Author name code: bethge
ADS astronomy entries on 2022-09-14
author:"Bethge, Christian" 
------------------------------------------------------------------------  

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: Magnetoseismology for the solar corona: from  10 Gauss to
    coronal magnetograms
Authors: Yang, Zihao; Gibson, Sarah; He, Jiansen; Del Zanna, Giulio;
   Tomczyk, Steven; Morton, Richard; McIntosh, Scott; Wang, Linghua;
   Karak, Bidya Binay; Samanta, Tanmoy; Tian, Hui; Chen, Yajie; Bethge,
   Christian; Bai, Xianyong
Bibcode: 2022cosp...44.2490Y
Altcode:
  Magnetoseismology, a technique of magnetic field diagnostics based
  on observations of magnetohydrodynamic (MHD) waves, has been widely
  used to estimate the field strengths of oscillating structures in
  the solar corona. However, previously magnetoseismology was mostly
  applied to occasionally occurring oscillation events, providing
  an estimate of only the average field strength or one-dimensional
  distribution of field strength along an oscillating structure. This
  restriction could be eliminated if we apply magnetoseismology to the
  pervasive propagating transverse MHD waves discovered with the Coronal
  Multi-channel Polarimeter (CoMP). Using several CoMP observations of
  the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
  the plasma density and wave phase speed in the corona, which allow us
  to map both the strength and direction of the coronal magnetic field
  in the plane of sky. We also examined distributions of the electron
  density and magnetic field strength, and compared their variations
  with height in the quiet Sun and active regions. Such measurements
  could provide critical information to advance our understanding of the
  Sun's magnetism and the magnetic coupling of the whole solar atmosphere.

Title: Magnetoseismology for the solar corona: from  10 Gauss to
    coronal magnetograms
Authors: Yang, Zihao; Bethge, Christian; Tian, Hui; Tomczyk, Steven;
   Morton, Richard; Del Zanna, Giulio; McIntosh, Scott; Karak, Bidya
   Binay; Gibson, Sarah; Samanta, Tanmoy; He, Jiansen; Chen, Yajie; Bai,
   Xianyong; Wang, Linghua
Bibcode: 2021AGUFMSH12C..07Y
Altcode:
  Magnetoseismology, a technique of magnetic field diagnostics based
  on observations of magnetohydrodynamic (MHD) waves, has been widely
  used to estimate the field strengths of oscillating structures in
  the solar corona. However, previously magnetoseismology was mostly
  applied to occasionally occurring oscillation events, providing
  an estimate of only the average field strength or one-dimensional
  distribution of field strength along an oscillating structure. This
  restriction could be eliminated if we apply magnetoseismology to the
  pervasive propagating transverse MHD waves discovered with the Coronal
  Multi-channel Polarimeter (CoMP). Using several CoMP observations of
  the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
  the plasma density and wave phase speed in the corona, which allow us
  to map both the strength and direction of the coronal magnetic field
  in the plane of sky. We also examined distributions of the electron
  density and magnetic field strength, and compared their variations
  with height in the quiet Sun and active regions. Such measurements
  could provide critical information to advance our understanding of the
  Sun's magnetism and the magnetic coupling of the whole solar atmosphere.

Title: Demonstration of Chromospheric Magnetic Mapping with CLASP2.1
Authors: McKenzie, David; Ishikawa, Ryohko; Trujillo Bueno, Javier;
   Auchere, F.; Kobayashi, Ken; Winebarger, Amy; Kano, Ryouhei; Song,
   Donguk; Okamoto, Joten; Rachmeler, Laurel; De Pontieu, Bart; Vigil,
   Genevieve; Belluzzi, Luca; Alsina Ballester, Ernest; del Pino Aleman,
   Tanausu; Bethge, Christian; Sakao, Taro; Stepan, Jiri
Bibcode: 2021AGUFMSH52A..06M
Altcode:
  Probing the magnetic nature of the Suns atmosphere requires measurement
  of the Stokes I, Q, U and V profiles of relevant spectral lines (of
  which Q, U and V encode the magnetic field information). Many of the
  magnetically sensitive lines formed in the chromosphere and transition
  region are in the ultraviolet spectrum, necessitating observations
  above the absorbing terrestrial atmosphere. The Chromospheric
  Layer Spectro-Polarimeter (CLASP2) sounding rocket was flown
  successfully in April 2019, as a follow-on to the successful flight in
  September 2015 of the Chromospheric Lyman-Alpha Spectro-Polarimeter
  (CLASP). Both projects were funded by NASAs Heliophysics Technology
  and Instrument Development for Science (H-TIDeS) program to develop
  and test a technique for observing the Sun in ultraviolet light,
  and for quantifying the polarization of that light. By demonstrating
  successful measurement and interpretation of the polarization in
  hydrogen Lyman-alpha and the Mg II h and k spectral lines, the CLASP
  and CLASP2 missions are vital first steps towards routine quantitative
  characterization of the local thermal and magnetic conditions in the
  solar chromosphere. In October of 2021, we re-flew the CLASP2 payload
  with a modified observing program to further demonstrate the maturity
  of the UV spectropolarimetry techniques, and readiness for development
  into a satellite observatory. During the reflight, called CLASP2.1,
  the spectrograph slit was scanned across an active region plage to
  acquire a two-dimensional map of Stokes V/I, to demonstrate the ability
  of UV spectropolarimetry to yield chromospheric magnetic fields over
  a large area. This presentation will display preliminary results from
  the flight of CLASP2.1.

Title: Enhancements to Hinode/SOT-SP Vector Magnetic Field Data
    Products
Authors: DeRosa, M. L.; Leka, K. D.; Barnes, G.; Wagner, E.; Centeno,
   R.; De Wijn, A.; Bethge, C.
Bibcode: 2021AAS...23821305D
Altcode:
  The Solar Optical Telescope Spectro-Polarimeter (SOT-SP), on board the
  Hinode spacecraft (launched in 2006), is a scanning-slit spectrograph
  that continues to provide polarization spectra useful for inferring the
  vector (three-component) magnetic field at the solar photosphere. SOT-SP
  achieves this goal by obtaining line profiles of two magnetically
  sensitive lines, namely the Fe I 6302 Angstrom doublet, using a
  0.16"×164" slit as it scans a region of interest. Once the data are
  merged, a Milne-Eddington based spectropolarimetric inversion scheme is
  used to infer multiple physical parameters in the solar photosphere,
  including the vector magnetic field, from the calibrated polarization
  spectra. All of these data are publicly available once the processing
  has occurred. <P />As of this year, the Hinode/SOT team is also making
  available the disambiguated vector magnetic field and the re-projected
  heliographic components of the field. In making the disambiguated vector
  field data product, the 180° ambiguity in the plane-of-sky component
  of the vector magnetic field inherent in the spectropolarimetric
  inversion process has been resolved. This ambiguity is resolved
  using the Minimum-Energy algorithm, which is the same algorithm used
  within the pipeline producing the vector-magnetogram data product
  for the Helioseismic and Magnetic Imager aboard the Solar Dynamics
  Observatory. The heliographic field components (B<SUB>phi</SUB>,
  B<SUB>theta</SUB>, B<SUB>r</SUB>) on the same grid as the inverted data
  are also now provided. This poster provides more details about these
  data product enhancements, and some examples on how the scientific
  community may readily obtain these data.

Title: Mapping of Solar Magnetic Fields from the Photosphere to the
    Top of the Chromosphere with CLASP2
Authors: McKenzie, D.; Ishikawa, R.; Trujillo Bueno, J.; Auchere, F.;
   del Pino Aleman, T.; Okamoto, T.; Kano, R.; Song, D.; Yoshida, M.;
   Rachmeler, L.; Kobayashi, K.; Narukage, N.; Kubo, M.; Ishikawa, S.;
   Hara, H.; Suematsu, Y.; Sakao, T.; Bethge, C.; De Pontieu, B.; Vigil,
   G.; Winebarger, A.; Alsina Ballester, E.; Belluzzi, L.; Stepan, J.;
   Asensio Ramos, A.; Carlsson, M.; Leenaarts, J.
Bibcode: 2021AAS...23810603M
Altcode:
  Coronal heating, chromospheric heating, and the heating &amp;
  acceleration of the solar wind, are well-known problems in solar
  physics. Additionally, knowledge of the magnetic energy that
  powers solar flares and coronal mass ejections, important drivers
  of space weather, is handicapped by imperfect determination of the
  magnetic field in the sun's atmosphere. Extrapolation of photospheric
  magnetic measurements into the corona is fraught with difficulties and
  uncertainties, partly due to the vastly different plasma beta between
  the photosphere and the corona. Better results in understanding
  the coronal magnetic field should be derived from measurements of
  the magnetic field in the chromosphere. To that end, we are pursuing
  quantitative determination of the magnetic field in the chromosphere,
  where plasma beta transitions from greater than unity to less than
  unity, via ultraviolet spectropolarimetry. The CLASP2 mission, flown
  on a sounding rocket in April 2019, succeeded in measuring all four
  Stokes polarization parameters in UV spectral lines formed by singly
  ionized Magnesium and neutral Manganese. Because these ions produce
  spectral lines under different conditions, CLASP2 thus was able to
  quantify the magnetic field properties at multiple heights in the
  chromosphere simultaneously, as shown in the recent paper by Ishikawa
  et al. In this presentation we will report the findings of CLASP2,
  demonstrating the variation of magnetic fields along a track on
  the solar surface and as a function of height in the chromosphere;
  and we will illustrate what is next for the CLASP missions and the
  demonstration of UV spectropolarimetry in the solar chromosphere.

Title: Mapping the global magnetic field in the solar corona through
    magnetoseismology
Authors: Yang, Zihao; Bethge, Christian; Tian, Hui; Tomczyk, Steven;
   Morton, Richard; Del Zanna, Giulio; McIntosh, Scott; Karak, Bidya
   Binay; Gibson, Sarah; Samanta, Tanmoy; He, Jiansen; Chen, Yajie;
   Wang, Linghua; Bai, Xianyong
Bibcode: 2021EGUGA..23..642Y
Altcode:
  Magnetoseismology, a technique of magnetic field diagnostics based
  on observations of magnetohydrodynamic (MHD) waves, has been widely
  used to estimate the field strengths of oscillating structures in
  the solar corona. However, previously magnetoseismology was mostly
  applied to occasionally occurring oscillation events, providing
  an estimate of only the average field strength or one-dimensional
  distribution of field strength along an oscillating structure. This
  restriction could be eliminated if we apply magnetoseismology to the
  pervasive propagating transverse MHD waves discovered with the Coronal
  Multi-channel Polarimeter (CoMP). Using several CoMP observations of
  the Fe XIII 1074.7 nm and 1079.8 nm spectral lines, we obtained maps of
  the plasma density and wave phase speed in the corona, which allow us
  to map both the strength and direction of the coronal magnetic field
  in the plane of sky. We also examined distributions of the electron
  density and magnetic field strength, and compared their variations
  with height in the quiet Sun and active regions. Such measurements
  could provide critical information to advance our understanding of the
  Sun's magnetism and the magnetic coupling of the whole solar atmosphere.

Title: Mapping solar magnetic fields from the photosphere to the
    base of the corona
Authors: Ishikawa, Ryohko; Bueno, Javier Trujillo; del Pino Alemán,
   Tanausú; Okamoto, Takenori J.; McKenzie, David E.; Auchère,
   Frédéric; Kano, Ryouhei; Song, Donguk; Yoshida, Masaki; Rachmeler,
   Laurel A.; Kobayashi, Ken; Hara, Hirohisa; Kubo, Masahito; Narukage,
   Noriyuki; Sakao, Taro; Shimizu, Toshifumi; Suematsu, Yoshinori; Bethge,
   Christian; De Pontieu, Bart; Dalda, Alberto Sainz; Vigil, Genevieve D.;
   Winebarger, Amy; Ballester, Ernest Alsina; Belluzzi, Luca; Štěpán,
   Jiří; Ramos, Andrés Asensio; Carlsson, Mats; Leenaarts, Jorrit
Bibcode: 2021SciA....7.8406I
Altcode: 2021arXiv210301583I
  Routine ultraviolet imaging of the Sun's upper atmosphere shows the
  spectacular manifestation of solar activity; yet we remain blind to
  its main driver, the magnetic field. Here we report unprecedented
  spectropolarimetric observations of an active region plage and
  its surrounding enhanced network, showing circular polarization in
  ultraviolet (Mg II $h$ &amp; $k$ and Mn I) and visible (Fe I) lines. We
  infer the longitudinal magnetic field from the photosphere to the
  very upper chromosphere. At the top of the plage chromosphere the
  field strengths reach more than 300 gauss, strongly correlated with
  the Mg II $k$ line core intensity and the electron pressure. This
  unique mapping shows how the magnetic field couples the different
  atmospheric layers and reveals the magnetic origin of the heating in
  the plage chromosphere.

Title: Calibration of the MaGIXS Experiment. I. Calibration of the
    X-Ray Source at the X-Ray and Cryogenic Facility
Authors: Athiray, P. S.; Winebarger, Amy R.; Champey, Patrick;
   Kobayashi, Ken; Vigil, Genevieve D.; Haight, Harlan; Johnson, Steven;
   Bethge, Christian; Rachmeler, Laurel A.; Savage, Sabrina; Beabout,
   Brent; Beabout, Dyana; Hogue, William; Guillory, Anthony; Siler,
   Richard; Wright, Ernest; Kegley, Jeffrey
Bibcode: 2020ApJ...905...66A
Altcode: 2020arXiv201009823A
  The Marshall Grazing Incidence Spectrometer (MaGIXS) is a sounding
  rocket experiment that will observe the soft X-ray spectrum of the
  Sun from 24 to 6.0 Å (0.5-2.0 keV) and is scheduled for launch in
  2021. Component- and instrument-level calibrations for the MaGIXS
  instrument are carried out using the X-ray and Cryogenic Facility (XRCF)
  at NASA Marshall Space Flight Center. In this paper, we present the
  calibration of the incident X-ray flux from the electron impact source
  with different targets at the XRCF using a CCD camera; the photon flux
  at the CCD was low enough to enable its use as a "photon counter," i.e.,
  the ability to identify individual photon hits and calculate their
  energy. The goal of this paper is two-fold: (1) to confirm that the
  flux measured by the XRCF beam normalization detectors is consistent
  with the values reported in the literature and therefore reliable for
  MaGIXS calibration and (2) to develop a method of counting photons in
  CCD images that best captures their number and energy.

Title: Global maps of the magnetic field in the solar corona
Authors: Yang, Zihao; Bethge, Christian; Tian, Hui; Tomczyk, Steven;
   Morton, Richard; Del Zanna, Giulio; McIntosh, Scott W.; Karak, Bidya
   Binay; Gibson, Sarah; Samanta, Tanmoy; He, Jiansen; Chen, Yajie;
   Wang, Linghua
Bibcode: 2020Sci...369..694Y
Altcode: 2020arXiv200803136Y
  Understanding many physical processes in the solar atmosphere requires
  determination of the magnetic field in each atmospheric layer. However,
  direct measurements of the magnetic field in the Sun’s corona are
  difficult to obtain. Using observations with the Coronal Multi-channel
  Polarimeter, we have determined the spatial distribution of the
  plasma density in the corona and the phase speed of the prevailing
  transverse magnetohydrodynamic waves within the plasma. We combined
  these measurements to map the plane-of-sky component of the global
  coronal magnetic field. The derived field strengths in the corona,
  from 1.05 to 1.35 solar radii, are mostly 1 to 4 gauss. Our results
  demonstrate the capability of imaging spectroscopy in coronal magnetic
  field diagnostics.

Title: Unfolding Overlapping Spectral Images to Determine the Plasma
    Velocity During a Solar Flare
Authors: Treffner, B.; Winebarger, A. R.; Bethge, C.; Lee, K. S.;
   Savage, S. L.
Bibcode: 2019AGUFMSH31C3322T
Altcode:
  Spectroscopic images of the Sun can provide temperature and velocity
  information when monitoring and detecting solar flares. Solar Flares
  and the associated Coronal Mass Ejections (CMEs) can send fast
  moving charged particles directly into the path of Earth and impact
  space-borne instrumentation and astronauts. Strong CMEs can affect
  power grids on the surface of Earth. Therefore, there is significant
  interest and research is being conducted to try to predict these
  events. <P />As most spectrometers have a comparatively small slit
  width to avoid overlapping spectral images, their field of view is
  limited and scanning slit spectrometers often miss rapidly evolving
  events such as flares. Slot spectrometers measure both the imaging
  and spectral information over a much larger field of view. However,
  in these "overlappogram" images, the spectral and spatial information
  is convolved, making the data difficult to interpret. <P />Recently,
  a method to unfold slitless spectrometer data was developed for the
  COronal Spectroscopic Imager in the EUV (COSIE) instrument. Building
  upon this research, Extreme-ultraviolet Imaging Spectrometer (EIS)
  and Atmospheric Imaging Assembly (AIA) data are used to determine the
  best spatial, temperature, and velocity parameters for the preflare
  data inversion, or unfolding. These parameters are then applied to the
  flare data inversion with the goal of determining the velocity of the
  plasma involved in a solar flare.

Title: The High-Resolution Coronal Imager, Flight 2.1
Authors: Rachmeler, Laurel A.; Winebarger, Amy R.; Savage, Sabrina L.;
   Golub, Leon; Kobayashi, Ken; Vigil, Genevieve D.; Brooks, David H.;
   Cirtain, Jonathan W.; De Pontieu, Bart; McKenzie, David E.; Morton,
   Richard J.; Peter, Hardi; Testa, Paola; Tiwari, Sanjiv K.; Walsh,
   Robert W.; Warren, Harry P.; Alexander, Caroline; Ansell, Darren;
   Beabout, Brent L.; Beabout, Dyana L.; Bethge, Christian W.; Champey,
   Patrick R.; Cheimets, Peter N.; Cooper, Mark A.; Creel, Helen K.;
   Gates, Richard; Gomez, Carlos; Guillory, Anthony; Haight, Harlan;
   Hogue, William D.; Holloway, Todd; Hyde, David W.; Kenyon, Richard;
   Marshall, Joseph N.; McCracken, Jeff E.; McCracken, Kenneth; Mitchell,
   Karen O.; Ordway, Mark; Owen, Tim; Ranganathan, Jagan; Robertson,
   Bryan A.; Payne, M. Janie; Podgorski, William; Pryor, Jonathan; Samra,
   Jenna; Sloan, Mark D.; Soohoo, Howard A.; Steele, D. Brandon; Thompson,
   Furman V.; Thornton, Gary S.; Watkinson, Benjamin; Windt, David
Bibcode: 2019SoPh..294..174R
Altcode: 2019arXiv190905942R
  The third flight of the High-Resolution Coronal Imager (Hi-C 2.1)
  occurred on May 29, 2018; the Sounding Rocket was launched from White
  Sands Missile Range in New Mexico. The instrument has been modified
  from its original configuration (Hi-C 1) to observe the solar corona
  in a passband that peaks near 172 Å, and uses a new, custom-built
  low-noise camera. The instrument targeted Active Region 12712, and
  captured 78 images at a cadence of 4.4 s (18:56:22 - 19:01:57 UT; 5
  min and 35 s observing time). The image spatial resolution varies due
  to quasi-periodic motion blur from the rocket; sharp images contain
  resolved features of at least 0.47 arcsec. There are coordinated
  observations from multiple ground- and space-based telescopes providing
  an unprecedented opportunity to observe the mass and energy coupling
  between the chromosphere and the corona. Details of the instrument
  and the data set are presented in this paper.

Title: Unfolding Overlapped Slitless Imaging Spectrometer Data for
    Extended Sources
Authors: Winebarger, Amy R.; Weber, Mark; Bethge, Christian; Downs,
   Cooper; Golub, Leon; DeLuca, Edward; Savage, Sabrina; del Zanna,
   Giulio; Samra, Jenna; Madsen, Chad; Ashraf, Afra; Carter, Courtney
Bibcode: 2019ApJ...882...12W
Altcode: 2018arXiv181108329W
  Slitless spectrometers can provide simultaneous imaging and spectral
  data over an extended field of view, thereby allowing rapid data
  acquisition for extended sources. In some instances, when the object
  is greatly extended or the spectral dispersion is too small, there
  may be locations in the focal plane where emission lines at different
  wavelengths contribute. It is then desirable to unfold the overlapped
  regions in order to isolate the contributions from the individual
  wavelengths. In this paper, we describe a method for such an unfolding,
  using an inversion technique developed for an extreme ultraviolet
  imaging spectrometer and coronagraph named the COronal Spectroscopic
  Imager in the EUV (COSIE). The COSIE spectrometer wavelength range
  (18.6-20.5 nm) contains a number of strong coronal emission lines and
  several density sensitive lines. We focus on optimizing the unfolding
  process to retrieve emission measure maps at constant temperature,
  maps of spectrally pure intensity in the Fe XII and Fe XIII lines,
  and density maps based on both Fe XII and Fe XIII diagnostics.

Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: McKenzie, D. E.; Ishikawa, R.; Trujillo Bueno, J.; Auchére,
   F.; Rachmeler, L. A.; Kubo, M.; Kobayashi, K.; Winebarger, A. R.;
   Bethge, C. W.; Narukage, N.; Kano, R.; Ishikawa, S.; de Pontieu,
   B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Štěpán, J.; del Pino
   Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A.
Bibcode: 2019ASPC..526..361M
Altcode:
  The hydrogen Lyman-α line at 121.6 nm and the Mg k line at 279.5
  nm are especially relevant for deciphering the magnetic structure
  of the chromosphere since their line-center signals are formed in
  the chromosphere and transition region, with unique sensitivities to
  magnetic fields. We propose the Chromospheric LAyer Spectro-Polarimeter
  (CLASP2), to build upon the success of the first CLASP flight, which
  measured the linear polarization in H I Lyman-α. The existing CLASP
  instrument will be refitted to measure all four Stokes parameters in
  the 280 nm range, including variations due to the anisotropic radiation
  pumping, the Hanle effect, and the Zeeman effect.

Title: Combining sparsity DEM inversions with event tracking for
    AIA data
Authors: Bethge, Christian; Winebarger, Amy; Tiwari, Sanjiv
Bibcode: 2018csc..confE.108B
Altcode:
  We apply a modified event tracking code (ASGARD - Automated Selection
  and Grouping of events in AIA Regional Data) to the results from
  sparsity DEM inversions (Cheung et al, 2015) using AIA EUV data. Outputs
  are grouped regions (x/y/t) in multiple defined temperature bins
  that can then be correlated in space and time to track the thermal
  evolution of coronal structures. We show examples and an overview of
  the methodology.

Title: Current State of UV Spectro-Polarimetry and its Future
    Direction
Authors: Ishikawa, Ryohko; Sakao, Taro; Katsukawa, Yukio; Hara,
   Hirohisa; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito;
   Auchere, Frederic; De Pontieu, Bart; Winebarger, Amy; Kobayashi,
   . Ken; Kano, Ryouhei; Narukage, Noriyuki; Trujillo Bueno, Javier;
   Song, Dong-uk; Manso Sainz, Rafael; Asensio Ramos, Andres; Leenaarts,
   Jorritt; Carlsson, Mats; Bando, Takamasa; Ishikawa, Shin-nosuke;
   Tsuneta, Saku; Belluzzi, Luca; Suematsu, Yoshinori; Giono, Gabriel;
   Yoshida, Masaki; Goto, Motoshi; Del Pino Aleman, Tanausu; Stepan,
   Jiri; Okamoto, Joten; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Champey,
   Patrick; Alsina Ballester, Ernest; Casini, Roberto; McKenzie, David;
   Rachmeler, Laurel; Bethge, Christian
Bibcode: 2018cosp...42E1564I
Altcode:
  To obtain quantitative information on the magnetic field in low beta
  regions (i.e., upper chromosphere and above) has been increasingly
  important to understand the energetic phenomena of the outer
  solar atmosphere such as flare, coronal heating, and the solar wind
  acceleration. In the UV range, there are abundant spectral lines that
  originate in the upper chromosphere and transition region. However,
  the Zeeman effect in these spectral lines does not give rise to easily
  measurable polarization signals because of the weak magnetic field
  strength and the larger Doppler broadening compared with the Zeeman
  effect. Instead, the Hanle effect in UV lines is expected to be a
  suitable diagnostic tool of the magnetic field in the upper atmospheric
  layers. To investigate the validity of UV spectro-polarimetry and
  the Hanle effect, the Chromospheric Lyman-Alpha Spectro-Polarimeter
  (CLASP), which is a NASA sounding- rocket experiment, was launched at
  White Sands in US on September 3, 2015. During its 5 minutes ballistic
  flight, it successfully performed spectro-polarimetric observations
  of the hydrogen Lyman-alpha line (121.57 nm) with an unprecedentedly
  high polarization sensitivity of 0.1% in this wavelength range. CLASP
  observed the linear polarization produced by scattering process in VUV
  lines for the first time and detected the polarization signals which
  indicate the operation of the Hanle effect. Following the success
  of CLASP, we are confident that UV spectro-polarimetry is the way
  to proceed, and we are planning the second flight of CLASP (CLASP2:
  Chromospheric LAyer SpectroPolarimeter 2). For this second flight we
  will carry out spectro-polarimetry in the Mg II h and k lines around
  280 nm, with minimum modifications of the CLASP1 instrument. The linear
  polarization in the Mg II k line is induced by scattering processes and
  the Hanle effect, being sensitive to magnetic field strengths of 5 to 50
  G. In addition, the circular polarizations in the Mg II h and k lines
  induced by the Zeeman effect can be measurable in at least plage and
  active regions. The combination of the Hanle and Zeeman effects could
  help us to more reliably infer the magnetic fields of the upper solar
  chromosphere. CLASP2 was selected for flight and is being developed for
  launch in the spring of 2019.Based on these sounding rocket experiments
  (CLASP1 and 2), we aim at establishing the strategy and refining the
  instrument concept for future space missions to explore the enigmatic
  atmospheric layers via UV spectro-polarimetry.

Title: Linearity Analysis and Efficiency Testing of The Chromospheric
    Lyman-Alpha Spectro-Polarimeter (CLASP) Science Cameras for Flight
Authors: Walker, S. C.; Rachmeler, L.; Winebarger, A. R.; Champey,
   P. R.; Bethge, C.
Bibcode: 2017AGUFMSH51C2503W
Altcode:
  To unveil the complexity of the solar atmosphere, measurement of the
  magnetic field in the upper chromosphere and transition region is
  fundamentally important, as this is where the forces transition from
  plasma to magnetic field dominated. Measurements of the field are also
  needed to shed light on the energy transport from the lower atmospheric
  regions to the corona beyond. Such an advance in heliospheric knowledge
  became possible with the first flight of the international solar
  sounding rocket mission, CLASP. For the first time, linear polarization
  was measured in H Lyman-Alpha at 121.60 nm in September 2015. For linear
  polarization measurements in this line, high sensitivity is required due
  to the relatively weak polarization signal compared to the intensity. To
  achieve this high sensitivity, a low-noise sensor is required with
  good knowledge of its characterization, including linearity. This work
  presents further refinement of the linearity characterization of the
  cameras flown in 2015. We compared the current from a photodiode in
  the light path to the digital response of the detectors. Pre-flight
  CCD linearity measurements were taken for all three flight cameras and
  calculations of the linear fits and residuals were performed. However,
  the previous calculations included a smearing pattern and a digital
  saturation region on the detectors which were not properly taken
  into account. The calculations have been adjusted and were repeated
  for manually chosen sub-regions on the detectors that were found not
  to be affected. We present a brief overview of the instrument, the
  calibration data and procedures, and a comparison of the old and new
  linearity results. The CLASP cameras will be reused for the successor
  mission, CLASP2, which will measure the Mg II h &amp; k lines between
  279.45 nm and 280.35 nm. The new approach will help to better prepare
  for and to improve the camera characterization for CLASP2.

Title: Comparison of Solar Fine Structure Observed Simultaneously
    in Lyα and Mg II h
Authors: Schmit, D.; Sukhorukov, A. V.; De Pontieu, B.; Leenaarts,
   J.; Bethge, C.; Winebarger, A.; Auchère, F.; Bando, T.; Ishikawa,
   R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J.
Bibcode: 2017ApJ...847..141S
Altcode: 2017arXiv170900035S
  The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the
  Sun in H I Lyα during a suborbital rocket flight on 2015 September
  3. The Interface Region Imaging Telescope (IRIS) coordinated with the
  CLASP observations and recorded nearly simultaneous and co-spatial
  observations in the Mg II h and k lines. The Mg II h and Lyα lines
  are important transitions, energetically and diagnostically, in the
  chromosphere. The canonical solar atmosphere model predicts that these
  lines form in close proximity to each other and so we expect that the
  line profiles will exhibit similar variability. In this analysis, we
  present these coordinated observations and discuss how the two profiles
  compare over a region of quiet Sun at viewing angles that approach the
  limb. In addition to the observations, we synthesize both line profiles
  using a 3D radiation-MHD simulation. In the observations, we find that
  the peak width and the peak intensities are well correlated between the
  lines. For the simulation, we do not find the same relationship. We
  have attempted to mitigate the instrumental differences between IRIS
  and CLASP and to reproduce the instrumental factors in the synthetic
  profiles. The model indicates that formation heights of the lines
  differ in a somewhat regular fashion related to magnetic geometry. This
  variation explains to some degree the lack of correlation, observed
  and synthesized, between Mg II and Lyα. Our analysis will aid in the
  definition of future observatories that aim to link dynamics in the
  chromosphere and transition region.

Title: Introduction of the ASGARD code (Automated Selection and
    Grouping of events in AIA Regional Data)
Authors: Bethge, Christian; Winebarger, Amy; Tiwari, Sanjiv K.;
   Fayock, Brian
Bibcode: 2017SPD....4810623B
Altcode:
  We have developed the ASGARD code to automatically detect and group
  brightenings ("events") in AIA data. The event selection and grouping
  can be optimized to the respective dataset with a multitude of control
  parameters. The code was initially written for IRIS data, but has since
  been optimized for AIA. However, the underlying algorithm is not limited
  to either and could be used for other data as well.Results from datasets
  in various AIA channels show that brightenings are reliably detected and
  that coherent coronal structures can be isolated by using the obtained
  information about the start, peak, and end times of events. We are
  presently working on a follow-up algorithm to automatically determine
  the heating and cooling timescales of coronal structures. This will
  be done by correlating the information from different AIA channels
  with different temperature responses. We will present the code and
  preliminary results.

Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: Rachmeler, Laurel; E McKenzie, David; Ishikawa, Ryohko;
   Trujillo Bueno, Javier; Auchère, Frédéric; Kobayashi, Ken;
   Winebarger, Amy; Bethge, Christian; Kano, Ryouhei; Kubo, Masahito;
   Song, Donguk; Narukage, Noriyuki; Ishikawa, Shin-nosuke; De Pontieu,
   Bart; Carlsson, Mats; Yoshida, Masaki; Belluzzi, Luca; Stepan, Jiri;
   del Pino Alemná, Tanausú; Ballester, Ernest Alsina; Asensio Ramos,
   Andres
Bibcode: 2017SPD....4811010R
Altcode:
  We present the instrument, science case, and timeline of the CLASP2
  sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha
  Spectro-Polarimeter) sounding rocket flight in 2015 resulted in
  the first-ever linear polarization measurements of solar hydrogen
  Lyman-alpha line, which is sensitive to the Hanle effect and can be used
  to constrain the magnetic field and geometric complexity of the upper
  chromosphere. Ly-alpha is one of several upper chromospheric lines that
  contain magnetic information. In the spring of 2019, we will re-fly
  the modified CLASP telescope to measure the full Stokes profile of Mg
  II h &amp; k near 280 nm. This set of lines is sensitive to the upper
  chromospheric magnetic field via both the Hanle and the Zeeman effects.

Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: Rachmeler, Laurel A.; McKenzie, D. E.; Ishikawa, R.;
   Trujillo-Bueno, J.; Auchere, F.; Kobayashi, K.; Winebarger, A.;
   Bethge, C.; Kano, R.; Kubo, M.; Song, D.; Narukage, N.; Ishikawa, S.;
   De Pontieu, B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Stepan, J.;
   del Pino Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A.
Bibcode: 2017shin.confE..79R
Altcode:
  We present the instrument, science case, and timeline of the CLASP2
  sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha
  Spectro-Polarimeter) sounding rocket flight in 2015 resulted in
  the first-ever linear polarization measurements of solar hydrogen
  Lyman-alpha line, which is sensitive to the Hanle effect and can be used
  to constrain the magnetic field and geometric complexity of the upper
  chromosphere. Ly-alpha is one of several upper chromospheric lines that
  contain magnetic information. In the spring of 2019, we will re-fly
  the modified CLASP telescope to measure the full Stokes profile of Mg
  II h &amp; k near 280 nm. This set of lines is sensitive to the upper
  chromospheric magnetic field via both the Hanle and the Zeeman effects.

Title: Magnetic fields of opposite polarity in sunspot penumbrae
Authors: Franz, M.; Collados, M.; Bethge, C.; Schlichenmaier, R.;
   Borrero, J. M.; Schmidt, W.; Lagg, A.; Solanki, S. K.; Berkefeld,
   T.; Kiess, C.; Rezaei, R.; Schmidt, D.; Sigwarth, M.; Soltau, D.;
   Volkmer, R.; von der Luhe, O.; Waldmann, T.; Orozco, D.; Pastor Yabar,
   A.; Denker, C.; Balthasar, H.; Staude, J.; Hofmann, A.; Strassmeier,
   K.; Feller, A.; Nicklas, H.; Kneer, F.; Sobotka, M.
Bibcode: 2016A&A...596A...4F
Altcode: 2016arXiv160800513F
  Context. A significant part of the penumbral magnetic field returns
  below the surface in the very deep photosphere. For lines in the
  visible, a large portion of this return field can only be detected
  indirectly by studying its imprints on strongly asymmetric and
  three-lobed Stokes V profiles. Infrared lines probe a narrow layer
  in the very deep photosphere, providing the possibility of directly
  measuring the orientation of magnetic fields close to the solar
  surface. <BR /> Aims: We study the topology of the penumbral magnetic
  field in the lower photosphere, focusing on regions where it returns
  below the surface. <BR /> Methods: We analyzed 71 spectropolarimetric
  datasets from Hinode and from the GREGOR infrared spectrograph. We
  inferred the quality and polarimetric accuracy of the infrared data
  after applying several reduction steps. Techniques of spectral
  inversion and forward synthesis were used to test the detection
  algorithm. We compared the morphology and the fractional penumbral
  area covered by reversed-polarity and three-lobed Stokes V profiles for
  sunspots at disk center. We determined the amount of reversed-polarity
  and three-lobed Stokes V profiles in visible and infrared data of
  sunspots at various heliocentric angles. From the results, we computed
  center-to-limb variation curves, which were interpreted in the context
  of existing penumbral models. <BR /> Results: Observations in visible
  and near-infrared spectral lines yield a significant difference in the
  penumbral area covered by magnetic fields of opposite polarity. In
  the infrared, the number of reversed-polarity Stokes V profiles is
  smaller by a factor of two than in the visible. For three-lobed Stokes
  V profiles the numbers differ by up to an order of magnitude.

Title: Statistical Evidence for the Existence of Alfvénic Turbulence
    in Solar Coronal Loops
Authors: Liu, Jiajia; McIntosh, Scott W.; De Moortel, Ineke; Threlfall,
   James; Bethge, Christian
Bibcode: 2014ApJ...797....7L
Altcode: 2014arXiv1411.5094L
  Recent observations have demonstrated that waves capable of
  carrying large amounts of energy are ubiquitous throughout the solar
  corona. However, the question of how this wave energy is dissipated
  (on which timescales and length scales) and released into the plasma
  remains largely unanswered. Both analytic and numerical models have
  previously shown that Alfvénic turbulence may play a key role not
  only in the generation of the fast solar wind, but in the heating
  of coronal loops. In an effort to bridge the gap between theory and
  observations, we expand on a recent study by analyzing 37 clearly
  isolated coronal loops using data from the Coronal Multi-channel
  Polarimeter instrument. We observe Alfvénic perturbations with phase
  speeds which range from 250 to 750 km s<SUP>-1</SUP> and periods from
  140 to 270 s for the chosen loops. While excesses of high-frequency wave
  power are observed near the apex of some loops (tentatively supporting
  the onset of Alfvénic turbulence), we show that this excess depends on
  loop length and the wavelength of the observed oscillations. In deriving
  a proportional relationship between the loop length/wavelength ratio
  and the enhanced wave power at the loop apex, and from the analysis
  of the line widths associated with these loops, our findings are
  supportive of the existence of Alfvénic turbulence in coronal loops.

Title: Observations of a Hybrid Double-streamer/Pseudostreamer in
    the Solar Corona
Authors: Rachmeler, L. A.; Platten, S. J.; Bethge, C.; Seaton, D. B.;
   Yeates, A. R.
Bibcode: 2014ApJ...787L...3R
Altcode: 2013arXiv1312.3153R
  We report on the first observation of a single hybrid magnetic structure
  that contains both a pseudostreamer and a double streamer. This
  structure was originally observed by the SWAP instrument on board
  the PROBA2 satellite between 2013 May 5 and 10. It consists of a pair
  of filament channels near the south pole of the Sun. On the western
  edge of the structure, the magnetic morphology above the filaments
  is that of a side-by-side double streamer, with open field between
  the two channels. On the eastern edge, the magnetic morphology is
  that of a coronal pseudostreamer without the central open field. We
  investigated this structure with multiple observations and modeling
  techniques. We describe the topology and dynamic consequences of such
  a unified structure.

Title: Potential Evidence for the Onset of Alfvénic Turbulence in
    Trans-equatorial Coronal Loops
Authors: De Moortel, I.; McIntosh, S. W.; Threlfall, J.; Bethge, C.;
   Liu, J.
Bibcode: 2014ApJ...782L..34D
Altcode:
  This study investigates Coronal Multi-channel Polarimeter Doppler-shift
  observations of a large, off-limb, trans-equatorial loop system observed
  on 2012 April 10-11. Doppler-shift oscillations with a broad range of
  frequencies are found to propagate along the loop with a speed of about
  500 km s<SUP>-1</SUP>. The power spectrum of perturbations travelling
  up from both loop footpoints is remarkably symmetric, probably due to
  the almost perfect north-south alignment of the loop system. Compared
  to the power spectrum at the footpoints of the loop, the Fourier power
  at the apex appears to be higher in the high-frequency part of the
  spectrum than expected from theoretical models. We suggest this excess
  high-frequency power could be tentative evidence for the onset of a
  cascade of the low-to-mid frequency waves into (Alfvénic) turbulence.

Title: The spatial relation between EUV cavities and linear
    polarization signatures
Authors: Bak-Stȩślicka, Urszula; Gibson, Sarah E.; Fan, Yuhong;
   Bethge, Christian; Forland, Blake; Rachmeler, Laurel A.
Bibcode: 2014IAUS..300..395B
Altcode:
  Solar coronal cavities are regions of rarefied density and elliptical
  cross-section. The Coronal Multi-channel Polarimeter (CoMP) obtains
  daily full-Sun coronal observations in linear polarization, allowing
  a systematic analysis of the coronal magnetic field in polar-crown
  prominence cavities. These cavities commonly possess a characteristic
  ``lagomorphic'' signature in linear polarization that may be explained
  by a magnetic flux-rope model. We analyze the spatial relation between
  the EUV cavity and the CoMP linear polarization signature.

Title: Observations of Coronal Mass Ejections with the Coronal
    Multichannel Polarimeter
Authors: Tian, H.; Tomczyk, S.; McIntosh, S. W.; Bethge, C.; de Toma,
   G.; Gibson, S.
Bibcode: 2013SoPh..288..637T
Altcode: 2013arXiv1303.4647T
  The Coronal Multichannel Polarimeter (CoMP) measures not only the
  polarization of coronal emission, but also the full radiance profiles of
  coronal emission lines. For the first time, CoMP observations provide
  high-cadence image sequences of the coronal line intensity, Doppler
  shift, and line width simultaneously over a large field of view. By
  studying the Doppler shift and line width we may explore more of the
  physical processes of the initiation and propagation of coronal mass
  ejections (CMEs). Here we identify a list of CMEs observed by CoMP
  and present the first results of these observations. Our preliminary
  analysis shows that CMEs are usually associated with greatly increased
  Doppler shift and enhanced line width. These new observations provide
  not only valuable information to constrain CME models and probe
  various processes during the initial propagation of CMEs in the low
  corona, but also offer a possible cost-effective and low-risk means
  of space-weather monitoring.

Title: The Evolving Magnetic Scales of the Outer Solar Atmosphere
    and Their Potential Impact on Heliospheric Turbulence
Authors: McIntosh, Scott W.; Bethge, Christian; Threlfall, James;
   De Moortel, Ineke; Leamon, Robert J.; Tian, Hui
Bibcode: 2013arXiv1311.2538M
Altcode:
  The presence of turbulent phenomena in the outer solar atmosphere
  is a given. However, because we are reduced to remotely sensing the
  atmosphere of a star with instruments of limited spatial and/or spectral
  resolution, we can only infer the physical progression from macroscopic
  to microscopic phenomena. Even so, we know that many, if not all,
  of the turbulent phenomena that pervade interplanetary space have
  physical origins at the Sun and so in this brief article we consider
  some recent measurements which point to sustained potential source(s)
  of heliospheric turbulence in the magnetic and thermal domains. In
  particular, we look at the scales of magnetism that are imprinted on
  the outer solar atmosphere by the relentless magneto-convection of the
  solar interior and combine state-of-the-art observations from the Solar
  Dynamics Observatory (SDO) and the Coronal Multi-channel Polarimeter
  (CoMP) which are beginning to hint at the origins of the wave/plasma
  interplay prevalent closer to the Earth. While linking these disparate
  scales of observation and understanding of their connection is near
  to impossible, it is clear that the constant evolution of subsurface
  magnetism on a host of scales guides and governs the flow of mass
  and energy at the smallest scales. In the near future significant
  progress in this area will be made by linking observations from high
  resolution platforms like the Interface Region Imaging Spectrograph
  (IRIS) and Advanced Technology Solar Telescope (ATST) with full-disk
  synoptic observations such as those presented herein.

Title: First comparison of wave observations from CoMP and AIA/SDO
Authors: Threlfall, J.; De Moortel, I.; McIntosh, S. W.; Bethge, C.
Bibcode: 2013A&A...556A.124T
Altcode: 2013arXiv1306.3354T
  Context. Waves have long been thought to contribute to the heating
  of the solar corona and the generation of the solar wind. Recent
  observations have demonstrated evidence of quasi-periodic longitudinal
  disturbances and ubiquitous transverse wave propagation in many
  different coronal environments. <BR /> Aims: This paper investigates
  signatures of different types of oscillatory behaviour, both above
  the solar limb and on-disk, by comparing findings from the Coronal
  Multi-channel Polarimeter (CoMP) and the Atmospheric Imaging
  Assembly (AIA) on-board the Solar Dynamics Observatory (SDO) for
  the same active region. <BR /> Methods: We study both transverse and
  longitudinal motion by comparing and contrasting time-distance images
  of parallel and perpendicular cuts along/across active region fan
  loops. Comparisons between parallel space-time diagram features in
  CoMP Doppler velocity and transverse oscillations in AIA images are
  made, together with space-time analysis of propagating quasi-periodic
  intensity features seen near the base of loops in AIA. <BR /> Results:
  Signatures of transverse motions are observed along the same magnetic
  structure using CoMP Doppler velocity (v<SUB>phase</SUB> = 600 → 750
  km s<SUP>-1</SUP>, P = 3 → 6 min) and in AIA/SDO above the limb (P =
  3 → 8 min). Quasi-periodic intensity features (v<SUB>phase</SUB> =
  100 → 200 km s<SUP>-1</SUP>, P = 6 → 11 min) also travel along the
  base of the same structure. On the disk, signatures of both transverse
  and longitudinal intensity features were observed by AIA, and both show
  similar properties to signatures found along structures anchored in
  the same active region three days earlier above the limb. Correlated
  features are recovered by space-time analysis of neighbouring tracks
  over perpendicular distances of ≲2.6 Mm.

Title: The Magnetic Structure of Solar Prominence Cavities: New
    Observational Signature Revealed by Coronal Magnetometry
Authors: Bąk-Stȩślicka, Urszula; Gibson, Sarah E.; Fan, Yuhong;
   Bethge, Christian; Forland, Blake; Rachmeler, Laurel A.
Bibcode: 2013ApJ...770L..28B
Altcode: 2013arXiv1304.7388B
  The Coronal Multi-Channel Polarimeter (CoMP) obtains daily full-Sun
  above-the-limb coronal observations in linear polarization, allowing,
  for the first time, a diagnostic of the coronal magnetic field
  direction in quiescent prominence cavities. We find that these cavities
  consistently possess a characteristic "lagomorphic" signature in linear
  polarization indicating twist or shear extending up into the cavity
  above the neutral line. We demonstrate that such a signature may be
  explained by a magnetic flux-rope model, a topology with implications
  for solar eruptions. We find corroborating evidence for a flux-rope
  structure in the pattern of concentric rings within cavities seen in
  CoMP line-of-sight velocity.

Title: The Chromosphere and Prominence Magnetometer
Authors: de Wijn, Alfred; Bethge, Christian; McIntosh, Scott; Tomczyk,
   Steven; Burkepile, Joan
Bibcode: 2013EGUGA..1512765D
Altcode:
  The Chromosphere and Prominence Magnetometer (ChroMag) is a synoptic
  instrument with the goal of quantifying the intertwined dynamics
  and magnetism of the solar chromosphere and in prominences through
  imaging spectro-polarimetry of the full solar disk in a synoptic
  fashion. The picture of chromospheric magnetism and dynamics is
  rapidly developing, and a pressing need exists for breakthrough
  observations of chromospheric vector magnetic field measurements
  at the true lower boundary of the heliospheric system. ChroMag will
  provide measurements that will enable scientists to study and better
  understand the energetics of the solar atmosphere, how prominences are
  formed, how energy is stored in the magnetic field structure of the
  atmosphere and how it is released during space weather events like
  flares and coronal mass ejections. An essential part of the ChroMag
  program is a commitment to develop and provide community access to the
  `inversion' tools necessary to interpret the measurements and derive
  the magneto-hydrodynamic parameters of the plasma. Measurements of an
  instrument like ChroMag provide critical physical context for the Solar
  Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph
  (IRIS) as well as ground-based observatories such as the future Advanced
  Technology Solar Telescope (ATST). A prototype is currently under
  construction at the High Altitude Observatory of the National Center
  for Atmospheric Research in Boulder, CO, USA. The heart of the ChroMag
  instrument is an electro-optically tunable wide-fielded narrow-band
  birefringent six-stage Lyot filter with a built-in polarimeter. We
  will present a progress update on the ChroMag design, and present
  results from the prototype instrument.

Title: The chromosphere and prominence magnetometer
Authors: de Wijn, Alfred G.; Bethge, Christian; Tomczyk, Steven;
   McIntosh, Scott
Bibcode: 2012SPIE.8446E..78D
Altcode: 2012arXiv1207.0969D
  The Chromosphere and Prominence Magnetometer (ChroMag) is conceived
  with the goal of quantifying the intertwined dynamics and magnetism
  of the solar chromosphere and in prominences through imaging spectro-
  polarimetry of the full solar disk. The picture of chromospheric
  magnetism and dynamics is rapidly developing, and a pressing need
  exists for breakthrough observations of chromospheric vector magnetic
  field measurements at the true lower boundary of the heliospheric
  system. ChroMag will provide measurements that will enable scientists
  to study and better understand the energetics of the solar atmosphere,
  how prominences are formed, how energy is stored in the magnetic field
  structure of the atmosphere and how it is released during space weather
  events like flares and coronal mass ejections. An integral part of the
  ChroMag program is a commitment to develop and provide community access
  to the "inversion" tools necessary for the difficult interpretation
  of the measurements and derive the magneto-hydrodynamic parameters of
  the plasma. Measurements of an instrument like ChroMag provide critical
  physical context for the Solar Dynamics Observatory (SDO) and Interface
  Region Imaging Spectrograph (IRIS) as well as ground-based observatories
  such as the future Advanced Technology Solar Telescope (ATST).

Title: Magnetic Structure of Coronal Cavities
Authors: Gibson, Sarah; Bak-Steslicka, Urszula; Bethge, Christian;
   de Toma, Giuliana; Dove, Jim; Fan, Yuhong; Forland, Blake; Rachmeler,
   Laurel
Bibcode: 2012shin.confE.209G
Altcode:
  Coronal cavities are dark, elliptical regions in which strong
  and twisted magnetism dwells. Polar-crown-prominence cavities in
  particular are excellent targets for coronal magnetometry, because
  they are long-lived (on the order of weeks) and extended along the
  line of sight. Using data from the Coronal Multichannel Polarimeter
  (CoMP), we show a specific structure in linear polarization that
  is very consistent from cavity to cavity, and that matches that of a
  forward-modeled flux rope. We discuss how this structure scales with the
  size of the cavity, and consider implications for future observations
  (e.g., ATST and COSMO) in probing and indeed predicting topological
  changes and instabilities leading up to eruptions.

Title: New insight into CME processes revealed by CoMP observations
Authors: Tian, Hui; McIntosh, Scott W.; Bethge, Christian; Tomczyk,
   Steve; Sitongia, Leonard E.
Bibcode: 2012shin.confE..11T
Altcode:
  CoMP measures not only the polarization of coronal emission, but also
  measures the full radiance profiles of coronal emission lines. For the
  first time, CoMP observations provide high-cadence image sequences
  of the coronal intensity, Doppler shift, line width and linear
  polarization simultaneously. These measurements may help us explore
  more of the physical processes at the onset of solar eruptions such
  as CMEs and flares. They should also provide important constraints to
  models of solar eruptions. Our preliminary analysis shows that CMEs are
  usually associated with greatly increased Doppler shift and enhanced
  line width. The linear polarization in CMEs measured by CoMP has also
  been investigated.

Title: The Chromospheric Magnetometer ChroMag
Authors: Bethge, Christian; de Wijn, A. G.; McIntosh, S. W.; Tomczyk,
   S.; Casini, R.
Bibcode: 2012AAS...22013506B
Altcode:
  We present the Chromosphere Magnetometer (ChroMag), which is part of
  the Coronal Solar Magnetism Observatory (COSMO) proposed by the High
  Altitude Observatory (HAO) in collaboration with the University of
  Hawaii and the University of Michigan. ChroMag will perform routine
  measurements of chromospheric magnetic fields in a synoptic manner. A <P
  />prototype is currently being assembled at HAO. The main component of
  the instrument is a Lyot-type filtergraph polarimeter for both on-disk
  and off-limb polarization measurements in <P />the spectral lines of
  H alpha at 656.3 nm, Fe I 617.3 nm, Ca II 854.2 nm, He I 587.6 nm,
  and He I 1083.0 nm. The Lyot filter is tunable at a fast rate. This
  allows to determine line-of-sight <P />velocities in addition to the
  magnetic field measurements. The instrument has a field-of-view of
  up to 2.5 solar radii and will acquire data at a cadence of less than
  1 minute and at a spatial resolution of 2 arcsec. The community will
  have open access to the data as well as to a set of inversion tools
  for an easier interpretation of the measurements. We show an overview
  of the proposed instrument and first results from the protoype.

Title: Recent Results from the Coronal Multi-Channel Polarimeter
Authors: Tomczyk, Steven; Bethge, C.; Gibson, S. E.; McIntosh, S. W.;
   Rachmeler, L. A.; Tian, H.
Bibcode: 2012AAS...22031001T
Altcode:
  The Coronal Multi-Channel Polarimeter (CoMP) instrument is a
  ground-based filter/polarimeter which can image the solar corona at
  wavelengths around the emission lines of FeXIII at 1074.7 and 1079.8
  nm and the chromospheric emission line of HeI at 1083.0 nm. The
  instrument consists of a 20-cm aperture coronagraph followed by a
  Stokes polarimeter and a Lyot birefringent filter with a passband
  of 0.14 nm width. Both the polarimeter and filter employ liquid
  crystals for rapid electro-optical tuning. This instrument measures
  the line-of-sight strength of the coronal magnetic field through the
  Zeeman effect and the plane-of-sky direction of the magnetic field via
  resonance scattering. The line-of-sight velocity can also be determined
  from the Doppler shift. The CoMP has obtained daily observations from
  the Mauna Loa Solar Observatory for almost one year. We will present
  recent measurements of the polarization signatures seen with the
  CoMP and a comparison with models that allow us to constrain coronal
  structure. We also will present observations of coronal waves taken
  with the CoMP and discuss their implications for the heating of the
  solar corona and the acceleration of the solar wind.

Title: The Chromosphere and Prominence Magnetometer
Authors: de Wijn, Alfred; Bethge, Christian; McIntosh, Scott; Tomczyk,
   Steven; Casini, Roberto
Bibcode: 2012decs.confE..63D
Altcode:
  ChroMag is an imaging polarimeter designed to measure on-disk
  chromosphere and off-disk prominence magnetic fields using the
  spectral lines of He I (587.6 and 1083 nm). It is part of the planned
  CoSMO suite, which includes two more instruments: a large 1.5-m
  refracting coronagraph for coronal magnetic field measurements, and
  the K-Coronagraph for measurement of the coronal density. ChroMag
  will provide insights in the energetics of the solar atmosphere,
  how prominences are formed, and how energy is stored and released
  in the magnetic field structure of the atmosphere. An essential
  part of the ChroMag program is a commitment to develop and provide
  community access to the "inversion" tools necessary to interpret the
  measurements and derive the magneto-hydrodynamic parameters of the
  plasma. A prototype instrument is currently under construction at the
  High Altitude Observatory. We will present an overview of the ChroMag
  instrument concept, target science, and prototype status.

Title: Synoptic measurements of chromospheric and prominence magnetic
    fields with the Chromosphere Magnetometer ChroMag
Authors: Bethge, C.; de Wijn, A. G.; McIntosh, S. W.; Tomczyk, S.;
   Casini, R.
Bibcode: 2012decs.confE..62B
Altcode:
  The Chromosphere Magnetometer is part of the Coronal Solar Magnetism
  Observatory (COSMO) proposed by the High Altitude Observatory (HAO)
  in collaboration with the University of Hawaii and the University of
  Michigan. Routine measurements of chromospheric and coronal magnetic
  fields are vital if we want to understand fundamental problems like
  the energy and mass balance of the corona, the onset and acceleration
  of the solar wind, the emergence of CMEs, and how these phenomena
  influence space weather. ChroMag is designed as a Lyot-type filtergraph
  polarimeter with an FOV of 2.5 solar radii, i.e., it will be capable of
  both on-disk and off-limb polarimetric measurements. The Lyot filter
  - currently being built at HAO - is tunable at a fast rate, which
  allows to determine line-of-sight velocities. This will be done in
  the spectral lines of H alpha at 656.3 nm, Fe I 617.3 nm, Ca II 854.2
  nm, He I 587.6 nm, and He I 1083.0 nm at a high cadence of less than
  1 minute, and at a moderate spatial resolution of 2 arcsec. ChroMag
  data will be freely accessible to the community, along with inversion
  tools for an easier interpretation of the data. A protoype instrument
  for ChroMag is currently being assembled at HAO and is expected to
  perform first measurements at the Boulder Mesa Lab in Summer 2012. We
  present an overview of the ChroMag instrument and the current status
  of the protoype.

Title: Siphon flow in a cool magnetic loop
Authors: Bethge, C.; Beck, C.; Peter, H.; Lagg, A.
Bibcode: 2012A&A...537A.130B
Altcode: 2011arXiv1111.5564B
  Context. Siphon flows that are driven by a gas pressure difference
  between two photospheric footpoints of different magnetic field strength
  connected by magnetic field lines are a well-studied phenomenon in
  theory, but observational evidence is scarce. Aims. We investigate the
  properties of a structure in the solar chromosphere in an active region
  to find out whether the feature is consistent with a siphon flow in
  a magnetic loop filled with chromospheric material. <P />Methods. We
  derived the line-of-sight (LOS) velocity of several photospheric
  spectral lines and two chromospheric spectral lines, Ca II H 3968.5
  *Aring; and He I 10830 Å, in spectropolarimetric observations of
  NOAA 10978 done with the Tenerife Infrared Polarimeter (TIP-II) and
  the POlarimetric LIttrow Spectrograph (POLIS). The structure can be
  clearly traced in the LOS velocity maps and the absorption depth of
  He I. The magnetic field configuration in the photosphere is inferred
  directly from the observed Stokes parameters and from inversions with
  the HELIX<SUP>+</SUP> code. Data from the full-disk Chromospheric
  Telescope (ChroTel) in He I in intensity and LOS velocity are used for
  tracking the temporal evolution of the flow, along with TRACE Fe IX/X
  171 Å data for additional information about coronal regions related to
  the structure under investigation. <P />Results. The inner end of the
  structure is located in the penumbra of a sunspot. It shows downflows
  whose strength decreases with decreasing height in the atmosphere. The
  flow velocity in He I falls abruptly from above 40 km s<SUP>-1</SUP>
  to about zero further into the penumbra. A slight increase of emission
  is seen in the Ca II H spectra at the endpoint. At the outer end of the
  structure, the photospheric lines that form higher up in the atmosphere
  show upflows that accelerate with height. The polarization signal near
  the outer end shows a polarity opposite to that of the sunspot, the
  magnetic field strength of 580 G is roughly half as large as at the
  inner end. The structure exists for about 90 min. Its appearance is
  preceeded by a brightening in its middle in the coronal TRACE data. <P
  />Conclusions. The observed flows match theoretical predictions of
  chromospheric and coronal siphon flows, with accelerating upflowing
  plasma at one footpoint with low field strength and decelerating
  downflowing plasma at the other end. A tube shock at the inner end is
  probable, but the evidence is not conclusive. The TRACE data suggest
  that the structure forms because of a reorganization of field lines
  after a reconnection event.

Title: The Chromospheric Telescope
Authors: Bethge, C.; Peter, H.; Kentischer, T. J.; Halbgewachs, C.;
   Elmore, D. F.; Beck, C.
Bibcode: 2011A&A...534A.105B
Altcode: 2011arXiv1108.4880B
  <BR /> Aims: We introduce the Chromospheric Telescope (ChroTel) at the
  Observatorio del Teide in Izaña on Tenerife as a new multi-wavelength
  imaging telescope for full-disk synoptic observations of the solar
  chromosphere. We describe the design of the instrument and summarize
  its performance during the first one and a half years of operation. We
  present a method to derive line-of-sight velocity maps of the full
  solar disk from filtergrams taken in and near the He i infrared line
  at 10 830 Å. <BR /> Methods: ChroTel observations are conducted
  using Lyot-type filters for the chromospheric lines of Ca ii K,
  Hα, and He i 10 830 Å. The instrument operates autonomically and
  gathers imaging data in all three channels with a cadence of down to
  one minute. The use of a tunable filter for the He i line allows us
  to determine line-shifts by calibrating the line-of-sight velocity
  maps derived from the filtergram intensities with spectrographic data
  from the Tenerife Infrared Polarimeter at high spatial and spectral
  resolution. <BR /> Results: The robotic operation and automated data
  reduction have proven to operate reliably in the first one and and
  half years. The achieved spatial resolution of the data is close to
  the theoretical limit of 2 arcsec in Hα and Ca ii K and 3 arcsec in He
  i. Line-of-sight velocities in He i can be determined with a precision
  of better than 3-4 km s<SUP>-1</SUP> when co-temporal spectrographic
  maps are available for calibration. <BR /> Conclusions: ChroTel offers a
  unique combination of imaging in the most important chromospheric lines,
  along with the possibility to determine line-of-sight velocities in
  one of the lines. This is of interest for scientific investigations
  of large-scale structures in the solar chromosphere, as well as for
  context imaging of high-resolution solar observations.

Title: The Slow Control System of the Auger Fluorescence Detectors
Authors: Barenthien, N.; Bethge, C.; Daumiller, K.; Gemmeke, H.;
   Kampert, K. -H.; Wiebusch, C.
Bibcode: 2003ICRC....2..895B
Altcode: 2003ICRC...28..895B; 2003ICRC....2..895G
  The fluorescence detector (FD) of the Pierre Auger experiment [1]
  comprises 24 telescopes that will be situated in 4 remote buildings in
  the Pampa Amarilla. It is planned to run the fluorescence detectors
  in absence of operators on site. Therefore, the main task of the
  Slow Control System (SCS) is to ensure a secure remote operation
  of the FD system. The Slow Control System works autonomously and
  continuously monitors those parameters which may disturb a secure
  operation. Commands from the data-acquisition system or the remote
  operator are accepted only if they do not violate safety rules that
  depend on the actual experimental conditions (e.g. high-voltage,
  wind-sp eed, light, etc.). In case of malfunctions (power failure,
  communication breakdown, ...) the SCS performs an orderly shutdown and
  subsequent startup of the fluorescence detector system. The concept
  and the implementation of the Slow Control System are presented.

