, a small, magnetically bipolar active area associated with a
  coronal bright point, was chosen for showing reasonable dynamics in the
  chromosphere (as dictated by AIA 304 data from the day prior), and being
  near disk center to better facilitate magnetic field measurement. The
  campaign was designed to capture the dynamics of the target with as
  rapid a timescale as possible for each instrument. Photospheric dynamics
  are available from broadband IBIS data and the HMI. New to this dataset,
  the chromospheric dynamics were observed in radio frequencies using ALMA
  (Band 3: 92-108GHz) at a 2s cadence. Additional chromospheric data are
  spectral H-α from the IBIS instrument at the DST, spectropolarimetic
  HeI 10830 from the FIRS instrument at the DST, and the medium linelist
  from IRIS; coronal data includes imaging from XRT and spectral data
  from EIS. In this first set of results, we discuss the frequency of
  transient brightenings observed in each set of imaging data and how
  the spatial distribution relates across each data channel and to the
  regions magnetic topology.

Title: Radio Propagation Diagnostics of the Inner Heliosphere in
    the Era of the Parker Solar Probe
Authors: Kobelski, Adam; Bastian, Timothy S.; Vourlidas, Angelos
Bibcode: 2019AAS...23410706K
Altcode:
  The solar wind offers and extraordinary laboratory for studying
  turbulence, turbulent dissipation, and heating. The Parker Solar Probe
  (PSP) was launched in August 2018 to study these and other important
  processes in the inner heliosphere. One type of observation that will
  complement those of PSP are radio propagation measurements of solar
  wind turbulence in the outer corona and the inner heliosphere. This
  type of observation can provide measurements of the angular broadening
  of distant spatially coherent background sources that transilluminate
  the foreground solar wind plasma. This well-known technique can be used
  to measure the spatial spectrum of electron density inhomogeneities in
  the solar wind on scales of 100s of meters to 10s of kilometers inside
  of 10-15 solar radii over a wide range of position angles. <P />Here
  we report the results of a pilot study of background sources using the
  Jansky Very Large Array (JVLA) in summer 2015. Unlike previous studies
  of this kind, the JVLA's much greater sensitivity allows fainter
  and more numerous sources to be used as probes of the foreground
  medium. We observed 11 background sources in 16 sessions at apparent
  radial distances of 2-7 solar radii. We confirm previous findings:
  that the spectrum is flatter than Kolmogorov and that is highly
  anisotropic. Unlike previous studies we find breaks into steeper spectra
  for some sources on short spatial scales, suggestive of a transition to
  dissipation. <P />Looking forward, we describe observations planned in
  August 2019 in support of the third PSP perihelion passage (35.7 solar
  radii). The VLA will be used to observe the corona and inner heliosphere
  along 70 pierce points &lt;10 solar radii. These observations will not
  only provide global context about the state of the inner heliosphere
  at time of perihelion passage, they will also baseline key solar wind
  parameters that can be compared directly with PSP measurements. These
  include turbulence level, spectral index, degree of anisotropy, and
  the orientation of the magnetic field. The PSP measurements will, in
  turn, provide measurements that will validate key assumptions made in
  interpreting the radio data.

Title: High Frequency Solar Observing at the Green Bank Observatory
Authors: Kobelski, Adam
Bibcode: 2019BAAS...51c.533K
Altcode: 2019astro2020T.533K
  Here we discuss the utility of performing high frequency observations of
  the solar chromosphere with the 100 m Green Bank Telescope at 100 GHz.

Title: Radio Observational Constraints on Turbulent Astrophysical
    Plasmas
Authors: Bastian, Tim; Cordes, James; Kasper, Justin; Kobelski,
   Adam; Korreck, Kelly; Howes, Gregory; Salem, Chadi; Spangler, Steve;
   Vourlidas, Angelos
Bibcode: 2019astro2020T.307B
Altcode: 2019arXiv190405807B
  Using radio observations of background sources, scattering phenomena
  may be used to characterize the properties of foreground turbulent
  plasma. We discuss the potential of such techniques to explore
  turbulence in the solar wind and interstellar medium. The Next
  Generation VLA will be an ideal instrument to exploit these techniques.

Title: Observations of the solar chromosphere with ALMA and comparison
    with theoretical models
Authors: Brajsa, Roman; Sudar, Davor; Skokic, Ivica; Benz, Arnold O.;
   Kuhar, Matej; Kobelski, Adam; Wedemeyer, Sven; White, Stephen M.;
   Ludwig, Hans-G.; Temmer, Manuela; Saar, Steven H.; Selhorst, Caius L.
Bibcode: 2018csss.confE..37B
Altcode: 2018arXiv181207293B
  In this work we use solar observations with the ALMA radio telescope
  at the wavelength of 1.21 mm. The aim of the analysisis to improve
  understanding of the solar chromosphere, a dynamic layer in the
  solar atmosphere between the photosphere andcorona. The study has
  an observational and a modeling part. In the observational part
  full-disc solar images are analyzed.Based on a modied FAL atmospheric
  model, radiation models for various observed solar structures are
  developed. Finally, theobservational and modeling results are compared
  and discussed.

Title: Probing the Inner Heliosphere Using Radio Diagnostic Techniques
Authors: Bastian, Tim; Kobelski, Adam
Bibcode: 2018shin.confE..38B
Altcode:
  A variety of radio propagation techniques - angular and spectral
  broadening, scintillation, and Faraday rotation - can be used to probe
  regions in the corona and solar wind that are otherwise inaccessible to
  direct observation. We present some recent pilot observations made by
  the Jansky Very Large Array to illustrate their potential for deducing
  key properties of solar wind turbulence in the inner heliosphere. We
  discuss prospects for exploiting these techniques in a more systematic
  way in the era of the Parker Solar Probe and the Solar Obiter.

Title: Searching for Supra Arcade Downflows in the Earth's Magnetotail
    and Dipolarization Fronts in Solar Flares
Authors: Kobelski, Adam; Savage, Sabrina L.; Malaspina, David
Bibcode: 2018tess.conf10207K
Altcode:
  Pinpointing the location of a single reconnection event in the corona
  is difficult due to observational constraints, although features
  directly resulting from this rapid reconfiguration of the field lines
  can be observed beyond the reconnection site. One set of such features
  are outflows in the form of post-reconnection loops, which have been
  linked to observations of supra-arcade downflows (SADs). SADs appear
  as sunward-traveling, density-depleted regions above flare arcades
  that develop during long duration eruptions. The limitations of
  remote sensing methods inherently results in ambiguities regarding the
  interpretation of SAD formation. Of particular interest is how these
  features are related to post-reconnection retracting magnetic field
  lines. <P />In planetary magnetospheres, similar events to solar flares
  occur in the form of substorms, where reconnection in the anti-sunward
  tail of the magnetosphere causes field lines to retract toward the
  planet. Using data from the Time History of Events and Macroscopic
  Interactions during Substorms (THEMIS), we compare one particular
  aspect of substorms, dipolarization fronts, to SADs. Dipolarization
  fronts are observed as rapid but temporary changes in the magnetic
  field of the magnetotail plasma sheet into a more potential-like,
  dipolar shape. These dipolarization fronts are believed to be retracting
  post-reconnection field lines. We combine data sets to show that the
  while the densities and magnetic fields involved vary greatly between
  the regimes, the plasma βs and Alfvén speeds are similar. These
  similarities allow direct comparison between the retracting field lines
  and their accompanying wakes of rarified plasma observed with THEMIS
  around the Earth to the observed morphological density depletions
  visible with XRT and AIA on the Sun. These results are an important
  source of feedback for models of coronal current sheets.

Title: First analysis of solar structures in 1.21 mm full-disc ALMA
    image of the Sun
Authors: Brajša, R.; Sudar, D.; Benz, A. O.; Skokić, I.; Bárta,
   M.; De Pontieu, B.; Kim, S.; Kobelski, A.; Kuhar, M.; Shimojo, M.;
   Wedemeyer, S.; White, S.; Yagoubov, P.; Yan, Y.
Bibcode: 2018A&A...613A..17B
Altcode: 2017arXiv171106130B
  Context. Various solar features can be seen in emission or absorption
  on maps of the Sun in the millimetre and submillimetre wavelength
  range. The recently installed Atacama Large Millimetre/submillimetre
  Array (ALMA) is capable of observing the Sun in that wavelength range
  with an unprecedented spatial, temporal and spectral resolution. To
  interpret solar observations with ALMA, the first important step is to
  compare solar ALMA maps with simultaneous images of the Sun recorded in
  other spectral ranges. <BR /> Aims: The first aim of the present work
  is to identify different structures in the solar atmosphere seen in the
  optical, infrared, and EUV parts of the spectrum (quiet Sun, active
  regions, prominences on the disc, magnetic inversion lines, coronal
  holes and coronal bright points) in a full-disc solar ALMA image. The
  second aim is to measure the intensities (brightness temperatures) of
  those structures and to compare them with the corresponding quiet Sun
  level. <BR /> Methods: A full-disc solar image at 1.21 mm obtained on
  December 18, 2015, during a CSV-EOC campaign with ALMA is calibrated and
  compared with full-disc solar images from the same day in Hα line, in
  He I 1083 nm line core, and with various SDO images (AIA at 170 nm, 30.4
  nm, 21.1 nm, 19.3 nm, and 17.1 nm and HMI magnetogram). The brightness
  temperatures of various structures are determined by averaging over
  corresponding regions of interest in the calibrated ALMA image. <BR />
  Results: Positions of the quiet Sun, active regions, prominences on
  the disc, magnetic inversion lines, coronal holes and coronal bright
  points are identified in the ALMA image. At the wavelength of 1.21
  mm, active regions appear as bright areas (but sunspots are dark),
  while prominences on the disc and coronal holes are not discernible
  from the quiet Sun background, despite having slightly less intensity
  than surrounding quiet Sun regions. Magnetic inversion lines appear as
  large, elongated dark structures and coronal bright points correspond
  to ALMA bright points. <BR /> Conclusions: These observational results
  are in general agreement with sparse earlier measurements at similar
  wavelengths. The identification of coronal bright points represents
  the most important new result. By comparing ALMA and other maps,
  it was found that the ALMA image was oriented properly and that the
  procedure of overlaying the ALMA image with other images is accurate
  at the 5 arcsec level. The potential of ALMA for physics of the solar
  chromosphere is emphasised.

Title: Exploring the Sun with ALMA
Authors: Bastian, T. S.; Bárta, M.; Brajša, R.; Chen, B.; Pontieu,
   B. D.; Gary, D. E.; Fleishman, G. D.; Hales, A. S.; Iwai, K.; Hudson,
   H.; Kim, S.; Kobelski, A.; Loukitcheva, M.; Shimojo, M.; Skokić,
   I.; Wedemeyer, S.; White, S. M.; Yan, Y.
Bibcode: 2018Msngr.171...25B
Altcode:
  The Atacama Large Millimeter/submillimeter Array (ALMA) Observatory
  opens a new window onto the Universe. The ability to perform continuum
  imaging and spectroscopy of astrophysical phenomena at millimetre and
  submillimetre wavelengths with unprecedented sensitivity opens up new
  avenues for the study of cosmology and the evolution of galaxies, the
  formation of stars and planets, and astrochemistry. ALMA also allows
  fundamentally new observations to be made of objects much closer
  to home, including the Sun. The Sun has long served as a touchstone
  for our understanding of astrophysical processes, from the nature of
  stellar interiors, to magnetic dynamos, non-radiative heating, stellar
  mass loss, and energetic phenomena such as solar flares. ALMA offers
  new insights into all of these processes.

Title: A comparison of solar ALMA observations and model based
    predictions of the brightness temperature
Authors: Brajša, R.; Kuhar, M.; Benz, A. O.; Skokić, I.; Sudar,
   D.; Wedemeyer, S.; Báarta, M.; De Pontieu, B.; Kim, S.; Kobelski,
   A.; Shimojo, M.; White, S.; Yagoubov, P.; Yan, Y.; Ludwig, H. G.;
   Temmer, M.; Saar, S. H.; Selhorst, C. L.; Beuc, R.
Bibcode: 2018CEAB...42....1B
Altcode:
  The new facility Atacama Large Millimeter/submillimeter Array (ALMA) is
  capable of observing the Sun in the wavelength range from 0.3 mm to 10
  mm with an unprecedented spatial, temporal and spectral resolution. The
  first aim of the present work is to identify different structures
  in the solar atmosphere (quiet Sun, active regions, filaments on the
  disc, and coronal holes) in a full disc solar ALMA image at 1.21 mm
  obtained on December 18, 2015 during a CSV-EOC campaign. It is compared
  with full disc solar images from the same day in the Hα line (Cerro
  Tololo Observatory, NISP), and at three EUV wavelengths (30.4 nm,
  21.1 nm, 17.1 nm; a composite SDO image). Positions of the quiet Sun
  areas, active regions, filaments on the disc, and coronal holes are
  identified in the ALMA image. To interpret solar observations with ALMA
  it is important to compare the measured and calculated intensities
  of various solar structures. So, the second aim of this work is to
  calculate the intensity (brightness temperature) for those structures
  (quiet Sun, active regions, filaments on the disc, and coronal holes)
  for a broad wavelength range (from 0.3 mm to 10 mm), closely related
  to that of the ALMA, and to compare the results with available
  ALMA observations. Thermal bremsstrahlung is the dominant radiation
  mechanism for explanation of the observed phenomena. A procedure for
  calculating the brightness temperature for a given wavelength and
  model atmosphere, which integrates the radiative transfer equation
  for thermal bremsstrahlung, is used. At the wavelength of 1.21 mm
  active regions appear as bright areas, while filaments on the disc and
  coronal holes are not discernible from the quiet Sun background. The
  models generally agree with the observed results: Active regions are
  bright primarily due to higher densities, filaments can appear bright,
  dark or not at all and coronal holes cannot be easily identified.

Title: Supra Arcade Downflows in the Earth's Magnetotail
Authors: Kobelski, A.; Savage, S. L.; Malaspina, D.
Bibcode: 2017AGUFMSH41A2752K
Altcode:
  Pinpointing the location of a single reconnection event in the corona
  is difficult due to observational constraints, although features
  directly resulting from this rapid reconfiguration of the field lines
  can be observed beyond the reconnection site. One set of such features
  are outflows in the form of post-reconnection loops, which have been
  linked to observations of supra-arcade downflows (SADs). SADs appear
  as sunward-traveling, density-depleted regions above flare arcades
  that develop during long duration eruptions. The limitations of
  remote sensing methods inherently results in ambiguities regarding the
  interpretation of SAD formation. Of particular interest is how these
  features are related to post-reconnection retracting magnetic field
  lines. In planetary magnetospheres, similar events to solar flares
  occur in the form of substorms, where reconnection in the anti-sunward
  tail of the magnetosphere causes field lines to retract toward the
  planet. Using data from the Time History of Events and Macroscopic
  Interactions during Substorms (THEMIS), we compare one particular aspect
  of substorms, dipolarization fronts, to SADs. Dipolarization fronts
  are observed as rapid but temporary changes in the magnetic field
  of the magnetotail plasma sheet into a more potential-like dipolar
  shape. These dipolarization fronts are believed to be retracting
  post-reconnection field lines. We combine data sets to show that the
  while the densities and magnetic fields involved vary greatly between
  the regimes, the plasma βs and Alfvén speeds are similar. These
  similarities allow direct comparison between the retracting field lines
  and their accompanying wakes of rarified plasma observed with THEMIS
  around the Earth to the observed morphological density depletions
  visible with XRT and AIA on the Sun. These results are an important
  source of feedback for models of coronal current sheets.

Title: Large Scale Coordination of Small Scale Structures
Authors: Kobelski, Adam; Tarr, Lucas A.; Jaeggli, Sarah A.; Savage,
   Sabrina
Bibcode: 2017SPD....4820005K
Altcode:
  Transient brightenings are ubiquitous features of the solar atmosphere
  across many length and energy scales, the most energetic of which
  manifest as large-class solar flares. Often, transient brightenings
  originate in regions of strong magnetic activity and create strong
  observable enhancements across wavelengths from X-ray to radio, with
  notable dynamics on timescales of seconds to hours.The coronal aspects
  of these brightenings have often been studied by way of EUV and X-ray
  imaging and spectra. These events are likely driven by photospheric
  activity (such as flux emergence) with the coronal brightenings
  originating largely from chromospheric ablation (evaporation). Until
  recently, chromospheric and transition region observations of these
  events have been limited. However, new observational capabilities have
  become available which significantly enhance our ability to understand
  the bi-directional flow of energy through the chromosphere between the
  photosphere and the corona.We have recently obtained a unique data set
  with which to study this flow of energy through the chromosphere via
  the Interface Region Imaging Spectrograph (IRIS), Hinode EUV Imaging
  Spectrometer (EIS), Hinode X-Ray Telescope (XRT), Hinode Solar Optical
  Telescope (SOT), Solar Dynamics Observatory (SDO) Atmospheric Imaging
  Assembly (AIA), SDO Helioseismic and Magnetic Imager (HMI), Nuclear
  Spectroscopic Telescope Array (NuStar), Atacama Large Millimeter Array
  (ALMA), and Interferometric BIdimensional Spectropolarimeter (IBIS)
  at the Dunn Solar Telescope (DST). This data set targets a small active
  area near disk center which was tracked simultaneously for approximately
  four hours. Within this region, many transient brightenings detected
  through multiple layers of the solar atmosphere. In this study, we
  combine the imaging data and use the spectra from EIS and IRIS to
  track flows from the photosphere (HMI, SOT) through the chromosphere
  and transition region (AIA, IBIS, IRIS, ALMA) into the corona (EIS,
  XRT, AIA).

Title: High-cadence Hinode/XRT observations for studying coronal
    events with very short timescales
Authors: McKenzie, David Eugene; Kobelski, Adam; Savage, Sabrina
Bibcode: 2017SPD....4830406M
Altcode:
  The Hinode X-Ray Telescope’s capability for high time cadence
  observations makes it an excellent tool for probing highly variable
  conditions in the corona, including wave-like activity, dynamic
  plasma motions, and short-duration transient events. XRT is capable
  of producing images at cadences faster than one image per 10 seconds,
  which is comparable to the energy release timescales, and/or ionization
  evolution timescales, predicted by a range of models of coronal
  activity. In the present work, we demonstrate XRT’s high-cadence
  capability through observations of active region AR 10923 (2006
  November), with cadences of 6-20 seconds. The image sequences, made
  sequentially with multiple analysis filters, reveal many transient
  brightenings (i.e., microflares), for which we derive heating and
  cooling timescales. We also forward model the observed light curves to
  estimate the temperature, density, filling factors, and lengths of the
  observed loops. These estimates allow us to prioritize different heating
  mechanisms, and to better understand the unresolved structures within
  the observations. This study provides a test of capabilities, which
  have still not yet been fully utilized by the ten-year-old Hinode X-Ray
  Telescope, and thus provides a starting point for future investigations
  of short-timescale/high-frequency variations in coronal X-ray intensity.

Title: Reconnection Outflows in the Extended Corona and Magnetotail
Authors: Savage, Sabrina; Kobelski, Adam
Bibcode: 2017SPD....4830303S
Altcode:
  Observational signatures of reconnection have been studied extensively
  in the lower corona for decades, successfully providing insight into
  energy release mechanisms in the region above post-flare arcade
  loops and below 1.5 solar radii. During large eruptive events,
  however, energy release continues to occur well beyond the presence of
  reconnection signatures at these low heights. Supra-arcade downflows
  (SADs) and downflowing loops (SADLs) are particularly useful measures of
  continual reconnection in the corona as they may indicate the presence
  and path of retracting post-reconnection loops. SADs and SADLs have
  been observed for days beyond the passage of corona mass ejections
  through the SOHO/LASCO field of view and for nearly a week after an
  eruption on 14 October 2014. The association of these features with
  magnetic reconnection increases the significance of understanding
  their genesis. SADs have been interpreted as wakes behind newly
  reconnected and outflowing loops (SADLs). Models have shown the
  plausibility of this interpretation, though this interpretation has
  not yet been fully accepted. We will present a preliminary study of
  complementary observations of magnetic reconnection detected via in situ
  instruments in the magnetosphere. These observations, provided by five
  THEMIS spacecraft, reveal similar structures and conditions to those
  related to SADs. We compare data from multiple SADs and dipolarization
  fronts to test the similarity between these plasma regimes, strongly
  favoring the interpretation of SADs as instabilities trailing retracting
  loops. We will also use these observations to strengthen the case for
  the development of an EUV wide-field coronal imager.

Title: Observational Signatures of Magnetic Reconnection in the
    Extended Corona
Authors: Savage, Sabrina L.; West, Matthew; Seaton, Daniel; Kobelski,
   Adam
Bibcode: 2017shin.confE..40S
Altcode:
  Observational signatures of reconnection have been studied extensively
  in the lower corona for decades, successfully providing insight into
  energy release mechanisms in the region above post-flare arcade
  loops and below 1.5 solar radii. During large eruptive events,
  however, energy release continues to occur well beyond the presence of
  reconnection signatures at these low heights. Supra-arcade downflows
  (SADs) and downflowing loops (SADLs) are particularly useful measures
  of continual reconnection in the corona as they may indicate the
  presence and path of retracting post-reconnection loops. SADs and
  SADLs have been faintly observed up to 18 hours beyond the passage
  of corona mass ejections through the SOHO/LASCO field of view, but a
  recent event from 2014 October 14 associated with giant arches provides
  very clear observations of these downflows for days after the initial
  eruption. We report on this unique event and compare these findings
  with observational signatures of magnetic reconnection in the extended
  corona for more typical eruptions.

Title: Observing the Sun with the Atacama Large
Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric
    Imaging
Authors: Shimojo, M.; Bastian, T. S.; Hales, A. S.; White, S. M.;
   Iwai, K.; Hills, R. E.; Hirota, A.; Phillips, N. M.; Sawada, T.;
   Yagoubov, P.; Siringo, G.; Asayama, S.; Sugimoto, M.; Brajša, R.;
   Skokić, I.; Bárta, M.; Kim, S.; de Gregorio-Monsalvo, I.; Corder,
   S. A.; Hudson, H. S.; Wedemeyer, S.; Gary, D. E.; De Pontieu, B.;
   Loukitcheva, M.; Fleishman, G. D.; Chen, B.; Kobelski, A.; Yan, Y.
Bibcode: 2017SoPh..292...87S
Altcode: 2017arXiv170403236S
  Observations of the Sun at millimeter and submillimeter wavelengths
  offer a unique probe into the structure, dynamics, and heating of the
  chromosphere; the structure of sunspots; the formation and eruption
  of prominences and filaments; and energetic phenomena such as jets
  and flares. High-resolution observations of the Sun at millimeter and
  submillimeter wavelengths are challenging due to the intense, extended,
  low-contrast, and dynamic nature of emission from the quiet Sun,
  and the extremely intense and variable nature of emissions associated
  with energetic phenomena. The Atacama Large Millimeter/submillimeter
  Array (ALMA) was designed with solar observations in mind. The
  requirements for solar observations are significantly different from
  observations of sidereal sources and special measures are necessary
  to successfully carry out this type of observations. We describe the
  commissioning efforts that enable the use of two frequency bands,
  the 3-mm band (Band 3) and the 1.25-mm band (Band 6), for continuum
  interferometric-imaging observations of the Sun with ALMA. Examples of
  high-resolution synthesized images obtained using the newly commissioned
  modes during the solar-commissioning campaign held in December 2015
  are presented. Although only 30 of the eventual 66 ALMA antennas
  were used for the campaign, the solar images synthesized from the
  ALMA commissioning data reveal new features of the solar atmosphere
  that demonstrate the potential power of ALMA solar observations. The
  ongoing expansion of ALMA and solar-commissioning efforts will continue
  to enable new and unique solar observing capabilities.

Title: Observing the Sun with the Atacama Large
Millimeter/submillimeter Array (ALMA): Fast-Scan Single-Dish Mapping
Authors: White, S. M.; Iwai, K.; Phillips, N. M.; Hills, R. E.; Hirota,
   A.; Yagoubov, P.; Siringo, G.; Shimojo, M.; Bastian, T. S.; Hales,
   A. S.; Sawada, T.; Asayama, S.; Sugimoto, M.; Marson, R. G.; Kawasaki,
   W.; Muller, E.; Nakazato, T.; Sugimoto, K.; Brajša, R.; Skokić, I.;
   Bárta, M.; Kim, S.; Remijan, A. J.; de Gregorio, I.; Corder, S. A.;
   Hudson, H. S.; Loukitcheva, M.; Chen, B.; De Pontieu, B.; Fleishmann,
   G. D.; Gary, D. E.; Kobelski, A.; Wedemeyer, S.; Yan, Y.
Bibcode: 2017SoPh..292...88W
Altcode: 2017arXiv170504766W
  The Atacama Large Millimeter/submillimeter Array (ALMA) radio
  telescope has commenced science observations of the Sun starting
  in late 2016. Since the Sun is much larger than the field of view
  of individual ALMA dishes, the ALMA interferometer is unable to
  measure the background level of solar emission when observing the
  solar disk. The absolute temperature scale is a critical measurement
  for much of ALMA solar science, including the understanding of energy
  transfer through the solar atmosphere, the properties of prominences,
  and the study of shock heating in the chromosphere. In order to provide
  an absolute temperature scale, ALMA solar observing will take advantage
  of the remarkable fast-scanning capabilities of the ALMA 12 m dishes
  to make single-dish maps of the full Sun. This article reports on the
  results of an extensive commissioning effort to optimize the mapping
  procedure, and it describes the nature of the resulting data. Amplitude
  calibration is discussed in detail: a path that uses the two loads in
  the ALMA calibration system as well as sky measurements is described
  and applied to commissioning data. Inspection of a large number of
  single-dish datasets shows significant variation in the resulting
  temperatures, and based on the temperature distributions, we derive
  quiet-Sun values at disk center of 7300 K at λ =3 mm and 5900 K at
  λ =1.3 mm. These values have statistical uncertainties of about 100
  K, but systematic uncertainties in the temperature scale that may be
  significantly larger. Example images are presented from two periods
  with very different levels of solar activity. At a resolution of about
  25<SUP>″</SUP>, the 1.3 mm wavelength images show temperatures on
  the disk that vary over about a 2000 K range. Active regions and plages
  are among the hotter features, while a large sunspot umbra shows up as
  a depression, and filament channels are relatively cool. Prominences
  above the solar limb are a common feature of the single-dish images.

Title: Supra Arcade Downflows in the Corona Informed by Magnetospheric
    Dipolarization Fronts with THEMIS
Authors: Kobelski, A.; Savage, S. L.; Malaspina, D.
Bibcode: 2016AGUFMSM33A2500K
Altcode:
  Magnetic reconnection rapidly reconfigures the magnetic
  field of the corona, accelerating plasma through the site of
  reconnection. Ambiguities (such as line-of-sight effects) due to
  the nature of the remote sensing instruments available to study the
  corona complicate the interpretation of observations of the inflowing
  and outflowing plasma in reconnecting regions. In particular, the
  interpretation of sunward moving density depletions above flare arcades
  (known as Supra Arcade Downflows — SADs) is still debated. SADs have
  been interpreted as wakes behind newly reconnected and outflowing loops
  (Supra Arcade Downflowing Loops — SADLs). Hinode/XRT and SDO/AIA
  have provided a wealth of observations for SADs and helped inform
  our current understanding of these structures. Models have shown the
  plausibility of the interpretation of SADs as wakes behind loops,
  though this interpretation has not yet been fully accepted. We present
  here observations of newly reconnected outflowing loops observed
  via in situ instruments in the magnetosphere. These observations,
  provided by up to five THEMIS spacecraft, show that around retracting
  loops (dipolarization fronts in this context), similar temperature and
  density structures as seen in SADs. We compare data from multiple SADs
  and dipolarization fronts to show that the observational signatures
  implied in the corona can be directly observed in similar plasma regimes
  in the magnetosphere, strongly favoring the interpretation of SADs as
  wakes behind retracting loops.

Title: Observational Signatures of Magnetic Reconnection in the Corona
Authors: Savage, S. L.; West, M. J.; Seaton, D. B.; Kobelski, A.
Bibcode: 2016AGUFMSM33A2501S
Altcode:
  Observational signatures of reconnection have been studied extensively
  in the lower corona for decades, successfully providing insight into
  energy release mechanisms in the region above post-flare arcade
  loops and below 1.5 solar radii. During large eruptive events,
  however, energy release continues to occur well beyond the presence of
  reconnection signatures at these low heights. Supra-arcade downflows
  (SADs) and downflowing loops (SADLs) are particularly useful measures
  of continual reconnection in the corona as they may indicate the
  presence and path of retracting post-reconnection loops. SADs and
  SADLs have been faintly observed up to 18 hours beyond the passage
  of corona mass ejections through the SOHO/LASCO field of view, but a
  recent event from 2014 October 14 associated with giant arches provides
  very clear observations of these downflows for days after the initial
  eruption. We report on this unique event and compare these findings
  with observational signatures of magnetic reconnection in the extended
  corona for more typical eruptions.

Title: Observational Signatures of Magnetic Reconnection in the
    Extended Corona
Authors: Savage, Sabrina; West, Matthew; Seaton, Daniel B.; Kobelski,
   Adam
Bibcode: 2016SPD....4730703S
Altcode:
  Observational signatures of reconnection have been studied extensively
  in the lower corona for decades, successfully providing insight into
  energy release mechanisms in the region above post-flare arcade
  loops and below 1.5 solar radii. During large eruptive events,
  however, energy release continues to occur well beyond the presence of
  reconnection signatures at these low heights. Supra-arcade downflows
  (SADs) and downflowing loops (SADLs) are particularly useful measures
  of continual reconnection in the corona as they may indicate the
  presence and path of retracting post-reconnection loops. SADs and
  SADLs have been faintly observed up to 18 hours beyond the passage
  of corona mass ejections through the SOHO/LASCO field of view, but a
  recent event from 2014 October 14 associated with giant arches provides
  very clear observations of these downflows for days after the initial
  eruption. We report on this unique event and compare these findings
  with observational signatures of magnetic reconnection in the extended
  corona for more typical eruptions.

Title: Solar Observations with the Atacama Large
    Millimeter/submillimeter Array (ALMA)
Authors: Kobelski, A.; Bastian, T. S.; Bárta, M.; Brajša, R.; Chen,
   B.; De Pontieu, B.; Fleishman, G.; Gary, D.; Hales, A.; Hills, R.;
   Hudson, H.; Hurford, G.; Loukitcheva, M.; Iwai, K.; Krucker, S.;
   Shimojo, M.; Skokić, I.; Wedemeyer, S.; White, S.; Yan, Y.; ALMA
   Solar Development Team
Bibcode: 2016ASPC..504..327K
Altcode:
  The Atacama Large Millimeter/Submillimeter Array (ALMA) is a
  joint North American, European, and East Asian project that opens
  the mm-sub mm wavelength part of the electromagnetic spectrum for
  general astrophysical exploration, providing high-resolution imaging
  in frequency bands currently ranging from 84 GHz to 950 GHz (300
  microns to 3 mm). It is located in the Atacama desert in northern
  Chile at an elevation of 5000 m. Despite being a general purpose
  instrument, provisions have been made to enable solar observations
  with ALMA. Radiation emitted at ALMA wavelengths originates mostly
  from the chromosphere, which plays an important role in the transport
  of matter and energy, and the in heating the outer layers of the solar
  atmosphere. Despite decades of research, the solar chromosphere remains
  a significant challenge: both to observe, owing to the complicated
  formation mechanisms of currently available diagnostics; and to
  understand, as a result of the complex nature of the structure and
  dynamics of the chromosphere. ALMA has the potential to change the
  scene substantially as it serves as a nearly linear thermometer at
  high spatial and temporal resolution, enabling us to study the complex
  interaction of magnetic fields and shock waves and yet-to-be-discovered
  dynamical processes. Moreover, ALMA will play an important role in
  the study of energetic emissions associated with solar flares at
  sub-THz frequencies.

Title: Measuring the Solar Magnetic Field with STEREO A Radio
Transmissions: Faraday Rotation Observations using the 100m Green
    Bank Telescope
Authors: Kobelski, A.; Jensen, E.; Wexler, D.; Heiles, C.; Kepley,
   A.; Kuiper, T.; Bisi, M.
Bibcode: 2016ASPC..504...99K
Altcode:
  The STEREO mission spacecraft recently passed through superior
  conjunction, providing an opportunity to probe the solar corona using
  radio transmissions. Strong magnetic field and dense plasma environment
  induce Faraday rotation of the linearly polarized fraction of the
  spacecraft radio carrier signal. Variations in the Faraday rotation
  signify changes in magnetic field components and plasma parameters,
  and thus can be used to gain understanding processes of the quiescent
  sun as well as active outbursts including coronal mass ejections. Our
  2015 observing campaign resulted in a series of measurements over
  several months with the 100m Green Bank Telescope (GBT) to investigate
  the coronal Faraday rotation at various radial distances. These
  observations reveal notable fluctuations in the Faraday rotation of
  the signal in the deep corona, and should yield unique insights into
  coronal magnetohydrodynamics down to a 1.5 solar radius line-of-sight
  solar elongation.

Title: Probing Solar Wind Turbulence with the Jansky Very Large Array
Authors: Kobelski, A.; Bastian, T. S.; Betti, S.
Bibcode: 2016ASPC..504...97K
Altcode:
  The solar wind offers an extraordinary laboratory for studying MHD
  turbulence, turbulent dissipation, and heating. Radio propagation
  phenomena can be exploited as probes of the solar wind in regions that
  are generally inaccessible to in situ spacecraft measurements. Here,
  we have undertaken a study with the Jansky Very Large Array (VLA)
  to observe point-like sources drawn from the JVAS catalog, and 3 VLA
  calibrator sources, to trans-illuminate the outer corona/inner solar
  wind. In doing so, we will exploit angular broadening and refractive
  scintillation to deduce properties of the solar wind along ≍23 lines
  of sight within 7 solar radii of the Sun and a wide range of position
  angles. By fitting the complex visibilities using well-known techniques
  we can deduce or constrain a number of key parameters. In particular,
  we fit the visibilities to a function of the known source flux,
  displacement of the source due to refraction, source broadening due to
  an elliptical structure function, spectral slope of the turbulence, and
  the coherence scale. Of particular interest is α, the spectral slope of
  the turbulence which we probe at both small (km to 10s of km) and large
  (thousands of km) scales. This will help us determine the presence
  and evolution of an inner scale, measure the degree of anisotropy,
  and constrain the topology of the global coronal magnetic field. The
  inner scale is of particular interest for constraining current theories
  of turbulence dissipation and heating. Initial analysis show the
  visibilities vary notably on timescales of individual integrations
  (2 seconds) and that the source is not uniformly broadened. All
  sources appear to preferentially broaden perpendicular to the magnetic
  field, consistent with theories of kinetic Alfvén waves. This type
  of observation will also help to interpret data from the upcoming
  Solar Probe Plus and Solar Orbiter missions. A full set of results
  and analysis is forthcoming. More details on previous results can be
  found in Bastian (1999), which used the previous generation VLA.

Title: High-Resolution Bistatic Radar Imaging of Near-Earth Asteroids
    in 2015 using New Capabilities of Goldstone and Green Bank Telescopes
Authors: Naidu, S.; Benner, L.; Brozovic, M.; Giorgini, J. D.; Jao,
   J. S.; Lee, C. G.; Busch, M.; Ghigo, F. D.; Ford, A.; Kobelski, A.;
   Marshall, S.
Bibcode: 2015AGUFM.P53G..07N
Altcode:
  We present new results from bistatic Goldstone to Green Bank
  Telescope (GBT) high-resolution radar imaging of near-Earth asteroids
  (NEAs). Previously, most radar observations used either the 305-m
  Arecibo radar or the 70-m DSS-14 radar at Goldstone. Following the
  installation of new data-taking equipment at the GBT in late 2014,
  the number of bistatic Goldstone/GBT observations has increased
  substantially. Receiving Goldstone radar echoes at the 100-m GBT
  improves the signal-to-noise ratios (SNRs) two- to three-fold relative
  to monostatic reception at DSS-14. The higher SNRs allow us to obtain
  higher resolution images than is possible with DSS-14 both transmitting
  and receiving. Thus far in 2015, we have used the GBT receiver in
  combination with the 450 kW DSS-14 antenna and a new low-power 80kW
  transmitter on the 34-m DSS-13 antenna at the Goldstone complex
  to image five and two NEAs respectively. Asteroids 2005 YQ96, 2004
  BL86, and 1994 AW1 are binary systems. 2011 UW158 has a spin period
  of 36 minutes that is unusually fast among asteroids its size (~500
  m). 1999 JD6 is a deeply bifurcated double-lobed object. 2015 HM10 is
  an elongated 80 m asteroid with a spin period of 22 minutes. Our best
  images of these objects resolve the surface with resolutions of 3.75 m
  and reveal numerous features. Such images are useful to estimate the 3D
  shape, spin state, and other physical and dynamical properties of the
  objects. This knowledge is of particular interest for spacecraft mission
  planning, impact threat assessment, and resource utilization. Over the
  long term, such observations will help answer fundamental questions
  regarding the origin of the diversity in asteroid morphologies,
  the importance of spin-up mechanisms and collisional influences,
  the interior structure and thermal properties of asteroids, and the
  variety of dynamical states.

Title: Arecibo and Goldstone Radar Observations of the
First-Recognized Binary Near-Earth Asteroid: (385186) 1994 AW1
Authors: Richardson, James E.; Taylor, Patrick A.; Rivera-Valentin,
   Edgard G.; Rodriguez-Ford, Linda A.; Benner, Lance A. M.; Naidu,
   Shantanu P.; Giorgini, Jon D.; Busch, Michael W.; Ghigo, Frank d.;
   Kobelski, Adam; Warner, Brian D.; Springmann, Alessondra; Marshall,
   Sean E.; Steckloff, Jordan K.; Sharkey, Benjamin
Bibcode: 2015DPS....4730808R
Altcode:
  Near-Earth asteroid (385186) 1994 AW1 was discovered at Palomar
  Observatory on 11 January 1994. Subsequent observations of this Amor
  family, Sa-class asteroid also identified it as the first candidate
  binary NEA, as indicated by multiple periodicities and possible
  mutual eclipsing/occulting events in the object’s lightcurve. On 15
  July 2015 this asteroid made its closest approach to Earth since its
  discovery, coming within 0.065 AU (25 lunar distances), and prompting
  an extended observation campaign using both the JPL-Goldstone and
  Arecibo Observatory planetary radars. Goldstone observations covered
  the 14-19 July period of closest approach (0.066-0.070 AU) while the
  object remained below Arecibo’s observing horizon, with Arecibo
  picking up the observations between 20-30 July, as the object moved
  from 0.075 to 0.126 AU distance. At Goldstone, we were able to observe
  this object with range resolutions of 150 m using a Goldstone (DSS-14)
  to Green Bank Telescope (GBT) bistatic configuration, while at Arecibo,
  we conducted monostatic observations of 1994 AW1 using the 2380 MHz
  (12.6 cm) radar at resolutions of 30 m and 75 m.As a result, and
  twenty years after its discovery, these observations have confirmed
  the binary nature of 1994 AW1, showing the primary body to be about
  600 m in diameter, the secondary body to be about half the diameter
  of the primary, with the two orbiting a common center of mass at a
  distance of about 1.2 km apart. Delay-Doppler image comparisons of the
  primary over the course of six nights (at 30 m resolution) confirm a
  lightcurve-derived rotation period of 2.518 +/- 0.002 hr, as &gt;90%
  longitude coverage was achieved, revealing a slightly elongated,
  irregular surface morphology. Delay-Doppler images of the secondary
  reveal an elongated, irregular body which appears to be tidally
  locked, with its long axis pointed towards the primary as it orbits
  with a period of about 22 hr (also consistent with the lightcurve
  analysis). These very early results point to a total system mass of
  (1.6 +/- 0.5) x 10^11 kg and a crude, mean system density estimate
  of 1400 +/- 500 kg/m^3. Additional analysis and shape-modeling will
  be presented.

Title: Potentially Hazardous Asteroid (85989) 1999 JD6: Radar,
    Infrared, and Lightcurve Observations and a Preliminary Shape Model
Authors: Marshall, Sean E.; Howell, Ellen S.; Brozović, Marina;
   Taylor, Patrick A.; Campbell, Donald B.; Benner, Lance A. M.; Naidu,
   Shantanu P.; Giorgini, Jon D.; Jao, Joseph S.; Lee, Clement G.;
   Richardson, James E.; Rodriguez-Ford, Linda A.; Rivera-Valentin,
   Edgard G.; Ghigo, Frank; Kobelski, Adam; Busch, Michael W.; Pravec,
   Petr; Warner, Brian D.; Reddy, Vishnu; Hicks, Michael D.; Crowell,
   Jenna L.; Fernandez, Yanga R.; Vervack, Ronald J.; Nolan, Michael C.;
   Magri, Christopher; Sharkey, Benjamin; Bozek, Brandon
Bibcode: 2015DPS....4720409M
Altcode:
  We report observations of potentially hazardous asteroid (85989) 1999
  JD6, which passed 0.048 AU from Earth (19 lunar distances) during
  its close approach on July 25, 2015. During eleven days between July
  15 and August 4, 2015, we observed 1999 JD6 with the Goldstone Solar
  System Radar and with Arecibo Observatory's planetary radar, including
  bistatic reception of some Goldstone echoes at Green Bank. We obtained
  delay-Doppler radar images at a wide range of latitudes, with range
  resolutions varying from 7.5 to 150 meters per pixel, depending on
  the observing conditions. We acquired near-infrared spectra from the
  NASA InfraRed Telescope Facility (IRTF) on two nights in July 2015, at
  wavelengths from 0.75 to 5.0 microns, showing JD6's thermal emission. We
  also obtained optical lightcurves from Ondrejov Observatory (in 1999),
  Table Mountain Observatory (in 2000), and Palmer Divide Station
  (in 2015). Previous observers had suggested that 1999 JD6 was most
  likely an elongated object, based on its large lightcurve amplitude of
  1.2 magnitudes (Szabo et al. 2001; Polishook and Brosch 2008; Warner
  2014). The radar images reveal an elongated peanut-shaped object, with
  two lobes separated by a sharp concavity. JD6's maximum diameter is
  about two kilometers, and its larger lobe is approximately 50% longer
  than its smaller lobe. The larger lobe has a concavity on its end. We
  will present more details on the shape and rotation state of 1999 JD6,
  as well as its surface properties from optical and infrared data and
  thermal modeling.

Title: Radar observations of near-Earth asteroid (436724) 2011 UW158
    using the Arecibo, Goldstone, and Green Bank Telescopes
Authors: Naidu, Shantanu P.; Benner, Lance A. M.; Brozovic, Marina;
   Giorgini, Jon D.; Jao, Joseph S.; Busch, Michael W.; Taylor, Patrick
   A.; Richardson, James E.; Rivera-Valentin, Edgard G.; Ford, Linda A.;
   Ghigo, Frank D.; Kobelski, Adam
Bibcode: 2015DPS....4720408N
Altcode:
  Near-Earth asteroid (436724) 2011 UW158 made a close approach
  to the Earth on 2015 July 19 at a distance of 0.016 au (6.4 lunar
  distances). We observed it between July 13-26 using the Arecibo S-band
  (2380 MHz, 12.5 cm) radar, the Goldstone X-band (8560 MHz, 3.5 cm)
  radar, and the Green Bank Telescope (GBT). Arecibo delay-Doppler
  observations achieved range resolutions as fine as 7.5 m. At the GBT,
  we used a newly installed radar backend to record the radar echoes,
  which improved signal-to-noise ratios (SNRs) two-fold relative to
  monostatic reception at the 70-m DSS-14 antenna at Goldstone. The higher
  SNRs allowed us to obtain images with range resolutions comparable to
  those at Arecibo that reveal the asteroid’s surface topography with
  great detail. The visible extents of the asteroid in the radar images
  suggest an elongated object with dimensions of about 600 x 300 m. The
  shape of the object is angular with a facet on one side that spans the
  entire length of the asteroid. Three parallel radar-bright features
  are visible when the asteroid is oriented broadside and may represent
  ridges. These features cause unusually large brightness variations in
  the echo as the asteroid rotates. There are other radar-bright regions
  that suggest small-scale (tens of meters) topography. Repetition of
  the leading edge profiles in the images indicates a spin period of
  ~37 minutes, which is consistent with the period that was previously
  reported using lightcurves (B. Gary, T. Lister, H. K. Moon, P. Pravec,
  and B. D. Warner, pers. comm.). This spin period is unusually fast
  among asteroids its size and suggests that the object has relatively
  high cohesive strength. 2011 UW158 has a relatively low delta-V
  for spacecraft missions and is on NASA’s Near-Earth Object Human
  Accessible Targets Study list.

Title: The versatile GBT astronomical spectrometer (VEGAS): Current
    status and future plans
Authors: Prestage, Richard M.; Bloss, Marty; Brandt, Joe; Chen, Hong;
   Creager, Ray; Demorest, Paul; Ford, John; Jones, Glenn; Kepley,
   Amanda; Kobelski, Adam; Marganian, Paul; Mello, Melinda; McMahon,
   David; McCullough, Randy; Ray, Jason; Roshi, D. Anish; Werthimer,
   Dan; Whitehead, Mark
Bibcode: 2015ursi.confE...4P
Altcode:
  The VEGAS multi-beam spectrometer (VEGAS) was built for the Green
  Bank Telescope (GBT) through a partnership between the National
  Radio Astronomy Observatory (NRAO) and the University of California
  at Berkeley. VEGAS is based on a Field Programmable Gate Array (FPGA)
  frontend and a heterogeneous computing backend comprised of Graphical
  Processing Units (GPUs) and CPUs. This system provides processing
  power to analyze up to 8 dual-polarization or 16 single-polarization
  inputs at bandwidths of up to 1.25 GHz per input. VEGAS was released
  for "shared-risk" observing in March 2014 and it became the default
  GBT spectral line backend in August 2014. Some of the early VEGAS
  observations include the Radio Ammonia Mid-Plane Survey, mapping of
  HCN/HCO+ in nearby galaxies, and a variety of radio-recombination
  line and pulsar projects. We will present some of the latest VEGAS
  science highlights.

Title: Forward Modeling Transient Brightenings and Microflares around
    an Active Region Observed with Hi-C
Authors: Kobelski, Adam R.; McKenzie, David E.
Bibcode: 2014ApJ...794..119K
Altcode: 2014arXiv1408.5440K
  Small-scale flare-like brightenings around active regions are among
  the smallest and most fundamental of energetic transient events in
  the corona, providing a testbed for models of heating and active
  region dynamics. In a previous study, we modeled a large collection
  of these microflares observed with Hinode/X-Ray Telescope (XRT) using
  EBTEL and found that they required multiple heating events, but could
  not distinguish between multiple heating events on a single strand,
  or multiple strands each experiencing a single heating event. We
  present here a similar study, but with extreme-ultraviolet data of
  Active Region 11520 from the High Resolution Coronal Imager (Hi-C)
  sounding rocket. Hi-C provides an order of magnitude improvement to
  the spatial resolution of XRT, and a cooler temperature sensitivity,
  which combine to provide significant improvements to our ability to
  detect and model microflare activity around active regions. We have
  found that at the spatial resolution of Hi-C (≈0.''3), the events
  occur much more frequently than expected (57 events detected, only 1
  or 2 expected), and are most likely made from strands of the order
  of 100 km wide, each of which is impulsively heated with multiple
  heating events. These findings tend to support bursty reconnection as
  the cause of the energy release responsible for the brightenings.

Title: Calibrating Data from the Hinode/X-Ray Telescope and Associated
    Uncertainties
Authors: Kobelski, Adam R.; Saar, Steven H.; Weber, Mark A.; McKenzie,
   David E.; Reeves, Katharine K.
Bibcode: 2014SoPh..289.2781K
Altcode: 2013arXiv1312.4850K; 2014SoPh..tmp...27K
  The X-Ray Telescope (XRT) onboard the Hinode satellite, launched 23
  September 2006 by the Japan Aerospace Exploration Agency (JAXA), is a
  joint mission of Japan, the United States, and the United Kingdom to
  study the solar corona. In particular, XRT was designed to study solar
  plasmas with temperatures between 1 and 10 MK with ≈ 1″ pixels
  (≈ 2″ resolution). Prior to analysis, the data product from this
  instrument must be properly calibrated and data values quantified to
  accurately assess the information contained within. We present here
  the standard methods of calibration for these data. The calibration
  was performed on an empirical basis that uses the least complicated
  correction that accurately describes the data while suppressing
  spurious features. By analyzing the uncertainties remaining in the
  data after calibration, we conclude that the procedure is successful,
  because the remaining uncertainty after calibration is dominated by
  photon noise. This calibration software is available in the SolarSoft
  software library.

Title: The Heating of Active Regions Using Active Region Transient
    Brightenings Observed with XRT and Hi-C
Authors: Kobelski, Adam; McKenzie, David Eugene
Bibcode: 2014AAS...22431201K
Altcode:
  Active region transient brightentings (ARTBs) are among the smallest
  and most fundamental of energetic transient events in the corona; as
  such, they provide a testbed for models of heating and active region
  dynamics. We have modeled a large collection of ARTBs observed with
  Hinode/XRT and with Hi-C as both (a) multi-stranded loops and (b)
  monolithic loops which experience multiple heating events, to explore
  the energetic ramifications and characteristics in active region
  dynamics. Even for these small, short-lived transients, our modeling
  indicates that multiple heating events are required for each ARTB. We
  compare the quality of model fits for two different temporal envelopes
  of the heating function, and discuss whether the results more strongly
  favor nanoflare or wave-absorption heating.

Title: Modeling Active Region Transient Brightenings Observed with
    X-Ray Telescope as Multi-stranded Loops
Authors: Kobelski, Adam R.; McKenzie, David E.; Donachie, Martin
Bibcode: 2014ApJ...786...82K
Altcode: 2014arXiv1403.7834K
  Strong evidence exists that coronal loops as observed in extreme
  ultraviolet and soft X-rays may not be monolithic isotropic structures,
  but can often be more accurately modeled as bundles of independent
  strands. Modeling the observed active region transient brightenings
  (ARTBs) within this framework allows for the exploration of the
  energetic ramifications and characteristics of these stratified
  structures. Here we present a simple method of detecting and modeling
  ARTBs observed with the Hinode X-Ray Telescope (XRT) as groups of
  zero-dimensional strands, which allows us to probe parameter space to
  better understand the spatial and temporal dependence of strand heating
  in impulsively heated loops. This partially automated method can be
  used to analyze a large number of observations to gain a statistical
  insight into the parameters of coronal structures, including the number
  of heating events required in a given model to fit the observations. In
  this article, we present the methodology and demonstrate its use in
  detecting and modeling ARTBs in a sample data set from Hinode/XRT. These
  initial results show that, in general, multiple heating events are
  necessary to reproduce observed ARTBs, but the spatial dependence of
  these heating events cannot yet be established.

Title: Empirical studies on the initiation of impulsive heating in
    coronal loops
Authors: Kobelski, Adam Robert
Bibcode: 2014PhDT........78K
Altcode: 2014PhDT.......546K
  The heating of the solar corona is an important topic both
  for scientists and modern society. One of the most fundamental of
  structures in the corona are bundles of plasma confined to the magnetic
  field, loops. Here we perform empirical studies to better understand
  the mechanisms responsible for heating loops. We observe loops in
  X-rays with XRT and model the observations as bundles of independent
  strands, showing that the mechanisms instigating the heating of loops
  is likely impulsive, yet requires multiple heating events to match
  observations. We also observe and model very small loops with Hi-C,
  exploiting the high resolution to show that the frequency with which
  small loops are heated is larger than expected. This study also puts
  constraints on the size of the heating events. We also perform a
  study on the initiation of magnetic reconnection between neighboring
  active regions, in hopes of understanding how magnetic fields interact,
  evolve and heat coronal loops. We close with a discussion on calibrating
  the data from a solar X-ray telescope and interpret the uncertainties
  within.

Title: Fixing the Leak: Empirical Corrections for the Small Light
    Leak in Hinode XRT
Authors: Saar, Steven H.; DeLuca, E. E.; McCauley, P.; Kobelski, A.
Bibcode: 2013SPD....44...93S
Altcode:
  On May 9, 2012, the the straylight level of XRT on Hinode suddenly
  increased, consistent with the appearance of a pinhole in the entrance
  filter (possibly a micrometeorite breach). The effect of this event
  is most noticeable in the optical G band data, which shows an average
  light excess of ~30%. However, data in several of the X-ray filters is
  also affected, due to low sensitivity "tails" of their filter responses
  into the visible. Observations taken with the G band filter but with
  the visible light shutter (VLS) closed show a weak, slightly shifted,
  out-of-focus image, revealing the leaked light. The intensity of
  the leak depends on telescope pointing, dropping strongly for images
  taken off-disk. By monitoring light levels in the corners of full-Sun
  Ti-poly filter images, we determine the approximate time of the event:
  ~13:30 UT. We use pairs of images taken just-before and after the filter
  breach to directly measure the leakage in two affected X-ray filters. We
  then develop a model using a scaled, shifted, and smoothed versions
  of the VLS closed images to remove the contamination. We estimate
  the uncertainties involved in our proposed correction procedure. This
  research was supported under NASA contract NNM07AB07C for Hinode XRT.

Title: Modeling Active Region Transient Brightenings Observed with
    XRT as Multistranded Loops
Authors: Kobelski, Adam; McKenzie, D. E.
Bibcode: 2013SPD....44...77K
Altcode:
  Strong evidence exists that coronal loops as observed in EUV and soft
  X-rays are not monolithic isotropic structures, but are more accurately
  modeled as bundles of independent strands. Modeling the observed
  active region transient brightenings (ARTBs) within this framework
  allows exploration of the energetic ramifications and characteristics
  of these stratified structures. Here we present a simple method of
  detecting and modeling ARTBs observed with the Hinode X-Ray Telescope
  (XRT) as groups of simple 0-dimensional strands. We probe parameter
  space to understand better the spatial and temporal dependence of
  strand heating in impulsively heated loops. We present results from
  using this partially automated method to analyze observations and gain
  a statistical insight into the heating of these structures.

Title: Inferring Nonthermal Particle Characteristics from Thermal
    Emission Signatures
Authors: Kobelski, A. R.; McKenzie, D. E.; Winter, H. D.
Bibcode: 2012ASPC..454..333K
Altcode:
  Much work has been done in characterizing the nonthermal particle
  beams found in flares. Most of this work has concentrated on the
  interpretation of hard X-ray (HXR) emission. While HXR emission does
  have a direct connection to the nonthermal particle beam, there
  are other emission mechanisms that can also provide insight into
  the nature of the nonthermal beam. In the impulsive phase of solar
  flares the primary source of plasma heating is collisions between
  the nonthermal particles and the ambient, thermal plasma in the flare
  loop. The properties of the nonthermal particle beam directly affect
  the heating of the thermal plasma. Thus the thermal emission (e.g.,
  soft X-rays) can also yield clues to the properties of the nonthermal
  beam. Recent flare modeling in the dissertation of Winter (2009)
  makes specific predictions about the behavior of the soft X-ray (SXR)
  emission from the flaring loop, depending on the properties of the
  nonthermal particle beam. As an initial test of the applicability of
  these predictions to real flares, we have undertaken a comparison to HXR
  and SXR observations from the Yohkoh mission. We present preliminary
  results from the analysis of Yohkoh-observed solar flares, which show
  consistent temporal profiles in the apex to footpoint ratio.

Title: Elemental Abundances as a New Source of Uncertainty of the
    Hinode/XRT Filter-ratio T and EM Analysis
Authors: Takeda, A.; Kobelski, A.; McKenzie, D. E.; Yoshimura, K.
Bibcode: 2012ASPC..456..133T
Altcode:
  We calculated the Hinode/XRT temperature response functions with
  different assumptions of elemental abundances. The enhancement of
  the low FIP elements significantly affects the amplitude of the XRT
  response curves. This yields a significant difference in the emission
  measures calculated from the filter ratio method, while the effect on
  derived temperatures is relatively small.

Title: Photometric Uncertainties within Hinode XRT
Authors: Kobelski, Adam; Saar, S. H.; Weber, M. A.; McKenzie, D. E.;
   Reeves, K. K.
Bibcode: 2012AAS...22020126K
Altcode:
  We have developed estimates of the systematic uncertainties for
  the X-Ray Telescope (XRT) on Hinode. These estimates are included
  as optional returns from the standard XRT data reduction software,
  xrt_prep.pro. Included in these software estimates are uncertainties
  from instrument vignetting, dark current subtraction, split bias
  leveling, Fourier filtering and JPEG compression. Sources of uncertainty
  that rely heavily on models of plasma radiation or assumptions of
  elemental abundances, such as photon noise, are discussed, but not
  included in the software. It will be shown that the photon noise
  is much larger than the systematic uncertainty. <P />This work is
  supported by NASA under contract NNM07AB07C with the Harvard-Smithsonian
  Astrophysical Observatory

Title: Multi-Stranded Coronal Loops - A Statistical Forward Model
Authors: Kobelski, Adam; McKenzie, D. E.
Bibcode: 2012AAS...22020431K
Altcode:
  Strong evidence currently exists that coronal loops as observed in
  EUVs and soft X-rays are not monolithic structures, but actually exist
  as bundles of independent strands. It is of significant importance
  to determine the size and number density of these strands in order
  to better understand the spatial and temporal scales of magnetic
  reconnection in the corona. In order to empirically estimate these
  parameters, we have developed software to forward model the cooling
  of flaring loops as bundles of strands in order to estimate their
  observational signatures. By applying this forward model to a large
  database of flares observed by Yohkoh/SXT, we employ a statistical
  analysis to constrain the parameters in flaring coronal plasma. Results
  of this analysis will be presented.

Title: Measuring Uncertainties in the Hinode X-Ray Telescope
Authors: Kobelski, A.; Saar, S.; McKenzie, D. E.; Weber, M.; Reeves,
   K.; DeLuca, E.
Bibcode: 2012ASPC..456..241K
Altcode:
  We have developed estimates of the systematic photometric uncertainties
  the X-Ray Telescope (Kano et al. (2008)) on Hinode (Kosugi et
  al.(2007)). These estimates are included as optional returns from the
  standard XRT data reduction software, xrt_prep.pro. Included in the
  software estimates are uncertainties from instrument vignetting, dark
  current subtraction, split bias leveling, fourier filtering and JPEG
  compression. We show that these uncertainties are generally smaller
  than the photon counting uncertainty. However, due to the reliance
  on assumptions of plasma radiation models and elemental abundances,
  photon counting is not included in the software.

Title: Forward Modeling for Unresolved Flaring Loops
Authors: Kobelski, Adam; McKenzie, D. E.
Bibcode: 2011SPD....42.1824K
Altcode: 2011BAAS..43S.1824K
  The apparent width of observed coronal loops can have
  significant effects on the perceived evolution of flaring active
  regions. Frequently, comparing a model flare to observation requires an
  estimate of the filling factor of loops contributing to the signal. If
  the analysis assumes the loops are resolved, the cooling times
  derived from the observations are often much longer than predicted
  by models. We have developed software to forward model the cooling
  of flaring loops, and estimate their observational signatures. This
  allows exploration of the physical parameters necessary within a given
  model to reproduce the observations. We can then estimate the number of
  unresolved strands contained within the observed flare loop. We will
  present early results from this study using data from Yohkoh/SXT. The
  implementation of Hinode/XRT observations to improve our spatial
  resolution and thermal range will also discussed. <P />This work is
  supported by NASA under contract NNM07AB07C with the Harvard-Smithsonian
  Astrophysical Observatory. Yohkoh data are provided courtesy of the
  NASA-supported Yohkoh Legacy Archive at Montana State University.

Title: Inferring Nonthermal Particle Characteristics from Thermal
Emission Signatures: Temperature Evolution
Authors: Kobelski, Adam; Winter, H.; McKenzie, D. E.
Bibcode: 2010AAS...21640422K
Altcode: 2010BAAS...41..903K
  In the impulsive phase of solar flares the primary source of plasma
  heating is collisions between the nonthermal particles and the ambient,
  thermal plasma in the flare loop. Thus the thermal emission (e.g.,
  soft X-rays) can yield clues to the properties of the nonthermal
  beam. We have undertaken a study of the nonthermal particle signatures
  contained within the thermal emission of a flaring coronal loop to
  test predictions modeled in the dissertation of Winter (2009). Here we
  study loops as observed in thermal soft X-ray (SXR) emission by the
  Yohkoh satellite. We present the temperature evolution as viewed in
  SXR to that predicted by the model, and continue an analysis of the
  temporal profile of the SXR emission.

Title: Inferring Nonthermal Particle Characteristics from Thermal
    Emission Signatures
Authors: Kobelski, A.; Winter, H. D.; McKenzie, D. E.
Bibcode: 2009AGUFMSH23A1528K
Altcode:
  Much work has been done in characterizing the nonthermal particle
  beams found in flares. Most of this work has concentrated on the
  interpretation of hard X-ray (HXR) emission. While HXR emission does
  have a direct connection to the nonthermal particle beam, there
  are other emission mechanisms that can also provide insight into
  the nature of the nonthermal beam. In the impulsive phase of solar
  flares the primary source of plasma heating is collisions between
  the nonthermal particles and the ambient, thermal plasma in the flare
  loop. The properties of the nonthermal particle beam directly affect
  the heating of the thermal plasma. Thus the thermal emission (e.g.,
  soft X-rays) can also yield clues to the properties of the nonthermal
  beam. Recent flare modeling in the dissertation of Winter (2009)
  makes specific predictions about the behavior of the soft X-ray (SXR)
  emission from the flaring loop, depending on the properties of the
  nonthermal particle beam. As an initial test of the applicability of
  these predictions to real flares, we have undertaken a comparison to HXR
  and SXR observations from the Yohkoh mission. We present preliminary
  results from the analysis of Yohkoh-observed solar flares, pursuant
  to the predictions of the model.

Title: Thermal Evolution of Hyperon-Mixed Neutron Stars
Authors: Tsuruta, S.; Sadino, J.; Kobelski, A.; Teter, M. A.; Liebmann,
   A. C.; Takatsuka, T.; Nomoto, K.; Umeda, H.
Bibcode: 2009ApJ...691..621T
Altcode:
  With the impressive amount of data that have poured out from Chandra
  and XMM/Newton X-ray space missions, as well as the lower energy band
  observations, we are now in the position where careful comparison of
  neutron star thermal evolution theories with observations will help
  us to distinguish among various competing theories. For instance,
  the latest theoretical and observational developments probably will
  contradict with the direct Urca cooling of neutron stars without some
  exotic particles. In this paper, we investigate one of the remaining
  possible fast cooling scenarios—direct Urca cooling of neutron stars
  in the hyperon-mixed phase. We conclude that this cooling scenario is
  a valid process if hyperon superfluidity is not too weak.

Title: Sloan/Johnson-Cousins/2MASS Color Transformations for Cool
    Stars
Authors: Davenport, James R. A.; West, Andrew A.; Matthiesen, Caleb
   K.; Schmieding, Michael; Kobelski, Adam
Bibcode: 2006PASP..118.1679D
Altcode: 2006astro.ph.11087D
  We present multicolor transformations and photometric parallaxes for
  a sample of 40 low-mass dwarfs selected from the Sloan Digital Sky
  Survey (SDSS) and the General Catalogue of Trigonometric Stellar
  Parallaxes. Our sample was reobserved at the Manastash Ridge
  Observatory (MRO) using both Sloan and Johnson-Cousin filters,
  and color transformations between the two photometric systems were
  derived. A subset of the sample had previously measured Johnson-Cousins
  photometry and parallaxes as well as 2MASS photometry. We observed
  these stars at MRO using Sloan filters and used these data to derive
  photometric parallax relations as well as SDSS/Johnson-Cousins/2MASS
  color transformations. We present the data and derived transformations
  for use in future low-mass-star studies.

