Author name code: gonzalez-manrique
ADS astronomy entries on 2022-09-14
author:"Gonzalez Manrique, Sergio Javier" 
------------------------------------------------------------------------  

Title: The European Solar Telescope
Authors: Quintero Noda, C.; Schlichenmaier, R.; Bellot Rubio, L. R.;
   Löfdahl, M. G.; Khomenko, E.; Jurcak, J.; Leenaarts, J.; Kuckein,
   C.; González Manrique, S. J.; Gunar, S.; Nelson, C. J.; de la Cruz
   Rodríguez, J.; Tziotziou, K.; Tsiropoula, G.; Aulanier, G.; Collados,
   M.; the EST team
Bibcode: 2022arXiv220710905Q
Altcode:
  The European Solar Telescope (EST) is a project aimed at studying
  the magnetic connectivity of the solar atmosphere, from the deep
  photosphere to the upper chromosphere. Its design combines the knowledge
  and expertise gathered by the European solar physics community during
  the construction and operation of state-of-the-art solar telescopes
  operating in visible and near-infrared wavelengths: the Swedish 1m Solar
  Telescope (SST), the German Vacuum Tower Telescope (VTT) and GREGOR,
  the French Télescope Héliographique pour l'Étude du Magnétisme
  et des Instabilités Solaires (THÉMIS), and the Dutch Open Telescope
  (DOT). With its 4.2 m primary mirror and an open configuration, EST will
  become the most powerful European ground-based facility to study the Sun
  in the coming decades in the visible and near-infrared bands. EST uses
  the most innovative technological advances: the first adaptive secondary
  mirror ever used in a solar telescope, a complex multi-conjugate
  adaptive optics with deformable mirrors that form part of the optical
  design in a natural way, a polarimetrically compensated telescope design
  that eliminates the complex temporal variation and wavelength dependence
  of the telescope Mueller matrix, and an instrument suite containing
  several (etalon-based) tunable imaging spectropolarimeters and several
  integral field unit spectropolarimeters. This publication summarises
  some fundamental science questions that can be addressed with the
  telescope, together with a complete description of its major subsystems.

Title: Observational evidence for two-component distributions
    describing solar magnetic bright points
Authors: Berrios Saavedra, Gerardine; Utz, Dominik; Vargas Domínguez,
   Santiago; Campos Rozo, José Iván; González Manrique, Sergio Javier;
   Gömöry, Peter; Kuckein, Christoph; Balthasar, Horst; Zelina, Peter
Bibcode: 2022A&A...657A..79B
Altcode: 2021arXiv211012404B
  Context. High-resolution observations of the solar photosphere reveal
  the presence of fine structures, in particular the so-called Magnetic
  Bright Points (MBPs), which are small-scale features associated with
  strong magnetic field regions of the order of kilogauss (kG). It
  is especially relevant to study these magnetic elements, which are
  extensively detected in all moments during the solar cycle, in order to
  establish their contribution to the behavior of the solar atmosphere,
  and ultimately a plausible role within the coronal heating problem. <BR
  /> Aims: Characterisation of size and velocity distributions of MBPs in
  the solar photosphere in two different datasets of quiet Sun images
  acquired with high-resolution solar instruments i.e. Solar Optical
  Telescope SOT/Hinode and the High-resolution Fast Imager HiFI/GREGOR,
  in the G-band (4308 Å). <BR /> Methods: In order to detect the
  MBPs, an automatic segmentation and identification algorithm is
  used. Next, the identified features were tracked to measure their
  proper motions. Finally, a statistical analysis of hundreds of MBPs is
  carried out, generating histograms for areas, diameters and horizontal
  velocities. <BR /> Results: This work establishes that areas and
  diameters of MBPs display log-normal distributions that are well-fitted
  by two different components, whereas the velocity vector components
  follow Gaussians and the vector magnitude a Rayleigh distribution
  revealing again for all vector elements a two component composition. <BR
  /> Conclusions: The results can be interpreted as due to the presence of
  two different populations of MBPs in the solar photosphere one likely
  related to stronger network magnetic flux elements and the other one
  to weaker intranetwork flux elemens. In particular this work concludes
  on the effect of the different spatial resolution of GREGOR and Hinode
  telescopes, affecting detections and average values.

Title: Properties of the inner penumbra boundary and temporal
    evolution of a decaying sunspot (Corrigendum)
Authors: Benko, M.; González Manrique, S. J.; Balthasar, H.; Gömöry,
   P.; Kuckein, C.; Jurčák, J.
Bibcode: 2021A&A...652C...7B
Altcode:
  No abstract at ADS

Title: Evidence For Two-component Distributions Describing Magnetic
    Bright Points In The Solar Photosphere
Authors: Vargas Domínguez, S.; Berrios Saavedra, G.; Utz, D.;
   Campos Rozo, J. I.; González Manrique, S.; Gömöry, Peter; Kuckein,
   Christoph; Balthasar, Horst; Zelina, Peter
Bibcode: 2021AAS...23811310V
Altcode:
  High-resolution observations of the Sun reveal the presence of Magnetic
  Bright Points (MBPs), which are small-scale features associated with
  strong magnetic field regions, that are found all over the solar
  photosphere. In this work, we characterize some physical properties
  and dynamics of MBPs in a quiet Sun region by using time series of
  images acquired with the High-resolution Fast Imager HiFI/GREGOR and
  Solar Optical Telescope SOT/Hinode in the G-band (4308 Angstrom). An
  automated segmentation algorithm is used to identify the MBPs and
  track their evolution. The results show observational evidence for
  two-component distributions of areas, diameters and velocities, that
  can be interpreted as corresponding to different populations of MBPs.

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

Title: Chromospheric Resonances above Sunspots and Potential
    Seismological Applications
Authors: Felipe, Tobias; Kuckein, Christoph; González Manrique,
   Sergio Javier; Milic, Ivan; Sangeetha, C. R.
Bibcode: 2020ApJ...900L..29F
Altcode: 2020arXiv200810623F
  Oscillations in sunspot umbrae exhibit remarkable differences
  between the photosphere and chromosphere. We evaluate two competing
  scenarios proposed for explaining those observations: a chromospheric
  resonant cavity and waves traveling from the photosphere to upper
  atmospheric layers. We have employed numerical simulations to
  analyze the oscillations in both models. They have been compared with
  observations in the low (Na I D<SUB>2</SUB>) and high (He I 10830 Å)
  chromosphere. The nodes of the resonant cavity can be detected as
  phase jumps or power dips, although the identification of the latter
  is not sufficient to claim the existence of resonances. In contrast,
  phase differences between velocity and temperature fluctuations reveal
  standing waves and unequivocally prove the presence of an acoustic
  resonator above umbrae. Our findings offer a new seismic method to probe
  active region chromospheres through the detection of resonant nodes.

Title: Determining the dynamics and magnetic fields in He I 10830
    Å during a solar filament eruption
Authors: Kuckein, C.; González Manrique, S. J.; Kleint, L.; Asensio
   Ramos, A.
Bibcode: 2020A&A...640A..71K
Altcode: 2020arXiv200610473K
  <BR /> Aims: We investigate the dynamics and magnetic properties of
  the plasma, including the line-of-sight velocity (LOS) and optical
  depth, as well as the vertical and horizontal magnetic fields,
  belonging to an erupted solar filament. <BR /> Methods: The filament
  eruption was observed with the GREGOR Infrared Spectrograph at
  the 1.5-meter GREGOR telescope on July 3, 2016. We acquired three
  consecutive full-Stokes slit-spectropolarimetric scans in the He
  I 10830 Å spectral range. The Stokes I profiles were classified
  using the machine learning k-means algorithm and then inverted with
  different initial conditions using the HAZEL code. <BR /> Results: The
  erupting-filament material presents the following physical conditions:
  (1) ubiquitous upward motions with peak LOS velocities of ∼73 km
  s<SUP>-1</SUP>; (2) predominant large horizontal components of the
  magnetic field, on average, in the range of 173-254 G, whereas the
  vertical components of the fields are much lower, on average between
  39 and 58 G; (3) optical depths in the range of 0.7-1.1. The average
  azimuth orientation of the field lines between two consecutive
  raster scans (&lt;2.5 min) remained constant. <BR /> Conclusions:
  The analyzed filament eruption belongs to the fast rising phase, with
  total velocities of about 124 km s<SUP>-1</SUP>. The orientation of the
  magnetic field lines does not change from one raster scan to the other,
  indicating that the untwisting phase has not yet started. The untwisting
  appears to start about 15 min after the beginning of the filament
  eruption. <P />Movies attached to Figs. 1 and 3 are available at <A
  href="https://www.aanda.org/10.1051/0004-6361/202038408/olm">https://www.aanda.org</A>

Title: Solar observatory Einstein Tower: Data release of the digitized
    solar full-disk photographic plate archive
Authors: Pal, Partha S.; Verma, Meetu; Rendtel, Jürgen; González
   Manrique, Sergio Javier; Enke, Harry; Denker, Carsten
Bibcode: 2020AN....341..575P
Altcode: 2020arXiv200714744P
  We present solar full-disk observations that were recorded
  at the Einstein Tower during the years 1943-1991 (solar cycles
  18-22). High-school students from Potsdam and Berlin digitized more than
  3,500 full-disk images during 2-3-week internships at Leibniz-Institut
  für Astrophysik Potsdam (AIP). The digital images cover a 15 cm × 15
  cm region on photographic plates, which were scanned at a resolution
  of 7,086 × 7,086 pixels. The raw data are monochromatic 8-bit images
  in the tagged image file format (TIFF). These images were calibrated
  and saved with improved photometric precision as 16-bit images with
  2,048 × 2,048 pixels in the Flexible Image Transport System (FITS)
  format, which contains extensive headers describing the full-disk
  images and the observations. The various calibration steps include,
  for example, accurate measurements of the solar radius, determination
  of the limb-darkening function, and establishing an accurate coordinate
  system. The contrast-enhanced and limb-darkening corrected images,
  as well as the raw data, are freely available to researchers and
  the general public in a publicly accessible repository. The data are
  published as a special data release of the Archives of Photographic
  PLates for Astronomical USE (APPLAUSE) project.

Title: The dynamics of a solar arch filament system from the
    chromosphere to the photosphere
Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.;
   Diercke, A.; Collados, M.; Gömöry, P.; Zhong, S.; Hou, Y.; Denker, C.
Bibcode: 2020sea..confE.199G
Altcode:
  We study the dynamics of plasma along the legs of an arch filament
  system (AFS) from the chromosphere to the photosphere, observed with
  high-cadence spectroscopic data from two ground-based solar telescopes:
  the GREGOR telescope (Tenerife) using the GREGOR Infrared Spectrograph
  in the He I 10830 Å range and the Swedish Solar Telescope (La Palma)
  using the CRisp Imaging Spectro-Polarimeter to observe the Ca II 8542
  Å and Fe I 6173 Å spectral lines. The temporal evolution of the
  draining of the plasma was followed along the legs of a single arch
  filament from the chromosphere to the photosphere. The average Doppler
  velocities inferred at the upper chromosphere from the He I 10830 Å
  triplet reach velocities up to 20-24 km s<SUP>-1</SUP>, and in the lower
  chromosphere and upper photosphere the Doppler velocities reach up to
  11 km s<SUP>-1</SUP> and 1.5 km s<SUP>-1</SUP> in the case of the Ca II
  8542 Å and Si I 10827 Å spectral lines, respectively. The evolution
  of the Doppler velocities at different layers of the solar atmosphere
  (chromosphere and upper photosphere) shows that they follow the same
  line-of-sight (LOS) velocity patern, which confirms the observational
  evidence that the plasma drains toward the photosphere as proposed in
  models of AFSs. The observations and the nonlinear force-free field
  (NLFFF) extrapolations demonstrate that the magnetic field loops of
  the AFS rise with time.

Title: Chromospheric resonant cavities in umbrae: unequivocal
    detection and seismic applications
Authors: Felipe, T.; Kuckein, C.; González Manrique, S. J.; Milic,
   I.; Sangeetha, C. R.
Bibcode: 2020sea..confE.196F
Altcode:
  Umbral chromospheric oscillations exhibit significant differences
  compared to their photospheric counterparts. We evaluate two competing
  scenarios proposed for explaining those observations: a chromospheric
  resonant cavity and waves traveling from the photosphere to upper
  atmospheric layers. The oscillatory signatures of both models have been
  determined from numerical simulations, and they have been compared to
  observations. We find that a high-frequency peak in the He I 10830 Å
  power spectra cannot discriminate between both theories, contrary to the
  claims of Jess et al. (2019). In contrast, phase differences between
  velocity and temperature fluctuations reveal a standing pattern and
  unequivocally prove the presence of an acoustic cavity above umbrae. Our
  findings offer a new seismic method to probe sunspot chromospheres
  through the identification of resonant nodes in phase spectra.

Title: Determining the dynamics and magnetic fields in the
    chromospheric He I 10830 Å triplet during a solar filament eruption
Authors: Kuckein, C.; González Manrique, S. J.; Kleint, L.; Asensio
   Ramos, A.
Bibcode: 2020sea..confE.202K
Altcode:
  We investigate the dynamics and magnetic properties of the plasma, such
  as line-of-sight velocity (LOS), optical depth, vertical and horizontal
  magnetic fields, belonging to an erupted solar filament. The filament
  eruption was observed with the GREGOR Infrared Spectrograph (GRIS)
  at the 1.5-meter GREGOR telescope on 2016 July 3. Three consecutive
  full-Stokes slit-spectropolarimetric scans in the He I 10830 Å
  spectral range were acquired. The Stokes I profiles were classified
  using the machine learning k-means algorithm and then inverted with
  different initial conditions using the inversion code HAZEL. The
  erupting-filament material presents the following physical conditions:
  (i) ubiquitous upward motions with peak LOS velocities of ∼73 km/s;
  (ii) predominant large horizontal components of the magnetic field, on
  average, in the range of 173-254 G, whereas the vertical components of
  the fields are much lower, on average between 39-58 G; (iii) optical
  depths in the range of 0.7-1.1. The average azimuth orientation of
  the field lines between two consecutive raster scans (&lt;2.5 minutes)
  remained constant. The analyzed filament eruption belonged to the fast
  rising phase, with total velocities of about 124 km/s.

Title: Magnetic Flux Emergence in a Coronal Hole
Authors: Palacios, Judith; Utz, Dominik; Hofmeister, Stefan; Krikova,
   Kilian; Gömöry, Peter; Kuckein, Christoph; Denker, Carsten; Verma,
   Meetu; González Manrique, Sergio Javier; Campos Rozo, Jose Iván;
   Koza, Július; Temmer, Manuela; Veronig, Astrid; Diercke, Andrea;
   Kontogiannis, Ioannis; Cid, Consuelo
Bibcode: 2020SoPh..295...64P
Altcode: 2020arXiv200611779P
  A joint campaign of various space-borne and ground-based observatories,
  comprising the Japanese Hinode mission (Hinode Observing Plan 338,
  20 - 30 September 2017), the GREGOR solar telescope, and the Vacuum
  Tower Telescope (VTT), investigated numerous targets such as pores,
  sunspots, and coronal holes. In this study, we focus on the coronal
  hole region target. On 24 September 2017, a very extended non-polar
  coronal hole developed patches of flux emergence, which contributed
  to the decrease of the overall area of the coronal hole. These flux
  emergence patches erode the coronal hole and transform the area into a
  more quiet-Sun-like area, whereby bipolar magnetic structures play an
  important role. Conversely, flux cancellation leads to the reduction
  of opposite-polarity magnetic fields and to an increase in the area
  of the coronal hole.

Title: Tracking Downflows from the Chromosphere to the Photosphere
    in a Solar Arch Filament System
Authors: González Manrique, Sergio Javier; Kuckein, Christoph;
   Pastor Yabar, Adur; Diercke, Andrea; Collados, Manuel; Gömöry,
   Peter; Zhong, Sihui; Hou, Yijun; Denker, Carsten
Bibcode: 2020ApJ...890...82G
Altcode: 2020arXiv200107078G
  We study the dynamics of plasma along the legs of an arch filament
  system (AFS) from the chromosphere to the photosphere, observed with
  high-cadence spectroscopic data from two ground-based solar telescopes:
  the GREGOR telescope (Tenerife) using the GREGOR Infrared Spectrograph
  in the He I 10830 Å range and the Swedish Solar Telescope (La Palma)
  using the CRisp Imaging Spectro-Polarimeter to observe the Ca II 8542
  Å and Fe I 6173 Å spectral lines. The temporal evolution of the
  draining of the plasma was followed along the legs of a single arch
  filament from the chromosphere to the photosphere. The average Doppler
  velocities inferred at the upper chromosphere from the He I 10830 Å
  triplet reach velocities up to 20-24 km s<SUP>-1</SUP>, and in the lower
  chromosphere and upper photosphere the Doppler velocities reach up to
  11 km s<SUP>-1</SUP> and 1.5 km s<SUP>-1</SUP> in the case of the Ca II
  8542 Å and Si I 10827 Å spectral lines, respectively. The evolution
  of the Doppler velocities at different layers of the solar atmosphere
  (chromosphere and upper photosphere) shows that they follow the same
  line-of-sight (LOS) velocity pattern, which confirms the observational
  evidence that the plasma drains toward the photosphere as proposed
  in models of AFSs. The Doppler velocity maps inferred from the lower
  photospheric Ca I 10839 Å or Fe I 6173 Å spectral lines do not
  show the same LOS velocity pattern. Thus, there is no evidence that
  the plasma reaches the lower photosphere. The observations and the
  nonlinear force-free field (NLFFF) extrapolations demonstrate that
  the magnetic field loops of the AFS rise with time. We found flow
  asymmetries at different footpoints of the AFS. The NLFFF values of
  the magnetic field strength help us to explain these flow asymmetries.

Title: Capabilities of bisector analysis of the Si I 10 827 Å line
    for estimating line-of-sight velocities in the quiet Sun
Authors: González Manrique, S. J.; Quintero Noda, C.; Kuckein, C.;
   Ruiz Cobo, B.; Carlsson, M.
Bibcode: 2020A&A...634A..19G
Altcode: 2020arXiv200100508G
  We examine the capabilities of a fast and simple method to infer
  line-of-sight (LOS) velocities from observations of the photospheric
  Si I 10 827 Å line. This spectral line is routinely observed together
  with the chromospheric He I 10 830 Å triplet as it helps to constrain
  the atmospheric parameters. We study the accuracy of bisector analysis
  and a line core fit of Si I 10 827 Å. We employ synthetic profiles
  starting from the Bifrost enhanced network simulation. The profiles are
  computed solving the radiative transfer equation, including non-local
  thermodynamic equilibrium effects on the determination of the atomic
  level populations of Si I. We found a good correlation between the
  inferred velocities from bisectors taken at different line profile
  intensities and the original simulation velocity at given optical
  depths. This good correlation means that we can associate bisectors
  taken at different line-profile percentages with atmospheric layers
  that linearly increase as we scan lower spectral line intensities. We
  also determined that a fit to the line-core intensity is robust and
  reliable, providing information about atmospheric layers that are
  above those accessible through bisectors. Therefore, by combining
  both methods on the Si I 10 827 Å line, we can seamlessly trace the
  quiet-Sun LOS velocity stratification from the deep photosphere to
  higher layers until around logτ = -3.5 in a fast and straightforward
  way. This method is ideal for generating quick-look reference images
  for future missions like the Daniel K. Inoue Solar Telescope and the
  European Solar Telescope, for example.

Title: The magnetic structure and dynamics of a decaying active region
Authors: Kontogiannis, Ioannis; Kuckein, Christoph; González
   Manrique, Sergio Javier; Felipe, Tobias; Verma, Meetu; Balthasar,
   Horst; Denker, Carsten
Bibcode: 2020IAUS..354...53K
Altcode:
  We study the evolution of the decaying active region NOAA 12708, from
  the photosphere up to the corona using high resolution, multi-wavelength
  GREGOR observations taken on May 9, 2018. We utilize spectropolarimetric
  scans of the 10830 Å spectral range by the GREGOR Infrared Spectrograph
  (GRIS), spectral imaging time-series in the Na ID<SUP>2</SUP> spectral
  line by the GREGOR Fabry-Pérot Interferometer (GFPI) and context
  imaging in the Ca IIH and blue continuum by the High-resolution Fast
  Imager (HiFI). Context imaging in the UV/EUV from the Atmospheric
  Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO)
  complements our dataset. The region under study contains one pore with a
  light-bridge, a few micro-pores and extended clusters of magnetic bright
  points. We study the magnetic structure from the photosphere up to the
  upper chromosphere through the spectropolarimetric observations in He
  II and Si I and through the magnetograms provided by the Helioseismic
  and Magnetic Imager (HMI). The high-resolution photospheric images
  reveal the complex interaction between granular-scale convective
  motions and a range of scales of magnetic field concentrations in
  unprecedented detail. The pore itself shows a strong interaction with
  the convective motions, which eventually leads to its decay, while,
  under the influence of the photospheric flow field, micro-pores
  appear and disappear. Compressible waves are generated, which are
  guided towards the upper atmosphere along the magnetic field lines of
  the various magnetic structures within the field-of-view. Modelling
  of the He i absorption profiles reveals high velocity components,
  mostly associated with magnetic bright points at the periphery
  of the active region, many of which correspond to asymmetric Si I
  Stokes-V profiles revealing a coupling between upper photospheric
  and upper chromospheric dynamics. Time-series of Na ID<SUP>2</SUP>
  spectral images reveal episodic high velocity components at the same
  locations. State-of-the-art multi-wavelength GREGOR observations allow
  us to track and understand the mechanisms at work during the decay
  phase of the active region.

Title: Coordinated observations between China and Europe to follow
    active region 12709
Authors: González Manrique, S. J.; Kuckein, C.; Gömöry, P.; Yuan,
   S.; Xu, Z.; Rybák, J.; Balthasar, H.; Schwartz, P.
Bibcode: 2020IAUS..354...58G
Altcode: 2020IAUS..354...58M; 2019arXiv191208611G
  We present the first images of a coordinated campaign to follow active
  region NOAA 12709 on 2018 May 13 as part of a joint effort between
  three observatories (China-Europe). The active region was close to
  disk center and enclosed a small pore, a tight polarity inversion line
  and a filament in the chromosphere. The active region was observed
  with the 1.5-meter GREGOR solar telescope on Tenerife (Spain) with
  spectropolarimetry using GRIS in the He i 10830 Å spectral range
  and with HiFI using two broad-band filter channels. In addition,
  the Lomnicky Stit Observatory (LSO, Slovakia) recorded the same
  active region with the new Solar Chromospheric Detector (SCD) in
  spectroscopic mode at Hα 6562 Å. The third ground-based telescope
  was located at the Fuxian Solar Observatory (China), where the active
  region was observed with the 1-meter New Vacuum Solar Telescope
  (NVST), using the Multi-Channel High Resolution Imaging System at
  Hα 6562 Å. Overlapping images of the active region from all three
  telescopes will be shown as well as preliminary Doppler line-of-sight
  (LOS) velocities. The potential of such observations are discussed.

Title: Cloud model inversions of strong chromospheric absorption
    lines using principal component analysis
Authors: Dineva, Ekaterina; Verma, Meetu; González Manrique, Sergio
   J.; Schwartz, Pavol; Denker, Carsten
Bibcode: 2020AN....341...64D
Altcode: 2019arXiv191210476D
  High-resolution spectroscopy of strong chromospheric absorption
  lines delivers nowadays several millions of spectra per observing
  day, when using fast scanning devices to cover large regions on
  the solar surface. Therefore, fast and robust inversion schemes are
  needed to explore the large data volume. Cloud model (CM) inversions
  of the chromospheric Hα line are commonly employed to investigate
  various solar features including filaments, prominences, surges, jets,
  mottles, and (macro-) spicules. The choice of the CM was governed by
  its intuitive description of complex chromospheric structures as clouds
  suspended above the solar surface by magnetic fields. This study is
  based on observations of active region NOAA 11126 in Hα, which were
  obtained November 18-23, 2010 with the echelle spectrograph of the
  vacuum tower telescope at the Observatorio del Teide, Spain. Principal
  component analysis reduces the dimensionality of spectra and conditions
  noise-stripped spectra for CM inversions. Modeled Hα intensity and
  contrast profiles as well as CM parameters are collected in a database,
  which facilitates efficient processing of the observed spectra. Physical
  maps are computed representing the line-core and continuum intensity,
  absolute contrast, equivalent width, and Doppler velocities, among
  others. Noise-free spectra expedite the analysis of bisectors. The data
  processing is evaluated in the context of "big data," in particular
  with respect to automatic classification of spectra.

Title: Revisiting the building blocks of solar magnetic fields
    by GREGOR
Authors: Utz, Dominik; Kuckein, Christoph; Campos Rozo, Jose Iván;
   González Manrique, Sergio Javier; Balthasar, Horst; Gömöry,
   Peter; Hernández, Judith Palacios; Denker, Carsten; Verma, Meetu;
   Kontogiannis, Ioannis; Krikova, Kilian; Hofmeister, Stefan; Diercke,
   Andrea
Bibcode: 2020IAUS..354...38U
Altcode:
  The Sun is our dynamic host star due to its magnetic fields causing
  plentiful of activity in its atmosphere. From high energetic flares
  and coronal mass ejections (CMEs) to lower energetic phenomena such
  as jets and fibrils. Thus, it is of crucial importance to learn about
  formation and evolution of solar magnetic fields. These fields cover a
  wide range of spatial and temporal scales, starting on the larger end
  with active regions harbouring complex sunspots, via isolated pores,
  down to the smallest yet resolved elements - so-called magnetic bright
  points (MBPs). Here, we revisit the various manifestations of solar
  magnetic fields by the largest European solar telescope in operation,
  the 1.5-meter GREGOR telescope. We show images from the High-resolution
  Fast Imager (HiFI) and spectropolarimetric data from the GREGOR Infrared
  Spectrograph (GRIS). Besides, we outline resolved convective features
  inside the larger structures - so-called light-bridges occurring on
  large to mid-sized scales.

Title: Polarimetry with the GREGOR Fabry-Pérot Interferometer
Authors: Balthasar, H.; Gisler, D.; González Manrique, S. J.; Kuckein,
   C.; Verma, M.; Denker, C.
Bibcode: 2019spw..confE...3B
Altcode:
  No abstract at ADS

Title: Spectropolarimetric Observations of an Arch Filament System
    with GREGOR
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
   Kuckein, C.; Kučera, A.; Schwartz, P.; Berkefeld, T.; Collados, M.;
   Denker, C.; Feller, A.; Hofmann, A.; Schlichenmaier, R.; Schmidt,
   D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau,
   D.; Staude, J.; Strassmeier, K. G.; von der Lühe, O.
Bibcode: 2019ASPC..526..217B
Altcode: 2018arXiv180401789B
  We observed an arch filament system (AFS) in a sunspot group with the
  GREGOR Infrared Spectrograph attached to the GREGOR solar telescope. The
  AFS was located between the leading sunspot of negative polarity and
  several pores of positive polarity forming the following part of the
  sunspot group. We recorded five spectro-polarimetric scans of this
  region. The spectral range included the spectral lines Si I 1082.7
  nm, He I 1083.0 nm, and Ca I 1083.9 nm. In this work we concentrate
  on the silicon line which is formed in the upper photosphere. The
  line profiles are inverted with the code 'Stokes Inversion based
  on Response functions' to obtain the magnetic field vector. The
  line-of-sight velocities are determined independently with a Fourier
  phase method. Maximum velocities are found close to the ends of AFS
  fibrils. These maximum values amount to 2.4 km s<SUP>-1</SUP> next
  to the pores and to 4 km s<SUP>-1</SUP> at the sunspot side. Between
  the following pores, we encounter an area of negative polarity that
  is decreasing during the five scans. We interpret this by new emerging
  positive flux in this area canceling out the negative flux. In summary,
  our findings confirm the scenario that rising magnetic flux tubes
  cause the AFS.

Title: Photospheric Magnetic Fields of the Trailing Sunspots in
    Active Region NOAA 12396
Authors: Verma, M.; Balthasar, H.; Denker, C.; Böhm, F.; Fischer,
   C. E.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello
   González, N.; Diercke, A.; Berkefeld, T.; Collados, M.; Feller, A.;
   Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar,
   A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
   M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K.; Volkmer,
   R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2019ASPC..526..291V
Altcode: 2018arXiv180507752V
  The solar magnetic field is responsible for all aspects of solar
  activity. Sunspots are the main manifestation of the ensuing solar
  activity. Combining high-resolution and synoptic observations has
  the ambition to provide a comprehensive description of the sunspot
  growth and decay processes. Active region NOAA 12396 emerged on 2015
  August 3 and was observed three days later with the 1.5-meter GREGOR
  solar telescope on 2015 August 6. High-resolution spectropolarimetric
  data from the GREGOR Infrared Spectrograph (GRIS) are obtained in the
  photospheric lines Si I λ1082.7 nm and Ca I λ1083.9 nm, together
  with the chromospheric He I λ1083.0 nm triplet. These near-infrared
  spectropolarimetric observations were complemented by synoptic
  line-of-sight magnetograms and continuum images of the Helioseismic
  and Magnetic Imager (HMI) and EUV images of the Atmospheric Imaging
  Assembly (AIA) on board the Solar Dynamics Observatory (SDO).

Title: Properties of the inner penumbral boundary and temporal
    evolution of a decaying sunspot
Authors: Benko, M.; González Manrique, S. J.; Balthasar, H.; Gömöry,
   P.; Kuckein, C.; Jurčák, J.
Bibcode: 2018A&A...620A.191B
Altcode: 2018arXiv181013185B
  Context. It has been empirically determined that the umbra-penumbra
  boundaries of stable sunspots are characterized by a constant value of
  the vertical magnetic field. <BR /> Aims: We analyzed the evolution
  of the photospheric magnetic field properties of a decaying sunspot
  belonging to NOAA 11277 between August 28-September 3, 2011. The
  observations were acquired with the spectropolarimeter on-board of
  the Hinode satellite. We aim to prove the validity of the constant
  vertical magnetic-field boundary between the umbra and penumbra in
  decaying sunspots. <BR /> Methods: A spectral-line inversion technique
  was used to infer the magnetic field vector from the full-Stokes
  profiles. In total, eight maps were inverted and the variation of
  the magnetic properties in time were quantified using linear or
  quadratic fits. <BR /> Results: We find a linear decay of the umbral
  vertical magnetic field, magnetic flux, and area. The penumbra showed
  a linear increase of the vertical magnetic field and a sharp decay
  of the magnetic flux. In addition, the penumbral area quadratically
  decayed. The vertical component of the magnetic field is weaker on the
  umbra-penumbra boundary of the studied decaying sunspot compared to
  stable sunspots. Its value seem to be steadily decreasing during the
  decay phase. Moreover, at any time of the sunspot decay shown, the inner
  penumbra boundary does not match with a constant value of the vertical
  magnetic field, contrary to what is seen in stable sunspots. <BR />
  Conclusions: During the decaying phase of the studied sunspot, the
  umbra does not have a sufficiently strong vertical component of the
  magnetic field and is thus unstable and prone to be disintegrated by
  convection or magnetic diffusion. No constant value of the vertical
  magnetic field is found for the inner penumbral boundary.

Title: sTools - a software package for data reduction of GREGOR
    instruments and general data analysis
Authors: Kuckein, Christoph; Denker, Carsten; Verma, Meetu; Balthasar,
   Horst; Diercke, Andrea; González Manrique, Sergio Javier; Dineva,
   Ekaterina; Kontogiannis, Ioannis; Shen, Zili
Bibcode: 2018csc..confE.105K
Altcode:
  The optical solar physics group at AIP is responsible for the GREGOR
  Fabry-Perot Interferometer (GFPI) and the large-format facility cameras
  (Blue Imaging Channel (BIC) and High-resolution Fast Imager (HiFI))
  at the 1.5-meter GREGOR solar telescope (Tenerife, Spain). Since
  the »Early Science Phase« of the telescope in 2014, the group
  developed a data reduction pipeline for these two instruments. The
  pipeline »sTools« is based on the Interactive Data Language
  (IDL) and delivers reduced and image-restored data with a minimum
  of user interaction. Furthermore, it creates quick-look data and
  builds a webpage with an overview of the observations and their
  statistics (http://gregor.aip.de). However, during the last years,
  sTools continuously evolved and currently hosts many additional
  routines for data analysis: (1) A local correlation tracking (LCT)
  algorithm adapted for both high-resolution (GREGOR and Hinode) and
  synoptic full-disk (SDO) data. (2) A new quantitative tool, i.e.,
  a Background-subtracted Solar Activity Map (BaSAM), to assess and
  visualize the temporal variation of the photospheric magnetic field
  and the EUV 160 nm intensity. This method utilizes SDO data and is
  applicable to both full-disk observations and regions-of-interest. (3)
  Calibration of synoptic full-disk data from the Chromospheric Telescope
  (ChroTel) including extraction of Doppler velocities from He I 1083
  nm filtergrams. (4) Analysis tools for sun-as-a-star spectroscopy
  for the Solar Disk-Integrated (SDI) telescope of the Potsdam Echelle
  Polarimetric and Spectroscopic Instrument (PEPSI). sTools is licensed
  under a creative commons license and is freely available, after
  registration, at the abovementioned website.

Title: Temporal evolution of arch filaments as seen in He I 10 830 Å
Authors: González Manrique, S. J.; Kuckein, C.; Collados, M.; Denker,
   C.; Solanki, S. K.; Gömöry, P.; Verma, M.; Balthasar, H.; Lagg,
   A.; Diercke, A.
Bibcode: 2018A&A...617A..55G
Altcode: 2018arXiv180700728G
  <BR /> Aims: We study the evolution of an arch filament system (AFS)
  and of its individual arch filaments to learn about the processes
  occurring in them. <BR /> Methods: We observed the AFS at the
  GREGOR solar telescope on Tenerife at high cadence with the very
  fast spectroscopic mode of the GREGOR Infrared Spectrograph (GRIS)
  in the He I 10 830 Å spectral range. The He I triplet profiles
  were fitted with analytic functions to infer line-of-sight (LOS)
  velocities to follow plasma motions within the AFS. <BR /> Results:
  We tracked the temporal evolution of an individual arch filament
  over its entire lifetime, as seen in the He I 10 830 Å triplet. The
  arch filament expanded in height and extended in length from 13″ to
  21″. The lifetime of this arch filament is about 30 min. About 11
  min after the arch filament is seen in He I, the loop top starts to
  rise with an average Doppler velocity of 6 km s<SUP>-1</SUP>. Only two
  minutes later, plasma drains down with supersonic velocities towards
  the footpoints reaching a peak velocity of up to 40 km s<SUP>-1</SUP>
  in the chromosphere. The temporal evolution of He I 10 830 Å profiles
  near the leading pore showed almost ubiquitous dual red components of
  the He I triplet, indicating strong downflows, along with material
  nearly at rest within the same resolution element during the whole
  observing time. <BR /> Conclusions: We followed the arch filament as it
  carried plasma during its rise from the photosphere to the corona. The
  material then drained toward the photosphere, reaching supersonic
  velocities, along the legs of the arch filament. Our observational
  results support theoretical AFS models and aids in improving future
  models. <P />The movie associated to Fig. 3 is available at <A
  href="https://www.aanda.org/10.1051/0004-6361/201832684/olm">https://www.aanda.org/</A>

Title: High-resolution imaging and near-infrared spectroscopy of
    penumbral decay
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; Rezaei,
   R.; Sobotka, M.; Deng, N.; Wang, H.; Tritschler, A.; Collados, M.;
   Diercke, A.; González Manrique, S. J.
Bibcode: 2018A&A...614A...2V
Altcode: 2018arXiv180103686V
  <BR /> Aims: Combining high-resolution spectropolarimetric and imaging
  data is key to understanding the decay process of sunspots as it
  allows us to scrutinize the velocity and magnetic fields of sunspots
  and their surroundings. <BR /> Methods: Active region NOAA 12597
  was observed on 2016 September 24 with the 1.5-meter GREGOR solar
  telescope using high-spatial-resolution imaging as well as imaging
  spectroscopy and near-infrared (NIR) spectropolarimetry. Horizontal
  proper motions were estimated with local correlation tracking, whereas
  line-of-sight (LOS) velocities were computed with spectral line fitting
  methods. The magnetic field properties were inferred with the "Stokes
  Inversions based on Response functions" (SIR) code for the Si I and Ca
  I NIR lines. <BR /> Results: At the time of the GREGOR observations,
  the leading sunspot had two light bridges indicating the onset of
  its decay. One of the light bridges disappeared, and an elongated,
  dark umbral core at its edge appeared in a decaying penumbral sector
  facing the newly emerging flux. The flow and magnetic field properties
  of this penumbral sector exhibited weak Evershed flow, moat flow, and
  horizontal magnetic field. The penumbral gap adjacent to the elongated
  umbral core and the penumbra in that penumbral sector displayed LOS
  velocities similar to granulation. The separating polarities of a new
  flux system interacted with the leading and central part of the already
  established active region. As a consequence, the leading spot rotated
  55° clockwise over 12 h. <BR /> Conclusions: In the high-resolution
  observations of a decaying sunspot, the penumbral filaments facing the
  flux emergence site contained a darkened area resembling an umbral core
  filled with umbral dots. This umbral core had velocity and magnetic
  field properties similar to the sunspot umbra. This implies that the
  horizontal magnetic fields in the decaying penumbra became vertical
  as observed in flare-induced rapid penumbral decay, but on a very
  different time-scale.

Title: High-cadence Imaging and Imaging Spectroscopy at the
    GREGOR Solar Telescope—A Collaborative Research Environment for
    High-resolution Solar Physics
Authors: Denker, Carsten; Kuckein, Christoph; Verma, Meetu; González
   Manrique, Sergio J.; Diercke, Andrea; Enke, Harry; Klar, Jochen;
   Balthasar, Horst; Louis, Rohan E.; Dineva, Ekaterina
Bibcode: 2018ApJS..236....5D
Altcode: 2018arXiv180210146D
  In high-resolution solar physics, the volume and complexity
  of photometric, spectroscopic, and polarimetric ground-based
  data significantly increased in the last decade, reaching data
  acquisition rates of terabytes per hour. This is driven by the
  desire to capture fast processes on the Sun and the necessity
  for short exposure times “freezing” the atmospheric seeing,
  thus enabling ex post facto image restoration. Consequently,
  large-format and high-cadence detectors are nowadays used in
  solar observations to facilitate image restoration. Based on our
  experience during the “early science” phase with the 1.5 m
  GREGOR solar telescope (2014-2015) and the subsequent transition
  to routine observations in 2016, we describe data collection and
  data management tailored toward image restoration and imaging
  spectroscopy. We outline our approaches regarding data processing,
  analysis, and archiving for two of GREGOR’s post-focus instruments
  (see <A href="http://gregor.aip.de">http://gregor.aip.de</A>), i.e.,
  the GREGOR Fabry-Pérot Interferometer (GFPI) and the newly installed
  High-Resolution Fast Imager (HiFI). The heterogeneous and complex
  nature of multidimensional data arising from high-resolution solar
  observations provides an intriguing but also a challenging example for
  “big data” in astronomy. The big data challenge has two aspects: (1)
  establishing a workflow for publishing the data for the whole community
  and beyond and (2) creating a collaborative research environment
  (CRE), where computationally intense data and postprocessing tools are
  colocated and collaborative work is enabled for scientists of multiple
  institutes. This requires either collaboration with a data center or
  frameworks and databases capable of dealing with huge data sets based on
  virtual observatory (VO) and other community standards and procedures.

Title: Image Quality in High-resolution and High-cadence Solar Imaging
Authors: Denker, C.; Dineva, E.; Balthasar, H.; Verma, M.; Kuckein,
   C.; Diercke, A.; González Manrique, S. J.
Bibcode: 2018SoPh..293...44D
Altcode: 2018arXiv180200760D
  Broad-band imaging and even imaging with a moderate bandpass (about 1
  nm) provides a photon-rich environment, where frame selection (lucky
  imaging) becomes a helpful tool in image restoration, allowing us to
  perform a cost-benefit analysis on how to design observing sequences
  for imaging with high spatial resolution in combination with real-time
  correction provided by an adaptive optics (AO) system. This study
  presents high-cadence (160 Hz) G-band and blue continuum image sequences
  obtained with the High-resolution Fast Imager (HiFI) at the 1.5-meter
  GREGOR solar telescope, where the speckle-masking technique is used
  to restore images with nearly diffraction-limited resolution. The
  HiFI employs two synchronized large-format and high-cadence sCMOS
  detectors. The median filter gradient similarity (MFGS) image-quality
  metric is applied, among others, to AO-corrected image sequences of
  a pore and a small sunspot observed on 2017 June 4 and 5. A small
  region of interest, which was selected for fast-imaging performance,
  covered these contrast-rich features and their neighborhood, which were
  part of Active Region NOAA 12661. Modifications of the MFGS algorithm
  uncover the field- and structure-dependency of this image-quality
  metric. However, MFGS still remains a good choice for determining image
  quality without a priori knowledge, which is an important characteristic
  when classifying the huge number of high-resolution images contained in
  data archives. In addition, this investigation demonstrates that a fast
  cadence and millisecond exposure times are still insufficient to reach
  the coherence time of daytime seeing. Nonetheless, the analysis shows
  that data acquisition rates exceeding 50 Hz are required to capture a
  substantial fraction of the best seeing moments, significantly boosting
  the performance of post-facto image restoration.

Title: Ca II 8542 Å brightenings induced by a solar microflare
Authors: Kuckein, C.; Diercke, A.; González Manrique, S. J.; Verma,
   M.; Löhner-Böttcher, J.; Socas-Navarro, H.; Balthasar, H.; Sobotka,
   M.; Denker, C.
Bibcode: 2017A&A...608A.117K
Altcode: 2017arXiv170906861K
  <BR /> Aims: We study small-scale brightenings in Ca II 8542 Å
  line-core images to determine their nature and effect on localized
  heating and mass transfer in active regions. <BR /> Methods:
  High-resolution two-dimensional spectroscopic observations of a solar
  active region in the near-infrared Ca II 8542 Å line were acquired
  with the GREGOR Fabry-Pérot Interferometer attached to the 1.5-m GREGOR
  telescope. Inversions of the spectra were carried out using the NICOLE
  code to infer temperatures and line-of-sight (LOS) velocities. Response
  functions of the Ca II line were computed for temperature and LOS
  velocity variations. Filtergrams of the Atmospheric Imaging Assembly
  (AIA) and magnetograms of the Helioseismic and Magnetic Imager (HMI)
  were coaligned to match the ground-based observations and to follow the
  Ca II brightenings along all available layers of the atmosphere. <BR />
  Results: We identified three brightenings of sizes up to 2'' × 2''
  that appeared in the Ca II 8542 Å line-core images. Their lifetimes
  were at least 1.5 min. We found evidence that the brightenings belonged
  to the footpoints of a microflare (MF). The properties of the observed
  brightenings disqualified the scenarios of Ellerman bombs or Interface
  Region Imaging Spectrograph (IRIS) bombs. However, this MF shared some
  common properties with flaring active-region fibrils or flaring arch
  filaments (FAFs): (1) FAFs and MFs are both apparent in chromospheric
  and coronal layers according to the AIA channels; and (2) both show
  flaring arches with lifetimes of about 3.0-3.5 min and lengths of
  20'' next to the brightenings. The inversions revealed heating by
  600 K at the footpoint location in the ambient chromosphere during
  the impulsive phase. Connecting the footpoints, a dark filamentary
  structure appeared in the Ca II line-core images. Before the
  start of the MF, the spectra of this structure already indicated
  average blueshifts, meaning upward motions of the plasma along the
  LOS. During the impulsive phase, these velocities increased up to -
  2.2 km s<SUP>-1</SUP>. The structure did not disappear during the
  observations. Downflows dominated at the footpoints. However, in
  the upper photosphere, slight upflows occurred during the impulsive
  phase. Hence, bidirectional flows are present in the footpoints
  of the MF. <BR /> Conclusions: We detected Ca II brightenings that
  coincided with the footpoint location of an MF. The MF event led to
  a rise of plasma in the upper photosphere, both before and during the
  impulsive phase. Excess mass, previously raised to at most chromospheric
  layers, slowly drained downward along arches toward the footpoints
  of the MF. <P />The movie associated to Fig. 2 is available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201731319/olm">http://www.aanda.org</A>

Title: sTools - a data reduction pipeline for the GREGOR Fabry-Pérot
    Interferometer and the High-resolution Fast Imager at the GREGOR
    solar telescope
Authors: Kuckein, C.; Denker, C.; Verma, M.; Balthasar, H.; González
   Manrique, S. J.; Louis, R. E.; Diercke, A.
Bibcode: 2017IAUS..327...20K
Altcode: 2017arXiv170101670K
  A huge amount of data has been acquired with the GREGOR Fabry-Pérot
  Interferometer (GFPI), large-format facility cameras, and since 2016
  with the High-resolution Fast Imager (HiFI). These data are processed
  in standardized procedures with the aim of providing science-ready data
  for the solar physics community. For this purpose, we have developed a
  user-friendly data reduction pipeline called ``sTools'' based on the
  Interactive Data Language (IDL) and licensed under creative commons
  license. The pipeline delivers reduced and image-reconstructed data
  with a minimum of user interaction. Furthermore, quick-look data are
  generated as well as a webpage with an overview of the observations and
  their statistics. All the processed data are stored online at the GREGOR
  GFPI and HiFI data archive of the Leibniz Institute for Astrophysics
  Potsdam (AIP). The principles of the pipeline are presented together
  with selected high-resolution spectral scans and images processed
  with sTools.

Title: Flows along arch filaments observed in the GRIS `very fast
    spectroscopic mode'
Authors: González Manrique, S. J.; Denker, C.; Kuckein, C.; Pastor
   Yabar, A.; Collados, M.; Verma, M.; Balthasar, H.; Diercke, A.;
   Fischer, C. E.; Gömöry, P.; Bello González, N.; Schlichenmaier,
   R.; Cubas Armas, M.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann,
   A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt,
   W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude,
   J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2017IAUS..327...28G
Altcode: 2017arXiv170102206G
  A new generation of solar instruments provides improved spectral,
  spatial, and temporal resolution, thus facilitating a better
  understanding of dynamic processes on the Sun. High-resolution
  observations often reveal multiple-component spectral line profiles,
  e.g., in the near-infrared He i 10830 Å triplet, which provides
  information about the chromospheric velocity and magnetic fine
  structure. We observed an emerging flux region, including two small
  pores and an arch filament system, on 2015 April 17 with the `very
  fast spectroscopic mode' of the GREGOR Infrared Spectrograph (GRIS)
  situated at the 1.5-meter GREGOR solar telescope at Observatorio del
  Teide, Tenerife, Spain. We discuss this method of obtaining fast (one
  per minute) spectral scans of the solar surface and its potential to
  follow dynamic processes on the Sun. We demonstrate the performance
  of the `very fast spectroscopic mode' by tracking chromospheric
  high-velocity features in the arch filament system.

Title: Flare-induced changes of the photospheric magnetic field in
    a δ-spot deduced from ground-based observations
Authors: Gömöry, P.; Balthasar, H.; Kuckein, C.; Koza, J.;
   Veronig, A. M.; González Manrique, S. J.; Kučera, A.; Schwartz,
   P.; Hanslmeier, A.
Bibcode: 2017A&A...602A..60G
Altcode: 2017arXiv170406089G
  <BR /> Aims: Changes of the magnetic field and the line-of-sight
  velocities in the photosphere are being reported for an M-class
  flare that originated at a δ-spot belonging to active region NOAA
  11865. <BR /> Methods: High-resolution ground-based near-infrared
  spectropolarimetric observations were acquired simultaneously in
  two photospheric spectral lines, Fe I 10783 Å and Si I 10786 Å,
  with the Tenerife Infrared Polarimeter at the Vacuum Tower Telescope
  (VTT) in Tenerife on 2013 October 15. The observations covered several
  stages of the M-class flare. Inversions of the full-Stokes vector of
  both lines were carried out and the results were put into context using
  (extreme)-ultraviolet filtergrams from the Solar Dynamics Observatory
  (SDO). <BR /> Results: The active region showed high flaring activity
  during the whole observing period. After the M-class flare, the
  longitudinal magnetic field did not show significant changes along
  the polarity inversion line (PIL). However, an enhancement of the
  transverse magnetic field of approximately 550 G was found that
  bridges the PIL and connects umbrae of opposite polarities in the
  δ-spot. At the same time, a newly formed system of loops appeared
  co-spatially in the corona as seen in 171 Å filtergrams of the
  Atmospheric Imaging Assembly (AIA) on board SDO. However, we cannot
  exclude that the magnetic connection between the umbrae already existed
  in the upper atmosphere before the M-class flare and became visible
  only later when it was filled with hot plasma. The photospheric
  Doppler velocities show a persistent upflow pattern along the PIL
  without significant changes due to the flare. <BR /> Conclusions:
  The increase of the transverse component of the magnetic field after
  the flare together with the newly formed loop system in the corona
  support recent predictions of flare models and flare observations. <P
  />The movie associated to Figs. 4 and 5 is available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201730644/olm">http://www.aanda.org</A>

Title: High-resolution imaging spectroscopy of two micro-pores and
    an arch filament system in a small emerging-flux region
Authors: González Manrique, S. J.; Bello González, N.; Denker, C.
Bibcode: 2017A&A...600A..38G
Altcode: 2017arXiv170310140G
  Context. Emerging flux regions mark the first stage in the accumulation
  of magnetic flux eventually leading to pores, sunspots, and (complex)
  active regions. These flux regions are highly dynamic, show a variety
  of fine structure, and in many cases live only for a short time (less
  than a day) before dissolving quickly into the ubiquitous quiet-Sun
  magnetic field. <BR /> Aims: The purpose of this investigation is to
  characterize the temporal evolution of a minute emerging flux region,
  the associated photospheric and chromospheric flow fields, and the
  properties of the accompanying arch filament system. We aim to explore
  flux emergence and decay processes and investigate if they scale with
  structure size and magnetic flux contents. <BR /> Methods: This study
  is based on imaging spectroscopy with the Göttingen Fabry-Pérot
  Interferometer at the Vacuum Tower Telescope, Observatorio del Teide,
  Tenerife, Spain on 2008 August 7. Photospheric horizontal proper motions
  were measured with Local correlation tracking using broadband images
  restored with multi-object multi-frame blind deconvolution. Cloud model
  (CM) inversions of line scans in the strong chromospheric absorption
  Hαλ656.28 nm line yielded CM parameters (Doppler velocity, Doppler
  width, optical thickness, and source function), which describe the
  cool plasma contained in the arch filament system. <BR /> Results:
  The high-resolution observations cover the decay and convergence of two
  micro-pores with diameters of less than one arcsecond and provide decay
  rates for intensity and area. The photospheric horizontal flow speed
  is suppressed near the two micro-pores indicating that the magnetic
  field is already sufficiently strong to affect the convective energy
  transport. The micro-pores are accompanied by a small arch filament
  system as seen in Hα, where small-scale loops connect two regions
  with Hα line-core brightenings containing an emerging flux region
  with opposite polarities. The Doppler width, optical thickness,
  and source function reach the largest values near the Hα line-core
  brightenings. The chromospheric velocity of the cloud material is
  predominantly directed downwards near the footpoints of the loops
  with velocities of up to 12 km s<SUP>-1</SUP>, whereas loop tops show
  upward motions of about 3 km s<SUP>-1</SUP>. Some of the loops exhibit
  signs of twisting motions along the loop axis. <BR /> Conclusions:
  Micro-pores are the smallest magnetic field concentrations leaving a
  photometric signature in the photosphere. In the observed case, they
  are accompanied by a miniature arch filament system indicative of newly
  emerging flux in the form of Ω-loops. Flux emergence and decay take
  place on a time-scale of about two days, whereas the photometric decay
  of the micro-pores is much more rapid (a few hours), which is consistent
  with the incipient submergence of Ω-loops. Considering lifetime and
  evolution timescales, impact on the surrounding photospheric proper
  motions, and flow speed of the chromospheric plasma at the loop tops
  and footpoints, the results are representative for the smallest emerging
  flux regions still recognizable as such.

Title: Photospheric and chromospheric observations of dynamic features
    in an arch filament system
Authors: González Manrique, S. J.
Bibcode: 2017psio.confE..38G
Altcode:
  No abstract at ADS

Title: Center-to-limb variation of the velocity field in and around
    a sunspot with light-bridges
Authors: Denker, Carsten; Verma, Meetu; Balthasar, Horst; Diercke,
   Andrea; González Manrique, S. J.; Löhner-Böttcher, Johannes;
   Kuckein, Christoph; Sobotka, Michal
Bibcode: 2017psio.confE.104D
Altcode:
  No abstract at ADS

Title: Velocity fields in sunspots derived from observations with
    the GREGOR Fabry-Pérot Interferometer
Authors: Balthasar, H.; Denker, C.; Diercke, A.; González Manrique,
   S. J.; Kuckein, C.; Louis, R. E.; Verma, M., Löhner-Böttcher, J.;
   Sobotka, M.
Bibcode: 2017psio.confE.105B
Altcode:
  No abstract at ADS

Title: Flare induced changes of the photospheric magnetic field in
    a delta-spot deduced from ground-based observations
Authors: Gömöry, P.; Balthasar, H.; Kuckein, C.; Koza, J.;
   Kuĉera, A.; González Manrique, S. J.; Schwartz, P.; Veronig, A. M.;
   Hanslmeier, A.
Bibcode: 2017psio.confE.107G
Altcode:
  No abstract at ADS

Title: High-resolution observations of emerging flux regions
Authors: Gonzalez Manrique, Sergio Javier
Bibcode: 2017PhDT.......251G
Altcode:
  No abstract at ADS

Title: Spectropolarimetric observations of an arch filament system
    with the GREGOR solar telescope
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
   Kuckein, C.; Kavka, J.; Kučera, A.; Schwartz, P.; Vašková, R.;
   Berkefeld, T.; Collados Vera, M.; Denker, C.; Feller, A.; Hofmann,
   A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.;
   Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
   M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016AN....337.1050B
Altcode: 2016arXiv160901514B
  Arch filament systems occur in active sunspot groups, where a fibril
  structure connects areas of opposite magnetic polarity, in contrast to
  active region filaments that follow the polarity inversion line. We
  used the GREGOR Infrared Spectrograph (GRIS) to obtain the full
  Stokes vector in the spectral lines Si I λ1082.7 nm, He I λ1083.0
  nm, and Ca I λ1083.9 nm. We focus on the near-infrared calcium line
  to investigate the photospheric magnetic field and velocities, and
  use the line core intensities and velocities of the helium line to
  study the chromospheric plasma. The individual fibrils of the arch
  filament system connect the sunspot with patches of magnetic polarity
  opposite to that of the spot. These patches do not necessarily coincide
  with pores, where the magnetic field is strongest. Instead, areas are
  preferred not far from the polarity inversion line. These areas exhibit
  photospheric downflows of moderate velocity, but significantly higher
  downflows of up to 30 km s<SUP>-1</SUP> in the chromospheric helium
  line. Our findings can be explained with new emerging flux where the
  matter flows downward along the field lines of rising flux tubes,
  in agreement with earlier results.

Title: Horizontal flow fields in and around a small active region. The
    transition period between flux emergence and decay
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
   Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
   A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
   A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
   Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
   M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016A&A...596A...3V
Altcode: 2016arXiv160507462V
  Context. The solar magnetic field is responsible for all aspects
  of solar activity. Thus, emergence of magnetic flux at the surface
  is the first manifestation of the ensuing solar activity. <BR />
  Aims: Combining high-resolution and synoptic observations aims to
  provide a comprehensive description of flux emergence at photospheric
  level and of the growth process that eventually leads to a mature
  active region. <BR /> Methods: The small active region NOAA 12118
  emerged on 2014 July 17 and was observed one day later with the 1.5-m
  GREGOR solar telescope on 2014 July 18. High-resolution time-series
  of blue continuum and G-band images acquired in the blue imaging
  channel (BIC) of the GREGOR Fabry-Pérot Interferometer (GFPI) were
  complemented by synoptic line-of-sight magnetograms and continuum
  images obtained with the Helioseismic and Magnetic Imager (HMI) onboard
  the Solar Dynamics Observatory (SDO). Horizontal proper motions and
  horizontal plasma velocities were computed with local correlation
  tracking (LCT) and the differential affine velocity estimator (DAVE),
  respectively. Morphological image processing was employed to measure
  the photometric and magnetic area, magnetic flux, and the separation
  profile of the emerging flux region during its evolution. <BR />
  Results: The computed growth rates for photometric area, magnetic
  area, and magnetic flux are about twice as high as the respective
  decay rates. The space-time diagram using HMI magnetograms of five days
  provides a comprehensive view of growth and decay. It traces a leaf-like
  structure, which is determined by the initial separation of the two
  polarities, a rapid expansion phase, a time when the spread stalls,
  and a period when the region slowly shrinks again. The separation
  rate of 0.26 km s<SUP>-1</SUP> is highest in the initial stage, and
  it decreases when the separation comes to a halt. Horizontal plasma
  velocities computed at four evolutionary stages indicate a changing
  pattern of inflows. In LCT maps we find persistent flow patterns such
  as outward motions in the outer part of the two major pores, a diverging
  feature near the trailing pore marking the site of upwelling plasma and
  flux emergence, and low velocities in the interior of dark pores. We
  detected many elongated rapidly expanding granules between the two
  major polarities, with dimensions twice as large as the normal granules.

Title: Solar physics at the Einstein Tower
Authors: Denker, C.; Heibel, C.; Rendtel, J.; Arlt, K.; Balthasar,
   Juergen H.; Diercke, A.; González Manrique, S. J.; Hofmann, A.;
   Kuckein, C.; Önel, H.; Senthamizh Pavai, V.; Staude, J.; Verman, M.
Bibcode: 2016AN....337.1105D
Altcode: 2016arXiv160906949D
  The solar observatory Einstein Tower ({Einsteinturm}) at the
  Telegrafenberg in Potsdam is both a landmark of modern architecture
  and an important place for solar physics. Originally built for
  high-resolution spectroscopy and measuring the gravitational redshift,
  research shifted over the years to understanding the active Sun and
  its magnetic field. Nowadays, telescope and spectrographs are used for
  research and development, i.e., testing instruments and in particular
  polarization optics for advanced instrumentation deployed at major
  European and international astronomical and solar telescopes. In
  addition, the Einstein Tower is used for educating and training of the
  next generation astrophysicists as well as for education and public
  outreach activities directed at the general public. This article
  comments on the observatory's unique architecture and the challenges
  of maintaining and conserving the building. It describes in detail the
  characteristics of telescope, spectrographs, and imagers; it portrays
  some of the research and development activities.

Title: Flow and magnetic field properties in the trailing sunspots
    of active region NOAA 12396
Authors: Verma, M.; Denker, C.; Böhm, F.; Balthasar, H.; Fischer,
   C. E.; Kuckein, C.; Bello González, N.; Berkefeld, T.; Collados,
   M.; Diercke, A.; Feller, A.; González Manrique, S. J.; Hofmann, A.;
   Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei,
   R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.;
   Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016AN....337.1090V
Altcode:
  Improved measurements of the photospheric and chromospheric
  three-dimensional magnetic and flow fields are crucial for a precise
  determination of the origin and evolution of active regions. We present
  an illustrative sample of multi-instrument data acquired during a
  two-week coordinated observing campaign in August 2015 involving,
  among others, the GREGOR solar telescope (imaging and near-infrared
  spectroscopy) and the space missions Solar Dynamics Observatory (SDO)
  and Interface Region Imaging Spectrograph (IRIS). The observations
  focused on the trailing part of active region NOAA 12396 with complex
  polarity inversion lines and strong intrusions of opposite polarity
  flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV
  spectral profiles in the photospheric Si I λ1082.7 nm line, the
  chromospheric He I λ1083.0 nm triplet, and the photospheric Ca I
  λ1083.9 nm line. Carefully calibrated GRIS scans of the active region
  provided maps of Doppler velocity and magnetic field at different
  atmospheric heights. We compare quick-look maps with those obtained
  with the ``Stokes Inversions based on Response functions'' (SIR)
  code, which furnishes deeper insight into the magnetic properties
  of the region. We find supporting evidence that newly emerging flux
  and intruding opposite polarity flux are hampering the formation
  of penumbrae, i.e., a penumbra fully surrounding a sunspot is only
  expected after cessation of flux emergence in proximity to the sunspots.

Title: Inference of magnetic fields in the very quiet Sun
Authors: Martínez González, M. J.; Pastor Yabar, A.; Lagg, A.;
   Asensio Ramos, A.; Collados, M.; Solanki, S. K.; Balthasar, H.;
   Berkefeld, T.; Denker, C.; Doerr, H. P.; Feller, A.; Franz, M.;
   González Manrique, S. J.; Hofmann, A.; Kneer, F.; Kuckein, C.;
   Louis, R.; von der Lühe, O.; Nicklas, H.; Orozco, D.; Rezaei, R.;
   Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
   M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Waldman,
   T.; Volkmer, R.
Bibcode: 2016A&A...596A...5M
Altcode: 2018arXiv180410089M
  Context. Over the past 20 yr, the quietest areas of the solar surface
  have revealed a weak but extremely dynamic magnetism occurring
  at small scales (&lt;500 km), which may provide an important
  contribution to the dynamics and energetics of the outer layers of
  the atmosphere. Understanding this magnetism requires the inference
  of physical quantities from high-sensitivity spectro-polarimetric
  data with high spatio-temporal resolution. <BR /> Aims: We present
  high-precision spectro-polarimetric data with high spatial resolution
  (0.4'') of the very quiet Sun at 1.56 μm obtained with the GREGOR
  telescope to shed some light on this complex magnetism. <BR /> Methods:
  We used inversion techniques in two main approaches. First, we assumed
  that the observed profiles can be reproduced with a constant magnetic
  field atmosphere embedded in a field-free medium. Second, we assumed
  that the resolution element has a substructure with either two constant
  magnetic atmospheres or a single magnetic atmosphere with gradients of
  the physical quantities along the optical depth, both coexisting with
  a global stray-light component. <BR /> Results: Half of our observed
  quiet-Sun region is better explained by magnetic substructure within
  the resolution element. However, we cannot distinguish whether this
  substructure comes from gradients of the physical parameters along the
  line of sight or from horizontal gradients (across the surface). In
  these pixels, a model with two magnetic components is preferred, and
  we find two distinct magnetic field populations. The population with
  the larger filling factor has very weak ( 150 G) horizontal fields
  similar to those obtained in previous works. We demonstrate that the
  field vector of this population is not constrained by the observations,
  given the spatial resolution and polarimetric accuracy of our data. The
  topology of the other component with the smaller filling factor is
  constrained by the observations for field strengths above 250 G:
  we infer hG fields with inclinations and azimuth values compatible
  with an isotropic distribution. The filling factors are typically
  below 30%. We also find that the flux of the two polarities is not
  balanced. From the other half of the observed quiet-Sun area 50% are
  two-lobed Stokes V profiles, meaning that 23% of the field of view
  can be adequately explained with a single constant magnetic field
  embedded in a non-magnetic atmosphere. The magnetic field vector and
  filling factor are reliable inferred in only 50% based on the regular
  profiles. Therefore, 12% of the field of view harbour hG fields with
  filling factors typically below 30%. At our present spatial resolution,
  70% of the pixels apparently are non-magnetised.

Title: Fitting peculiar spectral profiles in He I 10830Å absorption
    features
Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.;
   Collados, M.; Denker, C.; Fischer, C. E.; Gömöry, P.; Diercke, A.;
   Bello González, N.; Schlichenmaier, R.; Balthasar, H.; Berkefeld, T.;
   Feller, A.; Hoch, S.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.;
   Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
   M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma,
   M.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016AN....337.1057G
Altcode: 2016arXiv160300679G
  The new generation of solar instruments provides better
  spectral, spatial, and temporal resolution for a better
  understanding of the physical processes that take place on the
  Sun. Multiple-component profiles are more commonly observed with these
  instruments. Particularly, the He I 10830 Å triplet presents such
  peculiar spectral profiles, which give information on the velocity
  and magnetic fine structure of the upper chromosphere. The purpose
  of this investigation is to describe a technique to efficiently fit
  the two blended components of the He I 10830 Å triplet, which are
  commonly observed when two atmospheric components are located within
  the same resolution element. The observations used in this study were
  taken on 2015 April 17 with the very fast spectroscopic mode of the
  GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar
  telescope, located at the Observatorio del Teide, Tenerife, Spain. We
  apply a double-Lorentzian fitting technique using Levenberg-Marquardt
  least-squares minimization. This technique is very simple and much
  faster than inversion codes. Line-of-sight Doppler velocities can
  be inferred for a whole map of pixels within just a few minutes. Our
  results show sub- and supersonic downflow velocities of up to 32 km
  s<SUP>-1</SUP> for the fast component in the vicinity of footpoints of
  filamentary structures. The slow component presents velocities close
  to rest.

Title: Flows in and around Active Region NOAA12118 Observed with
    the GREGOR Solar Telescope and SDO/HMI
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
   Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
   A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
   A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
   Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
   M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016ASPC..504...29V
Altcode: 2016arXiv160301109V
  Accurate measurements of magnetic and velocity fields in and around
  solar active regions are key to unlocking the mysteries of the
  formation and the decay of sunspots. High spatial resolution images
  and spectral sequences with a high cadence obtained with the GREGOR
  solar telescope give us an opportunity to scrutinize 3-D flow fields
  with local correlation tracking and imaging spectroscopy. We present
  GREGOR early science data acquired in 2014 July - August with the GREGOR
  Fabry-Pérot Interferometer and the Blue Imaging Channel. Time-series
  of blue continuum (λ 450.6 nm) images of the small active region
  NOAA 12118 were restored with the speckle masking technique to derive
  horizontal proper motions and to track the evolution of morphological
  changes. In addition, high-resolution observations are discussed in
  the context of synoptic data from the Solar Dynamics Observatory.

