Author name code: deltoro-iniesta
ADS astronomy entries on 2022-09-14
author:"Del Toro Iniesta, Jose Carlos"
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Title: The on-ground data reduction and calibration pipeline for
    SO/PHI-HRT
Authors: Sinjan, J.; Calchetti, D.; Hirzberger, J.; Orozco Suárez,
   D.; Albert, K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero,
   A.; Blanco Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero,
   L.; Gutierrez Marquez, P.; Kahil, F.; Kolleck, M.; Solanki, S. K.; del
   Toro Iniesta, J. C.; Volkmer, R.; Woch, J.; Fiethe, B.; Gómez Cama,
   J. M.; Pérez-Grande, I.; Sanchis Kilders, E.; Balaguer Jiménez,
   M.; Bellot Rubio, L. R.; Carmona, M.; Deutsch, W.; Fernandez-Rico,
   G.; Fernández-Medina, A.; García Parejo, P.; Gasent Blesa, J. L.;
   Gizon, L.; Grauf, B.; Heerlein, K.; Korpi-Lagg, A.; Lange, T.; López
   Jiménez, A.; Maue, T.; Meller, R.; Michalik, H.; Moreno Vacas, A.;
   Müller, R.; Nakai, E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub,
   J.; Strecker, H.; Torralbo, I.; Valori, G.
Bibcode: 2022arXiv220814904S
Altcode:
  The ESA/NASA Solar Orbiter space mission has been successfully launched
  in February 2020. Onboard is the Polarimetric and Helioseismic Imager
  (SO/PHI), which has two telescopes, a High Resolution Telescope
  (HRT) and the Full Disc Telescope (FDT). The instrument is designed
  to infer the photospheric magnetic field and line-of-sight velocity
  through differential imaging of the polarised light emitted by the
  Sun. It calculates the full Stokes vector at 6 wavelength positions
  at the Fe I 617.3 nm absorption line. Due to telemetry constraints,
  the instrument nominally processes these Stokes profiles onboard,
  however when telemetry is available, the raw images are downlinked and
  reduced on ground. Here the architecture of the on-ground pipeline
  for HRT is presented, which also offers additional corrections not
  currently available on board the instrument. The pipeline can reduce
  raw images to the full Stokes vector with a polarimetric sensitivity
  of $10^{-3}\cdot I_{c}$ or better.

Title: Unipolar versus Bipolar Internetwork Flux Appearance
Authors: Gosic, Milan; Katsukawa, Yukio; Bellot Rubio, L. R.; Del
   Toro Iniesta, Jose Carlos; Cheung, Mark; Orozco Suárez, David
Bibcode: 2022cosp...44.2513G
Altcode:
  Small-scale internetwork (IN) magnetic fields are considered to be
  the main building blocks of the quiet Sun magnetism. It is therefore
  of paramount importance to understand how these fields are generated
  on the solar surface. To shed new light on this open question,
  we studied the appearance modes and spatio-temporal evolution of
  individual IN magnetic elements inside one supergranular cell. For
  that purpose, we employed a high-resolution, high-sensitivity,
  long-duration Hinode/NFI magnetogram sequence. From identification
  of flux patches and magnetofrictional simulations, we show that there
  are two distinct populations of IN flux concentrations: unipolar and
  bipolar features. Bipolar features tend to be bigger, live longer
  and carry more flux than unipolar features. About $70$% of the total
  instantaneous IN flux detected inside the supergranule is in the form
  of bipoles. Both types of flux concentrations are uniformly distributed
  over the solar surface. However, bipolar features appear (randomly
  oriented) at a faster rate than unipolar features (68 as opposed to
  55~Mx~cm$^{-2}$~day$^{-1}$). Our results lend support to the idea that
  bipolar features may be the signature of local dynamo action, while
  unipolar features seem to be formed by coalescence of background flux.

Title: The magnetic drivers of campfires seen by the Polarimetric
    and Helioseismic Imager (PHI) on Solar Orbiter
Authors: Kahil, F.; Hirzberger, J.; Solanki, S. K.; Chitta, L. P.;
   Peter, H.; Auchère, F.; Sinjan, J.; Orozco Suárez, D.; Albert,
   K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero, A.; Blanco
   Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero, L.; Gutiérrez
   Márquez, P.; Kolleck, M.; del Toro Iniesta, J. C.; Volkmer, R.;
   Woch, J.; Fiethe, B.; Gómez Cama, J. M.; Pérez-Grande, I.; Sanchis
   Kilders, E.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Calchetti,
   D.; Carmona, M.; Deutsch, W.; Fernández-Rico, G.; Fernández-Medina,
   A.; García Parejo, P.; Gasent-Blesa, J. L.; Gizon, L.; Grauf, B.;
   Heerlein, K.; Lagg, A.; Lange, T.; López Jiménez, A.; Maue, T.;
   Meller, R.; Michalik, H.; Moreno Vacas, A.; Müller, R.; Nakai,
   E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub, J.; Strecker, H.;
   Torralbo, I.; Valori, G.; Aznar Cuadrado, R.; Teriaca, L.; Berghmans,
   D.; Verbeeck, C.; Kraaikamp, E.; Gissot, S.
Bibcode: 2022A&A...660A.143K
Altcode: 2022arXiv220213859K
  Context. The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter
  (SO) spacecraft observed small extreme ultraviolet (EUV) bursts,
  termed campfires, that have been proposed to be brightenings near the
  apexes of low-lying loops in the quiet-Sun atmosphere. The underlying
  magnetic processes driving these campfires are not understood. <BR
  /> Aims: During the cruise phase of SO and at a distance of 0.523
  AU from the Sun, the Polarimetric and Helioseismic Imager on Solar
  Orbiter (SO/PHI) observed a quiet-Sun region jointly with SO/EUI,
  offering the possibility to investigate the surface magnetic field
  dynamics underlying campfires at a spatial resolution of about 380
  km. <BR /> Methods: We used co-spatial and co-temporal data of the
  quiet-Sun network at disc centre acquired with the High Resolution
  Imager of SO/EUI at 17.4 nm (HRI<SUB>EUV</SUB>, cadence 2 s) and the
  High Resolution Telescope of SO/PHI at 617.3 nm (HRT, cadence 2.5
  min). Campfires that are within the SO/PHI−SO/EUI common field
  of view were isolated and categorised according to the underlying
  magnetic activity. <BR /> Results: In 71% of the 38 isolated events,
  campfires are confined between bipolar magnetic features, which seem to
  exhibit signatures of magnetic flux cancellation. The flux cancellation
  occurs either between the two main footpoints, or between one of the
  footpoints of the loop housing the campfire and a nearby opposite
  polarity patch. In one particularly clear-cut case, we detected the
  emergence of a small-scale magnetic loop in the internetwork followed
  soon afterwards by a campfire brightening adjacent to the location
  of the linear polarisation signal in the photosphere, that is to
  say near where the apex of the emerging loop lays. The rest of the
  events were observed over small scattered magnetic features, which
  could not be identified as magnetic footpoints of the campfire hosting
  loops. <BR /> Conclusions: The majority of campfires could be driven
  by magnetic reconnection triggered at the footpoints, similar to the
  physical processes occurring in the burst-like EUV events discussed
  in the literature. About a quarter of all analysed campfires, however,
  are not associated to such magnetic activity in the photosphere, which
  implies that other heating mechanisms are energising these small-scale
  EUV brightenings.

Title: Nice memories from a collaboration on sunspots
Authors: del Toro Iniesta, J.
Bibcode: 2022fysr.confE..52D
Altcode:
  Back in 1994, when I still was at the IAC, I had the idea of using the
  (by then) new SIR inversion code to a full vector spectropolarimetric
  map of a sunspot as obtained with the HAO's Advanced Stokes
  Polarimeter. The opportunity was open to study the three-dimensional
  structure of sunspots from a semi-empirical basis. A collaboration
  between HAO and IAC had already started a few years earlier with the
  stays in HAO of Jorge Sánchez Almeida and Valentín Martínez Pillet
  (today's NSO director) as postdocs. Direct contact with the champions
  of ASP, Andy and Bruce, Bruce and Andy, was hence granted and I readily
  suggested them to undertake the study with their data and our code in
  the frame of the PhD thesis of a new student of mine, Carlos Westendorp
  Plaza. A few years later (1997), the discovery that penumbral material
  comes back to the solar interior at the external penumbral border was
  published in the Nature journal. The paper was followed by a series in
  ApJ on an optical tomography of a sunspot. The friendly and enriching
  discussions with Andy and Bruce remain as one of the most rewarding
  experiences in my (already long) career.

Title: CASPER: A mission to study the time-dependent evolution of
    the magnetic solar chromosphere and transition regions
Authors: Orozco Suárez, D.; del Toro Iniesta, J. C.; Bailén, F. J.;
   López Jiménez, A.; Balaguez Jiménez, M.; Bellot Rubio, L. R.;
   Ishikawa, R.; Katsukawa, Y.; Kano, R.; Shimizu, T.; Trujillo Bueno,
   J.; Asensio Ramos, A.; del Pino Alemán, T.
Bibcode: 2022ExA...tmp...26O
Altcode:
  Our knowledge about the solar chromosphere and transition region (TR)
  has increased in the last decade thanks to the huge scientific return
  of space-borne observatories like SDO, IRIS, and Hinode, and suborbital
  rocket experiments like CLASP1, CLASP2, and Hi-C. However, the magnetic
  nature of those solar regions remain barely explored. The chromosphere
  and TR of the Sun harbor weak fields and are in a low ionization stage
  both having critical effects on their thermodynamic behavior. Relatively
  cold gas structures, such as spicules and prominences, are located in
  these two regions and display a dynamic evolution in high-resolution
  observations that static and instantaneous 3D-magnetohydrodynamic (MHD)
  models are not able to reproduce. The role of the chromosphere and TR
  as the necessary path to a (largely unexplained) very hot corona calls
  for the generation of observationally based, time-dependent models
  of these two layers that include essential, up to now disregarded,
  ingredients in the modeling such as the vector magnetic field. We
  believe that the community is convinced that the origin of both the
  heat and kinetic energy observed in the upper layers of the solar
  atmosphere is of magnetic origin, but reliable magnetic field
  measurements are missing. The access to sensitive polarimetric
  measurements in the ultraviolet wavelengths has been elusive until
  recently due to limitations in the available technology. We propose a
  low-risk and high-Technology Readiness Level (TRL) mission to explore
  the magnetism and dynamics of the solar chromosphere and TR. The mission
  baseline is a low-Earth, Sun-synchronous orbit at an altitude between
  600 and 800 km. The proposed scientific payload consists of a 30 cm
  aperture telescope with a spectropolarimeter covering the hydrogen
  Ly-alpha and the Mg II h&amp;k ultraviolet lines. The instrument shall
  record high-cadence, full spectropolarimetric observations of the
  solar upper atmosphere. Besides the answers to a fundamental solar
  problem the mission has a broader scientific return. For example,
  the time-dependent modeling of the chromospheres of stars harboring
  exoplanets is fundamental for estimating the planetary radiation
  environment. The mission is based on technologies that are mature
  enough for space and will provide scientific measurements that are
  not available by other means.

Title: The Solar Internetwork. III. Unipolar versus Bipolar Flux
    Appearance
Authors: Gošić, M.; Bellot Rubio, L. R.; Cheung, M. C. M.; Orozco
   Suárez, D.; Katsukawa, Y.; del Toro Iniesta, J. C.
Bibcode: 2022ApJ...925..188G
Altcode: 2021arXiv211103208G
  Small-scale internetwork (IN) magnetic fields are considered to be the
  main building blocks of quiet Sun magnetism. For this reason, it is
  crucial to understand how they appear on the solar surface. Here,
  we employ a high-resolution, high-sensitivity, long-duration
  Hinode/NFI magnetogram sequence to analyze the appearance modes and
  spatiotemporal evolution of individual IN magnetic elements inside a
  supergranular cell at the disk center. From identification of flux
  patches and magnetofrictional simulations, we show that there are
  two distinct populations of IN flux concentrations: unipolar and
  bipolar features. Bipolar features tend to be bigger and stronger
  than unipolar features. They also live longer and carry more flux
  per feature. Both types of flux concentrations appear uniformly over
  the solar surface. However, we argue that bipolar features truly
  represent the emergence of new flux on the solar surface, while
  unipolar features seem to be formed by the coalescence of background
  flux. Magnetic bipoles appear at a faster rate than unipolar features
  (68 as opposed to 55 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>), and provide
  about 70% of the total instantaneous IN flux detected in the interior
  of the supergranule.

Title: Probing Upflowing Regions in the Quiet Sun and Coronal Holes
Authors: Schwanitz, Conrad; Harra, Louise; Raouafi, Nour E.; Sterling,
   Alphonse C.; Moreno Vacas, Alejandro; del Toro Iniesta, Jose Carlos;
   Orozco Suárez, David; Hara, Hirohisa
Bibcode: 2021SoPh..296..175S
Altcode: 2021arXiv211012753S
  Recent observations from Parker Solar Probe have revealed that the
  solar wind has a highly variable structure. How this complex behaviour
  is formed in the solar corona is not yet known, since it requires
  omnipresent fluctuations, which constantly emit material to feed
  the wind. In this article we analyse 14 upflow regions in the solar
  corona to find potential sources for plasma flow. The upflow regions
  are derived from spectroscopic data from the EUV Imaging Spectrometer
  (EIS) on board Hinode determining their Doppler velocity and defining
  regions which have blueshifts stronger than −6 kms−<SUP>1</SUP>. To
  identify the sources of these blueshift data from the Atmospheric
  Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI),
  on board the Solar Dynamics Observatory (SDO), and the X-ray Telescope
  (XRT), on board Hinode, are used. The analysis reveals that only 5 out
  of 14 upflows are associated with frequent transients, like obvious
  jets or bright points. In contrast to that, seven events are associated
  with small-scale features, which show a large variety of dynamics. Some
  resemble small bright points, while others show an eruptive nature, all
  of which are faint and only live for a few minutes; we cannot rule out
  that several of these sources may be fainter and, hence, less obvious
  jets. Since the complex structure of the solar wind is known, this
  suggests that new sources have to be considered or better methods used
  to analyse the known sources. This work shows that small and frequent
  features, which were previously neglected, can cause strong upflows in
  the solar corona. These results emphasise the importance of the first
  observations from the Extreme-Ultraviolet Imager (EUI) on board Solar
  Orbiter, which revealed complex small-scale coronal structures.

Title: On Fabry-Pérot Etalon-based Instruments. IV. Analytical
    Formulation of Telecentric Etalons
Authors: Bailén, F. J.; Orozco Suárez, D.; del Toro Iniesta, J. C.
Bibcode: 2021ApJS..254...18B
Altcode: 2022arXiv220506026B
  Fabry-Pérot etalons illuminated with collimated beams have been
  analytically characterized in detail since their invention. Meanwhile,
  most of the features of etalons located in telecentric planes have been
  studied only numerically, despite the wide use of this configuration
  in astrophysical instrumentation for decades. In this work we present
  analytical expressions for the transmitted electric field and its
  derivatives that are valid for etalons placed in slow telecentric
  beams, like the ones commonly employed in solar instruments. We use
  the derivatives to infer the sensitivity of the electric field to
  variations in the optical thickness for different reflectivities and
  apertures of the incident beam, and we compare them to the collimated
  case. This allows us to estimate the wavefront degradation produced by
  roughness errors on the surfaces of the Fabry-Pérot etalons and to
  establish the maximum allowed rms value of the cavity irregularities
  across the footprint of the incident beam on the etalons that ensures
  diffraction-limited performance. We also evaluate the wavefront
  degradation intrinsic to these mounts, which is produced only by the
  finite aperture of the beam and that must be added to the one produced
  by defects. Finally, we discuss the differences in performance of
  telecentric and collimated etalon-based instruments and we generalize
  our formulation to anisotropic etalons.

Title: SUNRISE Chromospheric Infrared spectroPolarimeter (SCIP)
for SUNRISE III: Scan mirror mechanism
Authors: Oba, Takayoshi; Shimizu, Toshifumi; Katsukawa, Yukio; Kubo,
   Masahito; Uraguchi, Fumihiro; Tsuzuki, Toshihiro; Tamura, Tomonori;
   Shinoda, Kazuya; Kodeki, Kazuhide; Fukushima, Kazuhiko; Gandorfer,
   Achim; del Toro Iniesta, Jose Carlos
Bibcode: 2020SPIE11445E..4FO
Altcode:
  The SUNRISE Chromospheric Infrared spectroPolarimeter (SCIP) is a
  balloon-borne long-slit spectrograph for SUNRISE III to precisely
  measure magnetic fields in the solar atmosphere. The scan mirror
  mechanism (SMM) is installed in the optical path to the entrance slit
  of the SCIP to move solar images focused on the slit for 2-dimensional
  mapping. The SMM is required to have (1) the tilt stability better
  than 0.035″ (3σ) on the sky angle for the diffraction-limited
  spatial resolution of 0.2″, (2) step response shorter than 32 msec
  for rapid scanning observations, and (3) good linearity (i.e. step
  uniformity) over the entire field-of-view (60″x60″). To achieve
  these performances, we have developed a flight-model mechanism
  and its electronics, in which the mirror tilt is controlled by
  electromagnetic actuators with a closed-loop feedback logic with
  tilt angles from gap-based capacitance sensors. Several optical
  measurements on the optical bench verified that the mechanism meets
  the requirements. In particular, the tilt stability achives better
  than 0.012″ (3σ). Thermal cycling and thermal vacuum tests have
  been completed to demonstrate the performance in the vacuum and the
  operational temperature range expected in the balloon flight. We
  found a small temperature dependence in the step uniformity and this
  dependence will be corrected to have 2-demensional maps with the
  sub-arcsec spatial accuracy in the data post-processing.

Title: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for SUNRISE III: polarization modulation unit
Authors: Kubo, Masahito; Shimizu, Toshifumi; Katsukawa, Yukio;
   Kawabata, Yusuke; Anan, Tetsu; Ichimoto, Kiyoshi; Shinoda, Kazuya;
   Tamura, Tomonori; Nodomi, Yoshifumi; Nakayama, Satoshi; Yamada, Takuya;
   Tajima, Takao; Nakata, Shimpei; Nakajima, Yoshihito; Okutani, Kousei;
   Feller, Alex; del Toro Iniesta, Jose Carlos
Bibcode: 2020SPIE11447E..A3K
Altcode:
  Polarization measurements of the solar chromospheric lines at
  high precision are key to present and future solar telescopes for
  understanding magnetic field structures in the chromosphere. The
  Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) for Sunrise
  III is a spectropolarimeter with a polarimetric precision of 0.03 %
  (1 σ). The key to high-precision polarization measurements using
  SCIP is a polarization modulation unit that rotates a waveplate
  continuously at a constant speed. The rotating mechanism is a DC
  brushless motor originally developed for a future space mission, and
  its control logic was originally developed for the sounding rocket
  experiment CLASP. Because of our requirement on a speed of rotation
  (0.512 s/rotation) that was 10 times faster than that of CLASP, we
  optimized the control logic for the required faster rotation. Fast
  polarization modulation is essential for investigating the fine-scale
  magnetic field structures related to the dynamical chromospheric
  phenomena. We have verified that the rotation performance can achieve
  the polarization precision of 0.03 % (1 σ) required by SCIP and such
  a significant rotation performance is maintained under thermal vacuum
  conditions by simulating the environment of the Sunrise III balloon
  flight. The waveplate was designed as a pair of two birefringent
  plates made of quartz and sapphire to achieve a constant retardation
  in a wide wavelength range. We have confirmed that the retardation
  is almost constant in the 770 nm and 850nm wavelength bands of SCIP
  under the operational temperature conditions.

Title: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for SUNRISE III: opto-mechanical analysis and design
Authors: Uraguchi, Fumihiro; Tsuzuki, Toshihiro; Katsukawa, Yukio;
   Hara, Hirohisa; Iwamura, Satoru; Kubo, Masahito; Nodomi, Yoshifumi;
   Suematsu, Yoshinori; Kawabata, Yusuke; Shimizu, Toshifumi; Gandorfer,
   Achim; del Toro Iniesta, Jose Carlos
Bibcode: 2020SPIE11447E..ABU
Altcode:
  The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is a
  near-IR spectro-polarimeter instrument newly designed for Sunrise III,
  a balloon-borne solar observatory with a 1-m diameter telescope. In
  order to achieve the strict requirements the SCIP wavefront error, it is
  necessary to quantify the errors due to environmen- tal effects such as
  gravity and temperature variation under the observation conditions. We
  therefore conducted an integrated opto-mechanical analysis incorporating
  mechanical and thermal disturbances into a finite element model of
  the entire SCIP structure to acquire the nodal displacements of each
  optical element, then fed them back to the optical analysis software
  in the form of rigid body motion and surface deformation fitted by
  polynomials. This method allowed us to determine the error factors
  having a significant influence on optical performance. For example,
  no significant wavefront degradation was associated with the structural
  mountings because the optical element mounts were well designed based
  on quasi-kinematic constraints. In contrast, we found that the main
  factor affecting wavefront degradation was the rigid body motions of
  the optical elements, which must be mini- mized within the allowable
  level. Based on these results, we constructed the optical bench using a
  sandwich panel as the optical bench consisting of an aluminum-honeycomb
  core and carbon fiber reinforced plastic skins with a high stiffness
  and low coefficient of thermal expansion. We then confirmed that the
  new opto-mechanical model achieved the wavefront error requirement. In
  this paper, we report the details of this integrated opto-mechanical
  analysis, including the wavefront error budgeting and the design of
  the opto-mechanics.

Title: Power spectrum of turbulent convection in the solar photosphere
Authors: Yelles Chaouche, L.; Cameron, R. H.; Solanki, S. K.;
   Riethmüller, T. L.; Anusha, L. S.; Witzke, V.; Shapiro, A. I.;
   Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; van Noort,
   M.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.; Orozco Suárez,
   D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2020A&A...644A..44Y
Altcode: 2020arXiv201009037Y
  The solar photosphere provides us with a laboratory for understanding
  turbulence in a layer where the fundamental processes of transport
  vary rapidly and a strongly superadiabatic region lies very closely
  to a subadiabatic layer. Our tools for probing the turbulence are
  high-resolution spectropolarimetric observations such as have recently
  been obtained with the two balloon-borne SUNRISE missions, and numerical
  simulations. Our aim is to study photospheric turbulence with the
  help of Fourier power spectra that we compute from observations
  and simulations. We also attempt to explain some properties of the
  photospheric overshooting flow with the help of its governing equations
  and simulations. We find that quiet-Sun observations and smeared
  simulations are consistent with each other and exhibit a power-law
  behavior in the subgranular range of their Doppler velocity power
  spectra with a power-law index of ≈ - 2. The unsmeared simulations
  exhibit a power law that extends over the full range between the
  integral and Taylor scales with a power-law index of ≈ - 2.25. The
  smearing, reminiscent of observational conditions, considerably reduces
  the extent of the power-law-like portion of the power spectra. This
  suggests that the limited spatial resolution in some observations
  might eventually result in larger uncertainties in the estimation of
  the power-law indices. The simulated vertical velocity power spectra
  as a function of height show a rapid change in the power-law index
  (at the subgranular range) from roughly the optical depth unity layer,
  that is, the solar surface, to 300 km above it. We propose that the
  cause of the steepening of the power-law index is the transition from
  a super- to a subadiabatic region, in which the dominant source of
  motions is overshooting convection. A scale-dependent transport of
  the vertical momentum occurs. At smaller scales, the vertical momentum
  is more efficiently transported sideways than at larger scales. This
  results in less vertical velocity power transported upward at small
  scales than at larger scales and produces a progressively steeper
  vertical velocity power law below 180 km. Above this height, the
  gravity work progressively gains importance at all relevant scales,
  making the atmosphere progressively more hydrostatic and resulting
  in a gradually less steep power law. Radiative heating and cooling of
  the plasma is shown to play a dominant role in the plasma energetics
  in this region, which is important in terms of nonadiabatic damping
  of the convective motions.

Title: Sunrise Chromospheric Infrared SpectroPolarimeter (SCIP)
for sunrise III: system design and capability
Authors: Katsukawa, Y.; del Toro Iniesta, J. C.; Solanki, S. K.;
   Kubo, M.; Hara, H.; Shimizu, T.; Oba, T.; Kawabata, Y.; Tsuzuki,
   T.; Uraguchi, F.; Nodomi, Y.; Shinoda, K.; Tamura, T.; Suematsu,
   Y.; Ishikawa, R.; Kano, R.; Matsumoto, T.; Ichimoto, K.; Nagata, S.;
   Quintero Noda, C.; Anan, T.; Orozco Suárez, D.; Balaguer Jiménez,
   M.; López Jiménez, A. C.; Cobos Carrascosa, J. P.; Feller, A.;
   Riethmueller, T.; Gandorfer, A.; Lagg, A.
Bibcode: 2020SPIE11447E..0YK
Altcode:
  The Sunrise balloon-borne solar observatory carries a 1 m aperture
  optical telescope and provides us a unique platform to conduct
  continuous seeing-free observations at UV-visible-IR wavelengths from
  an altitude of higher than 35 km. For the next flight planned for
  2022, the post-focus instrumentation is upgraded with new spectro-
  polarimeters for the near UV (SUSI) and the near-IR (SCIP), whereas
  the imaging spectro-polarimeter Tunable Magnetograph (TuMag) is capable
  of observing multiple spectral lines within the visible wavelength. A
  new spectro-polarimeter called the Sunrise Chromospheric Infrared
  spectroPolarimeter (SCIP) is under development for observing near-IR
  wavelength ranges of around 770 nm and 850 nm. These wavelength ranges
  contain many spectral lines sensitive to solar magnetic fields and
  SCIP will be able to obtain magnetic and velocity structures in the
  solar atmosphere with a sufficient height resolution by combining
  spectro-polarimetric data of these lines. Polarimetric measurements are
  conducted using a rotating waveplate as a modulator and polarizing beam
  splitters in front of the cameras. The spatial and spectral resolutions
  are 0.2" and 2 105, respectively, and a polarimetric sensitivity of
  0.03 % (1σ) is achieved within a 10 s integration time. To detect
  minute polarization signals with good precision, we carefully designed
  the opto-mechanical system, polarization optics and modulation, and
  onboard data processing.

Title: Solar Orbiter: connecting remote sensing and in situ
    measurements
Authors: Horbury, T. S.; Auchere, F.; Antonucci, E.; Berghmans, D.;
   Bruno, R.; Carlsson, M.; del Toro Iniesta, J. C.; Fludra, A.; Harra,
   L.; Hassler, D.; Heinzel, P.; Howard, R. A.; Krucker, S.; Livi, S. A.;
   Long, D.; Louarn, P.; Maksimovic, M.; Mueller, D.; Owen, C. J.; Peter,
   H.; Rochus, P. L.; Rodriguez-Pacheco, J.; Romoli, M.; Schühle, U.;
   Solanki, S. K.; Teriaca, L.; Wimmer-Schweingruber, R. F.; Zouganelis,
   Y.; Laker, R.
Bibcode: 2020AGUFMSH038..10H
Altcode:
  A key science goal of the Solar Orbiter mission is to make connections
  between phenomena on the Sun and their manifestations in interplanetary
  space. To that end, the spacecraft carries a carefully tailored
  payload of six remote sensing instruments and four making in situ
  measurements. During June 2020, while the spacecraft was around 0.5
  AU from the Sun, the remote sensing instruments operated for several
  days. While this was primarily an engineering activity, the resulting
  observations provided outstanding measurements and represent the ideal
  first opportunity to investigate the potential for making connections
  between the remote sensing and in situ payloads on Solar Orbiter. <P
  />We present a preliminary analysis of the available remote sensing and
  in situ observations, showing how connections can be made, and discuss
  the potential for further, more precise mapping to be performed as
  the mission progresses.

Title: Coordination within the remote sensing payload on the Solar
    Orbiter mission
Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.;
   Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade,
   S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.;
   Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy,
   S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy,
   T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.;
   Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.;
   Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey,
   B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.;
   Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi,
   M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.;
   Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.;
   Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.;
   Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.;
   Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams,
   D.; Woch, J.; Zhukov, A. N.; Zouganelis, I.
Bibcode: 2020A&A...642A...6A
Altcode:
  Context. To meet the scientific objectives of the mission, the Solar
  Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing
  (RS) instruments designed for joint operations with inter-instrument
  communication capabilities. Indeed, previous missions have shown that
  the Sun (imaged by the RS instruments) and the heliosphere (mainly
  sampled by the IS instruments) should be considered as an integrated
  system rather than separate entities. Many of the advances expected
  from Solar Orbiter rely on this synergistic approach between IS and
  RS measurements. <BR /> Aims: Many aspects of hardware development,
  integration, testing, and operations are common to two or more
  RS instruments. In this paper, we describe the coordination effort
  initiated from the early mission phases by the Remote Sensing Working
  Group. We review the scientific goals and challenges, and give an
  overview of the technical solutions devised to successfully operate
  these instruments together. <BR /> Methods: A major constraint for the
  RS instruments is the limited telemetry (TM) bandwidth of the Solar
  Orbiter deep-space mission compared to missions in Earth orbit. Hence,
  many of the strategies developed to maximise the scientific return from
  these instruments revolve around the optimisation of TM usage, relying
  for example on onboard autonomy for data processing, compression,
  and selection for downlink. The planning process itself has been
  optimised to alleviate the dynamic nature of the targets, and an
  inter-instrument communication scheme has been implemented which can
  be used to autonomously alter the observing modes. We also outline the
  plans for in-flight cross-calibration, which will be essential to the
  joint data reduction and analysis. <BR /> Results: The RS instrument
  package on Solar Orbiter will carry out comprehensive measurements
  from the solar interior to the inner heliosphere. Thanks to the close
  coordination between the instrument teams and the European Space
  Agency, several challenges specific to the RS suite were identified
  and addressed in a timely manner.

Title: Models and data analysis tools for the Solar Orbiter mission
Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.;
   Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.;
   Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.;
   Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi,
   N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla,
   T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.;
   Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.;
   Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.;
   Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.;
   Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot,
   V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.;
   Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.;
   Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp,
   E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud,
   B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.;
   Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.;
   Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti,
   S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.;
   Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez,
   L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca,
   L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.;
   Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov,
   A. N.
Bibcode: 2020A&A...642A...2R
Altcode:
  Context. The Solar Orbiter spacecraft will be equipped with a wide
  range of remote-sensing (RS) and in situ (IS) instruments to record
  novel and unprecedented measurements of the solar atmosphere and
  the inner heliosphere. To take full advantage of these new datasets,
  tools and techniques must be developed to ease multi-instrument and
  multi-spacecraft studies. In particular the currently inaccessible
  low solar corona below two solar radii can only be observed
  remotely. Furthermore techniques must be used to retrieve coronal
  plasma properties in time and in three dimensional (3D) space. Solar
  Orbiter will run complex observation campaigns that provide interesting
  opportunities to maximise the likelihood of linking IS data to their
  source region near the Sun. Several RS instruments can be directed
  to specific targets situated on the solar disk just days before
  data acquisition. To compare IS and RS, data we must improve our
  understanding of how heliospheric probes magnetically connect to the
  solar disk. <BR /> Aims: The aim of the present paper is to briefly
  review how the current modelling of the Sun and its atmosphere
  can support Solar Orbiter science. We describe the results of a
  community-led effort by European Space Agency's Modelling and Data
  Analysis Working Group (MADAWG) to develop different models, tools,
  and techniques deemed necessary to test different theories for the
  physical processes that may occur in the solar plasma. The focus here
  is on the large scales and little is described with regards to kinetic
  processes. To exploit future IS and RS data fully, many techniques have
  been adapted to model the evolving 3D solar magneto-plasma from the
  solar interior to the solar wind. A particular focus in the paper is
  placed on techniques that can estimate how Solar Orbiter will connect
  magnetically through the complex coronal magnetic fields to various
  photospheric and coronal features in support of spacecraft operations
  and future scientific studies. <BR /> Methods: Recent missions such as
  STEREO, provided great opportunities for RS, IS, and multi-spacecraft
  studies. We summarise the achievements and highlight the challenges
  faced during these investigations, many of which motivated the Solar
  Orbiter mission. We present the new tools and techniques developed
  by the MADAWG to support the science operations and the analysis of
  the data from the many instruments on Solar Orbiter. <BR /> Results:
  This article reviews current modelling and tool developments that ease
  the comparison of model results with RS and IS data made available
  by current and upcoming missions. It also describes the modelling
  strategy to support the science operations and subsequent exploitation
  of Solar Orbiter data in order to maximise the scientific output
  of the mission. <BR /> Conclusions: The on-going community effort
  presented in this paper has provided new models and tools necessary
  to support mission operations as well as the science exploitation of
  the Solar Orbiter data. The tools and techniques will no doubt evolve
  significantly as we refine our procedure and methodology during the
  first year of operations of this highly promising mission.

Title: The Solar Orbiter Science Activity Plan. Translating solar
    and heliospheric physics questions into action
Authors: Zouganelis, I.; De Groof, A.; Walsh, A. P.; Williams, D. R.;
   Müller, D.; St Cyr, O. C.; Auchère, F.; Berghmans, D.; Fludra,
   A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.;
   Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.;
   Watson, C.; Sanchez, L.; Lefort, J.; Osuna, P.; Gilbert, H. R.;
   Nieves-Chinchilla, T.; Abbo, L.; Alexandrova, O.; Anastasiadis, A.;
   Andretta, V.; Antonucci, E.; Appourchaux, T.; Aran, A.; Arge, C. N.;
   Aulanier, G.; Baker, D.; Bale, S. D.; Battaglia, M.; Bellot Rubio,
   L.; Bemporad, A.; Berthomier, M.; Bocchialini, K.; Bonnin, X.; Brun,
   A. S.; Bruno, R.; Buchlin, E.; Büchner, J.; Bucik, R.; Carcaboso,
   F.; Carr, R.; Carrasco-Blázquez, I.; Cecconi, B.; Cernuda Cangas, I.;
   Chen, C. H. K.; Chitta, L. P.; Chust, T.; Dalmasse, K.; D'Amicis, R.;
   Da Deppo, V.; De Marco, R.; Dolei, S.; Dolla, L.; Dudok de Wit, T.;
   van Driel-Gesztelyi, L.; Eastwood, J. P.; Espinosa Lara, F.; Etesi,
   L.; Fedorov, A.; Félix-Redondo, F.; Fineschi, S.; Fleck, B.; Fontaine,
   D.; Fox, N. J.; Gandorfer, A.; Génot, V.; Georgoulis, M. K.; Gissot,
   S.; Giunta, A.; Gizon, L.; Gómez-Herrero, R.; Gontikakis, C.; Graham,
   G.; Green, L.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler,
   D. M.; Hirzberger, J.; Ho, G. C.; Hurford, G.; Innes, D.; Issautier,
   K.; James, A. W.; Janitzek, N.; Janvier, M.; Jeffrey, N.; Jenkins,
   J.; Khotyaintsev, Y.; Klein, K. -L.; Kontar, E. P.; Kontogiannis,
   I.; Krafft, C.; Krasnoselskikh, V.; Kretzschmar, M.; Labrosse, N.;
   Lagg, A.; Landini, F.; Lavraud, B.; Leon, I.; Lepri, S. T.; Lewis,
   G. R.; Liewer, P.; Linker, J.; Livi, S.; Long, D. M.; Louarn, P.;
   Malandraki, O.; Maloney, S.; Martinez-Pillet, V.; Martinovic, M.;
   Masson, A.; Matthews, S.; Matteini, L.; Meyer-Vernet, N.; Moraitis,
   K.; Morton, R. J.; Musset, S.; Nicolaou, G.; Nindos, A.; O'Brien,
   H.; Orozco Suarez, D.; Owens, M.; Pancrazzi, M.; Papaioannou, A.;
   Parenti, S.; Pariat, E.; Patsourakos, S.; Perrone, D.; Peter, H.;
   Pinto, R. F.; Plainaki, C.; Plettemeier, D.; Plunkett, S. P.; Raines,
   J. M.; Raouafi, N.; Reid, H.; Retino, A.; Rezeau, L.; Rochus, P.;
   Rodriguez, L.; Rodriguez-Garcia, L.; Roth, M.; Rouillard, A. P.;
   Sahraoui, F.; Sasso, C.; Schou, J.; Schühle, U.; Sorriso-Valvo, L.;
   Soucek, J.; Spadaro, D.; Stangalini, M.; Stansby, D.; Steller, M.;
   Strugarek, A.; Štverák, Š.; Susino, R.; Telloni, D.; Terasa, C.;
   Teriaca, L.; Toledo-Redondo, S.; del Toro Iniesta, J. C.; Tsiropoula,
   G.; Tsounis, A.; Tziotziou, K.; Valentini, F.; Vaivads, A.; Vecchio,
   A.; Velli, M.; Verbeeck, C.; Verdini, A.; Verscharen, D.; Vilmer, N.;
   Vourlidas, A.; Wicks, R.; Wimmer-Schweingruber, R. F.; Wiegelmann,
   T.; Young, P. R.; Zhukov, A. N.
Bibcode: 2020A&A...642A...3Z
Altcode: 2020arXiv200910772Z
  Solar Orbiter is the first space mission observing the solar plasma
  both in situ and remotely, from a close distance, in and out of the
  ecliptic. The ultimate goal is to understand how the Sun produces
  and controls the heliosphere, filling the Solar System and driving
  the planetary environments. With six remote-sensing and four in-situ
  instrument suites, the coordination and planning of the operations are
  essential to address the following four top-level science questions:
  (1) What drives the solar wind and where does the coronal magnetic field
  originate?; (2) How do solar transients drive heliospheric variability?;
  (3) How do solar eruptions produce energetic particle radiation that
  fills the heliosphere?; (4) How does the solar dynamo work and drive
  connections between the Sun and the heliosphere? Maximising the
  mission's science return requires considering the characteristics
  of each orbit, including the relative position of the spacecraft
  to Earth (affecting downlink rates), trajectory events (such
  as gravitational assist manoeuvres), and the phase of the solar
  activity cycle. Furthermore, since each orbit's science telemetry
  will be downloaded over the course of the following orbit, science
  operations must be planned at mission level, rather than at the level
  of individual orbits. It is important to explore the way in which those
  science questions are translated into an actual plan of observations
  that fits into the mission, thus ensuring that no opportunities are
  missed. First, the overarching goals are broken down into specific,
  answerable questions along with the required observations and the
  so-called Science Activity Plan (SAP) is developed to achieve this. The
  SAP groups objectives that require similar observations into Solar
  Orbiter Observing Plans, resulting in a strategic, top-level view of
  the optimal opportunities for science observations during the mission
  lifetime. This allows for all four mission goals to be addressed. In
  this paper, we introduce Solar Orbiter's SAP through a series of
  examples and the strategy being followed.

Title: Autonomous on-board data processing and instrument calibration
    software for the Polarimetric and Helioseismic Imager on-board the
    Solar Orbiter mission
Authors: Albert, Kinga; Hirzberger, Johann; Kolleck, Martin; Jorge,
   Nestor Albelo; Busse, Dennis; Rodríguez, Julian Blanco; Carrascosa,
   Juan Pedro Cobos; Fiethe, Björn; Gandorfer, Achim; Germerott, Dietmar;
   Guan, Yejun; Guerrero, Lucas; Gutierrez-Marques, Pablo; Expósito,
   David Hernández; Lange, Tobias; Michalik, Harald; Suárez, David
   Orozco; Schou, Jesper; Solanki, Sami K.; del Toro Iniesta, José
   Carlos; Woch, Joachim
Bibcode: 2020JATIS...6d8004A
Altcode:
  A frequent problem arising for deep space missions is the discrepancy
  between the amount of data desired to be transmitted to the ground
  and the available telemetry bandwidth. A part of these data consists
  of scientific observations, being complemented by calibration data
  to help remove instrumental effects. We present our solution for this
  discrepancy, implemented for the Polarimetric and Helioseismic Imager
  on-board the Solar Orbiter mission, the first solar spectropolarimeter
  in deep space. We implemented an on-board data reduction system that
  processes calibration data, applies them to the raw science observables,
  and derives science-ready physical parameters. This process reduces
  the raw data for a single measurement from 24 images to five, thus
  reducing the amount of downlinked data, and in addition, renders the
  transmission of the calibration data unnecessary. Both these on-board
  actions are completed autonomously.

Title: The Polarimetric and Helioseismic Imager on Solar Orbiter
Authors: Solanki, S. K.; del Toro Iniesta, J. C.; Woch, J.; Gandorfer,
   A.; Hirzberger, J.; Alvarez-Herrero, A.; Appourchaux, T.; Martínez
   Pillet, V.; Pérez-Grande, I.; Sanchis Kilders, E.; Schmidt, W.;
   Gómez Cama, J. M.; Michalik, H.; Deutsch, W.; Fernandez-Rico, G.;
   Grauf, B.; Gizon, L.; Heerlein, K.; Kolleck, M.; Lagg, A.; Meller, R.;
   Müller, R.; Schühle, U.; Staub, J.; Albert, K.; Alvarez Copano, M.;
   Beckmann, U.; Bischoff, J.; Busse, D.; Enge, R.; Frahm, S.; Germerott,
   D.; Guerrero, L.; Löptien, B.; Meierdierks, T.; Oberdorfer, D.;
   Papagiannaki, I.; Ramanath, S.; Schou, J.; Werner, S.; Yang, D.;
   Zerr, A.; Bergmann, M.; Bochmann, J.; Heinrichs, J.; Meyer, S.;
   Monecke, M.; Müller, M. -F.; Sperling, M.; Álvarez García, D.;
   Aparicio, B.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Cobos
   Carracosa, J. P.; Girela, F.; Hernández Expósito, D.; Herranz, M.;
   Labrousse, P.; López Jiménez, A.; Orozco Suárez, D.; Ramos, J. L.;
   Barandiarán, J.; Bastide, L.; Campuzano, C.; Cebollero, M.; Dávila,
   B.; Fernández-Medina, A.; García Parejo, P.; Garranzo-García, D.;
   Laguna, H.; Martín, J. A.; Navarro, R.; Núñez Peral, A.; Royo, M.;
   Sánchez, A.; Silva-López, M.; Vera, I.; Villanueva, J.; Fourmond,
   J. -J.; de Galarreta, C. Ruiz; Bouzit, M.; Hervier, V.; Le Clec'h,
   J. C.; Szwec, N.; Chaigneau, M.; Buttice, V.; Dominguez-Tagle, C.;
   Philippon, A.; Boumier, P.; Le Cocguen, R.; Baranjuk, G.; Bell,
   A.; Berkefeld, Th.; Baumgartner, J.; Heidecke, F.; Maue, T.; Nakai,
   E.; Scheiffelen, T.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Blanco
   Rodríguez, J.; Domingo, V.; Ferreres Sabater, A.; Gasent Blesa,
   J. L.; Rodríguez Martínez, P.; Osorno Caudel, D.; Bosch, J.; Casas,
   A.; Carmona, M.; Herms, A.; Roma, D.; Alonso, G.; Gómez-Sanjuan, A.;
   Piqueras, J.; Torralbo, I.; Fiethe, B.; Guan, Y.; Lange, T.; Michel,
   H.; Bonet, J. A.; Fahmy, S.; Müller, D.; Zouganelis, I.
Bibcode: 2020A&A...642A..11S
Altcode: 2019arXiv190311061S
  <BR /> Aims: This paper describes the Polarimetric and Helioseismic
  Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and
  helioseismology instrument to observe the Sun from outside the Sun-Earth
  line. It is the key instrument meant to address the top-level science
  question: How does the solar dynamo work and drive connections between
  the Sun and the heliosphere? SO/PHI will also play an important role
  in answering the other top-level science questions of Solar Orbiter,
  while hosting the potential of a rich return in further science. <BR
  /> Methods: SO/PHI measures the Zeeman effect and the Doppler shift
  in the Fe I 617.3 nm spectral line. To this end, the instrument
  carries out narrow-band imaging spectro-polarimetry using a tunable
  LiNbO<SUB>3</SUB> Fabry-Perot etalon, while the polarisation modulation
  is done with liquid crystal variable retarders. The line and the nearby
  continuum are sampled at six wavelength points and the data are recorded
  by a 2k × 2k CMOS detector. To save valuable telemetry, the raw data
  are reduced on board, including being inverted under the assumption of
  a Milne-Eddington atmosphere, although simpler reduction methods are
  also available on board. SO/PHI is composed of two telescopes; one,
  the Full Disc Telescope, covers the full solar disc at all phases of
  the orbit, while the other, the High Resolution Telescope, can resolve
  structures as small as 200 km on the Sun at closest perihelion. The high
  heat load generated through proximity to the Sun is greatly reduced by
  the multilayer-coated entrance windows to the two telescopes that allow
  less than 4% of the total sunlight to enter the instrument, most of
  it in a narrow wavelength band around the chosen spectral line. <BR />
  Results: SO/PHI was designed and built by a consortium having partners
  in Germany, Spain, and France. The flight model was delivered to
  Airbus Defence and Space, Stevenage, and successfully integrated into
  the Solar Orbiter spacecraft. A number of innovations were introduced
  compared with earlier space-based spectropolarimeters, thus allowing
  SO/PHI to fit into the tight mass, volume, power and telemetry budgets
  provided by the Solar Orbiter spacecraft and to meet the (e.g. thermal)
  challenges posed by the mission's highly elliptical orbit.

Title: The Solar Orbiter mission. Science overview
Authors: Müller, D.; St. Cyr, O. C.; Zouganelis, I.; Gilbert, H. R.;
   Marsden, R.; Nieves-Chinchilla, T.; Antonucci, E.; Auchère, F.;
   Berghmans, D.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic,
   M.; Owen, C. J.; Rochus, P.; Rodriguez-Pacheco, J.; Romoli, M.;
   Solanki, S. K.; Bruno, R.; Carlsson, M.; Fludra, A.; Harra, L.;
   Hassler, D. M.; Livi, S.; Louarn, P.; Peter, H.; Schühle, U.;
   Teriaca, L.; del Toro Iniesta, J. C.; Wimmer-Schweingruber, R. F.;
   Marsch, E.; Velli, M.; De Groof, A.; Walsh, A.; Williams, D.
Bibcode: 2020A&A...642A...1M
Altcode: 2020arXiv200900861M
  <BR /> Aims: Solar Orbiter, the first mission of ESA's Cosmic Vision
  2015-2025 programme and a mission of international collaboration between
  ESA and NASA, will explore the Sun and heliosphere from close up and
  out of the ecliptic plane. It was launched on 10 February 2020 04:03
  UTC from Cape Canaveral and aims to address key questions of solar and
  heliospheric physics pertaining to how the Sun creates and controls
  the Heliosphere, and why solar activity changes with time. To answer
  these, the mission carries six remote-sensing instruments to observe
  the Sun and the solar corona, and four in-situ instruments to measure
  the solar wind, energetic particles, and electromagnetic fields. In
  this paper, we describe the science objectives of the mission, and how
  these will be addressed by the joint observations of the instruments
  onboard. <BR /> Methods: The paper first summarises the mission-level
  science objectives, followed by an overview of the spacecraft and
  payload. We report the observables and performance figures of each
  instrument, as well as the trajectory design. This is followed by a
  summary of the science operations concept. The paper concludes with a
  more detailed description of the science objectives. <BR /> Results:
  Solar Orbiter will combine in-situ measurements in the heliosphere
  with high-resolution remote-sensing observations of the Sun to address
  fundamental questions of solar and heliospheric physics. The performance
  of the Solar Orbiter payload meets the requirements derived from the
  mission's science objectives. Its science return will be augmented
  further by coordinated observations with other space missions and
  ground-based observatories. <P />ARRAY(0x207ce98)

Title: PMI: The Photospheric Magnetic Field Imager
Authors: Staub, Jan; Fernandez-Rico, German; Gandorfer, Achim; Gizon,
   Laurent; Hirzberger, Johann; Kraft, Stefan; Lagg, Andreas; Schou,
   Jesper; Solanki, Sami K.; del Toro Iniesta, Jose Carlos; Wiegelmann,
   Thomas; Woch, Joachim
Bibcode: 2020JSWSC..10...54S
Altcode:
  We describe the design and the capabilities of the Photospheric Magnetic
  field Imager (PMI), a compact and lightweight vector magnetograph,
  which is being developed for ESA's Lagrange mission to the Lagrange
  L5 point. After listing the design requirements and give a scientific
  justification for them, we describe the technical implementation and
  the design solution capable of fulfilling these requirements. This is
  followed by a description of the hardware architecture as well as the
  operations principle. An outlook on the expected performance concludes
  the paper.

Title: On the Magnetic Nature of an Exploding Granule as Revealed
    by Sunrise/IMaX
Authors: Guglielmino, Salvo L.; Martínez Pillet, Valentín; Ruiz
   Cobo, Basilio; Bellot Rubio, Luis R.; del Toro Iniesta, José Carlos;
   Solanki, Sami K.; Riethmüller, Tino L.; Zuccarello, Francesca
Bibcode: 2020ApJ...896...62G
Altcode: 2020arXiv200503371G
  We study the photospheric evolution of an exploding granule
  observed in the quiet Sun at high spatial (∼0"3) and temporal
  (31.5 s) resolution by the imaging magnetograph Sunrise/IMaX in 2009
  June. These observations show that the exploding granule is cospatial
  to a magnetic flux emergence event occurring at mesogranular scale
  (up to ∼12 Mm<SUP>2</SUP> area). Using a modified version of the
  SIR code for inverting the IMaX spectropolarimetric measurements, we
  obtain information about the magnetic configuration of this photospheric
  feature. In particular, we find evidence of highly inclined emerging
  fields in the structure, carrying a magnetic flux content up to ∼4
  × 10<SUP>18</SUP> Mx. The balance between gas and magnetic pressure
  in the region of flux emergence, compared with a very quiet region of
  the Sun, indicates that the additional pressure carried by the emerging
  flux increases the total pressure by about 5% and appears to allow the
  granulation to be modified, as predicted by numerical simulations. The
  overall characteristics suggest that a multipolar structure emerges
  into the photosphere, resembling an almost horizontal flux sheet. This
  seems to be associated with exploding granules. Finally, we discuss
  the origin of such flux emergence events.

Title: The SO/PHI instrument on Solar Orbiter and its data products
Authors: Solanki, Sami K.; Hirzberger, Johann; Wiegelmann, Thomas;
   Gandorfer, Achim; Woch, Joachim; del Toro Iniesta, José Carlos
Bibcode: 2020EGUGA..2217904S
Altcode:
  A central instrument of Solar Orbiter is the Polarimetric and
  Helioseismic Imager, SO/PHI. It is a vector magnetograph that also
  provides data for helioseismology. SO/PHI is composed of two telescopes,
  a full-disk telescope (FDT) and a high-resolution telescope (HRT). The
  HRT will observe at a resolution as high as 200 km on the solar
  surface, while the FDT will obtain the magnetic field and velocity of
  the full solar disc whenever it observes. SO/PHI will be the first
  solar spectro-polarimeter to leave the Sun-Earth line, opening up
  some unique perspectives, such as the first detailed view of the solar
  poles. This will allow not just a more precise and exact mapping of the
  polar magnetic field than possible so far, but will also enable us to
  follow the dynamics of individual magnetic features at high latitudes
  and to determine solar surface and sub-surface flows right up to the
  poles. In addition to its standard data products (vector magnetograms,
  continuum images and maps of the line-of-sight velocity), SO/PHI will
  also provide higher-level data products. These will include synoptic
  charts, local magnetic field extrapolations starting from HRT data and
  global magnetic field extrapolations (from FDT data) with potential
  field source-surface (PFSS) models and possibly also non-potential
  models such as NLFFF (non-linear force-free fields), magnetostatics
  and MHD. The SO/PHI data products will usefully complement the data
  taken by other instruments on Solar Orbiter and on Solar Probe, as
  well as instruments on the ground or in Earth orbit. Combining with
  observations by Earth-based and near-Earth telescopes will enable
  new types of investigations, such as stereoscopic polarimetry and
  stereoscopic helioseismology.

Title: On Fabry-Pérot Etalon-based Instruments. III. Instrument
    Applications
Authors: Bailén, F. J.; Orozco Suárez, D.; del Toro Iniesta, J. C.
Bibcode: 2020ApJS..246...17B
Altcode: 2020arXiv200200599B
  The spectral, imaging, and polarimetric behavior of Fabry-Pérot
  etalons have an influence on imaging vector magnetograph instruments
  based on these devices. The impact depends on the optical configuration
  (collimated or telecentric), on the relative position of the etalon
  with respect to the polarimeter, on the type of etalon (air-gapped
  or crystalline), and even on the polarimetric technique to be used
  (single-beam or dual-beam). In this paper, we evaluate the artificial
  line-of-sight velocities and magnetic field strengths that arise
  in etalon-based instruments, attending to the factors mentioned. We
  differentiate between signals that are implicit to telecentric mounts
  due to the wavelength dependence of the point-spread function and
  those emerging in both collimated and telecentric setups from the
  polarimetric response of birefringent etalons. For the anisotropic
  case, we consider two possible locations of the etalon—between the
  modulator and the analyzer or after it—and we include the effect on
  different channels when dual-beam polarimetry is employed. We also
  evaluate the impact of the loss of symmetry produced in telecentric
  mounts due to imperfections in the illumination and/or to a tilt of
  the etalon relative to the incident beam.

Title: The Polarimetric and Helioseismic Imager on Solar Orbiter
Authors: Mueller, D.; Solanki, S. K.; del Toro Iniesta, J. C.
Bibcode: 2019AGUFMSH21D3292M
Altcode:
  The Polarimetric and Helioseismic Imager on the Solar Orbiter mission
  (SO/PHI) is the first magnetograph and helioseismology instrument
  to observe the Sun from outside the Sun-Earth line. It is the key
  instrument meant to address the top-level science question: How does
  the solar dynamo work and drive connections between the Sun and the
  heliosphere? SO/PHI will also play an important role in answering the
  other top-level science questions of Solar Orbiter. It will provide
  valuable supporting observations for Parker Solar Probe. <P />The
  instrument carries out narrow-band imaging spectro-polarimetry using a
  tunable LiNbO3 Fabry-Perot etalon, while the polarisation modulation is
  done with liquid crystal variable retarders (LCVRs). The line and the
  nearby continuum are sampled at six wavelength points and the data are
  recorded by a 2k x 2k CMOS detector. To save valuable telemetry, the
  raw data are reduced already on board, including being inverted under
  the assumption of a Milne-Eddington atmosphere. SO/PHI is composed of
  two telescopes, the Full Disc Telescope (FDT), covers the full solar
  disc at all phases of the orbit, while the High Resolution Telescope
  (HRT), can resolve structures as small as 200 km on the Sun at closest
  perihelion. <P />The standard data products of SO/PHI are maps of the
  photospheric magnetic field vector, line-of-sight velocity and continuum
  intensity with a highest cadence of one minute. The operational modes
  of SO/PHI are kept highly flexible allowing to adjust to the actual
  science goal chosen for a Solar Orbiter operation window.

Title: Performance Analysis of the SO/PHI Software Framework for
    On-board Data Reduction
Authors: Albert, K.; Hirzberger, J.; Busse, D.; Rodríguez, J. Blanco;
   Castellanos Duran, J. S.; Cobos Carrascosa, J. P.; Fiethe, B.;
   Gandorfer, A.; Guan, Y.; Kolleck, M.; Lagg, A.; Lange, T.; Michalik,
   H.; Solanki, S. K.; del Toro Iniesta, J. C.
Bibcode: 2019ASPC..523..151A
Altcode: 2019arXiv190508690A
  The Polarimetric and Helioseismic Imager (PHI) is the first deep-space
  solar spectropolarimeter, on-board the Solar Orbiter (SO) space
  mission. It faces: stringent requirements on science data accuracy, a
  dynamic environment, and severe limitations on telemetry volume. SO/PHI
  overcomes these restrictions through on-board instrument calibration
  and science data reduction, using dedicated firmware in FPGAs. This
  contribution analyses the accuracy of a data processing pipeline by
  comparing the results obtained with SO/PHI hardware to a reference
  from a ground computer. The results show that for the analyzed pipeline
  the error introduced by the firmware implementation is well below the
  requirements of SO/PHI.

Title: On Fabry-Pérot Etalon-based Instruments. II. The Anisotropic
    (Birefringent) Case
Authors: Bailén, F. J.; Orozco Suárez, D.; del Toro Iniesta, J. C.
Bibcode: 2019ApJS..242...21B
Altcode: 2019arXiv190610361B
  Crystalline etalons present several advantages with respect to other
  types of filtergraphs when employed in magnetographs, especially that
  they can be tuned by only applying electric fields. However, anisotropic
  crystalline etalons can also introduce undesired birefringent effects
  that corrupt the polarization of the incoming light. In particular,
  uniaxial Fabry-Pérots, such as LiNbO<SUB>3</SUB> etalons, are
  birefringent when illuminated with an oblique beam. The farther the
  incidence from the normal, the larger the induced retardance between the
  two orthogonal polarization states. The application of high voltages,
  as well as fabrication defects, can also change the direction of
  the optical axis of the crystal, introducing birefringence even at
  normal illumination. Here we obtain analytical expressions for the
  induced retardance and for the Mueller matrix of uniaxial etalons
  located in both collimated and telecentric configurations. We also
  evaluate the polarimetric behavior of Z-cut crystalline etalons with
  the incident angle, with the orientation of the optical axis, and with
  the f-number of the incident beam for the telecentric case. We study
  artificial signals produced in the output Stokes vector in the two
  configurations. Last, we discuss the polarimetric dependence of the
  imaging response of the etalon for both collimated and telecentric
  setups.

Title: On the Magnetic Nature of Solar Exploding Granules
Authors: Guglielmino, S. L.; Martínez Pillet, V.; Ruiz Cobo,
   B.; Bellot Rubio, L. R.; del Toro Iniesta, J. C.; Solanki, S. K.;
   Zuccarello, F.
Bibcode: 2019ASPC..526..299G
Altcode:
  We report on spectropolarimetric observations acquired by the imaging
  magnetograph SUNRISE/IMaX at high spatial 0.''3 and temporal (31.5 s)
  resolution during the first science flight of this balloon-borne solar
  observatory. We describe the photospheric evolution of an exploding
  granule observed in the quiet Sun. This granule is cospatial with
  a magnetic flux emergence event occurring at mesogranular scales
  (up to ∼12 Mm<SUP>2</SUP> area). Using a modified version of the
  SIR code, we show that we can estimate the longitudinal field also
  in the presence of a residual cross-talk in these IMaX longitudinal
  measurements. We determine the magnetic flux content of the structure
  (∼3 ×10<SUP>18</SUP> Mx), which appears to have a multipolar
  configuration, and discuss the origin of such flux emergence events.

Title: On Fabry-Pérot Etalon-based Instruments. I. The Isotropic Case
Authors: Bailén, F. J.; Orozco Suárez, D.; del Toro Iniesta, J. C.
Bibcode: 2019ApJS..241....9B
Altcode: 2019arXiv190306403B
  Here we assess the spectral and imaging properties of Fabry-Pérot
  etalons when located in solar magnetographs. We discuss the chosen
  configuration (collimated or telecentric) for both ideal and real
  cases. For the real cases, we focus on the effects caused by the
  polychromatic illumination of the filter by the irregularities in
  the optical thickness of the etalon and by deviations from the ideal
  illumination in both setups. We first review the general properties of
  Fabry-Pérots and we then address the different sources of degradation
  of the spectral transmission profile. We review and extend the general
  treatment of defects followed by different authors. We discuss the
  differences between the point spread functions (PSFs) of the collimated
  and telecentric configurations for both monochromatic and (real)
  quasi-monochromatic illumination of the etalon. The PSF corresponding
  to collimated mounts is shown to have a better performance, although
  it varies from point to point due to an apodization of the image
  inherent to this configuration. This is in contrast to the (perfect)
  telecentric case, where the PSF remains constant but produces artificial
  velocities and magnetic field signals because of its strong spectral
  dependence. We find that the unavoidable presence of imperfections in
  the telecentrism produces a decrease of flux of photons and a shift,
  a broadening and a loss of symmetrization of both the spectral and PSF
  profiles over the field of view, thus compromising their advantages
  over the collimated configuration. We evaluate these effects for
  different apertures of the incident beam.

Title: SOPHISM: Software Instrument Simulator
Authors: Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco
   Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.;
   Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.
Bibcode: 2018ascl.soft10017B
Altcode:
  SOPHISM models astronomical instrumentation from the entrance
  of the telescope to data acquisition at the detector, along with
  software blocks dealing with, for example, demodulation, inversion,
  and compression. The code performs most analyses done with light
  in astronomy, such as differential photometry, spectroscopy, and
  polarimetry. The simulator offers flexibility and implementation of new
  effects and subsystems, making it user-adaptable for a wide variety
  of instruments. SOPHISM can be used for all stages of instrument
  definition, design, operation, and lifetime tracking evaluation.

Title: SOPHISM: An End-to-end Software Instrument Simulator
Authors: Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco
   Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.;
   Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.
Bibcode: 2018ApJS..237...35B
Altcode:
  We present a software simulator for the modeling of astronomical
  instrumentation, which includes platform effects and software
  processing. It is an end-to-end simulator, from the entrance of
  the telescope to the data acquisition at the detector, along with
  software blocks dealing, e.g., with demodulation, inversion, and
  compression. Developed following the Solar Orbiter/Polarimetric
  and Helioseismic Imager (SO/PHI) instrument, it comprises elements
  such as a filtergraph, polarimetric modulator, detector, vibrations,
  and accumulations. Through these, the simulator performs most of the
  analyses that can be done with light in astronomy, such as differential
  photometry, spectroscopy, and polarimetry. The simulator is coded
  with high flexibility and ease of implementation of new effects and
  subsystems. Thus, it allows for the user to adapt it to a wide variety
  of instruments, even not exclusively solar ones, as illustrated with
  an example of application to a night-time observation. The simulator
  can provide support in the phase of instrument design and help assess
  tolerances and test solutions to underperformances arising during the
  instrument operations. All this makes SOPHISM a very valuable tool
  for all the stages of astronomical instrument definition, design,
  operation, and lifetime tracking evaluation.

Title: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
    for the SUNRISE balloon-borne solar observatory
Authors: Suematsu, Yoshinori; Katsukawa, Yukio; Hara, Hirohisa;
   Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito; Barthol,
   Peter; Riethmueller, Tino; Gandorfer, Achim; Feller, Alex; Orozco
   Suárez, David; Del Toro Iniesta, Jose Carlos; Kano, Ryouhei; Ishikawa,
   Shin-nosuke; Ishikawa, Ryohko; Tsuzuki, Toshihiro; Uraguchi, Fumihiro;
   Quintero Noda, Carlos; Tamura, Tomonori; Oba, Takayoshi; Kawabata,
   Yusuke; Nagata, Shinichi; Anan, Tetsu; Cobos Carrascosa, Juan Pedro;
   Lopez Jimenez, Antonio Carlos; Balaguer Jimenez, Maria; Solanki, Sami
Bibcode: 2018cosp...42E3285S
Altcode:
  The SUNRISE balloon-borne solar observatory carries a 1 m aperture
  optical telescope, and allows us to perform seeing-free continuous
  observations at visible-IR wavelengths from an altitude higher than
  35 km. In the past two flights, in 2009 and 2013, observations mainly
  focused on fine structures of photospheric magnetic fields. For the
  third flight planned for 2021, we are developing a new instrument
  for conducting spectro-polarimetry of spectral lines formed over a
  larger height range in the solar atmosphere from the photosphere to
  the chromosphere. Targets of the spectro-polarimetric observation
  are (1) to determine 3D magnetic structure from the photosphere to
  the chromosphere, (2) to trace MHD waves from the photosphere to the
  chromosphere, and (3) to reveal the mechanism driving chromospheric
  jets, by measuring height- and time-dependent velocities and magnetic
  fields. To achieve these goals, a spectro-polarimeter called SCIP
  (Sunrise Chromospheric Infrared spectroPolarimeter) is designed to
  observe near-infrared spectrum lines sensitive to solar magnetic
  fields. The spatial and spectral resolutions are 0.2 arcsec and
  200,000, respectively, while 0.03% polarimetric sensitivity is
  achieved within a 10 sec integration time. The optical system employs
  an Echelle grating and off-axis aspheric mirrors to observe the two
  wavelength ranges centered at 850 nm and 770 nm simultaneously by
  two cameras. Polarimetric measurements are performed using a rotating
  waveplate and polarization beam-splitters in front of the cameras. For
  detecting minute polarization signals with good precision, we carefully
  assess the temperature dependence of polarization optics, and make
  the opto-structural design that minimizes the thermal deformation
  of the spectrograph optics. Another key technique is to attain good
  (better than 30 msec) synchronization among the rotating phase of
  the waveplate, read-out timing of cameras, and step timing of a
  slit-scanning mirror. On-board accumulation and data processing are
  also critical because we cannot store all the raw data read-out from the
  cameras. We demonstrate that we can reduce the data down to almost 10%
  with loss-less image compression and without sacrificing polarimetric
  information in the data. The SCIP instrument is developed by internal
  collaboration among Japanese institutes including Japan Aerospace
  Exploration Agency (JAXA), the Spanish Sunrise consortium, and the
  German Max Planck Institute for Solar System Research (MPS) with a
  leadership of the National Astronomical Observatory of Japan (NAOJ).

Title: The quick RTE inversion on FPGA for DKIST
Authors: Cobos Carrascosa, J. P.; Ramos Mas, J. L.; Aparicio del
   Moral, B.; Hernández Expósito, D.; Sánchez Gómez, A.; Balaguer,
   M.; López Jiménez, A. C.; Orozco Suárez, D.; del Toro Iniesta, J. C.
Bibcode: 2018SPIE10707E..0LC
Altcode:
  In this contribution we present a multi-core system-on-chip, embedded on
  FPGA, for real-time data processing, to be used in the Daniel K. Inouye
  Solar Telescope (DKIST). Our system will provide "quick-look" magnetic
  field vector and line-of-sight velocity maps to help solar physicists
  to react to specific solar events or features during observations or
  to address specific phenomena while analyzing the data off line. The
  stand-alone device will be installed at the National Solar Observatory
  (NSO) Data Center. It will be integrated in the processing data pipeline
  through a software interface, and is competitive in computing speed
  to complex computer clusters.

Title: Image compression on reconfigurable FPGA for the SO/PHI
    space instrument
Authors: Hernández Expósito, D.; Cobos Carrascosa, J. P.; Ramos
   Mas, J. L.; Rodríguez Valido, M.; Orozco Suárez, D.; Hirzberger,
   J.; Woch, J.; Solanki, S.; del Toro Iniesta, J. C.
Bibcode: 2018SPIE10707E..2FH
Altcode:
  In this paper we present a novel FPGA implementation of the Consultative
  Committee for Space Data Systems Image Data Compression (CCSDS-IDC
  122.0-B-1) for performing image compression aboard the Polarimetric
  Helioseismic Imager instrument of the ESA's Solar Orbiter mission. This
  is a System-On-Chip solution based on a light multicore architecture
  combined with an efficient ad-hoc Bit Plane Encoder core. This hardware
  architecture performs an acceleration of 30 times with respect to a
  software implementation running into space-qualified processors, like
  LEON3. The system stands out over other FPGA implementations because
  of the low resource usage, which does not use any external memory,
  and of its configurability.

Title: Getting Ready for the Third Science Flight of SUNRISE
Authors: Barthol, Peter; Katsukawa, Yukio; Lagg, Andreas; Solanki,
   Sami K.; Kubo, Masahito; Riethmueller, Tino; Martínez Pillet,
   Valentin; Gandorfer, Achim; Feller, Alex; Berkefeld, . Thomas; Orozco
   Suárez, David; Del Toro Iniesta, Jose Carlos; Bernasconi, Pietro;
   Álvarez-Herrero, Alberto; Quintero Noda, Carlos
Bibcode: 2018cosp...42E.215B
Altcode:
  SUNRISE is a balloon-borne, stratospheric solar observatory dedicated
  to the investigation of the structure and dynamics of the Sun's
  magnetic field and its interaction with convective plasma flows and
  waves. The previous science flights of SUNRISE in 2009 and 2013 have
  led to many new scientific results, so far described in around 90
  refereed publications. This success has shown the huge potential of the
  SUNRISE concept and the recovery of the largely intact payload offers
  the opportunity for a third flight.The scientific instrumentation of
  SUNRISE 3 will have extended capabilities in particular to measure
  magnetic fields, plasma velocities and temperatures with increased
  sensitivity and over a larger height range in the solar atmosphere, from
  the convectively dominated photosphere up to the still poorly understood
  chromosphere. The latter is the key interaction region between magnetic
  field, waves and radiation and plays a central role in transporting
  energy to the outer layers of the solar atmosphere including the
  corona.SUNRISE 3 will carry 2 new grating-based spectro-polarimeters
  with slit-scanning and context imaging with slitjaw cameras. The
  SUNRISE UV Spectro-polarimeter and Imager (SUSI) will explore the rich
  near-UV range between 300 nm and 430 nm which is poorly accessible
  from the ground. The SUNRISE Chromospheric Infrared spectro-Polarimeter
  (SCIP) will sample 2 spectral windows in the near-infrared, containing
  many spectral lines highly sensitive to magnetic fields at different
  formation heights. In addition to the two new instruments the Imaging
  Magnetograph eXperiment (IMaX), an etalon-based tunable filtergraph and
  spectro-polarimeter flown on both previous missions, will be upgraded
  to IMaX+, enhancing its cadence and giving access to 2 spectral lines
  in the visible spectral range. All three instruments will allow
  investigating both the photosphere and the chromosphere and will
  ideally complement each other in terms of sensitivity, height coverage
  and resolution.A new gondola with a sophisticated attitude control
  system including roll damping will provide improved pointing/tracking
  performance. Upgraded image stabilization with higher bandwidth will
  further reduce residual jitter, maximizing the quality of the science
  data.SUNRISE 3 is a joint project of the German Max-Planck-Institut für
  Sonnensystemforschung together with the Spanish SUNRISE consortium, the
  Johns Hopkins University Applied Physics Laboratory, USA, the German
  Kiepenheuer Institut für Sonnenphysik, the National Astronomical
  Observatory of Japan and the Japan Aerospace eXploraion Agency (JAXA).

Title: Autonomous on-board data processing and instrument calibration
    software for the SO/PHI
Authors: Albert, K.; Hirzberger, J.; Busse, D.; Lange, T.; Kolleck, M.;
   Fiethe, B.; Orozco Suárez, D.; Woch, J.; Schou, J.; Blanco Rodriguez,
   J.; Gandorfer, A.; Guan, Y.; Cobos Carrascosa, J. P.; Hernández
   Expósito, D.; del Toro Iniesta, J. C.; Solanki, S. K.; Michalik, H.
Bibcode: 2018SPIE10707E..0OA
Altcode: 2018arXiv181003493A
  The extension of on-board data processing capabilities is an
  attractive option to reduce telemetry for scientific instruments
  on deep space missions. The challenges that this presents, however,
  require a comprehensive software system, which operates on the limited
  resources a data processing unit in space allows. We implemented such
  a system for the Polarimetric and Helioseismic Imager (PHI) on-board
  the Solar Orbiter (SO) spacecraft. It ensures autonomous operation
  to handle long command-response times, easy changing of the processes
  after new lessons have been learned and meticulous book-keeping of all
  operations to ensure scientific accuracy. This contribution presents
  the requirements and main aspects of the software implementation,
  followed by an example of a task implemented in the software frame,
  and results from running it on SO/PHI. The presented example shows
  that the different parts of the software framework work well together,
  and that the system processes data as we expect. The flexibility of
  the framework makes it possible to use it as a baseline for future
  applications with similar needs and limitations as SO/PHI.

Title: The High Resolution Telescope (HRT) of the Polarimetric and
    Helioseismic Imager (PHI) onboard Solar Orbiter
Authors: Gandorfer, A.; Grauf, B.; Staub, J.; Bischoff, J.; Woch, J.;
   Hirzberger, J.; Solanki, S. K.; Álvarez-Herrero, A.; García Parejo,
   P.; Schmidt, W.; Volkmer, R.; Appourchaux, T.; del Toro Iniesta, J. C.
Bibcode: 2018SPIE10698E..4NG
Altcode:
  Solar Orbiter is a joint mission of ESA and NASA scheduled for
  launch in 2020. Solar Orbiter is a complete and unique heliophysics
  mission, combining remote sensing and in-situ analysis; its special
  elliptical orbit allows viewing the Sun from a distance of only 0.28
  AU, and - leaving the ecliptic plane - to observe the solar poles from
  a hitherto unexplored vantage point. One of the key instruments for
  Solar Orbiter's science is the "Polarimetric and Helioseismic Imager"
  (PHI), which will provide maps of the solar surface magnetic fields and
  the gas flows on the visible solar surface. Two telescopes, a full disc
  imager, and a high resolution channel feed a common Fabry-Perot based
  tunable filter and thus allow sampling a single Fraunhofer line at 617.3
  nm with high spectral resolution; a polarization modulation system
  makes the system sensitive to the full state of polarization. From
  the analysis of the Doppler shift and the magnetically induced Zeeman
  polarization in this line, the magnetic field and the line-of-sight
  gas motions can be detected for each point in the image. In this
  paper we describe the opto-mechanical system design of the high
  resolution telescope. It is based on a decentred Ritchey-Chrétien
  two-mirror telescope. The telescope includes a Barlow type magnifier
  lens group, which is used as in-orbit focus compensator, and a beam
  splitter, which sends a small fraction of the collected light onto
  a fast camera, which provides the error signals for the actively
  controlled secondary mirror compensating for spacecraft jitter and other
  disturbances. The elliptical orbit of the spacecraft poses high demands
  on the thermo-mechanical stability. The varying size of the solar disk
  image requires a special false-light suppression architecture, which is
  briefly described. In combination with a heat-rejecting entrance window,
  the optical energy impinging on the polarimetric and spectral analysis
  system is efficiently reduced. We show how the design can preserve the
  diffraction-limited imaging performance over the design temperature
  range of -20°C to +60°C. The decentred hyperbolical mirrors require
  special measures for the inter-alignment and their alignment with
  respect to the mechanical structure. A system of alignment flats and
  mechanical references is used for this purpose. We will describe the
  steps of the alignment procedure, and the dedicated optical ground
  support equipment, which are needed to reach the diffraction limited
  performance of the telescope. We will also report on the verification
  of the telescope performance, both - in ambient condition - and in
  vacuum at different temperatures.

Title: The Maximum Entropy Limit of Small-scale Magnetic Field
    Fluctuations in the Quiet Sun
Authors: Gorobets, A. Y.; Berdyugina, S. V.; Riethmüller, T. L.;
   Blanco Rodríguez, J.; Solanki, S. K.; Barthol, P.; Gandorfer, A.;
   Gizon, L.; Hirzberger, J.; van Noort, M.; Del Toro Iniesta, J. C.;
   Orozco Suárez, D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..233....5G
Altcode: 2017arXiv171008361G
  The observed magnetic field on the solar surface is characterized by a
  very complex spatial and temporal behavior. Although feature-tracking
  algorithms have allowed us to deepen our understanding of this behavior,
  subjectivity plays an important role in the identification and tracking
  of such features. In this paper, we continue studies of the temporal
  stochasticity of the magnetic field on the solar surface without relying
  either on the concept of magnetic features or on subjective assumptions
  about their identification and interaction. We propose a data analysis
  method to quantify fluctuations of the line-of-sight magnetic field by
  means of reducing the temporal field’s evolution to the regular Markov
  process. We build a representative model of fluctuations converging to
  the unique stationary (equilibrium) distribution in the long time limit
  with maximum entropy. We obtained different rates of convergence to the
  equilibrium at fixed noise cutoff for two sets of data. This indicates
  a strong influence of the data spatial resolution and mixing-polarity
  fluctuations on the relaxation process. The analysis is applied to
  observations of magnetic fields of the relatively quiet areas around an
  active region carried out during the second flight of the Sunrise/IMaX
  and quiet Sun areas at the disk center from the Helioseismic and
  Magnetic Imager on board the Solar Dynamics Observatory satellite.

Title: Erratum: Morphological Properties of
    Slender CaII H Fibrils Observed by sunrise II (<A
href="http://doi.org/10.3847/1538-4365/229/1/6">ApJS 229, 1, 6</A>)
Authors: Gafeira, R.; Lagg, A.; Solanki, S. K.; Jafarzadeh, S.;
   van Noort, M.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta,
   J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco
   Suárez, D.; Riethmüller, T. L.; Schmidt, W.
Bibcode: 2017ApJS..230...11G
Altcode:
  No abstract at ADS

Title: Slender Ca II H Fibrils Mapping Magnetic Fields in the Low
    Solar Chromosphere
Authors: Jafarzadeh, S.; Rutten, R. J.; Solanki, S. K.; Wiegelmann, T.;
   Riethmüller, T. L.; van Noort, M.; Szydlarski, M.; Blanco Rodríguez,
   J.; Barthol, P.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L.;
   Hirzberger, J.; Knölker, M.; Martínez Pillet, V.; Orozco Suárez,
   D.; Schmidt, W.
Bibcode: 2017ApJS..229...11J
Altcode: 2016arXiv161003104J
  A dense forest of slender bright fibrils near a small solar active
  region is seen in high-quality narrowband Ca II H images from the SuFI
  instrument onboard the Sunrise balloon-borne solar observatory. The
  orientation of these slender Ca II H fibrils (SCF) overlaps with the
  magnetic field configuration in the low solar chromosphere derived
  by magnetostatic extrapolation of the photospheric field observed
  with Sunrise/IMaX and SDO/HMI. In addition, many observed SCFs are
  qualitatively aligned with small-scale loops computed from a novel
  inversion approach based on best-fit numerical MHD simulation. Such
  loops are organized in canopy-like arches over quiet areas that differ
  in height depending on the field strength near their roots.

Title: Magneto-static Modeling from Sunrise/IMaX: Application to an
    Active Region Observed with Sunrise II
Authors: Wiegelmann, T.; Neukirch, T.; Nickeler, D. H.; Solanki, S. K.;
   Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Riethmüller,
   T. L.; van Noort, M.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.;
   Orozco Suárez, D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229...18W
Altcode: 2017arXiv170101458N; 2017arXiv170101458W
  Magneto-static models may overcome some of the issues facing force-free
  magnetic field extrapolations. So far they have seen limited use
  and have faced problems when applied to quiet-Sun data. Here we
  present a first application to an active region. We use solar vector
  magnetic field measurements gathered by the IMaX polarimeter during
  the flight of the Sunrise balloon-borne solar observatory in 2013
  June as boundary conditions for a magneto-static model of the higher
  solar atmosphere above an active region. The IMaX data are embedded
  in active region vector magnetograms observed with SDO/HMI. This work
  continues our magneto-static extrapolation approach, which was applied
  earlier to a quiet-Sun region observed with Sunrise I. In an active
  region the signal-to-noise-ratio in the measured Stokes parameters
  is considerably higher than in the quiet-Sun and consequently the
  IMaX measurements of the horizontal photospheric magnetic field allow
  us to specify the free parameters of the model in a special class of
  linear magneto-static equilibria. The high spatial resolution of IMaX
  (110-130 km, pixel size 40 km) enables us to model the non-force-free
  layer between the photosphere and the mid-chromosphere vertically
  by about 50 grid points. In our approach we can incorporate some
  aspects of the mixed beta layer of photosphere and chromosphere, e.g.,
  taking a finite Lorentz force into account, which was not possible with
  lower-resolution photospheric measurements in the past. The linear model
  does not, however, permit us to model intrinsic nonlinear structures
  like strongly localized electric currents.

Title: The Second Flight of the Sunrise Balloon-borne Solar
Observatory: Overview of Instrument Updates, the Flight, the Data,
    and First Results
Authors: Solanki, S. K.; Riethmüller, T. L.; Barthol, P.; Danilovic,
   S.; Deutsch, W.; Doerr, H. -P.; Feller, A.; Gandorfer, A.; Germerott,
   D.; Gizon, L.; Grauf, B.; Heerlein, K.; Hirzberger, J.; Kolleck, M.;
   Lagg, A.; Meller, R.; Tomasch, G.; van Noort, M.; Blanco Rodríguez,
   J.; Gasent Blesa, J. L.; Balaguer Jiménez, M.; Del Toro Iniesta,
   J. C.; López Jiménez, A. C.; Orozco Suarez, D.; Berkefeld, T.;
   Halbgewachs, C.; Schmidt, W.; Álvarez-Herrero, A.; Sabau-Graziati,
   L.; Pérez Grande, I.; Martínez Pillet, V.; Card, G.; Centeno, R.;
   Knölker, M.; Lecinski, A.
Bibcode: 2017ApJS..229....2S
Altcode: 2017arXiv170101555S
  The Sunrise balloon-borne solar observatory, consisting of a 1 m
  aperture telescope that provides a stabilized image to a UV filter
  imager and an imaging vector polarimeter, carried out its second science
  flight in 2013 June. It provided observations of parts of active regions
  at high spatial resolution, including the first high-resolution images
  in the Mg II k line. The obtained data are of very high quality, with
  the best UV images reaching the diffraction limit of the telescope
  at 3000 Å after Multi-Frame Blind Deconvolution reconstruction
  accounting for phase-diversity information. Here a brief update is
  given of the instruments and the data reduction techniques, which
  includes an inversion of the polarimetric data. Mainly those aspects
  that evolved compared with the first flight are described. A tabular
  overview of the observations is given. In addition, an example time
  series of a part of the emerging active region NOAA AR 11768 observed
  relatively close to disk center is described and discussed in some
  detail. The observations cover the pores in the trailing polarity of
  the active region, as well as the polarity inversion line where flux
  emergence was ongoing and a small flare-like brightening occurred in
  the course of the time series. The pores are found to contain magnetic
  field strengths ranging up to 2500 G, and while large pores are clearly
  darker and cooler than the quiet Sun in all layers of the photosphere,
  the temperature and brightness of small pores approach or even exceed
  those of the quiet Sun in the upper photosphere.

Title: A Tale of Two Emergences: Sunrise II Observations of Emergence
    Sites in a Solar Active Region
Authors: Centeno, R.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.;
   Solanki, S. K.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger,
   J.; Riethmüller, T. L.; van Noort, M.; Orozco Suárez, D.; Berkefeld,
   T.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229....3C
Altcode: 2016arXiv161003531C
  In 2013 June, the two scientific instruments on board the second Sunrise
  mission witnessed, in detail, a small-scale magnetic flux emergence
  event as part of the birth of an active region. The Imaging Magnetograph
  Experiment (IMaX) recorded two small (∼ 5<SUP>\prime\prime</SUP> )
  emerging flux patches in the polarized filtergrams of a photospheric Fe
  I spectral line. Meanwhile, the Sunrise Filter Imager (SuFI) captured
  the highly dynamic chromospheric response to the magnetic fields pushing
  their way through the lower solar atmosphere. The serendipitous capture
  of this event offers a closer look at the inner workings of active
  region emergence sites. In particular, it reveals in meticulous detail
  how the rising magnetic fields interact with the granulation as they
  push through the Sun’s surface, dragging photospheric plasma in
  their upward travel. The plasma that is burdening the rising field
  slides along the field lines, creating fast downflowing channels at
  the footpoints. The weight of this material anchors this field to the
  surface at semi-regular spatial intervals, shaping it in an undulatory
  fashion. Finally, magnetic reconnection enables the field to release
  itself from its photospheric anchors, allowing it to continue its
  voyage up to higher layers. This process releases energy that lights
  up the arch-filament systems and heats the surrounding chromosphere.

Title: Photospheric Response to an Ellerman Bomb-like Event—An
    Analogy of Sunrise/IMaX Observations and MHD Simulations
Authors: Danilovic, S.; Solanki, S. K.; Barthol, P.; Gandorfer,
   A.; Gizon, L.; Hirzberger, J.; Riethmüller, T. L.; van Noort, M.;
   Blanco Rodríguez, J.; Del Toro Iniesta, J. C.; Orozco Suárez, D.;
   Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229....5D
Altcode: 2016arXiv160903817D
  Ellerman Bombs are signatures of magnetic reconnection, which is an
  important physical process in the solar atmosphere. How and where they
  occur is a subject of debate. In this paper, we analyze Sunrise/IMaX
  data, along with 3D MHD simulations that aim to reproduce the exact
  scenario proposed for the formation of these features. Although
  the observed event seems to be more dynamic and violent than the
  simulated one, simulations clearly confirm the basic scenario for the
  production of EBs. The simulations also reveal the full complexity of
  the underlying process. The simulated observations show that the Fe I
  525.02 nm line gives no information on the height where reconnection
  takes place. It can only give clues about the heating in the aftermath
  of the reconnection. However, the information on the magnetic field
  vector and velocity at this spatial resolution is extremely valuable
  because it shows what numerical models miss and how they can be
  improved.

Title: Transverse Oscillations in Slender Ca II H Fibrils Observed
    with Sunrise/SuFI
Authors: Jafarzadeh, S.; Solanki, S. K.; Gafeira, R.; van Noort, M.;
   Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Gandorfer,
   A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco Suárez, D.;
   Riethmüller, T. L.; Schmidt, W.
Bibcode: 2017ApJS..229....9J
Altcode: 2016arXiv161007449J
  We present observations of transverse oscillations in slender Ca II
  H fibrils (SCFs) in the lower solar chromosphere. We use a 1 hr long
  time series of high- (spatial and temporal-) resolution seeing-free
  observations in a 1.1 Å wide passband covering the line core of Ca
  II H 3969 Å from the second flight of the Sunrise balloon-borne solar
  observatory. The entire field of view, spanning the polarity inversion
  line of an active region close to the solar disk center, is covered with
  bright, thin, and very dynamic fine structures. Our analysis reveals
  the prevalence of transverse waves in SCFs with median amplitudes and
  periods on the order of 2.4 ± 0.8 km s<SUP>-1</SUP> and 83 ± 29 s,
  respectively (with standard deviations given as uncertainties). We
  find that the transverse waves often propagate along (parts of) the
  SCFs with median phase speeds of 9 ± 14 km s<SUP>-1</SUP>. While the
  propagation is only in one direction along the axis in some of the
  SCFs, propagating waves in both directions, as well as standing waves
  are also observed. The transverse oscillations are likely Alfvénic
  and are thought to be representative of magnetohydrodynamic kink
  waves. The wave propagation suggests that the rapid high-frequency
  transverse waves, often produced in the lower photosphere, can
  penetrate into the chromosphere with an estimated energy flux of ≈15
  kW m<SUP>-2</SUP>. Characteristics of these waves differ from those
  reported for other fibrillar structures, which, however, were observed
  mainly in the upper solar chromosphere.

Title: Kinematics of Magnetic Bright Features in the Solar Photosphere
Authors: Jafarzadeh, S.; Solanki, S. K.; Cameron, R. H.; Barthol, P.;
   Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon,
   L.; Hirzberger, J.; Knölker, M.; Martínez Pillet, V.; Orozco Suárez,
   D.; Riethmüller, T. L.; Schmidt, W.; van Noort, M.
Bibcode: 2017ApJS..229....8J
Altcode: 2016arXiv161007634J
  Convective flows are known as the prime means of transporting magnetic
  fields on the solar surface. Thus, small magnetic structures are good
  tracers of turbulent flows. We study the migration and dispersal
  of magnetic bright features (MBFs) in intergranular areas observed
  at high spatial resolution with Sunrise/IMaX. We describe the flux
  dispersal of individual MBFs as a diffusion process whose parameters are
  computed for various areas in the quiet-Sun and the vicinity of active
  regions from seeing-free data. We find that magnetic concentrations
  are best described as random walkers close to network areas (diffusion
  index, γ =1.0), travelers with constant speeds over a supergranule
  (γ =1.9{--}2.0), and decelerating movers in the vicinity of flux
  emergence and/or within active regions (γ =1.4{--}1.5). The three
  types of regions host MBFs with mean diffusion coefficients of 130
  km<SUP>2</SUP> s<SUP>-1</SUP>, 80-90 km<SUP>2</SUP> s<SUP>-1</SUP>,
  and 25-70 km<SUP>2</SUP> s<SUP>-1</SUP>, respectively. The MBFs in
  these three types of regions are found to display a distinct kinematic
  behavior at a confidence level in excess of 95%.

Title: Spectropolarimetric Evidence for a Siphon Flow along an
    Emerging Magnetic Flux Tube
Authors: Requerey, Iker S.; Ruiz Cobo, B.; Del Toro Iniesta, J. C.;
   Orozco Suárez, D.; Blanco Rodríguez, J.; Solanki, S. K.; Barthol,
   P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Riethmüller, T. L.;
   van Noort, M.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229...15R
Altcode: 2016arXiv161106732R
  We study the dynamics and topology of an emerging magnetic flux
  concentration using high spatial resolution spectropolarimetric data
  acquired with the Imaging Magnetograph eXperiment on board the sunrise
  balloon-borne solar observatory. We obtain the full vector magnetic
  field and the line of sight (LOS) velocity through inversions of
  the Fe I line at 525.02 nm with the SPINOR code. The derived vector
  magnetic field is used to trace magnetic field lines. Two magnetic flux
  concentrations with different polarities and LOS velocities are found
  to be connected by a group of arch-shaped magnetic field lines. The
  positive polarity footpoint is weaker (1100 G) and displays an upflow,
  while the negative polarity footpoint is stronger (2200 G) and shows
  a downflow. This configuration is naturally interpreted as a siphon
  flow along an arched magnetic flux tube.

Title: Morphological Properties of Slender Ca II H Fibrils Observed
    by SUNRISE II
Authors: Gafeira, R.; Lagg, A.; Solanki, S. K.; Jafarzadeh, S.;
   van Noort, M.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta,
   J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco
   Suárez, D.; Riethmüller, T. L.; Schmidt, W.
Bibcode: 2017ApJS..229....6G
Altcode: 2016arXiv161200319G
  We use seeing-free high spatial resolution Ca II H data obtained by
  the SUNRISE observatory to determine properties of slender fibrils
  in the lower solar chromosphere. In this work we use intensity images
  taken with the SuFI instrument in the Ca II H line during the second
  scientific flight of the SUNRISE observatory to identify and track
  elongated bright structures. After identification, we analyze theses
  structures to extract their morphological properties. We identify
  598 slender Ca II H fibrils (SCFs) with an average width of around
  180 km, length between 500 and 4000 km, average lifetime of ≈400
  s, and average curvature of 0.002 arcsec<SUP>-1</SUP>. The maximum
  lifetime of the SCFs within our time series of 57 minutes is ≈2000
  s. We discuss similarities and differences of the SCFs with other
  small-scale, chromospheric structures such as spicules of type I and
  II, or Ca II K fibrils.

Title: A New MHD-assisted Stokes Inversion Technique
Authors: Riethmüller, T. L.; Solanki, S. K.; Barthol, P.; Gandorfer,
   A.; Gizon, L.; Hirzberger, J.; van Noort, M.; Blanco Rodríguez, J.;
   Del Toro Iniesta, J. C.; Orozco Suárez, D.; Schmidt, W.; Martínez
   Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229...16R
Altcode: 2016arXiv161105175R
  We present a new method of Stokes inversion of spectropolarimetric
  data and evaluate it by taking the example of a Sunrise/IMaX
  observation. An archive of synthetic Stokes profiles is obtained
  by the spectral synthesis of state-of-the-art magnetohydrodynamics
  (MHD) simulations and a realistic degradation to the level of the
  observed data. The definition of a merit function allows the archive
  to be searched for the synthetic Stokes profiles that best match the
  observed profiles. In contrast to traditional Stokes inversion codes,
  which solve the Unno-Rachkovsky equations for the polarized radiative
  transfer numerically and fit the Stokes profiles iteratively, the new
  technique provides the full set of atmospheric parameters. This gives
  us the ability to start an MHD simulation that takes the inversion
  result as an initial condition. After a relaxation process of half an
  hour solar time we obtain physically consistent MHD data sets with
  a target similar to the observation. The new MHD simulation is used
  to repeat the method in a second iteration, which further improves
  the match between observation and simulation, resulting in a factor
  of 2.2 lower mean {χ }<SUP>2</SUP> value. One advantage of the new
  technique is that it provides the physical parameters on a geometrical
  height scale. It constitutes a first step toward inversions that give
  results consistent with the MHD equations.

Title: Oscillations on Width and Intensity of Slender Ca II H Fibrils
    from Sunrise/SuFI
Authors: Gafeira, R.; Jafarzadeh, S.; Solanki, S. K.; Lagg, A.;
   van Noort, M.; Barthol, P.; Blanco Rodríguez, J.; del Toro Iniesta,
   J. C.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; Knölker, M.; Orozco
   Suárez, D.; Riethmüller, T. L.; Schmidt, W.
Bibcode: 2017ApJS..229....7G
Altcode: 2017arXiv170102801G
  We report the detection of oscillations in slender Ca II H fibrils
  (SCFs) from high-resolution observations acquired with the Sunrise
  balloon-borne solar observatory. The SCFs show obvious oscillations in
  their intensity, but also their width. The oscillatory behaviors are
  investigated at several positions along the axes of the SCFs. A large
  majority of fibrils show signs of oscillations in intensity. Their
  periods and phase speeds are analyzed using a wavelet analysis. The
  width and intensity perturbations have overlapping distributions
  of the wave period. The obtained distributions have median values
  of the period of 32 ± 17 s and 36 ± 25 s, respectively. We
  find that the fluctuations of both parameters propagate in
  the SCFs with speeds of {11}<SUB>-11</SUB><SUP>+49</SUP> km
  s<SUP>-1</SUP> and {15}<SUB>-15</SUB><SUP>+34</SUP> km s<SUP>-1</SUP>,
  respectively. Furthermore, the width and intensity oscillations have a
  strong tendency to be either in anti-phase or, to a smaller extent, in
  phase. This suggests that the oscillations of both parameters are caused
  by the same wave mode and that the waves are likely propagating. Taking
  all the evidence together, the most likely wave mode to explain all
  measurements and criteria is the fast sausage mode.

Title: Solar Coronal Loops Associated with Small-scale Mixed Polarity
    Surface Magnetic Fields
Authors: Chitta, L. P.; Peter, H.; Solanki, S. K.; Barthol, P.;
   Gandorfer, A.; Gizon, L.; Hirzberger, J.; Riethmüller, T. L.; van
   Noort, M.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.; Orozco
   Suárez, D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229....4C
Altcode: 2016arXiv161007484C
  How and where are coronal loops rooted in the solar lower
  atmosphere? The details of the magnetic environment and its evolution
  at the footpoints of coronal loops are crucial to understanding the
  processes of mass and energy supply to the solar corona. To address
  the above question, we use high-resolution line-of-sight magnetic
  field data from the Imaging Magnetograph eXperiment instrument on the
  Sunrise balloon-borne observatory and coronal observations from the
  Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory
  of an emerging active region. We find that the coronal loops are
  often rooted at the locations with minor small-scale but persistent
  opposite-polarity magnetic elements very close to the larger dominant
  polarity. These opposite-polarity small-scale elements continually
  interact with the dominant polarity underlying the coronal loop through
  flux cancellation. At these locations we detect small inverse Y-shaped
  jets in chromospheric Ca II H images obtained from the Sunrise Filter
  Imager during the flux cancellation. Our results indicate that magnetic
  flux cancellation and reconnection at the base of coronal loops due
  to mixed polarity fields might be a crucial feature for the supply of
  mass and energy into the corona.

Title: Moving Magnetic Features around a Pore
Authors: Kaithakkal, A. J.; Riethmüller, T. L.; Solanki, S. K.; Lagg,
   A.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; vanNoort,
   M.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.; Orozco Suárez,
   D.; Schmidt, W.; Martínez Pillet, V.; Knölker, M.
Bibcode: 2017ApJS..229...13K
Altcode: 2016arXiv160905664K
  Spectropolarimetric observations from Sunrise/IMaX, obtained in 2013
  June, are used for a statistical analysis to determine the physical
  properties of moving magnetic features (MMFs) observed near a pore. MMFs
  of the same and opposite polarity, with respect to the pore, are found
  to stream from its border at an average speed of 1.3 km s<SUP>-1</SUP>
  and 1.2 km s<SUP>-1</SUP>, respectively, with mainly same-polarity MMFs
  found further away from the pore. MMFs of both polarities are found to
  harbor rather weak, inclined magnetic fields. Opposite-polarity MMFs
  are blueshifted, whereas same-polarity MMFs do not show any preference
  for up- or downflows. Most of the MMFs are found to be of sub-arcsecond
  size and carry a mean flux of ∼1.2 × 10<SUP>17</SUP> Mx.

Title: Convectively Driven Sinks and Magnetic Fields in the Quiet-Sun
Authors: Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot
   Rubio, Luis R.; Martínez Pillet, Valentín; Solanki, Sami K.;
   Schmidt, Wolfgang
Bibcode: 2017ApJS..229...14R
Altcode: 2016arXiv161007622R
  We study the relation between mesogranular flows, convectively
  driven sinks and magnetic fields using high spatial resolution
  spectropolarimetric data acquired with the Imaging Magnetograph
  eXperiment on board Sunrise. We obtain the horizontal velocity
  flow fields of two quiet-Sun regions (31.2 × 31.2 Mm<SUP>2</SUP>)
  via local correlation tracking. Mesogranular lanes and the central
  position of sinks are identified using Lagrange tracers. We find
  6.7× {10}<SUP>-2</SUP> sinks per Mm<SUP>2</SUP> in the two observed
  regions. The sinks are located at the mesogranular vertices and turn
  out to be associated with (1) horizontal velocity flows converging to a
  central point and (2) long-lived downdrafts. The spatial distribution
  of magnetic fields in the quiet-Sun is also examined. The strongest
  magnetic fields are preferentially located at sinks. We find that 40% of
  the pixels with longitudinal components of the magnetic field stronger
  than 500 G are located in the close neighborhood of sinks. In contrast,
  the small-scale magnetic loops detected by Martínez González et al. in
  the same two observed areas do not show any preferential distribution
  at mesogranular scales. The study of individual examples reveals
  that sinks can play an important role in the evolution of quiet-Sun
  magnetic features.

Title: Far side Helioseismology with Solar Orbiter
Authors: Appourchaux, T.; Birch, A.; Gizon, L. C.; Löptien, B.;
   Schou, J.; Solanki, S. K.; del Toro Iniesta, J. C.; Gandorfer, A.;
   Hirzberger, J.; Alvarez-Herrero, A.; Woch, J. G.; Schmidt, W.
Bibcode: 2016AGUFMSH43A2554A
Altcode:
  The Solar Orbiter mission, to be launched in October 2018, will
  carry a suite of remote sensing and in-situ instruments, including
  the Polarimetric and Helioseismic Imager (PHI). PHI will deliver
  high-cadence images of the Sun in intensity and Doppler velocity
  suitable for carrying out novel helioseismic studies. The orbit
  of the Solar Orbiter spacecraft will reach a solar latitude up to
  34 degrees by the end of the extended mission and thus will enable
  the first local helioseismology studies of the polar regions. The
  full range of Earth-Sun-spacecraft angles provided by the orbit will
  enable helioseismology from two vantage points by combining PHI with
  another instrument: stereoscopic helioseismology will allow the study
  of the deep solar interior and a better understanding of the physics
  of solar oscillations in both quiet Sun and sunspots. In this paper
  we will review the helioseismic objectives achievable with PHI, and
  will also give a short status report of the development of the Flight
  Model of PHI.

Title: Inversion of the radiative transfer equation for polarized
    light
Authors: del Toro Iniesta, Jose Carlos; Ruiz Cobo, Basilio
Bibcode: 2016LRSP...13....4D
Altcode: 2016arXiv161010039D
  Since the early 1970s, inversion techniques have become the most
  useful tool for inferring the magnetic, dynamic, and thermodynamic
  properties of the solar atmosphere. Inversions have been proposed
  in the literature with a sequential increase in model complexity:
  astrophysical inferences depend not only on measurements but also on
  the physics assumed to prevail both on the formation of the spectral
  line Stokes profiles and on their detection with the instrument. Such
  an intrinsic model dependence makes it necessary to formulate specific
  means that include the physics in a properly quantitative way. The core
  of this physics lies in the radiative transfer equation (RTE), where the
  properties of the atmosphere are assumed to be known while the unknowns
  are the four Stokes profiles. The solution of the (differential)
  RTE is known as the direct or forward problem. From an observational
  point of view, the problem is rather the opposite: the data are made
  up of the observed Stokes profiles and the unknowns are the solar
  physical quantities. Inverting the RTE is therefore mandatory. Indeed,
  the formal solution of this equation can be considered an integral
  equation. The solution of such an integral equation is called the
  inverse problem. Inversion techniques are automated codes aimed at
  solving the inverse problem. The foundations of inversion techniques
  are critically revisited with an emphasis on making explicit the many
  assumptions underlying each of them.

Title: The RTE inversion on FPGA aboard the solar orbiter PHI
    instrument
Authors: Cobos Carrascosa, J. P.; Aparicio del Moral, B.; Ramos Mas,
   J. L.; Balaguer, M.; López Jiménez, A. C.; del Toro Iniesta, J. C.
Bibcode: 2016SPIE.9913E..42C
Altcode:
  In this work we propose a multiprocessor architecture to reach high
  performance in floating point operations by using radiation tolerant
  FPGA devices, and under narrow time and power constraints. This
  architecture is used in the PHI instrument that carries out the
  scientific analysis aboard the ESA's Solar Orbiter mission. The
  proposed architecture, in a SIMD flavor, is aimed to be an accelerator
  within the Data Processing Unit (it is composed by a main Leon
  processor and two FPGAs) for carrying out the RTE inversion on
  board the spacecraft using a relatively slow FPGA device - Xilinx
  XQR4VSX55-. The proposed architecture squeezes the FPGA resources
  in order to reach the computational requirements and improves the
  ground-based system performance based on commercial CPUs regarding time
  and power consumption. In this work we demonstrate the feasibility of
  using this FPGA devices embedded in the SO/PHI instrument. With that
  goal in mind, we perform tests to evaluate the scientific results and
  to measure the processing time and power consumption for carrying out
  the RTE inversion.

Title: Flux appearance and disappearance rates in the solar
    internetwork
Authors: Gosic, Milan; Bellot Rubio, Luis; Del Toro Iniesta, Jose
   Carlos; Orozco Suarez, David; Katsukawa, Yukio
Bibcode: 2016SPD....4740105G
Altcode:
  The solar internetwork contains weak and highly dynamic magnetic
  fields that are essential to understanding the solar magnetism at small
  spatial and temporal scales. Therefore, it is important to determine
  how these fields are maintained on the solar surface. Using unique
  Hinode observations, we follow the evolution of individual magnetic
  elements in the interior of two supergranular cells at the disk
  center. From up to 38 hr of continuous measurements, we show that
  magnetic flux appears in internetwork regions at a rate of 120±3
  Mx cm<SUP>-2</SUP> day<SUP>-1</SUP> (3.7±0.4 × 10<SUP>24</SUP> Mx
  day<SUP>-1</SUP> over the entire solar surface). Flux disappears from
  the internetwork at a rate of 125±6 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>
  (3.9±0.5 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP>) through fading of
  magnetic elements, cancellation between opposite-polarity features,
  and interactions with network patches, which converts internetwork
  elements into network features. The removal of flux from supergranules
  occurs mainly through fading and interactions with network, at nearly
  the same rate of about 50 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>. Our
  results demonstrate that the sources and sinks of internetwork magnetic
  flux are well balanced, reflecting the steady-state nature of the quiet
  Sun. Using the instantaneous flux appearance and disappearance rates,
  we successfully reproduce, for the first time, the temporal evolution
  of the total unsigned flux in the interior of supergranular cells.

Title: The Solar Internetwork. II. Flux Appearance and Disappearance
    Rates
Authors: Gošić, M.; Bellot Rubio, L. R.; del Toro Iniesta, J. C.;
   Orozco Suárez, D.; Katsukawa, Y.
Bibcode: 2016ApJ...820...35G
Altcode: 2016arXiv160205892G
  Small-scale internetwork magnetic fields are important ingredients of
  the quiet Sun. In this paper we analyze how they appear and disappear
  on the solar surface. Using high resolution Hinode magnetograms,
  we follow the evolution of individual magnetic elements in the
  interior of two supergranular cells at the disk center. From up to
  38 hr of continuous measurements, we show that magnetic flux appears
  in internetwork regions at a rate of 120 ± 3 Mx cm<SUP>-2</SUP>
  day<SUP>-1</SUP> (3.7 ± 0.4 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP>
  over the entire solar surface). Flux disappears from the internetwork
  at a rate of 125 ± 6 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP> (3.9
  ± 0.5 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP>) through fading of
  magnetic elements, cancelation between opposite-polarity features,
  and interactions with network patches, which converts internetwork
  elements into network features. Most of the flux is lost through
  fading and interactions with the network, at nearly the same rate of
  about 50 Mx cm<SUP>-2</SUP> day<SUP>-1</SUP>. Our results demonstrate
  that the sources and sinks of internetwork magnetic flux are well
  balanced. Using the instantaneous flux appearance and disappearance
  rates, we successfully reproduce the time evolution of the total
  unsigned flux in the two supergranular cells.

Title: Long-term trends of magnetic bright points. I. Number of
    magnetic bright points at disc centre
Authors: Utz, D.; Muller, R.; Thonhofer, S.; Veronig, A.; Hanslmeier,
   A.; Bodnárová, M.; Bárta, M.; del Toro Iniesta, J. C.
Bibcode: 2016A&A...585A..39U
Altcode: 2015arXiv151107767U
  Context. The Sun shows an activity cycle that is caused by its varying
  global magnetic field. During a solar cycle, sunspots, I.e. extended
  regions of strong magnetic fields, occur in activity belts that are
  slowly migrating from middle to lower latitudes, finally arriving
  close to the equator during the cycle maximum phase. While this
  and other facts about the strong extended magnetic fields have been
  well known for centuries, much less is known about the solar cycle
  evolution of small-scale magnetic fields. Thus the question arises
  if similar principles exist for small-scale magnetic fields. <BR />
  Aims: To address this question, we study magnetic bright points (MBPs)
  as proxies for such small-scale, kG solar magnetic fields. This study is
  based on a homogeneous data set that covers a period of eight years. The
  number of detected MBPs versus time is analysed to find out if there
  is an activity cycle for these magnetic features too and, if so, how
  it is related to the sunspot cycle. <BR /> Methods: An automated MBP
  identification algorithm was applied to the synoptic Hinode/SOT G-band
  data over the period November 2006 to August 2014, I.e. covering the
  decreasing phase of Cycle 23 and the rise, maximum, and early decrease
  of Cycle 24. This data set includes, at the moment of investigation, a
  total of 4162 images, with about 2.9 million single MBP detections. <BR
  /> Results: After a careful preselection and monthly median filtering
  of the data, the investigation revealed that the number of MBPs close
  to the equator is coupled to the global solar cycle but shifted in time
  by about 2.5 yr. Furthermore, the instantaneous number of detected MBPs
  depends on the hemisphere, with one hemisphere being more prominent,
  I.e. showing a higher number of MBPs. After the end of Cycle 23 and at
  the starting point of Cycle 24, the more active hemisphere changed from
  south to north. Clear peaks in the detected number of MBPs are found
  at latitudes of about ±7°, in congruence with the positions of the
  sunspot belts at the end of the solar cycle. <BR /> Conclusions: These
  findings suggest that there is indeed a coupling between the activity of
  MBPs close to the equator with the global magnetic field. The results
  also indicate that a significant fraction of the magnetic flux that
  is visible as MBPs close to the equator originates from the sunspot
  activity belts. However, even during the minimum of MBP activity,
  a percentage as large as 60% of the maximum number of detected MBPs
  has been observed, which may be related to solar surface dynamo action.

Title: Future of Inversion Tools
Authors: del Toro Iniesta, J. C.; Ruiz Cobo, B.
Bibcode: 2015AGUFMSH21C..02D
Altcode:
  Since the early 1970's, inversion techniques have become the most
  useful tool for inferring the magnetic, dynamic and thermodynamic
  properties of the solar atmosphere. They have evolved with model
  dependence as a driver: astrophysical inferences do not only depend
  on measurements but also on the physics assumed to prevail both on the
  formation of the spectral line Stokes profiles and on their detection
  with the instrument. Such an intrinsic model dependence makes it
  necessary to formulate specific means that include the physics in a
  proper quantitative way. The core of this physics is in the radiative
  transfer equation (RTE), where the properties of the atmosphere are
  assumed to be known while the unknowns are the four Stokes profiles. The
  solution of the (differential) RTE is known as the direct or forward
  problem. From an observational point of view, the problem is rather
  the opposite: the data are made up of the observed Stokes profiles and
  the unknowns are the solar physical quantities. Inverting the RTE is
  therefore mandatory. Indeed, the formal solution of this equation can
  be considered an integral equation. The solution of such an integral
  equation is called the inverse problem. Inversion techniques are
  automated codes aimed at solving the inverse problem. The foundations
  of inversion techniques are critically revisited with an emphasis
  on making explicit the many assumptions underlying each of them. An
  incremental complexity procedure is advised for the implementation in
  practice. Coarse details of the profiles or coarsely sampled profiles
  should be reproduced first with simple model atmospheres (with, for
  example, a few physical quantities that are constant with optical
  depth). If the Stokes profiles are well sampled and differences
  between synthetic and observed ones are larger than the noise, then
  the inversion should proceed by using more complex models (that is,
  models where physical quantities vary with depth or, eventually, with
  more than one component). Significant improvements are expected as
  well from the use of new inversion techniques that take the spatial
  degradation by the instruments into account.

Title: The Polarimetric and Helioseismic Imager for Solar Orbiter:
    SO/PHI
Authors: Solanki, Sami K.; del Toro Iniesta, Jose Carlos; Woch,
   Joachim; Gandorfer, Achim; Hirzberger, Johann; Schmidt, Wolfgang;
   Appourchaux, Thierry; Alvarez-Herrero, Alberto
Bibcode: 2015IAUS..305..108S
Altcode: 2015arXiv150203368S
  The Solar Orbiter is the next solar physics mission of the European
  Space Agency, ESA, in collaboration with NASA, with a launch planned in
  2018. The spacecraft is designed to approach the Sun to within 0.28 AU
  at perihelion of a highly eccentric orbit. The proximity with the Sun
  will also allow its observation at uniformly high resolution at EUV and
  visible wavelengths. Such observations are central for learning more
  about the magnetic coupling of the solar atmosphere. At a later phase
  in the mission the spacecraft will leave the ecliptic and study the
  enigmatic poles of the Sun from a heliographic latitude of up to 33°.

Title: Dynamics of Multi-cored Magnetic Structures in the Quiet Sun
Authors: Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot
   Rubio, Luis R.; Martínez Pillet, Valentín; Solanki, Sami K.;
   Schmidt, Wolfgang
Bibcode: 2015ApJ...810...79R
Altcode: 2015arXiv150806998R
  We report on the dynamical interaction of quiet-Sun magnetic fields and
  granular convection in the solar photosphere as seen by Sunrise. We
  use high spatial resolution (0.″15-0.″18) and temporal cadence
  (33 s) spectropolarimetric Imaging Magnetograph eXperiment data,
  together with simultaneous CN and Ca ii H filtergrams from Sunrise
  Filter Imager. We apply the SIR inversion code to the polarimetric
  data in order to infer the line of sight velocity and vector magnetic
  field in the photosphere. The analysis reveals bundles of individual
  flux tubes evolving as a single entity during the entire 23 minute data
  set. The group shares a common canopy in the upper photospheric layers,
  while the individual tubes continually intensify, fragment and merge in
  the same way that chains of bright points in photometric observations
  have been reported to do. The evolution of the tube cores are driven
  by the local granular convection flows. They intensify when they
  are “compressed” by surrounding granules and split when they are
  “squeezed” between two moving granules. The resulting fragments
  are usually later regrouped in intergranular lanes by the granular
  flows. The continual intensification, fragmentation and coalescence of
  flux results in magnetic field oscillations of the global entity. From
  the observations we conclude that the magnetic field oscillations first
  reported by Martínez González et al. correspond to the forcing by
  granular motions and not to characteristic oscillatory modes of thin
  flux tubes.

Title: Magnetic bright point dynamics and evolutions observed by
    Sunrise/IMaX and other instruments
Authors: Utz, D.; del Toro Iniesta, J. C.; Bellot Rubio, L.; Thonhofer,
   S.; Jurčák, J.
Bibcode: 2015hsa8.conf..689U
Altcode:
  In this proceeding we will have a closer look on recent observations
  and results regarding the dynamics and evolution of so-called magnetic
  bright points (MBPs). MBPs are manifestations of kG magnetic field
  strong flux concentrations seen in the solar photosphere. They belong
  to the class of small-scale solar magnetic features with diameters
  starting from low values around the current observational resolution
  limit - about 100 km - up to a few hundred km. They might play an
  important role in several key research questions like the total solar
  irradiance variation (TSI variation) as well as the solar atmospheric
  heating problem. Especially their dynamic behaviour is of interest
  for the heating problem as they might trigger all kinds of MHD waves
  which travel up to the higher solar atmospheric layers, where they can
  get damped leading to a heating of the plasma. Furthermore they might
  engage in magnetic field reconnection processes leading consequently
  also to a heating. Due to these reasons, and also for the sake of a
  better understanding of the physical processes involved on small-scales,
  detailed investigations on the dynamical behaviour and evolution of
  such magnetic field proxies like MBPs is in order. In this conference
  proceeding we wish to give in a first part an overview about the
  obtained knowledge so far. In a second part we highlight recent results
  regarding the dynamical evolution of plasma parameters of MBPs such as
  magnetic field strength, temperature, and line of sight velocity. This
  proceeding is completed by an outlook on what can and should be done
  in the near future with available data from recent telescopes.

Title: Long time variations of Magnetic Bright Points observed
    by Hinode/SOT
Authors: Utz, D.; del Toro Iniesta, J. C.; Bellot-Rubio, L.;
   Bodnárová, M.; Muller, R.; Bárta, M.; Thonhofer, S.; Hanslmeier, A.
Bibcode: 2015CEAB...39...91U
Altcode:
  Magnetic bright points (MBPs) are manifestations of small-scale solar
  magnetic flux concentrations, best observable due to their high contrast
  in molecular bands like the G-band. Moreover, they are among the most
  interesting magnetic features to be studied in high spatial and temporal
  resolution in the solar photosphere. Their relevance for solar physics
  is not only given by their contribution to fundamental solar plasma
  physics on small scales but in addition due to their involvement in
  processes like the solar atmospheric heating problem (chromosphere
  and corona), their influence on granulation and hence the convective
  energy transport, as well as their contribution to the variations in
  total solar irradiance caused by their higher relative intensity. In
  this ongoing study we focus on the long-time evolution of statistical
  parameters of MBPs over the solar cycle. Are parameters like the mean
  intensity, average size/diameter, and number of MBPs per unit surface
  element variable with time? If so, how do these parameters vary and is
  there a relationship to the solar cycle? In the actual contribution
  we will discuss preliminary results regarding the variation of the
  number of MBPs with time. We saw a decrease in the number of MBPs for
  the first years of observation (2006 until 2011) with two distinct
  local minima in the years 2009 and 2011. After 2011 the number of MBPs
  is increasing again along with an increase in general solar activity
  (as seen by the number of sunspots, flares, and CMEs).

Title: The Formation and Disintegration of Magnetic Bright Points
    Observed by Sunrise/IMaX
Authors: Utz, D.; del Toro Iniesta, J. C.; Bellot Rubio, L. R.;
   Jurčák, J.; Martínez Pillet, V.; Solanki, S. K.; Schmidt, W.
Bibcode: 2014ApJ...796...79U
Altcode: 2014arXiv1411.3240U
  The evolution of the physical parameters of magnetic bright points
  (MBPs) located in the quiet Sun (mainly in the interwork) during
  their lifetime is studied. First, we concentrate on the detailed
  description of the magnetic field evolution of three MBPs. This
  reveals that individual features follow different, generally complex,
  and rather dynamic scenarios of evolution. Next, we apply statistical
  methods on roughly 200 observed MBP evolutionary tracks. MBPs are found
  to be formed by the strengthening of an equipartition field patch,
  which initially exhibits a moderate downflow. During the evolution,
  strong downdrafts with an average velocity of 2.4 km s<SUP>-1</SUP>
  set in. These flows, taken together with the concurrent strengthening of
  the field, suggest that we are witnessing the occurrence of convective
  collapses in these features, although only 30% of them reach kG field
  strengths. This fraction might turn out to be larger when the new 4
  m class solar telescopes are operational as observations of MBPs with
  current state of the art instrumentation could still be suffering from
  resolution limitations. Finally, when the bright point disappears
  (although the magnetic field often continues to exist) the magnetic
  field strength has dropped to the equipartition level and is generally
  somewhat weaker than at the beginning of the MBP's evolution. Also,
  only relatively weak downflows are found on average at this stage of
  the evolution. Only 16% of the features display upflows at the time
  that the field weakens, or the MBP disappears. This speaks either for
  a very fast evolving dynamic process at the end of the lifetime, which
  could not be temporally resolved, or against strong upflows as the cause
  of the weakening of the field of these magnetic elements, as has been
  proposed based on simulation results. It is noteworthy that in about 10%
  of the cases, we observe in the vicinity of the downflows small-scale
  strong (exceeding 2 km s<SUP>-1</SUP>) intergranular upflows related
  spatially and temporally to these downflows. The paper is complemented
  by a detailed discussion of aspects regarding the applied methods,
  the complementary literature, and in depth analysis of parameters
  like magnetic field strength and velocity distributions. An important
  difference to magnetic elements and associated bright structures in
  active region plage is that most of the quiet Sun bright points display
  significant downflows over a large fraction of their lifetime (i.e.,
  in more than 46% of time instances/measurements they show downflows
  exceeding 1 km s<SUP>-1</SUP>).

Title: The Solar Internetwork. I. Contribution to the Network
    Magnetic Flux
Authors: Gošić, M.; Bellot Rubio, L. R.; Orozco Suárez, D.;
   Katsukawa, Y.; del Toro Iniesta, J. C.
Bibcode: 2014ApJ...797...49G
Altcode: 2014arXiv1408.2369G
  The magnetic network (NE) observed on the solar surface harbors a
  sizable fraction of the total quiet Sun flux. However, its origin and
  maintenance are not well known. Here we investigate the contribution
  of internetwork (IN) magnetic fields to the NE flux. IN fields permeate
  the interior of supergranular cells and show large emergence rates. We
  use long-duration sequences of magnetograms acquired by Hinode and
  an automatic feature tracking algorithm to follow the evolution of NE
  and IN flux elements. We find that 14% of the quiet Sun (QS) flux is
  in the form of IN fields with little temporal variations. IN elements
  interact with NE patches and modify the flux budget of the NE either
  by adding flux (through merging processes) or by removing it (through
  cancellation events). Mergings appear to be dominant, so the net flux
  contribution of the IN is positive. The observed rate of flux transfer
  to the NE is 1.5 × 10<SUP>24</SUP> Mx day<SUP>-1</SUP> over the entire
  solar surface. Thus, the IN supplies as much flux as is present in the
  NE in only 9-13 hr. Taking into account that not all the transferred
  flux is incorporated into the NE, we find that the IN would be able
  to replace the entire NE flux in approximately 18-24 hr. This renders
  the IN the most important contributor to the NE, challenging the view
  that ephemeral regions are the main source of flux in the QS. About 40%
  of the total IN flux eventually ends up in the NE.

Title: The History of a Quiet-Sun Magnetic Element Revealed by
    IMaX/SUNRISE
Authors: Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot
   Rubio, Luis R.; Bonet, José A.; Martínez Pillet, Valentín; Solanki,
   Sami K.; Schmidt, Wolfgang
Bibcode: 2014ApJ...789....6R
Altcode: 2014arXiv1405.2837R
  Isolated flux tubes are considered to be fundamental magnetic building
  blocks of the solar photosphere. Their formation is usually attributed
  to the concentration of magnetic field to kG strengths by the convective
  collapse mechanism. However, the small size of the magnetic elements in
  quiet-Sun areas has prevented this scenario from being studied in fully
  resolved structures. Here, we report on the formation and subsequent
  evolution of one such photospheric magnetic flux tube, observed in
  the quiet Sun with unprecedented spatial resolution (0.''15-0.''18)
  and high temporal cadence (33 s). The observations were acquired by
  the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne
  solar observatory. The equipartition field strength magnetic element
  is the result of the merging of several same polarity magnetic flux
  patches, including a footpoint of a previously emerged loop. The
  magnetic structure is then further intensified to kG field strengths
  by convective collapse. The fine structure found within the flux
  concentration reveals that the scenario is more complex than can be
  described by a thin flux tube model with bright points and downflow
  plumes being established near the edges of the kG magnetic feature. We
  also observe a daisy-like alignment of surrounding granules and a
  long-lived inflow toward the magnetic feature. After a subsequent
  weakening process, the field is again intensified to kG strengths. The
  area of the magnetic feature is seen to change in anti-phase with the
  field strength, while the brightness of the bright points and the speed
  of the downflows varies in phase. We also find a relation between the
  brightness of the bright point and the presence of upflows within it.

Title: Comparison between Mg II k and Ca II H Images Recorded by
    SUNRISE/SuFI
Authors: Danilovic, S.; Hirzberger, J.; Riethmüller, T. L.; Solanki,
   S. K.; Barthol, P.; Berkefeld, T.; Gandorfer, A.; Gizon, L.; Knölker,
   M.; Schmidt, W.; Blanco Rodríguez, J.; Del Toro Iniesta, J. C.
Bibcode: 2014ApJ...784...20D
Altcode:
  We present a comparison of high-resolution images of the solar surface
  taken in the Mg II k and Ca II H channels of the Filter Imager on the
  balloon-borne solar observatory SUNRISE. The Mg and Ca lines are sampled
  with 0.48 nm and 0.11 nm wide filters, respectively. The two channels
  show remarkable qualitative and quantitative similarities in the quiet
  Sun, in an active region plage and during a small flare. However, the Mg
  filtergrams display 1.4-1.7 times higher intensity contrast and appear
  more smeared and smoothed in the quiet Sun. In addition, the fibrils
  in a plage are wider. Although the exposure time is 100 times longer
  for Mg images, the evidence suggests that these differences cannot be
  explained only with instrumental effects or the evolution of the solar
  scene. The differences at least partially arise because of different
  line-formation heights, the stronger response of Mg k emission peaks
  to the higher temperatures, and the larger height range sampled by
  the broad Mg filter used here. This is evidently manifested during
  the flare when a surge in Mg evolves differently than in Ca.

Title: Time evolution of a single, quiet-Sun magnetic structure
Authors: Requerey, Iker S.; Bonet, José Antonio; Solanki, Sami K.;
   Bellot Rubio, L. R.; Del Toro Iniesta, Jose Carlos
Bibcode: 2014cosp...40E2828R
Altcode:
  Isolated flux tubes are considered to be fundamental magnetic building
  blocks of the solar photosphere. Their formation is usually attributed
  to the concentration of magnetic field to kG strengths by the convective
  instability mechanism. However, the small size of the magnetic elements
  in quiet-Sun areas has prevented this scenario from being studied
  in fully resolved structures. Here we report on the formation and
  subsequent evolution of a photospheric magnetic flux tube, observed
  in the quiet Sun with unprecedented spatial resolution (0. ('') 15 -
  0. ('') 18) and high temporal cadence (33 s). The observations were
  acquired by the Imaging Magnetograph Experiment (IMaX) aboard the
  textsc{Sunrise} balloon-borne solar observatory. The equipartition
  field strength magnetic element is reached from the merging of
  several magnetic flux patches in a mesogranule-sized sink. The
  magnetic structure is then further intensified to kG field strengths by
  convective collapse and granular compression. The fine structure found
  within the flux concentration reveal that the scenario is more complex
  than a canonical flux tube model. After a subsequent weakening process,
  the field is further intensified to kG strengths. Seen as a whole, the
  evolution of the magnetic structure is compatible with oscillations in
  all basic physical quantities. A discussion on whether this evolution
  fits to the current theoretical descriptions is also presented.

Title: New insights into the evolution of magnetic bright point
    plasma parameters
Authors: Utz, Dominik; Hanslmeier, Arnold; Bellot Rubio, L. R.;
   Del Toro Iniesta, Jose Carlos; Jurcak, Jan
Bibcode: 2014cosp...40E3448U
Altcode:
  The dynamics within the solar atmosphere are governed by the Suńs
  magnetic fields. In the recent years the resolution limits were steadily
  driven up by better and better instruments and telescopes (like Hinode,
  Sunrise, NST, Gregor, ..) leading to higher resolved data. Therefore
  the interest in ever smaller magnetic field structures within the solar
  atmosphere rises. Among the smallest yet identified structures are
  so-called magnetic bright points (MBPs). These features are thought to
  be made up of single flux tubes and they have been studied exhaustively
  in the Fraunhofer G-band since the 70´s of the last century. They are
  important features not only due to their small scale (about 200 km in
  diameter) and hence used as proxies for the smallest solar magnetic
  field physics and processes, but also because they are involved in
  topics like the chromospheric/coronal heating problem or the total
  solar irradiance variation. In the current contribution we want to
  study the evolution of important plasma parameters of MBPs, such
  as temperature, magnetic field strength and line of sight velocity,
  to get a deeper understanding of the involved physics and occuring
  processes. Among the used data will be G-band filtergam data from
  Hinode/SOT and spectro-polarimetric data from the IMaX instrument
  onboard the Sunrise mission.

Title: Inversions of Stokes profiles revisited
Authors: Del Toro Iniesta, Jose Carlos
Bibcode: 2014cosp...40E.666D
Altcode:
  The last thirty years have witnessed the appearance of a number
  of techniques that have revolutionized our way to measure magnetic
  fields, namely, the so-called inversions of the radiative transfer
  equation techniques. Starting from simple models and solutions
  of the transfer equation and ending with sophisticated processes
  including full numeric solution of the equation and instrumental
  effects at the same time, passing through different model approaches
  and mathematical tools, inversion techniques have become common usage
  for solar observers. A revision of the ideas, hypotheses, advantages,
  limitations, and constraints behind inversions is presented, beginning
  with critical reviews of commonly accepted approximations that are
  becoming useless as long as new instrumentation is providing better
  and better observables. The advent of state-of-the-art computing tools
  increase our capabilities for finer analyses of these new observations.

Title: New insights into the temporal evolution of MBPs
Authors: Utz, D.; del Toro Iniesta, J. C.; Bellot Rubio, L. R.;
   Jurčak, J.; Thonhofer, S.; Bodnárová, M.; Hanslmeier, A.; Lemmerer,
   B.; Piantschitsch, I.; Guttenbrunner, S.
Bibcode: 2014CEAB...38...73U
Altcode:
  Magnetic bright points (MBPs) are among the most fascinating and
  interesting manifestations of small-scale solar magnetic fields. In the
  present work the temporal evolution of MBPs is followed in data sets
  taken by the Hinode satellite. The analysed data and obtained results
  confirm a recently presented study done with Sunrise/IMaX data, namely
  that MBPs are features undergoing fast evolution with magnetic fields
  starting around the equipartition field strength, then showing strong
  downflows (between 2 to 4 km/s) causing the magnetic field to amplify
  into the kG range (700 to 1500 G) before dissolving again. Furthermore
  the initial field inclinations depend on the initial magnetic field
  strengths and show an evolution with more vertical angles at some
  point during the evolution.

Title: First High-resolution Images of the Sun in the 2796 Å Mg II
    k Line
Authors: Riethmüller, T. L.; Solanki, S. K.; Hirzberger, J.;
   Danilovic, S.; Barthol, P.; Berkefeld, T.; Gandorfer, A.; Gizon, L.;
   Knölker, M.; Schmidt, W.; Del Toro Iniesta, J. C.
Bibcode: 2013ApJ...776L..13R
Altcode: 2013arXiv1309.5213R
  We present the first high-resolution solar images in the Mg II k 2796
  Å line. The images, taken through a 4.8 Å broad interference filter,
  were obtained during the second science flight of Sunrise in 2013 June
  by the Sunrise Filter Imager (SuFI) instrument. The Mg II k images
  display structures that look qualitatively very similar to images taken
  in the core of Ca II H. The Mg II images exhibit reversed granulation
  (or shock waves) in the internetwork regions of the quiet Sun, at
  intensity contrasts that are similar to those found in Ca II H. Very
  prominent in Mg II are bright points, both in the quiet Sun and in plage
  regions, particularly near the disk center. These are much brighter than
  at other wavelengths sampled at similar resolution. Furthermore, Mg II k
  images also show fibril structures associated with plage regions. Again,
  the fibrils are similar to those seen in Ca II H images, but tend to
  be more pronounced, particularly in weak plage.

Title: Is Magnetic Reconnection the Cause of Supersonic Upflows in
    Granular Cells?
Authors: Borrero, J. M.; Martínez Pillet, V.; Schmidt, W.; Quintero
   Noda, C.; Bonet, J. A.; del Toro Iniesta, J. C.; Bellot Rubio, L. R.
Bibcode: 2013ApJ...768...69B
Altcode: 2013arXiv1303.2557B
  In a previous work, we reported on the discovery of supersonic magnetic
  upflows on granular cells in data from the SUNRISE/IMaX instrument. In
  the present work, we investigate the physical origin of these events
  employing data from the same instrument but with higher spectral
  sampling. By means of the inversion of Stokes profiles we are able
  to recover the physical parameters (temperature, magnetic field,
  line-of-sight velocity, etc.) present in the solar photosphere at the
  time of these events. The inversion is performed in a Monte-Carlo-like
  fashion, that is, repeating it many times with different initializations
  and retaining only the best result. We find that many of the events are
  characterized by a reversal in the polarity of the magnetic field along
  the vertical direction in the photosphere, accompanied by an enhancement
  in the temperature and by supersonic line-of-sight velocities. In
  about half of the studied events, large blueshifted and redshifted
  line-of-sight velocities coexist above/below each other. These features
  can be explained in terms of magnetic reconnection, where the energy
  stored in the magnetic field is released in the form of kinetic
  and thermal energy when magnetic field lines of opposite polarities
  coalesce. However, the agreement with magnetic reconnection is not
  perfect and, therefore, other possible physical mechanisms might also
  play a role.

Title: A Magnetic Bright Point Case Study
Authors: Utz, D.; Jurčák, J.; Bellot-Rubio, L.; del Toro Iniesta,
   J. C.; Thonhofer, S.; Hanslmeier, A.; Veronig, A.; Muller, R.;
   Lemmerer, B.
Bibcode: 2013CEAB...37..459U
Altcode:
  Due to its magnetic fields our host star - the Sun - becomes the
  interesting object for research as we know it. The magnetic fields
  themselves cover different spatial, lifetime and strength scales and
  reach down from enormous flux concentrations like active sunspot
  groups to single isolated magnetic flux tubes and even weaker,
  predominantly inclined intranetwork structures. Flux tubes can be seen
  in filtergram observations as magnetic bright points (MBPs). They are
  of interest for research not only due to their sheer existence but
  due to their important role in atmospheric heating (wave heating as
  well as reconnection processes), to their role in the understanding
  of creation and annihilation of magnetic fields as well as to their
  influence on the total solar irradiance variation. In this study we
  present a close look onto an evolutionary track of an MBP from its
  formation to its disintegration. Physical quantities of MBPs like
  their magnetic field strength and inclination, their line-of-sight
  velocity, and their temperature at different heights are inferred
  from the inversion of spectropolarimetric data. Original data are
  taken from the Sunrise/IMaX instrument and constitute a time series
  of some 60 min. The presented case resembles the convective collapse
  model and is in agreement with previous studies.

Title: Inversions of L12-2 IMaX data of an emerging flux mantle
Authors: Guglielmino, S. L.; Martínez Pillet, V.; Ruiz Cobo,
   B.; del Toro Iniesta, J. C.; Bellot Rubio, L. R.; Solanki, S. K.;
   Sunrise/IMaX Team
Bibcode: 2013MmSAI..84..355G
Altcode:
  We present the analysis of a flux emergence event observed with
  the IMaX magnetograph flown aboard the SUNRISE balloon. IMaX took a
  15' sequence with cadence of 31 s along the Fe I line at 525.0 nm,
  acquiring only Stokes I and V at 12 line positions (L12-2 mode). This
  sequence shows the emergence of a flux mantle at mesogranular scale,
  cospatial with a large exploding granule. An undesired cross-talk
  between Stokes U and V was found in such L12-2 data. We show that the
  use of a modified version of the SIR inversion code is able to remove
  such effect in inferring the physical quantities of interest.

Title: SIR: Stokes Inversion based on Response functions
Authors: Ruiz Cobo, B.; del Toro Iniesta, J. C.
Bibcode: 2012ascl.soft12008R
Altcode:
  SIR is a general-purpose code capable of dealing with gradients of
  the physical quantities with height. It admits one and two-component
  model atmospheres. It allows the recovery of the stratification of the
  temperature, the magnetic field vector, and the line of sight velocity
  through the atmosphere, and the micro- and macroturbulence velocities
  - which are assumed to be constant with depth. It is based on the
  response functions, which enter a Marquardt nonlinear least-squares
  algorithm in a natural way. Response functions are calculated at the
  same time as the full radiative transfer equation for polarized light
  is integrated, which determines values of many free parameters in a
  reasonable computation time. SIR demonstrates high stability, accuracy,
  and uniqueness of results, even when simulated observations present
  signal-to-noise ratios of the order of the lowest acceptable values
  in real observations.

Title: Resolving the Internal Magnetic Structure of the Solar Network
Authors: Martínez González, M. J.; Bellot Rubio, L. R.; Solanki,
   S. K.; Martínez Pillet, V.; Del Toro Iniesta, J. C.; Barthol, P.;
   Schmidt, W.
Bibcode: 2012ApJ...758L..40M
Altcode: 2012arXiv1209.2584M
  We analyze the spectral asymmetry of Stokes V (circularly polarized)
  profiles of an individual network patch in the quiet Sun observed
  by Sunrise/IMaX. At a spatial resolution of 0farcs15-0farcs18, the
  network elements contain substructure which is revealed by the spatial
  distribution of Stokes V asymmetries. The area asymmetry between the
  red and blue lobes of Stokes V increases from nearly zero at the core
  of the structure to values close to unity at its edges (single-lobed
  profiles). Such a distribution of the area asymmetry is consistent
  with magnetic fields expanding with height, i.e., an expanding
  magnetic canopy (which is required to fulfill pressure balance and
  flux conservation in the solar atmosphere). Inversion of the Stokes
  I and V profiles of the patch confirms this picture, revealing a
  decreasing field strength and increasing height of the canopy base
  from the core to the periphery of the network patch. However, the
  non-roundish shape of the structure and the presence of negative area
  and amplitude asymmetries reveal that the scenario is more complex than
  a canonical flux tube expanding with height surrounded by downflows.

Title: Assessing the Behavior of Modern Solar Magnetographs and
    Spectropolarimeters
Authors: Del Toro Iniesta, J. C.; Martínez Pillet, V.
Bibcode: 2012ApJS..201...22D
Altcode: 2012arXiv1205.4845D
  The design and later use of modern spectropolarimeters and magnetographs
  require a number of tolerance specifications that allow the developers
  to build the instrument and then the scientists to interpret the data
  accuracy. Such specifications depend both on device-specific features
  and on the physical assumptions underlying the particular measurement
  technique. Here we discuss general properties of every magnetograph,
  such as the detectability thresholds for the vector magnetic field and
  the line-of-sight velocity, as well as specific properties of a given
  type of instrument, namely, that based on a pair of nematic liquid
  crystal variable retarders and a Fabry-Pérot etalon (or several) for
  carrying out the light polarization modulation and spectral analysis,
  respectively. We derive formulae that give the detection thresholds
  in terms of the signal-to-noise ratio of the observations and the
  polarimetric efficiencies of the instrument. Relationships are also
  established between inaccuracies in the solar physical quantities and
  instabilities in the instrument parameters. Such relationships allow,
  for example, one to translate scientific requirements for the velocity
  or the magnetic field into requirements for temperature or voltage
  stability. We also demonstrate that this type of magnetograph can
  theoretically reach the optimum polarimetric efficiencies of an ideal
  polarimeter, regardless of the optics in between the modulator and the
  analyzer. Such optics induce changes in the instrument parameters that
  are calculated.

Title: The Frontier between Small-scale Bipoles and Ephemeral Regions
in the Solar Photosphere: Emergence and Decay of an Intermediate-scale
    Bipole Observed with SUNRISE/IMaX
Authors: Guglielmino, S. L.; Martínez Pillet, V.; Bonet, J. A.;
   del Toro Iniesta, J. Carlos; Bellot Rubio, L. R.; Solanki, S. K.;
   Schmidt, W.; Gandorfer, A.; Barthol, P.; Knölker, M.
Bibcode: 2012ApJ...745..160G
Altcode: 2011arXiv1110.1405G
  We report on the photospheric evolution of an intermediate-scale (≈4
  Mm footpoint separation) magnetic bipole, from emergence to decay,
  observed in the quiet Sun at high spatial (0farcs3) and temporal (33 s)
  resolution. The observations were acquired by the Imaging Magnetograph
  Experiment imaging magnetograph during the first science flight of the
  SUNRISE balloon-borne solar observatory. The bipole flux content is 6 ×
  10<SUP>17</SUP> Mx, representing a structure bridging the gap between
  granular scale bipoles and the smaller ephemeral regions. Footpoints
  separate at a speed of 3.5 km s<SUP>-1</SUP> and reach a maximum
  distance of 4.5 Mm before the field dissolves. The evolution of the
  bipole is revealed to be very dynamic: we found a proper motion of
  the bipole axis and detected a change of the azimuth angle of 90° in
  300 s, which may indicate the presence of some writhe in the emerging
  structure. The overall morphology and behavior are in agreement with
  previous analyses of bipolar structures emerging at the granular scale,
  but we also found several similarities with emerging flux structures
  at larger scales. The flux growth rate is 2.6 × 10<SUP>15</SUP> Mx
  s<SUP>-1</SUP>, while the mean decay rate is one order of magnitude
  smaller. We describe in some detail the decay phase of the bipole
  footpoints that includes break up into smaller structures, and
  interaction with preexisting fields leading to cancellation, but it
  appears to be dominated by an as-yet unidentified diffusive process
  that removes most of the flux with an exponential flux decay curve. The
  diffusion constant (8 × 10<SUP>2</SUP> km<SUP>2</SUP> s<SUP>-1</SUP>)
  associated with this decay is similar to the values used to describe
  the large-scale diffusion in flux transport models.

Title: Magnetic field emergence in mesogranular-sized exploding
    granules observed with sunrise/IMaX data
Authors: Palacios, J.; Blanco Rodríguez, J.; Vargas Domínguez, S.;
   Domingo, V.; Martínez Pillet, V.; Bonet, J. A.; Bellot Rubio, L. R.;
   Del Toro Iniesta, J. C.; Solanki, S. K.; Barthol, P.; Gandorfer, A.;
   Berkefeld, T.; Schmidt, W.; Knölker, M.
Bibcode: 2012A&A...537A..21P
Altcode: 2011arXiv1110.4555P
  We report on magnetic field emergences covering significant
  areas of exploding granules. The balloon-borne mission Sunrise
  provided high spatial and temporal resolution images of the solar
  photosphere. Continuum images, longitudinal and transverse magnetic
  field maps and Dopplergrams obtained by IMaX onboard Sunrise are
  analyzed by local correlation traking (LCT), divergence calculation
  and time slices, Stokes inversions and numerical simulations are also
  employed. We characterize two mesogranular-scale exploding granules
  where ~10<SUP>18</SUP> Mx of magnetic flux emerges. The emergence
  of weak unipolar longitudinal fields (~100 G) start with a single
  visible magnetic polarity, occupying their respective granules' top
  and following the granular splitting. After a while, mixed polarities
  start appearing, concentrated in downflow lanes. The events last around
  20 min. LCT analyses confirm mesogranular scale expansion, displaying
  a similar pattern for all the physical properties, and divergence
  centers match between all of them. We found a similar behaviour
  with the emergence events in a numerical MHD simulation. Granule
  expansion velocities are around 1 kms<SUP>-1</SUP> while magnetic
  patches expand at 0.65 kms<SUP>-1</SUP>. One of the analyzed events
  evidences the emergence of a loop-like structure. Advection of
  the emerging magnetic flux features is dominated by convective
  motion resulting from the exploding granule due to the magnetic
  field frozen in the granular plasma. Intensification of the
  magnetic field occurs in the intergranular lanes, probably
  because of being directed by the downflowing plasma. <P />Movies
  associated to Figs. 2-4 are available in electronic form at <A
  href="http://www.aanda.org">http://www.aanda.org</A>

Title: Space-qualified liquid-crystal variable retarders for
    wide-field-of-view coronagraphs
Authors: Uribe-Patarroyo, N.; Alvarez-Herrero, A.; García Parejo,
   P.; Vargas, J.; Heredero, R. L.; Restrepo, R.; Martínez Pillet, V.;
   del Toro Iniesta, J. C.; López, A.; Fineschi, S.; Capobianco, G.;
   Georges, M.; López, M.; Boer, G.; Manolis, I.
Bibcode: 2011SPIE.8148E..10U
Altcode: 2011SPIE.8148E..31U
  Liquid-crystal variable retarders (LCVRs) are an emergent technology
  for space-based polarimeters, following its success as polarization
  modulators in ground-based polarimeters and ellipsometers. Wide-field
  double nematic LCVRs address the high angular sensitivity of nematic
  LCVRs at some voltage regimes. We present a work in which wide-field
  LCVRs were designed and built, which are suitable for wide-field-of-view
  instruments such as polarimetric coronagraphs. A detailed model of
  their angular acceptance was made, and we validated this technology
  for space environmental conditions, including a campaign studying the
  effects of gamma, proton irradiation, vibration and shock, thermo-vacuum
  and ultraviolet radiation.

Title: The Sun at high resolution: first results from the Sunrise
    mission
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller,
   A.; Gandorfer, A.; Hirzberger, J.; Lagg, A.; Riethmüller, T. L.;
   Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; Pillet, V. Martínez;
   Khomenko, E.; del Toro Iniesta, J. C.; Domingo, V.; Palacios, J.;
   Knölker, M.; González, N. Bello; Borrero, J. M.; Berkefeld, T.;
   Franz, M.; Roth, M.; Schmidt, W.; Steiner, O.; Title, A. M.
Bibcode: 2011IAUS..273..226S
Altcode:
  The Sunrise balloon-borne solar observatory consists of a 1m aperture
  Gregory telescope, a UV filter imager, an imaging vector polarimeter,
  an image stabilization system and further infrastructure. The first
  science flight of Sunrise yielded high-quality data that reveal the
  structure, dynamics and evolution of solar convection, oscillations
  and magnetic fields at a resolution of around 100 km in the quiet
  Sun. Here we describe very briefly the mission and the first results
  obtained from the Sunrise data, which include a number of discoveries.

Title: Diagnostics for spectropolarimetry and magnetography
Authors: del Toro Iniesta, Jose Carlos; Pillet, Valentín Martínez
Bibcode: 2011IAUS..273...37D
Altcode: 2010arXiv1010.0504D
  An assessment on the capabilities of modern spectropolarimeters and
  magnetographs is in order since most of our astrophysical results rely
  upon the accuracy of the instrumentation and on the sensitivity of
  the observables to variations of the sought physical parameters. A
  contribution to such an assessment will be presented in this talk
  where emphasis will be made on the use of the so-called response
  functions to gauge the probing capabilities of spectral lines and on
  an analytical approach to estimate the uncertainties in the results
  in terms of instrumental effects. The Imaging Magnetograph eXperiment
  (IMaX) and the Polarimetric and Helioseismic Imager (PHI) will be used
  as study cases.

Title: Ubiquitous quiet-Sun jets
Authors: Martínez Pillet, V.; Del Toro Iniesta, J. C.; Quintero
   Noda, C.
Bibcode: 2011A&A...530A.111M
Altcode: 2011arXiv1104.5564M
  Context. IMaX/Sunrise has recently reported the temporal evolution
  of highly dynamic and strongly Doppler shifted Stokes V signals in
  the quiet Sun. <BR /> Aims: We attempt to identify the same quiet-Sun
  jets in the Hinode spectropolarimeter (SP) data set. <BR /> Methods:
  We generate combinations of linear polarization magnetograms with blue-
  and redshifted far-wing circular polarization magnetograms to allow an
  easy identification of the quiet-Sun jets. <BR /> Results: The jets are
  identified in the Hinode data where both red- and blueshifted cases
  are often found in pairs. They appear next to regions of transverse
  fields that exhibit quiet-Sun neutral lines. They also have a clear
  tendency to occur in the outer boundary of the granules. These regions
  always display highly displaced and anomalous Stokes V profiles. <BR />
  Conclusions: The quiet Sun is pervaded with jets formed when new field
  regions emerge at granular scales loaded with horizontal field lines
  that interact with their surroundings. This interaction is suggestive
  of some form of reconnection of the involved field lines that generates
  the observed high speed flows.

Title: Small-scale flux emergence events observed by Sunrise/IMaX
Authors: Guglielmino, S. L.; Pillet, V. Martínez; del Toro Iniesta,
   J. C.; Rubio, L. R. Bellot; Zuccarello, F.; Solanki, S. K.; Solanki
Bibcode: 2011IAUS..274..140G
Altcode:
  Thanks to the unprecedented combination of high spatial resolution
  (0''.2) and high temporal cadence (33 s) spectropolarimetric
  measurements, the IMaX magnetograph aboard the Sunrise balloon-borne
  telescope is revealing new insights about the plasma dynamics
  of the all-pervasive small-scale flux concentrations in the quiet
  Sun. We present the result of a case study concerning the appearance
  of a bipole, with a size of about 4'' and a flux content of 5 ×
  10<SUP>17</SUP> Mx, with strong signal of horizontal fields during
  the emergence. We analyze the data set using the SIR inversion code
  and obtain indications about the three-dimensional shape of the bipole
  and its evolution with time.

Title: Mesogranulation and the Solar Surface Magnetic Field
    Distribution
Authors: Yelles Chaouche, L.; Moreno-Insertis, F.; Martínez Pillet,
   V.; Wiegelmann, T.; Bonet, J. A.; Knölker, M.; Bellot Rubio, L. R.;
   del Toro Iniesta, J. C.; Barthol, P.; Gandorfer, A.; Schmidt, W.;
   Solanki, S. K.
Bibcode: 2011ApJ...727L..30Y
Altcode: 2010arXiv1012.4481Y
  The relation of the solar surface magnetic field with mesogranular
  cells is studied using high spatial (≈100 km) and temporal (≈30
  s) resolution data obtained with the IMaX instrument on board
  SUNRISE. First, mesogranular cells are identified using Lagrange
  tracers (corks) based on horizontal velocity fields obtained through
  local correlation tracking. After ≈20 minutes of integration, the
  tracers delineate a sharp mesogranular network with lanes of width
  below about 280 km. The preferential location of magnetic elements in
  mesogranular cells is tested quantitatively. Roughly 85% of pixels with
  magnetic field higher than 100 G are located in the near neighborhood
  of mesogranular lanes. Magnetic flux is therefore concentrated in
  mesogranular lanes rather than intergranular ones. Second, magnetic
  field extrapolations are performed to obtain field lines anchored in
  the observed flux elements. This analysis, therefore, is independent
  of the horizontal flows determined in the first part. A probability
  density function (PDF) is calculated for the distribution of distances
  between the footpoints of individual magnetic field lines. The PDF has
  an exponential shape at scales between 1 and 10 Mm, with a constant
  characteristic decay distance, indicating the absence of preferred
  convection scales in the mesogranular range. Our results support
  the view that mesogranulation is not an intrinsic convective scale
  (in the sense that it is not a primary energy-injection scale of solar
  convection), but also give quantitative confirmation that, nevertheless,
  the magnetic elements are preferentially found along mesogranular lanes.

Title: The Imaging Magnetograph eXperiment (IMaX) for the Sunrise
    Balloon-Borne Solar Observatory
Authors: Martínez Pillet, V.; del Toro Iniesta, J. C.;
   Álvarez-Herrero, A.; Domingo, V.; Bonet, J. A.; González Fernández,
   L.; López Jiménez, A.; Pastor, C.; Gasent Blesa, J. L.; Mellado, P.;
   Piqueras, J.; Aparicio, B.; Balaguer, M.; Ballesteros, E.; Belenguer,
   T.; Bellot Rubio, L. R.; Berkefeld, T.; Collados, M.; Deutsch, W.;
   Feller, A.; Girela, F.; Grauf, B.; Heredero, R. L.; Herranz, M.;
   Jerónimo, J. M.; Laguna, H.; Meller, R.; Menéndez, M.; Morales, R.;
   Orozco Suárez, D.; Ramos, G.; Reina, M.; Ramos, J. L.; Rodríguez,
   P.; Sánchez, A.; Uribe-Patarroyo, N.; Barthol, P.; Gandorfer, A.;
   Knoelker, M.; Schmidt, W.; Solanki, S. K.; Vargas Domínguez, S.
Bibcode: 2011SoPh..268...57M
Altcode: 2010SoPh..tmp..181M; 2010arXiv1009.1095M
  The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter
  built by four institutions in Spain that flew on board the Sunrise
  balloon-borne solar observatory in June 2009 for almost six days over
  the Arctic Circle. As a polarimeter, IMaX uses fast polarization
  modulation (based on the use of two liquid crystal retarders),
  real-time image accumulation, and dual-beam polarimetry to reach
  polarization sensitivities of 0.1%. As a spectrograph, the instrument
  uses a LiNbO<SUB>3</SUB> etalon in double pass and a narrow band
  pre-filter to achieve a spectral resolution of 85 mÅ. IMaX uses the
  high-Zeeman-sensitive line of Fe I at 5250.2 Å and observes all four
  Stokes parameters at various points inside the spectral line. This
  allows vector magnetograms, Dopplergrams, and intensity frames to be
  produced that, after reconstruction, reach spatial resolutions in the
  0.15 - 0.18 arcsec range over a 50×50 arcsec field of view. Time
  cadences vary between 10 and 33 s, although the shortest one only
  includes longitudinal polarimetry. The spectral line is sampled in
  various ways depending on the applied observing mode, from just two
  points inside the line to 11 of them. All observing modes include
  one extra wavelength point in the nearby continuum. Gauss equivalent
  sensitivities are 4 G for longitudinal fields and 80 G for transverse
  fields per wavelength sample. The line-of-sight velocities are estimated
  with statistical errors of the order of 5 - 40 m s<SUP>−1</SUP>. The
  design, calibration, and integration phases of the instrument,
  together with the implemented data reduction scheme, are described in
  some detail.

Title: The Sunrise Mission
Authors: Barthol, P.; Gandorfer, A.; Solanki, S. K.; Schüssler,
   M.; Chares, B.; Curdt, W.; Deutsch, W.; Feller, A.; Germerott, D.;
   Grauf, B.; Heerlein, K.; Hirzberger, J.; Kolleck, M.; Meller, R.;
   Müller, R.; Riethmüller, T. L.; Tomasch, G.; Knölker, M.; Lites,
   B. W.; Card, G.; Elmore, D.; Fox, J.; Lecinski, A.; Nelson, P.;
   Summers, R.; Watt, A.; Martínez Pillet, V.; Bonet, J. A.; Schmidt,
   W.; Berkefeld, T.; Title, A. M.; Domingo, V.; Gasent Blesa, J. L.;
   del Toro Iniesta, J. C.; López Jiménez, A.; Álvarez-Herrero, A.;
   Sabau-Graziati, L.; Widani, C.; Haberler, P.; Härtel, K.; Kampf,
   D.; Levin, T.; Pérez Grande, I.; Sanz-Andrés, A.; Schmidt, E.
Bibcode: 2011SoPh..268....1B
Altcode: 2010arXiv1009.2689B; 2010SoPh..tmp..224B
  The first science flight of the balloon-borne Sunrise telescope took
  place in June 2009 from ESRANGE (near Kiruna/Sweden) to Somerset
  Island in northern Canada. We describe the scientific aims and
  mission concept of the project and give an overview and a description
  of the various hardware components: the 1-m main telescope with its
  postfocus science instruments (the UV filter imager SuFI and the imaging
  vector magnetograph IMaX) and support instruments (image stabilizing
  and light distribution system ISLiD and correlating wavefront sensor
  CWS), the optomechanical support structure and the instrument mounting
  concept, the gondola structure and the power, pointing, and telemetry
  systems, and the general electronics architecture. We also explain
  the optimization of the structural and thermal design of the complete
  payload. The preparations for the science flight are described,
  including AIV and ground calibration of the instruments. The course
  of events during the science flight is outlined, up to the recovery
  activities. Finally, the in-flight performance of the instrumentation
  is discussed.

Title: SUNRISE: Instrument, Mission, Data, and First Results
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.;
   Gandorfer, A.; Hirzberger, J.; Riethmüller, T. L.; Schüssler, M.;
   Bonet, J. A.; Martínez Pillet, V.; del Toro Iniesta, J. C.; Domingo,
   V.; Palacios, J.; Knölker, M.; Bello González, N.; Berkefeld, T.;
   Franz, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.127S
Altcode: 2010arXiv1008.3460S
  The SUNRISE balloon-borne solar observatory consists of a 1 m aperture
  Gregory telescope, a UV filter imager, an imaging vector polarimeter,
  an image stabilization system, and further infrastructure. The first
  science flight of SUNRISE yielded high-quality data that revealed the
  structure, dynamics, and evolution of solar convection, oscillations,
  and magnetic fields at a resolution of around 100 km in the quiet
  Sun. After a brief description of instruments and data, the first
  qualitative results are presented. In contrast to earlier observations,
  we clearly see granulation at 214 nm. Images in Ca II H display narrow,
  short-lived dark intergranular lanes between the bright edges of
  granules. The very small-scale, mixed-polarity internetwork fields
  are found to be highly dynamic. A significant increase in detectable
  magnetic flux is found after phase-diversity-related reconstruction
  of polarization maps, indicating that the polarities are mixed right
  down to the spatial resolution limit and probably beyond.

Title: Supersonic Magnetic Upflows in Granular Cells Observed with
    SUNRISE/IMAX
Authors: Borrero, J. M.; Martínez-Pillet, V.; Schlichenmaier, R.;
   Solanki, S. K.; Bonet, J. A.; del Toro Iniesta, J. C.; Schmidt, W.;
   Barthol, P.; Gandorfer, A.; Domingo, V.; Knölker, M.
Bibcode: 2010ApJ...723L.144B
Altcode: 2010arXiv1009.1227B
  Using the IMaX instrument on board the SUNRISE stratospheric balloon
  telescope, we have detected extremely shifted polarization signals
  around the Fe I 5250.217 Å spectral line within granules in the solar
  photosphere. We interpret the velocities associated with these events
  as corresponding to supersonic and magnetic upflows. In addition, they
  are also related to the appearance of opposite polarities and highly
  inclined magnetic fields. This suggests that they are produced by the
  reconnection of emerging magnetic loops through granular upflows. The
  events occupy an average area of 0.046 arcsec<SUP>2</SUP> and last for
  about 80 s, with larger events having longer lifetimes. These supersonic
  events occur at a rate of 1.3 × 10<SUP>-5</SUP> occurrences per second
  per arcsec<SUP>2</SUP>.

Title: Detection of Vortex Tubes in Solar Granulation from
    Observations with SUNRISE
Authors: Steiner, O.; Franz, M.; Bello González, N.; Nutto, Ch.;
   Rezaei, R.; Martínez Pillet, V.; Bonet Navarro, J. A.; del Toro
   Iniesta, J. C.; Domingo, V.; Solanki, S. K.; Knölker, M.; Schmidt,
   W.; Barthol, P.; Gandorfer, A.
Bibcode: 2010ApJ...723L.180S
Altcode: 2010arXiv1009.4723S
  We have investigated a time series of continuum intensity maps and
  corresponding Dopplergrams of granulation in a very quiet solar region
  at the disk center, recorded with the Imaging Magnetograph eXperiment
  (IMaX) on board the balloon-borne solar observatory SUNRISE. We
  find that granules frequently show substructure in the form of lanes
  composed of a leading bright rim and a trailing dark edge, which move
  together from the boundary of a granule into the granule itself. We
  find strikingly similar events in synthesized intensity maps from an
  ab initio numerical simulation of solar surface convection. From cross
  sections through the computational domain of the simulation, we conclude
  that these granular lanes are the visible signature of (horizontally
  oriented) vortex tubes. The characteristic optical appearance of vortex
  tubes at the solar surface is explained. We propose that the observed
  vortex tubes may represent only the large-scale end of a hierarchy of
  vortex tubes existing near the solar surface.

Title: Where the Granular Flows Bend
Authors: Khomenko, E.; Martínez Pillet, V.; Solanki, S. K.; del Toro
   Iniesta, J. C.; Gandorfer, A.; Bonet, J. A.; Domingo, V.; Schmidt,
   W.; Barthol, P.; Knölker, M.
Bibcode: 2010ApJ...723L.159K
Altcode: 2010arXiv1008.0517K
  Based on IMaX/SUNRISE data, we report on a previously undetected
  phenomenon in solar granulation. We show that in a very narrow region
  separating granules and intergranular lanes, the spectral line width
  of the Fe I 5250.2 Å line becomes extremely small. We offer an
  explanation of this observation with the help of magneto-convection
  simulations. These regions with extremely small line widths correspond
  to the places where the granular flows bend from upflow in granules
  to downflow in intergranular lanes. We show that the resolution and
  image stability achieved by IMaX/SUNRISE are important requisites to
  detect this interesting phenomenon.

Title: Bright Points in the Quiet Sun as Observed in the Visible
    and Near-UV by the Balloon-borne Observatory SUNRISE
Authors: Riethmüller, T. L.; Solanki, S. K.; Martínez Pillet, V.;
   Hirzberger, J.; Feller, A.; Bonet, J. A.; Bello González, N.; Franz,
   M.; Schüssler, M.; Barthol, P.; Berkefeld, T.; del Toro Iniesta,
   J. C.; Domingo, V.; Gandorfer, A.; Knölker, M.; Schmidt, W.
Bibcode: 2010ApJ...723L.169R
Altcode: 2010arXiv1009.1693R
  Bright points (BPs) are manifestations of small magnetic elements
  in the solar photosphere. Their brightness contrast not only gives
  insight into the thermal state of the photosphere (and chromosphere) in
  magnetic elements, but also plays an important role in modulating the
  solar total and spectral irradiance. Here, we report on simultaneous
  high-resolution imaging and spectropolarimetric observations of
  BPs using SUNRISE balloon-borne observatory data of the quiet Sun
  at the disk center. BP contrasts have been measured between 214 nm
  and 525 nm, including the first measurements at wavelengths below
  388 nm. The histograms of the BP peak brightness show a clear trend
  toward broader contrast distributions and higher mean contrasts at
  shorter wavelengths. At 214 nm, we observe a peak brightness of up to
  five times the mean quiet-Sun value, the highest BP contrast so far
  observed. All BPs are associated with a magnetic signal, although in
  a number of cases it is surprisingly weak. Most of the BPs show only
  weak downflows, the mean value being 240 m s<SUP>-1</SUP>, but some
  display strong down- or upflows reaching a few km s<SUP>-1</SUP>.

Title: Transverse Component of the Magnetic Field in the Solar
    Photosphere Observed by SUNRISE
Authors: Danilovic, S.; Beeck, B.; Pietarila, A.; Schüssler, M.;
   Solanki, S. K.; Martínez Pillet, V.; Bonet, J. A.; del Toro Iniesta,
   J. C.; Domingo, V.; Barthol, P.; Berkefeld, T.; Gandorfer, A.;
   Knölker, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.149D
Altcode: 2010arXiv1008.1535D
  We present the first observations of the transverse component of
  a photospheric magnetic field acquired by the imaging magnetograph
  SUNRISE/IMaX. Using an automated detection method, we obtain statistical
  properties of 4536 features with significant linear polarization
  signal. We obtain a rate of occurrence of 7 × 10<SUP>-4</SUP>
  s<SUP>-1</SUP> arcsec<SUP>-2</SUP>, which is 1-2 orders of magnitude
  larger than the values reported by previous studies. We show that
  these features have no characteristic size or lifetime. They appear
  preferentially at granule boundaries with most of them being caught
  in downflow lanes at some point. Only a small percentage are entirely
  and constantly embedded in upflows (16%) or downflows (8%).

Title: Detection of Large Acoustic Energy Flux in the Solar Atmosphere
Authors: Bello González, N.; Franz, M.; Martínez Pillet, V.; Bonet,
   J. A.; Solanki, S. K.; del Toro Iniesta, J. C.; Schmidt, W.; Gandorfer,
   A.; Domingo, V.; Barthol, P.; Berkefeld, T.; Knölker, M.
Bibcode: 2010ApJ...723L.134B
Altcode: 2010arXiv1009.4795B
  We study the energy flux carried by acoustic waves excited by convective
  motions at sub-photospheric levels. The analysis of high-resolution
  spectropolarimetric data taken with IMaX/SUNRISE provides a total
  energy flux of ~6400-7700 W m<SUP>-2</SUP> at a height of ~250 km
  in the 5.2-10 mHz range, i.e., at least twice the largest energy
  flux found in previous works. Our estimate lies within a factor of
  two of the energy flux needed to balance radiative losses from the
  chromosphere according to the estimates of Anderson &amp; Athay and
  revives interest in acoustic waves for transporting energy to the
  chromosphere. The acoustic flux is mainly found in the intergranular
  lanes but also in small rapidly evolving granules and at the bright
  borders, forming dark dots and lanes of splitting granules.

Title: Magnetic Loops in the Quiet Sun
Authors: Wiegelmann, T.; Solanki, S. K.; Borrero, J. M.; Martínez
   Pillet, V.; del Toro Iniesta, J. C.; Domingo, V.; Bonet, J. A.;
   Barthol, P.; Gandorfer, A.; Knölker, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.185W
Altcode: 2010arXiv1009.4715W
  We investigate the fine structure of magnetic fields in the atmosphere
  of the quiet Sun. We use photospheric magnetic field measurements from
  SUNRISE/IMaX with unprecedented spatial resolution to extrapolate
  the photospheric magnetic field into higher layers of the solar
  atmosphere with the help of potential and force-free extrapolation
  techniques. We find that most magnetic loops that reach into the
  chromosphere or higher have one footpoint in relatively strong magnetic
  field regions in the photosphere. Ninety-one percent of the magnetic
  energy in the mid-chromosphere (at a height of 1 Mm) is in field
  lines, whose stronger footpoint has a strength of more than 300 G,
  i.e., above the equipartition field strength with convection. The
  loops reaching into the chromosphere and corona are also found to be
  asymmetric in the sense that the weaker footpoint has a strength B &lt;
  300 G and is located in the internetwork (IN). Such loops are expected
  to be strongly dynamic and have short lifetimes, as dictated by the
  properties of the IN fields.

Title: SUNRISE/IMaX Observations of Convectively Driven Vortex Flows
    in the Sun
Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Palacios,
   J.; Martínez Pillet, V.; Solanki, S. K.; del Toro Iniesta, J. C.;
   Domingo, V.; Berkefeld, T.; Schmidt, W.; Gandorfer, A.; Barthol, P.;
   Knölker, M.
Bibcode: 2010ApJ...723L.139B
Altcode: 2010arXiv1009.1992B
  We characterize the observational properties of the convectively driven
  vortex flows recently discovered on the quiet Sun, using magnetograms,
  Dopplergrams, and images obtained with the 1 m balloon-borne SUNRISE
  telescope. By visual inspection of time series, we find some 3.1
  × 10<SUP>-3</SUP> vortices Mm<SUP>-2</SUP> minute<SUP>-1</SUP>,
  which is a factor of ~1.7 larger than previous estimates. The mean
  duration of the individual events turns out to be 7.9 minutes, with
  a standard deviation of 3.2 minutes. In addition, we find several
  events appearing at the same locations along the duration of the time
  series (31.6 minutes). Such recurrent vortices show up in the proper
  motion flow field map averaged over the time series. The typical
  vertical vorticities are lsim6 × 10<SUP>-3</SUP> s<SUP>-1</SUP>,
  which corresponds to a period of rotation of some 35 minutes. The
  vortices show a preferred counterclockwise sense of rotation, which
  we conjecture may have to do with the preferred vorticity impinged by
  the solar differential rotation.

Title: Retrieval of solar magnetic fields from high-spatial resolution
filtergraph data: the Imaging Magnetograph eXperiment (IMaX)
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Martínez Pillet,
   V.; Bonet, J. A.; Vargas Domínguez, S.; Del Toro Iniesta, J. C.
Bibcode: 2010A&A...522A.101O
Altcode: 2010arXiv1006.5510O
  Context. The design of modern instruments does not only imply thorough
  studies of instrumental effects but also a good understanding of the
  scientific analysis planned for the data. <BR /> Aims: We investigate
  the reliability of Milne-Eddington (ME) inversions of high-resolution
  magnetograph measurements such as those to be obtained with the Imaging
  Magnetograph eXperiment (IMaX) aboard the Sunrise balloon. We also
  provide arguments to choose either Fe I 525.02 or 525.06 nm as the
  most suitable line for IMaX. <BR /> Methods: We reproduce an IMaX
  observation using magnetoconvection simulations of the quiet Sun
  and synthesizing the four Stokes profiles emerging from them. The
  profiles are degraded by spatial and spectral resolution, noise,
  and limited wavelength sampling, just as real IMaX measurements. We
  invert these data and estimate the uncertainties in the retrieved
  physical parameters caused by the ME approximation and the spectral
  sampling. <BR /> Results: It is possible to infer the magnetic field
  strength, inclination, azimuth, and line-of-sight velocity from
  standard IMaX measurements (4 Stokes parameters, 5 wavelength points,
  and a signal-to-noise ratio of 1000) applying ME inversions to any
  of the Fe I lines at 525 nm. We also find that telescope diffraction
  has important effects on the spectra coming from very high resolution
  observations of inhomogeneous atmospheres. Diffration reduces the
  amplitude of the polarization signals and changes the asymmetry of
  the Stokes profiles. <BR /> Conclusions: The two Fe I lines at 525 nm
  meet the scientific requirements of IMaX, but Fe I 525.02 nm is to be
  preferred because it leads to smaller uncertainties in the retrieved
  parameters and offers a better detectability of the weakest (linear)
  polarization signals prevailing in the quiet Sun.

Title: Surface Waves in Solar Granulation Observed with SUNRISE
Authors: Roth, M.; Franz, M.; Bello González, N.; Martínez Pillet,
   V.; Bonet, J. A.; Gandorfer, A.; Barthol, P.; Solanki, S. K.;
   Berkefeld, T.; Schmidt, W.; del Toro Iniesta, J. C.; Domingo, V.;
   Knölker, M.
Bibcode: 2010ApJ...723L.175R
Altcode: 2010arXiv1009.4790R
  Solar oscillations are expected to be excited by turbulent flows in
  the intergranular lanes near the solar surface. Time series recorded
  by the IMaX instrument on board the SUNRISE observatory reveal solar
  oscillations at high spatial resolution, which allow the study of
  the properties of oscillations with short wavelengths. We analyze
  two time series with synchronous recordings of Doppler velocity and
  continuum intensity images with durations of 32 minutes and 23 minutes,
  respectively, recorded close to the disk center of the Sun to study
  the propagation and excitation of solar acoustic oscillations. In
  the Doppler velocity data, both the standing acoustic waves and the
  short-lived, high-degree running waves are visible. The standing
  waves are visible as temporary enhancements of the amplitudes of the
  large-scale velocity field due to the stochastic superposition of
  the acoustic waves. We focus on the high-degree small-scale waves by
  suitable filtering in the Fourier domain. Investigating the propagation
  and excitation of f- and p <SUB>1</SUB>-modes with wavenumbers k&gt;1.4
  Mm<SUP>-1</SUP>, we also find that exploding granules contribute to
  the excitation of solar p-modes in addition to the contribution of
  intergranular lanes.

Title: Fully Resolved Quiet-Sun Magnetic flux Tube Observed with
    the SUNRISE/IMAX Instrument
Authors: Lagg, A.; Solanki, S. K.; Riethmüller, T. L.; Martínez
   Pillet, V.; Schüssler, M.; Hirzberger, J.; Feller, A.; Borrero,
   J. M.; Schmidt, W.; del Toro Iniesta, J. C.; Bonet, J. A.; Barthol, P.;
   Berkefeld, T.; Domingo, V.; Gandorfer, A.; Knölker, M.; Title, A. M.
Bibcode: 2010ApJ...723L.164L
Altcode: 2010arXiv1009.0996L
  Until today, the small size of magnetic elements in quiet-Sun areas has
  required the application of indirect methods, such as the line-ratio
  technique or multi-component inversions, to infer their physical
  properties. A consistent match to the observed Stokes profiles could
  only be obtained by introducing a magnetic filling factor that specifies
  the fraction of the observed pixel filled with magnetic field. Here,
  we investigate the properties of a small magnetic patch in the quiet
  Sun observed with the IMaX magnetograph on board the balloon-borne
  telescope SUNRISE with unprecedented spatial resolution and low
  instrumental stray light. We apply an inversion technique based on
  the numerical solution of the radiative transfer equation to retrieve
  the temperature stratification and the field strength in the magnetic
  patch. The observations can be well reproduced with a one-component,
  fully magnetized atmosphere with a field strength exceeding 1 kG and
  a significantly enhanced temperature in the mid to upper photosphere
  with respect to its surroundings, consistent with semi-empirical flux
  tube models for plage regions. We therefore conclude that, within the
  framework of a simple atmospheric model, the IMaX measurements resolve
  the observed quiet-Sun flux tube.

Title: Two-dimensional solar spectropolarimetry with the KIS/IAA
    Visible Imaging Polarimeter
Authors: Beck, C.; Bellot Rubio, L. R.; Kentischer, T. J.; Tritschler,
   A.; Del Toro Iniesta, J. C.
Bibcode: 2010A&A...520A.115B
Altcode: 2010arXiv1007.1153B
  Context. Spectropolarimetry at high spatial and spectral resolution
  is a basic tool to characterize the magnetic properties of the solar
  atmosphere. <BR /> Aims: We introduce the KIS/IAA Visible Imaging
  Polarimeter (VIP), a new post-focus instrument that upgrades the TESOS
  spectrometer at the German Vacuum Tower Telescope (VTT) into a full
  vector polarimeter. VIP is a collaboration between the Kiepenheuer
  Institut für Sonnenphysik (KIS) and the Instituto de Astrofísica
  de Andalucía (IAA-CSIC). <BR /> Methods: We describe the optical
  setup of VIP, the data acquisition procedure, and the calibration of
  the spectropolarimetric measurements. We show examples of data taken
  between 2005 and 2008 to illustrate the potential of the instrument. <BR
  /> Results: VIP is capable of measuring the four Stokes profiles of
  spectral lines in the range from 420 to 700 nm with a spatial resolution
  better than 0farcs5. Lines can be sampled at 40 wavelength positions
  in 60 s, achieving a noise level of about 2 × 10<SUP>-3</SUP> with
  exposure times of 300 ms and pixel sizes of 0farcs17 × 0farcs17 (2
  × 2 binning). The polarization modulation is stable over periods of a
  few days, ensuring high polarimetric accuracy. The excellent spectral
  resolution of TESOS allows the use of sophisticated data analysis
  techniques such as Stokes inversions. One of the first scientific
  results of VIP presented here is that the ribbon-like magnetic
  structures of the network are associated with a distinct pattern of
  net circular polarization away from disk center. <BR /> Conclusions:
  VIP performs spectropolarimetric measurements of solar magnetic fields
  at a spatial resolution that is only slightly worse than that of the
  Hinode spectropolarimeter, while providing a 2D field field of view and
  the possibility to observe up to four spectral regions sequentially
  with high cadence. VIP can be used as a stand-alone instrument or in
  combination with other spectropolarimeters and imaging systems of the
  VTT for extended wavelength coverage.

Title: Milne-Eddington inversion of the Fe I line pair at 630 nm
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Del Toro Iniesta,
   J. C.
Bibcode: 2010A&A...518A...3O
Altcode: 2010arXiv1005.5013S; 2010arXiv1005.5013O
  Context. The iron lines at 630.15 and 630.25 nm are often used to
  determine the physical conditions of the solar photosphere. A common
  approach is to invert them simultaneously under the Milne-Eddington
  approximation. The same thermodynamic parameters are employed for the
  two lines, except for their opacities, which are assumed to have a
  constant ratio. <BR /> Aims: We aim at investigating the validity of
  this assumption, since the two lines are not exactly the same. <BR
  /> Methods: We use magnetohydrodynamic simulations of the quiet
  Sun to examine the behavior of the ME thermodynamic parameters and
  their influence on the retrieval of vector magnetic fields and flow
  velocities. <BR /> Results: Our analysis shows that the two lines can
  be coupled and inverted simultaneously using the same thermodynamic
  parameters and a constant opacity ratio. The inversion of two lines
  is significantly more accurate than single-line inversions because of
  the larger number of observables.

Title: Applicability of Milne-Eddington inversions to high spatial
    resolution observations of the quiet Sun
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Vögler, A.; Del
   Toro Iniesta, J. C.
Bibcode: 2010A&A...518A...2O
Altcode: 2010arXiv1005.5012O
  Context. The physical conditions of the solar photosphere change on
  very small spatial scales both horizontally and vertically. Such a
  complexity may pose a serious obstacle to the accurate determination
  of solar magnetic fields. <BR /> Aims: We examine the applicability of
  Milne-Eddington (ME) inversions to high spatial resolution observations
  of the quiet Sun. Our aim is to understand the connection between
  the ME inferences and the actual stratifications of the atmospheric
  parameters. <BR /> Methods: We use magnetoconvection simulations of
  the solar surface to synthesize asymmetric Stokes profiles such as
  those observed in the quiet Sun. We then invert the profiles with the
  ME approximation. We perform an empirical analysis of the heights of
  formation of ME measurements and analyze the uncertainties brought
  about by the ME approximation. We also investigate the quality of the
  fits and their relationship with the model stratifications. <BR />
  Results: The atmospheric parameters derived from ME inversions of
  high-spatial resolution profiles are reasonably accurate and can be
  used for statistical analyses of solar magnetic fields, even if the
  fit is not always good. We also show that the ME inferences cannot be
  assigned to a specific atmospheric layer: different parameters sample
  different ranges of optical depths, and even the same parameter
  may trace different layers depending on the physical conditions
  of the atmosphere. Despite this variability, ME inversions tend
  to probe deeper layers in granules than in intergranular lanes. <P
  />Figure 10 and appendix are only available in electronic form at <A
  href="http://www.aanda.org">http://www.aanda.org</A>

Title: The IMaX polarimeter for the solar telescope SUNRISE of the
    NASA long duration balloon program
Authors: Alvarez-Herrero, A.; Martínez-Pillet, V.; Del Toro Iniesta,
   J. C.; Domingo, V.
Bibcode: 2010EPJWC...505002A
Altcode:
  On June 8th 2009 the SUNRISE mission was successfully launched. This
  mission consisted of a 1m aperture solar telescope on board of a
  stratospheric balloon within the Long Duration Balloon NASA program. The
  flight followed the foreseen circumpolar trajectory over the Artic
  and the duration was 5 days and 17 hours. One of the two postfocal
  instruments onboard was IMaX, the Imaging Magnetograph eXperiment. This
  instrument is a solar magnetograph which is a diffraction limited imager
  capable to resolve 100 km on the solar surface, and simultaneously
  a high sensitivity polarimeter (&lt;10<SUP>-3</SUP>) and a high
  resolution spectrograph (bandwidth &lt;70mÅ). The magnetic vectorial
  map can be extracted thanks to the well-know Zeeman effect, which takes
  place in the solar atoms, allowing to relate polarization and spectral
  measurements to magnetic fields. The technological challenge of the IMaX
  development has a special relevance due to the utilization of innovative
  technologies in the Aeroespacial field and it is an important precedent
  for future space missions such as Solar Orbiter from ESA. Among these
  novel technologies the utilization of Liquid Crystal Variable Retarders
  (LCVRs) as polarization modulators and a LiNbO<SUB>3</SUB> etalon as
  tunable spectral filter are remarkable. Currently the data obtained
  is being analyzed and the preliminary results show unprecedented
  information about the solar dynamics.

Title: Size matters
Authors: del Toro Iniesta, J. C.; Orozco Suárez, D.
Bibcode: 2010AN....331..558D
Altcode: 2010arXiv1002.3106D
  The new generation of ground-based, large-aperture solar telescopes
  promises to significantly increase our capabilities to understand the
  many basic phenomena taking place in the Sun at all atmospheric layers
  and how they relate to each other. A (non-exhaustive) summary of the
  main scientific arguments to pursue these impressive technological goals
  is presented. We illustrate how imaging, polarimetry, and spectroscopy
  can benefit from the new telescopes and how several wavelength bands
  should be observed to study the atmospheric coupling from the upper
  convection zone all the way to the corona. The particular science case
  of sunspot penumbrae is barely discussed as a specific example.

Title: On Spectropolarimetric Measurements with Visible Lines
Authors: del Toro Iniesta, J. C.; Orozco Suárez, D.; Bellot Rubio,
   L. R.
Bibcode: 2010ApJ...711..312D
Altcode: 2010arXiv1001.3022D
  The ability of new instruments for providing accurate inferences of
  vector magnetic fields and line-of-sight velocities of the solar
  plasma depends a great deal on the sensitivity to these physical
  quantities of the spectral lines chosen to be measured. Recently,
  doubts have been raised about visible Stokes profiles to provide
  a clear distinction between weak fields and strong ones filling a
  small fraction of the observed area. The goal of this paper is to
  give qualitative and quantitative arguments that help in settling the
  debate since several instruments that employ visible lines are either
  operating or planned for the near future. The sensitivity of the Stokes
  profiles is calculated through the response functions (RFs), for e.g.,
  by Ruiz Cobo &amp; Del Toro Iniesta. Both theoretical and empirical
  evidences are gathered in favor of the reliability of visible Stokes
  profiles. The RFs are also used for estimating the uncertainties in
  the physical quantities due to noise in observations. A useful formula
  has been derived that takes into account the measurement technique
  (number of polarization measurements, polarimetric efficiencies, and
  number of wavelength samples), the model assumptions (number of free
  parameters and the filling factor), and the radiative transfer (RFs). We
  conclude that a scenario with a weak magnetic field can reasonably
  be distinguished with visible lines from another with a strong field
  but a similar Stokes V amplitude, provided that the Milne-Eddington
  approximation is good enough to describe the solar atmosphere and the
  polarization signal is at least 3 or 4 times larger than the typical
  rms noise of 10<SUP>-3</SUP> I <SUB>c</SUB> reached in the observations.

Title: ASTRONET: Public Outreach
Authors: Ros, R. M.; Fosbury, R.; Christensen, L. L.; Del Toro Iniesta,
   J. C.; Fucili, L.; Hill, R.; Lorenzen, D.; Madsen, C.; Newsam, A.;
   Pickwick, A.; Radeva, V.
Bibcode: 2009CAPJ....5...26R
Altcode:
  We have all seen the spectacular images that the Hubble Space Telescope
  and other such observatories have revealed to the world. Their haunting
  splendour inspires and compels us as artists. But how can we capture
  the elusive essence of space in our own work?

Title: ASTRONET Panel E: Education, recruitment/training &amp;
    public outreach
Authors: Hill, Robert; Ros, Rosa Maria; Fosbury, Robert; Christensen,
   Lars Lindberg; Fucili, Leonarda; Lorenzen, Dirk; del Toro Iniesta, Jose
   Carlos; Madsen, Claus; Newsam, Andy; Pickwick, Alan; Radeva, Veselka
Bibcode: 2008ca07.conf..166H
Altcode:
  ASTRONET was created by a group of European funding agencies in order
  to establish a comprehensive long-term plan for the development of
  European astronomy. The objective of this effort is to consolidate
  and reinforce the world-leading position that European astronomy has
  attained at the beginning of this 21st century. This presentation
  concentrates on the work of Panel E.

Title: Magnetic field emergence in quiet Sun granules
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
   J. C.; Tsuneta, S.
Bibcode: 2008A&A...481L..33O
Altcode: 2007arXiv0712.2663O
  Aims:We describe a new form of small-scale magnetic flux emergence in
  the quiet Sun. This process seems to take vertical magnetic fields
  from subsurface layers to the photosphere, where they appear above
  granular convection cells. <BR />Methods: High-cadence time series
  of spectropolarimetric measurements obtained by Hinode in a quiet
  region near disk center are analyzed. We extract line parameters from
  the observed Stokes profiles and study their evolution with time. <BR
  />Results: The circular polarization maps derived from the observed Fe
  I 630 nm lines show clear magnetic signals emerging at the center of
  granular cells. We do not find any evidence for linear polarization
  signals associated with these events. The magnetic flux patches grow
  with time, occupying a significant fraction of the granular area. The
  signals then fade until they disappear completely. The typical lifetime
  of these events is of the order of 20 min. No significant changes in
  the chromosphere are seen to occur in response to the emergence, as
  revealed by co-spatial Ca II H filtergrams. The Stokes I and V profiles
  measured in the emerging flux concentrations show strong asymmetries
  and Doppler shifts. <BR />Conclusions: The origin of these events is
  unclear at present, but we suggest that they may represent the emergence
  of vertical fields lines from the bottom of the photosphere, possibly
  dragged by the convective upflows of granules. Preliminary inversions
  of the Stokes spectra indicate that this scenario is compatible with
  the observations, although the emergence of vertical field lines is
  not free from conceptual problems.

Title: Temporal evolution of the Evershed flow in
    sunspots. II. Physical properties and nature of Evershed clouds
Authors: Cabrera Solana, D.; Bellot Rubio, L. R.; Borrero, J. M.;
   Del Toro Iniesta, J. C.
Bibcode: 2008A&A...477..273C
Altcode: 2007arXiv0709.1601C
  Context: Evershed clouds (ECs) represent the most conspicuous
  variation of the Evershed flow in sunspot penumbrae. <BR />Aims:
  We determine the physical properties of ECs from high spatial and
  temporal resolution spectropolarimetric measurements. This information
  is used to investigate the nature of the EC phenomenon. <BR />Methods:
  The Stokes profiles of four visible and three infrared spectral lines
  are subject to inversions based on simple one-component models as well
  as more sophisticated realizations of penumbral flux tubes embedded
  in a static ambient field (uncombed models). <BR />Results: According
  to the one-component inversions, the EC phenomenon can be understood
  as a perturbation of the magnetic and dynamic configuration of the
  penumbral filaments along which the ECs move. The uncombed inversions,
  on the other hand, suggest that ECs are the result of enhancements
  in the visibility of penumbral flux tubes. We conjecture that
  these enhancements are caused by a perturbation of the thermodynamic
  properties of the tubes, rather than by changes in the vector magnetic
  field. This mechanism is investigated performing numerical experiments
  of thick penumbral tubes in mechanical equilibrium with a background
  field. <BR />Conclusions: While the one-component inversions confirm
  many of the properties indicated by a simple line parameter analysis
  (Paper I of this series), we give more credit to the results of the
  uncombed inversions because they take into account, at least in an
  approximate manner, the fine structure of the penumbra. <P />Appendix
  A is only available in electronic form at http://www.aanda.org

Title: Temporal evolution of the Evershed flow in
    sunspots. I. Observational characterization of Evershed clouds
Authors: Cabrera Solana, D.; Bellot Rubio, L. R.; Beck, C.; Del Toro
   Iniesta, J. C.
Bibcode: 2007A&A...475.1067C
Altcode: 2007arXiv0707.2629C
  Context: The magnetic and kinematic properties of the photospheric
  Evershed flow are relatively well known, but not completely
  understood. The evolution of the flow with time, which is mainly due
  to the appearance of velocity packets called Evershed clouds (ECs),
  may provide information to further constrain its origin. <BR />Aims:
  We undertake a detailed analysis of the evolution of the Evershed flow
  by studying the properties of ECs. In this first paper we determine
  the sizes, proper motions, location in the penumbra, and frequency
  of appearance of ECs, as well as their typical Doppler velocities,
  linear and circular polarization signals, Stokes V area asymmetries,
  and continuum intensities. <BR />Methods: High-cadence, high-resolution,
  full vector spectropolarimetric measurements in visible and infrared
  lines are used to characterize the EC phenomenon through a simple
  line-parameter analysis. <BR />Results: ECs appear in the mid penumbra
  and propagate outward along filaments having large linear polarization
  signals and enhanced Evershed flows. The frequency of appearance of
  ECs varies between 15 and 40 min in different filaments. ECs exhibit
  the largest Doppler velocities and linear-to-circular polarization
  ratios of the whole penumbra. In addition, lines formed deeper in the
  atmosphere show larger Doppler velocities, much in the same way as
  the “quiescent” Evershed flow. According to our observations, ECs
  can be classified in two groups: type I ECs, which vanish in the outer
  penumbra, and type II ECs, which cross the outer penumbral boundary and
  enter the sunspot moat. Most of the observed ECs belong to type I. On
  average, type II ECs can be detected as velocity structures outside
  of the spot for only about 14 min. Their proper motions in the moat
  are significantly reduced with respect to the ones they had in the
  penumbra. <P />Appendices A and B are only available in electronic
  form at http://www.aanda.org

Title: Quiet-Sun Internetwork Magnetic Fields from the Inversion of
    Hinode Measurements
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
   J. C.; Tsuneta, S.; Lites, B. W.; Ichimoto, K.; Katsukawa, Y.; Nagata,
   S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
   A. M.
Bibcode: 2007ApJ...670L..61O
Altcode: 2007arXiv0710.1405O
  We analyze Fe I 630 nm observations of the quiet Sun at disk center
  taken with the spectropolarimeter of the Solar Optical Telescope aboard
  the Hinode satellite. A significant fraction of the scanned area,
  including granules, turns out to be covered by magnetic fields. We
  derive field strength and inclination probability density functions from
  a Milne-Eddington inversion of the observed Stokes profiles. They show
  that the internetwork consists of very inclined, hG fields. As expected,
  network areas exhibit a predominance of kG field concentrations. The
  high spatial resolution of Hinode's spectropolarimetric measurements
  brings to an agreement the results obtained from the analysis of
  visible and near-infrared lines.

Title: Strategy for the Inversion of Hinode Spectropolarimetric
    Measurements in the Quiet Sun
Authors: Orozco Suárez, David; Bellot Rubio, Luis R.; Del Toro
   Iniesta, Jose Carlos; Tsuneta, Saku; Lites, Bruce; Ichimoto, Kiyoshi;
   Katsukawa, Yukio; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
   Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.837O
Altcode: 2007arXiv0709.2033O
  In this paper we propose an inversion strategy for the analysis of
  spectropolarimetric measurements taken by Hinode in the quiet Sun. The
  Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records
  the Stokes spectra of the FeI line pair at 630.2nm with unprecendented
  angular resolution, high spectral resolution, and high sensitivity. We
  discuss the need to consider a local stray-light contamination to
  account for the effects of telescope diffraction. The strategy is
  applied to observations of a wide quiet Sun area at disk center. Using
  these data we examine the influence of noise and initial guess models
  in the inversion results. Our analysis yields the distributions of
  magnetic field strengths and stray-light factors. They show that quiet
  Sun internetwork regions consist mainly of hG fields with stray-light
  contamination of about 0.8.

Title: Vector Spectropolarimetry of Dark-cored Penumbral Filaments
    with Hinode
Authors: Bellot Rubio, L. R.; Tsuneta, S.; Ichimoto, K.; Katsukawa,
   Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
   Y.; Tarbell, T. D.; Title, A. M.; del Toro Iniesta, J. C.
Bibcode: 2007ApJ...668L..91B
Altcode: 2007arXiv0708.2791B
  We present spectropolarimetric measurements of dark-cored penumbral
  filaments taken with Hinode at a resolution of 0.3". Our observations
  demonstrate that dark-cored filaments are more prominent in polarized
  light than in continuum intensity. Far from disk center, the Stokes
  profiles emerging from these structures are very asymmetric and show
  evidence for magnetic fields of different inclinations along the
  line of sight, together with strong Evershed flows of at least 6-7 km
  s<SUP>-1</SUP>. In sunspots closer to disk center, dark-cored penumbral
  filaments exhibit regular Stokes profiles with little asymmetries due
  to the vanishing line-of-sight component of the horizontal Evershed
  flow. An inversion of the observed spectra indicates that the magnetic
  field is weaker and more inclined in the dark cores as compared with
  the surrounding bright structures. This is compatible with the idea
  that dark-cored filaments are the manifestation of flux tubes carrying
  hot Evershed flows.

Title: Quiet-Sun Magnetic Fields from Space-borne Observations:
    Simulating Hinode's Case
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
   J. C.
Bibcode: 2007ApJ...662L..31O
Altcode: 2007arXiv0705.0096O
  We examine whether it is possible to derive the field strength
  distribution of quiet-Sun internetwork regions from very high spatial
  resolution polarimetric observations in the visible. In particular,
  we consider the case of the spectropolarimeter attached to the Solar
  Optical Telescope aboard Hinode. Radiative magnetoconvection simulations
  are used to synthesize the four Stokes profiles of the Fe I 630.2
  nm lines. Once the profiles are degraded to a spatial resolution of
  0.32" and added noise, we infer the atmospheric parameters by means
  of Milne-Eddington inversions. The comparison of the derived values
  with the real ones indicates that the visible lines yield correct
  internetwork field strengths and magnetic fluxes, with uncertainties
  smaller than ~150 G, when a stray-light contamination factor is
  included in the inversion. Contrary to the results of ground-based
  observations at 1", weak fields are retrieved wherever the field is
  weak in the simulation.

Title: Introduction to Spectropolarimetry
Authors: del Toro Iniesta, Jose Carlos
Bibcode: 2007insp.book.....D
Altcode:
  Preface; Acknowledgements; 1. Historical introduction; 2. A
  review of some basic concepts; 3. The polarization properties
  of quasi-monochromatic light; 4. Linear optical systems acting on
  polarized light; 5. Solar polarimetry; 6. Absorption and dispersion;
  7. The radiative transfer equation; 8. The RTE in the presence of a
  magnetic field; 9. Solving the radiative transfer equation; 10. Stokes
  spectrum diagnostics; 11. Inversion of the RTE; Index.

Title: The usefulness of analytic response functions
Authors: Orozco Suárez, D.; Del Toro Iniesta, J. C.
Bibcode: 2007A&A...462.1137O
Altcode: 2012arXiv1211.1502O
  Aims:We introduce analytical response functions and their main
  properties as an important diagnostic tool that help understand Stokes
  profile formation physics and the meaning of well-known behaviors of
  standard inversion codes of the radiative transfer equation often used
  to measure solar magnetic fields. <BR />Methods: A Milne-Eddington
  model atmosphere is used as an example where response functions are
  analytical. A sample spectral line has been chosen to show the main
  qualitative properties. <BR />Results: We show that analytic response
  functions readily provide explanations for various well-known behaviors
  of spectral lines, such as the sensitivity of visible lines to weak
  magnetic fields or the trade-offs often detected in inversion codes
  between the Milne-Eddington thermodynamic parameters. We also show
  that response functions are helpful in selecting sample wavelengths
  optimized for specific parameter diagnostics. <P />Appendix A is only
  available in electronic form at http://www.aanda.org

Title: S im ulation And Analysis Of VIM Measurements: Feedback On
    Design Parameters
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Vargas, S.; Bonet,
   J. A.; Martíez Pillet, V.; del Toro Iniesta, J. C.
Bibcode: 2007ESASP.641E..49O
Altcode: 2006astro.ph.11443O
  The Visible-light Imager and Magnetograph (VIM) proposed for the
  ESA Solar Orbiter mission will observe a photo spheric spectral
  line at high spatial resolution. Here we simulate and interpret VIM
  measurements. Realistic MHD models are used to synthesize "observed"
  Stokes profiles of the photospheric Fe I 617.3 nm line. The profiles are
  degraded by telescope diffraction and detector pixel size to a spatial
  resolution of 162 km on the solar surface. We stufy the influence
  of spectral resolving power, noise, and limited wavelength sampling
  on the vector magnetic fields and line-of-sight velocities derived
  from Milne-Eddington inversions of the simulated measurements. VIM
  will provide reasonably accurate values of the atmospheric parametes
  even with the filter widths of 120 Å and 3 wavelength positions plus
  continuum, as long as the noise level is kept below 10-3 Ic.

Title: First Steps Towards the Electronic Inversion of the Radiative
    Transfer Equation
Authors: Castillo Lorenzo, J. L.; Orozco Suárez, D.; Bellot Rubio,
   L. R.; Jiménez, L.; Del Toro Iniesta, J. C.
Bibcode: 2006ASPC..358..177C
Altcode:
  The radiative transfer equation (RTE) gives us information about how the
  light streams through the medium. It must be inverted in order to obtain
  the properties of the medium that generated the observation. While
  there are a number of well discussed methods to approach the solution
  of the inversion, none of them is suitable for the real-time analysis
  of high-resolution images due to their computational requirements. This
  document introduces an electronic inverter for the RTE, suitable for
  real-time inversion and mainly intended for space missions and on-line
  ground-based observations.

Title: Inversion of Visible and IR Stokes Profiles in Sunspots
Authors: Cabrera Solana, D.; Bellot Rubio, L. R.; Beck, C.; Del Toro
   Iniesta, J. C.
Bibcode: 2006ASPC..358...25C
Altcode:
  We present an analysis of simultaneous observations of a sunspot
  in two different spectral ranges (630 nm and 1565 nm). The dataset
  was acquired with the POlarimetric LIttrow Spectrograph (POLIS) and
  the Tenerife Infrared Polarimeter (TIP) at the German Vacuum Tower
  Telescope (VTT) of Observatorio del Teide. Inversions of both sets
  of lines are carried out to retrieve physical quantities such as
  temperature and magnetic fields. We find that: a) the differences
  between the atmospheric parameters inferred from the two ranges
  are small, demonstrating that inversion techniques provide unique
  results; b) there is a cross-talk between temperature and stray light
  for visible lines; c) a more realistic treatment of the stray light
  contamination is required. Making use of both visible and infrared
  lines we obtain &lt; dB/dz &gt;=-2.3±0.6 G km<SUP>-1</SUP> and &lt;
  dγ/dz &gt;=-0.019±0.015 deg km<SUP>-1</SUP> in the umbra. Finally,
  we show how simultaneous spectro-polarimetric observations of the Sun
  in visible and infrared wavelengths improve the diagnostic capabilities
  of a single spectral range alone.

Title: Milne-Eddington Response Functions and Their Applications
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Del Toro Iniesta,
   J. C.
Bibcode: 2006ASPC..358..197O
Altcode:
  We examine the errors in the atmospheric parameters recovered
  from the inversion of spectro-polarimetric data with limited
  wavelength sampling. We suggest that response functions evaluated in
  Milne-Eddington atmospheres may be useful as diagnostic tools that
  allow, for instance, the selection of the optimum wavelength positions
  to be observed by vector magnetographs.

Title: Evershed Clouds as Precursors of Moving Magnetic Features
    around Sunspots
Authors: Cabrera Solana, D.; Bellot Rubio, L. R.; Beck, C.; del Toro
   Iniesta, J. C.
Bibcode: 2006ApJ...649L..41C
Altcode: 2006astro.ph..9108C
  The relation between the Evershed flow and moving magnetic features
  (MMFs) is studied using high-cadence, simultaneous spectropolarimetric
  measurements of a sunspot in visible (630.2 nm) and near-infrared
  (1565 nm) lines. Doppler velocities, magnetograms, and total linear
  polarization maps are calculated from the observed Stokes profiles. We
  follow the temporal evolution of two Evershed clouds that move radially
  outward along the same penumbral filament. Eventually, the clouds
  cross the visible border of the spot and enter the moat region, where
  they become MMFs. The flux patch farther from the sunspot has the same
  polarity of the spot, while the MMF closer to it has opposite polarity
  and exhibits abnormal circular polarization profiles. Our results
  provide strong evidence that at least some MMFs are the continuation
  of the penumbral Evershed flow into the moat. This, in turn, suggests
  that MMFs are magnetically connected to sunspots.

Title: VIP - 2D Vector Spectropolarimetry of the Solar Atmosphere
    near the Diffraction Limit
Authors: Bellot Rubio, L. R.; Tritschler, A.; Kentischer, T.; Beck,
   C.; Del Toro Iniesta, J. C.
Bibcode: 2006IAUJD...3E..58B
Altcode:
  The KIS/IAA Vector Imaging Polarimeter (VIP) is a new instrument for
  two-dimensional spectropolarimetry of the solar atmosphere. It is used
  with TESOS, the triple etalon Fabry-Perot interferometer installed at
  the German Vacuum Tower Telescope of Observatorio del Teide (Tenerife,
  Spain). The polarimeter is based on a pair of nematic liquid crystal
  retarders and a Wollaston prism. VIP and TESOS are able to observe
  any spectral line in the range from 450 nm to 750 nm with a spectral
  resolving power of about 250000 and spatial resolutions better than
  0.5" (thanks to the Kiepenheuer Adaptive Optics System). Typically,
  the four Stokes parameters of a line can be measured at 40 wavelength
  points in less than 60 s, with a noise level of 1-2 x 10^-3 and a
  pixel size of 0.18" x 0.18" (2x2 binning). The modulation matrix of
  VIP is derived using the polarimetric calibration unit installed at
  the telescope. Here we present first-light observations of VIP carried
  out in November 2005. We recorded the full Stokes profiles of the 630.1
  and 630.2 nm Fe I lines emerging from a solar pore and its surroundings
  at a spatial resolution of ~0.4". Based on these data, we discuss the
  performance and capabilities of VIP as a powerful instrument for high
  spatial and temporal resolution measurements of vector magnetic fields
  in the solar atmosphere.

Title: Detailed design of the imaging magnetograph experiment (IMaX):
    a visible imager magnetograph for the Sunrise mission
Authors: Álvarez-Herrero, A.; Belenguer, T.; Pastor, C.; González,
   L.; Heredero, R. L.; Ramos, G.; Reina, M.; Sánchez, A.; Villanueva,
   J.; Sabau, L.; Martínez Pillet, V.; Bonet, J. A.; Collados, M.;
   Jochum, L.; Ballesteros, E.; Medina Trujillo, J. L.; Ruiz, Cobo B.;
   González, J. C.; del Toro Iniesta, J. C.; López Jiménez, A. C.;
   Castillo Lorenzo, J.; Herranz, M.; Jerónimo, J. M.; Mellado, P.;
   Morales, R.; Rodríguez, J.; Domingo, V.; Gasent, J. L.; Rodríquez, P.
Bibcode: 2006SPIE.6265E..4CA
Altcode: 2006SPIE.6265E.132A
  In this work, it is described the Imaging Magnetograph eXperiment,
  IMaX, one of the three postfocal instruments of the Sunrise mission. The
  Sunrise project consists on a stratospheric balloon with a 1 m aperture
  telescope, which will fly from the Antarctica within the NASA Long
  Duration Balloon Program. IMaX will provide vector magnetograms
  of the solar surface with a spatial resolution of 70 m. This data
  is relevant for understanding how the magnetic fields emerge in
  the solar surface, how they couple the photospheric base with the
  million degrees of temperature of the solar corona and which are the
  processes that are responsible of the generation of such an immense
  temperatures. To meet this goal IMaX should work as a high sensitivity
  polarimeter, high resolution spectrometer and a near diffraction
  limited imager. Liquid Crystal Variable Retarders will be used as
  polarization modulators taking advantage of the optical retardation
  induced by application of low electric fields and avoiding mechanical
  mechanisms. Therefore, the interest of these devices for aerospace
  applications is envisaged. The spectral resolution required will be
  achieved by using a LiNbO <SUB>3</SUB> Fabry-Perot etalon in double
  pass configuration as spectral filter before the two CCDs detectors. As
  well phase-diversity techniques will be implemented in order to improve
  the image quality. Nowadays, IMaX project is in the detailed design
  phase before fabrication, integration, assembly and verification. This
  paper briefly describes the current status of the instrument and the
  technical solutions developed to fulfil the scientific requirements.

Title: The many scales in the universe : JENAM 2004 astrophysics
    reviews
Authors: Del Toro Iniesta, Jose Carlos; Alfaro, Emilio J.; Gorgas,
   J. G.; Salvador-Sole, E.; Butcher, H.
Bibcode: 2006msu..conf.....D
Altcode:
  No abstract at ADS

Title: Sensitivity of spectral lines to temperature, velocity,
    and magnetic field
Authors: Cabrera Solana, D.; Bellot Rubio, L. R.; del Toro Iniesta,
   J. C.
Bibcode: 2005A&A...439..687C
Altcode:
  We present an analytical and numerical study of the sensitivity of
  weak solar photospheric lines to temperature, velocity, and magnetic
  fields. Our investigation is based on the concept of response functions
  (Landi degl'Innocenti &amp; Landi degl'Innocenti 1977; Ruiz Cobo &amp;
  del Toro Iniesta 1994). Lines commonly used in solar spectropolarimetry,
  like Fe I 630.25 nm in the visible and Fe I 1564.85 nm in the infrared,
  are examined in detail as emerging from reference quiet Sun and sunspot
  models. We develop a simple phenomenological model capable of describing
  the response of any given line to these atmospheric parameters. We
  find that: (a) the sensitivity of the lines to velocity and magnetic
  fields increases with the sharpness of the intensity and circular
  polarization profiles; (b) the sensitivity to temperature is determined
  mainly by the variation of the source function with temperature,
  which is smaller at longer wavelengths; and (c) lines quoted to be
  insensitive to temperature, like Fe I 1564.85 nm and Fe I 557.61 nm,
  exhibit larger changes in equivalent width than lines presumed to
  have higher sensitivities to T, such as Fe I 630.25 nm. The relations
  provided by our model are universal and can be used to decide which
  line is better suited to measuring a given atmospheric parameter. The
  results of this study are of practical interest for the design of new
  instruments and for better exploitation of existing ones.

Title: The imaging magnetograph eXperiment for the SUNRISE balloon
    Antarctica project
Authors: Martinez Pillet, Valentin; Bonet, Jose A.; Collados, Manuel
   V.; Jochum, Lieselotte; Mathew, S.; Medina Trujillo, J. L.; Ruiz Cobo,
   B.; del Toro Iniesta, Jose Carlos; Lopez Jimenez, A. C.; Castillo
   Lorenzo, J.; Herranz, M.; Jeronimo, J. M.; Mellado, P.; Morales, R.;
   Rodriguez, J.; Alvarez-Herrero, Alberto; Belenguer, Tomas; Heredero,
   R. L.; Menendez, M.; Ramos, G.; Reina, Manuel; Pastor, C.; Sanchez,
   A.; Villanueva, J.; Domingo, Vicente; Gasent, J. L.; Rodriguez, P.
Bibcode: 2004SPIE.5487.1152M
Altcode:
  The SUNRISE balloon project is a high-resolution mission to study solar
  magnetic fields able to resolve the critical scale of 100 km in the
  solar photosphere, or about one photon mean free path. The Imaging
  Magnetograph eXperiment (IMaX) is one of the three instruments that
  will fly in the balloon and will receive light from the 1m aperture
  telescope of the mission. IMaX should take advantage of the 15 days
  of uninterrupted solar observations and the exceptional resolution
  to help clarifying our understanding of the small-scale magnetic
  concentrations that pervade the solar surface. For this, IMaX should
  act as a diffraction limited imager able to carry out spectroscopic
  analysis with resolutions in the 50.000-100.000 range and capable
  to perform polarization measurements. The solutions adopted by the
  project to achieve all these three demanding goals are explained in this
  article. They include the use of Liquid Crystal Variable Retarders for
  the polarization modulation, one LiNbO<SUB>3</SUB> etalon in double pass
  and two modern CCD detectors that allow for the application of phase
  diversity techniques by slightly changing the focus of one of the CCDs.

Title: An orthonormal set of Stokes profiles
Authors: del Toro Iniesta, J. C.; López Ariste, A.
Bibcode: 2003A&A...412..875D
Altcode:
  A family of well-known orthonormal functions, the set of Hermite
  functions, is proposed as a suitable basis for expanding the
  Stokes profiles of any spectral line. An expansion series thus
  provides different degrees of approximation to the Stokes spectrum,
  depending on the number of basis elements used (or on the number
  of coefficients). Hence, an usually large number of wavelength
  samples, may be substituted by a few such coefficients, thus reducing
  considerably the size of data files and the analysis of observable
  information. Moreover, since the set of Hermite functions is an
  universal basis, it promises to help in modern inversion techniques
  of the radiative transfer equation that infer the solar physical
  quantities from previously compiled look-up tables or artificial neural
  networks. These features appear to be particularly important in modern
  solar applications producing huge amounts of spectropolarimetric data
  and on near-future, on-line applications aboard spacecrafts.

Title: Accurate atomic parameters for near-infrared spectral lines
Authors: Borrero, J. M.; Bellot Rubio, L. R.; Barklem, P. S.; del
   Toro Iniesta, J. C.
Bibcode: 2003A&A...404..749B
Altcode:
  A realistic two-component model of the quiet solar photosphere is
  used to fit the intensity spectrum of the Sun in the wavelength
  range 0.98-1.57 mu m. Our approach differs from earlier attempts in
  many respects: proper account of convective inhomogeneities is made,
  accurate collisional broadening parameters from quantum mechanical
  computations are used, and the effects of possible blends in the local
  continuum are corrected empirically. This allows us to derive oscillator
  strengths and central wavelengths for virtually any unblended line of
  the solar spectrum. The accuracy of the inferred atomic parameters,
  about 0.06 dex for oscillator strengths and 5 mÅ at 1 mu m for central
  wavelengths, is similar to that of the best laboratory measurements. We
  apply our method to 83 near-infrared lines belonging to 6 different
  atomic species. The availability of accurate oscillator strengths and
  central wavelengths for lines of different species is essential for
  the interpretation of high resolution spectroscopic observations. The
  method is especially useful in the infrared, a wavelength domain where
  laboratory measurements are scarce.

Title: Introduction to Spectropolarimetry
Authors: del Toro Iniesta, José Carlos
Bibcode: 2003isp..book.....D
Altcode: 2003insp.book.....D
  Spectropolarimetry embraces the most complete and detailed measurement
  and analysis of light, as well as its interaction with matter. This book
  provides an introductory overview of the subject because it is playing
  an increasingly important role in modern solar observations. Chapters
  include a comprehensive description of the polarization state of
  polychromatic light and its measurement; an overview of astronomical
  polarimetry; and the formation of spectral lines in the presence of
  a magnetic field. The text is a valuable reference for graduates and
  researchers in astrophysics, solar physics and optics.

Title: IMax: a visible magnetograph for SUNRISE
Authors: Jochum, Lieselotte; Collados, Manuel; Martínez Pillet,
   Valentin; Bonet, Jose A.; del Toro Iniesta, Jose Carlos; Lopez,
   Antonio; Alvarez-Herrero, Alberto; Reina, Manuel; Fabregat, Juan;
   Domingo, Vicente
Bibcode: 2003SPIE.4843...20J
Altcode:
  The description of the Imaging Magnetograph eXperiment (IMaX) is
  presented in this contribution. This is a magnetograph which will
  fly by the end of 2006 on a stratospheric balloon, together with
  other instruments (to be described elsewhere). Especial emphasis
  is put on the scientific requirements to obtain diffraction-limited
  visible magnetograms, on the optical design and several constraining
  characteristics, such as the wavelength tuning or the crosstalk between
  the Stokes parameters.

Title: Interpretation of observations by inversion
Authors: del Toro Iniesta, J. C.
Bibcode: 2003AN....324..383D
Altcode:
  The most recent developments in inversion techniques of the
  radiative transfer equation are critically reviewed and some of
  their findings are summarized to illustrating their achievements. Two
  significantly different approaches are currently being used that deserve
  consideration, each characterized by whether or not the model solar
  atmospheres are changed iteratively by the algorithm. The comparison
  between the two may help in finding future inversion techniques that
  can solve many challenging problems of solar physics that still need
  to be properly settled. These problems themselves suggest strategies
  that look more suitable than others.

Title: Accurate Atomic Parameters from the Solar Spectrum
Authors: Bellot Rubio, Luis Ramon; Borrero, Juan Manuel; Barklem,
   Paul; del Toro Iniesta, Jose Carlos
Bibcode: 2003IAUJD..20E..16B
Altcode:
  A realistic two-component model of the quiet solar photosphere is used
  to fit the full shape of the intensity profiles of unblended lines in
  the solar spectrum. Our approach differs from previous attempts in many
  respects: proper account of granulation inhomogeneities is made accurate
  collisional broadening parameters from quantum mechanical computations
  are used and possible absorptions in the local continuum due to blends
  are corrected empirically. This allows us to derive oscillator strengths
  and central wavelengths for any clean line with an accuracy comparable
  with that of the best laboratory measurements. The availability of
  very precise atomic parameters for lines of different species is
  essential for the interpretation of high resolution spectroscopic
  observations. Abundance determinations and investigations of granular
  motions in stellar atmospheres are among the applications that would
  benefit from such accurate atomic data. As an example we determine the
  oscillator strengths and central wavelengths of 100 unblended lines
  in the near-infrared (0.99-1.56 microns) a wavelength domain where
  laboratory measurements are particularly scarce.

Title: Solar Polarimetry and Magnetic Field Measurements
Authors: del Toro Iniesta, J. C.
Bibcode: 2001ASSL..259..183D
Altcode: 2001dysu.conf..183D
  The magnetic nature of most solar (spatially resolved or unresolved)
  structures is amply recognized. Magnetic fields of the Sun play a
  paramount rôle in the overall thermodynamic and dynamic state of
  our star. The main observable manifestation of solar magnetic fields
  is the polarization of light either through the Zeeman effect on
  spectral lines or through the Hanle effect (depolarization by very weak
  magnetic fields of light previously polarized by scattering). Hence,
  one can easily understand the increasing importance that polarimetry
  is experimenting continuously in solar physics. Under the title
  of this contribution a six-hour course was given during the summer
  school. Clearly, the limited extension allocated for the notes in
  these proceedings avoids an extensive account of the several topics
  discussed: 1) a description of light as an electromagnetic wave and
  the polarization properties of monochromatic, time-harmonic, plane
  waves; 2) the polarization properties of polychromatic light and, in
  particular, of quasi-monochromatic light; 3) the transformations of
  (partially) polarized light by linear optical systems and a description
  of the ways we measure the Stokes parameters by spatially and/or
  temporally modulating the polarimetric signal; 4) a discussion on
  specific problems relevant to solar polarimetry like seeing-induced
  and instrumental polarization, or modulation and demodulation, along
  with a brief description of current solar polarimeters; 5) the vector
  radiative transfer equation for polarized light and its links to the
  scalar one for unpolarized light, together with a summary of the Zeeman
  effect and its consequences on line formation in a magnetized stellar
  atmosphere; 7) an introduction of the paramount astrophysical problem,
  i.e., that of finding diagnostics that enable the solar physicist to
  interpret the observables in terms of the solar atmospheric quantities,
  including a discussion on contribution and response functions; and 8)
  a brief outline of inversion techniques as a recommended way to infer
  values of the vector magnetic field and other thermodynamic and dynamic
  quantities. Since most of the material presented in the lectures can
  be found in the literature, I decided to focus these pages to those
  topics that, in my opinion, need a particular stress and/or do not
  have received much attention in previous reviews or textbooks. These
  notes have been written with mostly didactical purposes so that,
  skipping the customary usage, just a few references will be cited
  within the text. Instead, a classified (and necessarily incomplete)
  bibliography is recommended at the end.

Title: Cold, Supersonic Evershed Downflows in a Sunspot
Authors: del Toro Iniesta, Jose Carlos; Bellot Rubio, Luis R.;
   Collados, Manuel
Bibcode: 2001ApJ...549L.139D
Altcode:
  We report here on the discovery of supersonic Evershed downflows
  in the penumbra of a sunspot. These flows are shown to occur along
  spatially unresolved, very cold magnetic flux tubes whose downflowing
  footpoints are found from the middle penumbra outward. Evershed
  flows along magnetic field lines returning to the solar surface were
  discovered by Westendorp Plaza and coworkers, but only in the outer
  parts of the penumbra and beyond its visible boundary; on the other
  hand, no supersonic flows of any type have ever been reported in the
  photosphere of sunspots, except for the very different case of the
  delta spot analyzed by Martínez Pillet and coworkers. We present
  unequivocal evidence of such supersonic motions, already predicted
  theoretically by the siphon-flow model, from the interpretation
  of infrared spectropolarimetric observations of a sunspot with
  unprecedented spatial resolution.

Title: Optical Tomography of a Sunspot. II. Vector Magnetic Field
    and Temperature Stratification
Authors: Westendorp Plaza, C.; del Toro Iniesta, J. C.; Ruiz Cobo,
   B.; Martínez Pillet, V.; Lites, B. W.; Skumanich, A.
Bibcode: 2001ApJ...547.1130W
Altcode:
  An observational determination of the three-dimensional magnetic
  and thermal structure of a sunspot is presented. It has been
  obtained through the application of the SIR inversion technique
  (Stokes Inversion based on Response functions) on a low-noise, full
  Stokes profile two-dimensional map of the sunspot as observed with
  the Advanced Stokes Polarimeter. As a result of the inversion, maps
  of the magnetic field strength, B, zenith angle, γ, azimuth, χ, and
  temperature, T, over 25 layers at given optical depths (i.e., an optical
  tomography) are obtained, of which those between logτ<SUB>5</SUB>=0 and
  logτ<SUB>5</SUB>=-2.8 are considered to provide accurate information on
  the physical parameters. All over the penumbra γ increases with depth,
  while B is larger at the bottom layers of the inner penumbra (as in
  the umbra) but larger at the top layers of the outer penumbra (as in
  the canopy). The corrugation of the penumbral magnetic field already
  observed by other authors has been confirmed by our different inversion
  technique. Such a corrugation is especially evident in the zenith angle
  maps of the intermediate layers, featuring the presence of the so-called
  spines that we further characterize: spines are warmer and have a less
  inclined magnetic field than the spaces between them and tend to have a
  smaller gradient of γ with optical depth over the entire penumbra, but
  with a field strength which is locally stronger in the middle penumbra
  and locally weaker in the outer penumbra and beyond in the canopy. In
  the lower layers of these external parts of the sunspot, most of the
  field lines are seen to return to the solar surface, a result that is
  closely connected with the Evershed effect (e.g., Westendorp et al.,
  the third paper in this series). The Stokes V net area asymmetry map
  as well as the average B, γ, and T radial distributions (and that
  of the line-of-sight velocities; see the third paper in this series)
  show a border between an inner and an outer penumbra with different
  three-dimensional structure. We suggest that it is in this middle zone
  where most of a new family of penumbral flux tubes (some of them with
  Evershed flow) emerge interlaced (both horizontally and vertically)
  among themselves and with the ``background'' magnetic field of the
  penumbra. The interlacing along the line of sight is witnessed by
  the indication of many points in the outer penumbra showing rapid
  transitions with height between two structures, one with very weak
  and inclined magnetic field at the bottom of the photosphere and the
  other with a stronger and less inclined magnetic field. Over the whole
  penumbra, and at all optical layers, a constant but weak deviation from
  radiality of some 5° is detected for the azimuth of the vector magnetic
  field, which may be in agreement with former detections but which is
  not significantly higher than the size of the errors for this parameter.

Title: Optical Tomography of a Sunspot. III. Velocity Stratification
    and the Evershed Effect
Authors: Westendorp Plaza, C.; del Toro Iniesta, J. C.; Ruiz Cobo,
   B.; Martínez Pillet, V.
Bibcode: 2001ApJ...547.1148W
Altcode:
  The stratification with optical depth of the line-of-sight (LOS)
  velocity of a simple, isolated, round sunspot observed with the Advanced
  Stokes Polarimeter (ASP; Elmore et al.) presented here completes this
  series of papers that investigates the stratification in optical depths
  of such a typical sunspot. These results have been obtained through the
  use of the SIR technique (Stokes Inversion based on Response functions
  of Ruiz Cobo &amp; del Toro Iniesta). From these data we have confirmed
  that there are strong downflowing velocities at logτ<SUB>5</SUB>=0
  that coincide spatially with the places where the magnetic field points
  downward (Westendorp Plaza et al.). Further confirmation is obtained
  by the application of the same method on a different sunspot, already
  analyzed with the Milne-Eddington inversion technique (Stanchfield,
  Thomas, &amp; Lites). These downflows reconcile observations that have
  detected Evershed velocities outside sunspots together with suggestions
  of the possible return of the flow within the penumbra. The Evershed
  flow seems to be concentrated in elevated channels not thicker than 1 or
  2 scale heights that are mostly located in the space between magnetic
  spines, i.e., in places where the magnetic field is more inclined,
  weaker in the inner-middle penumbra, and stronger in the outer penumbra
  and beyond the visible limits of the sunspot. This conclusion is
  based upon the tight correlation found between LOS velocities and
  the (reported in the second paper of this series) magnetic field
  strength and zenith angle. The upstreaming material is seen in the
  inner penumbra and the downstreaming in the outer penumbra. A strong
  increase with optical depth has been obtained for the LOS velocities
  that provides indications of the superposition of Evershed channels
  along the LOS. The differential opacity effect between the center-side
  and the limb-side penumbra, already reported in the second paper in
  this series, is also seen in the velocity maps and has suggested the
  comparison of the vertical mass flux through the upstreaming zones
  (mostly seen in the center side) and the downstreaming zones (mostly
  seen in the limb side), obtaining a fairly good balance between the two.

Title: Sunspot Magnetic Fields
Authors: del Toro Iniesta, J. C.
Bibcode: 2001ASPC..248...35D
Altcode: 2001mfah.conf...35D
  No abstract at ADS

Title: Sunspots: Evershed Effect
Authors: del Toro Iniesta, J.
Bibcode: 2000eaa..bookE2031D
Altcode:
  The Evershed Effect is an observational effect in the penumbra of
  SUNSPOTS consisting in displacements of the spectral line profiles
  towards either shorter wavelengths (that is, blueshifts) in the zones
  closest to the Sun's disk center or larger wavelengths (that is,
  redshifts) in those zones closest to the solar limb. Since the first
  detection in 1909, this effect was correctly interpreted by it...

Title: Optimum Modulation and Demodulation Matrices for Solar
    Polarimetry
Authors: del Toro Iniesta, Jose Carlos; Collados, Manuel
Bibcode: 2000ApOpt..39.1637D
Altcode:
  No abstract at ADS

Title: Granular and Intergranular Model Atmospheres from Inversion
    of Solar Two-Dimensional Spectroscopic Data
Authors: Rodríguez Hidalgo, I.; Ruiz Cobo, B.; Collados, M.; del
   Toro Iniesta, J. C.
Bibcode: 1999ASPC..173..313R
Altcode: 1999sstt.conf..313R
  No abstract at ADS

Title: Optical Tomography of a Sunspot. I. Comparison between Two
    Inversion Techniques
Authors: Westendorp Plaza, C.; del Toro Iniesta, J. C.; Ruiz Cobo,
   B.; Martínez Pillet, V.; Lites, B. W.; Skumanich, A.
Bibcode: 1998ApJ...494..453W
Altcode:
  A quantitative comparison between the Milne-Eddington (ME) inversion
  technique implemented by Skumanich &amp; Lites and the SIR (Stokes
  Inversion based on Response Functions) proposed by Ruiz Cobo &amp;
  del Toro Iniesta is presented. Numerical experiments are carried
  out to explore the capabilities and limitations of both diagnostic
  techniques. Such experiments consist of inversions of Stokes profiles
  previously synthesized in ``realistic'' solar atmospheric models. The
  results show that the ME inversion provides accurate, line-of-sight
  (LOS) averaged values for the input stratification of the vector
  magnetic field. Its greater speed compared to SIR makes it useful for
  quick analysis of large quantities of data (such as those currently
  provided by modern spectropolarimeters) if one is only interested
  in LOS-averaged quantities. However, the higher order description
  of the atmosphere used by SIR (which acknowledges variation of the
  thermal, dynamic, and magnetic parameters through the photosphere)
  allows retrieval of the stratification of all these parameters to good
  accuracy. This is so even in the presence of discontinuities such
  as those foreseen in magnetic canopies of sunspots. The trade-offs
  between thermodynamic and magnetic parameters observed in some ME
  inversions are reduced considerably in the case of SIR inversions
  because of the more realistic treatment of the thermodynamics in this
  analysis. Notably, both allow one to extract quantitative inferences of
  fairly weak magnetic fields (below 500 G), even when they are applied
  to Zeeman-sensitive lines in the visible spectrum; i.e., well below
  the commonly accepted limit of 500 G. The thermodynamic parameters
  resulting from the ME inversion are understood theoretically in terms
  of the generalized response functions introduced by Ruiz Cobo &amp;
  del Toro Iniesta and through the concept of height of formation
  for inferred values proposed by Sánchez Almeida, Ruiz Cobo, &amp;
  del Toro Iniesta. <P />The present comparison and verification of
  the reliability of inversion methods is a natural first step toward
  the ongoing analysis of the three-dimensional magnetic structure of
  a sunspot. By using SIR (with ME results for initialization) on maps
  of a whole sunspot observed by the Advanced Stokes Polarimeter, we
  obtain maps at different optical layers (i.e., an optical tomography)
  of the temperature, vector magnetic field, and LOS velocity. Such a
  tomography will appear in subsequent papers of the present series. To
  illustrate fits to the observed Stokes profiles, we show here actual
  inversion results for three points observed within a sunspot: one
  within the umbra, another from the outermost parts of the penumbra,
  and a third from the magnetic canopy surrounding the sunspot.

Title: Evidence for a downward mass flux in the penumbral region of
    a sunspot
Authors: Westendorp Plaza, C.; del Toro Iniesta, J. C.; Ruiz Cobo,
   B.; Martinez Pillet, V.; Lites, B. W.; Skumanich, A.
Bibcode: 1997Natur.389...47W
Altcode:
  No abstract at ADS

Title: Space Certifiability of LCVRs
Authors: del Toro Iniesta, J. C.; Martinez Pillet, V.; Gonzalez
   Escalera, V.
Bibcode: 1997ASPC..118..356D
Altcode: 1997fasp.conf..356D
  This contribution is a report on a test campaign carried out by the
  IAC, in collaboration with Construcciones Aeronauticas, S.A. (CASA) as
  a main contrac tor, for exploring the capabilities of liquid crystal
  variable retarders (LCVRs) to be u sed in future space missions as
  the core of the modulation package of a polarimetric device, used as
  a post-focus instrument of a visible solar telescope.

Title: Inversion of Stokes profiles: what's next?
Authors: Del Toro Iniesta, J. C.; Ruiz Cobo, B.
Bibcode: 1997ftst.conf...93D
Altcode:
  No abstract at ADS

Title: 1st Advances in Solar Physics Euroconference: Advances in
    the Physics of Sunspots
Authors: Schmieder, B.; del Toro Iniesta, J. C.; Vazquez, M.
Bibcode: 1997ASPC..118.....S
Altcode: 1997fasp.conf.....S
  No abstract at ADS

Title: Inversion Techniques Applied to Sunspot Spectropolarimetric
    Data
Authors: Westendorp Plaza, C.; del Toro Iniesta, J. C.; Ruiz Cobo,
   B.; Martinez Pillet, V.; Lites, B. W.; Skumanich, A.
Bibcode: 1997ASPC..118..197W
Altcode: 1997fasp.conf..197W
  Two inversion techniques are compared: the Unno-Rachkov\-sky fitting
  method (UR) and the Stokes Inversion based on Response functions
  (SIR). Results with synthetic profiles in sunspot model atmospheres and
  real data show that whilst UR is well suited for recovering a constant
  vec B, SIR enables us to know the run with depth of vec B and the line
  of sight velocity together with the temperature stratification.

Title: Optical Tomography of a Sunspot: Preliminary Results
Authors: Westendorp Plaza, C.; del Toro Iniesta, J. C.; Ruiz Cobo,
   B.; Martinez Pillet, V.; Lites, B. W.; Skumanich, A.
Bibcode: 1997ASPC..118..202W
Altcode: 1997fasp.conf..202W
  Preliminary results of the inversion of spectropolarimetric maps
  of a sunspot observed with the Advanced Stokes Polarimeter (ASP) are
  presented. The method used, Stokes Inversion based on Response functions
  (SIR), does not assume constancy of the different parameters with
  depth, thus enabling us to embark on an analysis of the information at
  different layers in continuum optical depth (i.e. optical tomography),
  of a sunspot's photosphere. Maps of the vector magnetic field and
  other physical quantities like temperature or line-of-sight velocity at
  several optical depths show a new and promising view of the structure
  of a sunspot, casting light on long standing debates as those over
  penumbral `corrugated' fields (spines), superpenumbral canopies,
  return flux, or the nature of the Evershed effect.

Title: Heights of formation for measurements of atmospheric
    parameters.
Authors: Sanchez Almeida, J.; Ruiz Cobo, B.; del Toro Iniesta, J. C.
Bibcode: 1996A&A...314..295S
Altcode:
  We argue that heights of formation (HOFs) should not be assigned to
  spectral lines since a single line my sample very different layers of
  the atmosphere, depending on the physical parameter of interest and
  the technique employed to determine it. HOFs should be assigned to
  specific measurements. General expressions to compute these HOFs for
  measurements are derived. The equations are subsequently used to show,
  in representative solar measurements, the uncertainties produced by
  assigning HOFs to lines. Only weak lines can probe a single height of
  the atmosphere.

Title: Stokes Profiles Inversion Techniques
Authors: Del Toro Iniesta, J. C.; Ruiz Cobo, B.
Bibcode: 1996SoPh..164..169D
Altcode:
  Inversion techniques of the radiative transfer equation for polarized
  light are presented as one of the best current procedures to infer
  the vector magnetic field, as well as other quantities governing the
  physical state of the atmospheric layers that photons are coming
  from. Several characteristics of the various available inversion
  procedures are pointed out. They are mostly based on the diagnostic
  contents of the spectral lines as well as on the main hypotheses
  assumed in these procedures. In particular, the role of gradients in
  the atmospheric quantities is emphasized as of paramount importance in
  any diagnostic analysis and, hence, in any interpretation of inversion
  results.

Title: Two-dimensional, high spatial resolution, solar spectroscopy
    using a Correlation Tracker. II. Maps of spectral quantities.
Authors: Collados, M.; Rodriguez Hidalgo, I.; Ballesteros, E.; Ruiz
   Cobo, B.; Sanchez Almeida, J.; del Toro Iniesta, J. C.
Bibcode: 1996A&AS..115..367C
Altcode:
  In this paper we illustrate some of the capabilities of the Correlation
  Tracker prototype developed at the Instituto de Astrofisica de
  Canarias used for two-dimensional, high spatial resolution, solar
  spectroscopy. Slit spectra have been taken, using the Correlation
  Tracker as a stabilizer (minimizing image motion during exposures) and
  as an accurate positioning device (allowing to precisely locate the
  entrance slit of the spectrograph at adjacent positions on the solar
  disc). Spectral information is obtained from several solar regions
  of different sizes. Granules (including some exploding ones) and
  intergranules are clearly resolved. Several sub-arcsecond structures
  are undoubtedly distinguished as well. The two-dimensional variation
  of several spectral quantities in the solar atmosphere is shown,
  demonstrating the power of this technique and its future possibilities.

Title: Empirical granular/intergranular average model atmospheres.
Authors: Rodríguez Hidalgo, I.; Ruiz Cobo, B.; Del Toro Iniesta,
   J. C.; Collados, M.; Sánchez Almeida, J.
Bibcode: 1996joso.proc..162R
Altcode:
  No abstract at ADS

Title: Empirical model of an average solar granule
Authors: Ruiz Cobo, B.; del Toro Iniesta, J. C.; Rodriguez Hidalgo,
   I.; Collados, M.; Sanchez Almeida, J.
Bibcode: 1996ASPC..109..155R
Altcode: 1996csss....9..155R
  No abstract at ADS

Title: On the discovery of the Zeeman effect on the sun and in
    the laboratory
Authors: del Toro Iniesta, Jose Carlos
Bibcode: 1996VA.....40..241D
Altcode:
  The origin of the discoveries, both on the Sun and in the laboratory,
  of the action of a magnetic field on spectral lines—the so-called
  Zeeman effect—is studied. The paper embraces the period from 1866,
  first date of which the author is aware of observed evidences about the
  widening of spectral lines in sunspots (as compared to those formed
  in the photosphere), until 1908, year in which the magnetic filed in
  sunspots is definitely discovered. The interval between 1896-1897,
  and 1908 is mainly dealt with from an astrophysical standpoint,
  although there are plenty of important contributions from laboratory
  experiments. The reason is two-fold: on the one hand, the significant
  role played by the Zeeman effect on the development of quantum mechanics
  has suggested major historical studies that have already appeared in
  the literature and that are mainly concerned with laboratory—but not
  with astrophysical—spectroscopy; on the other hand, the understanding
  of the sizeable delay between Zeeman's and Hale's discoveries (12
  years) seems to be of concern after accounting for the fact that the
  findings by the first author were soon brought to the notice of the
  astrophysical community.

Title: LTE polarized radiative transfer through interlaced
    atmospheres.
Authors: del Toro Iniesta, J. C.; Ruiz Cobo, B.; Bellot Rubio, L. R.;
   Collados, M.
Bibcode: 1995A&A...294..855D
Altcode:
  We show that the solution of the radiative transfer equation (RTE)
  through a line of sight that pierces several times two alternate
  atmospheres can be obtained in terms of the solutions of the RTE
  through both single atmospheres separately considered. This also
  applies to the response functions of the observed Stokes spectrum
  to perturbations of the physical quantities. The analytic solution
  of the RTE in case that the single atmospheres are Milne-Eddington
  is presented. The simplification of the solution in the case of a
  longitudinal or transversal (with constant azimuth) magnetic field
  is presented as well. Finally, as a numerical example, we synthesize
  the Stokes I- and V-spectrum emerging from a thin magnetic flux tube,
  achieving a considerable decrease in computation time with respect to
  conventional integrations and without loss of accuracy.

Title: Observed differences between large and small sunspots.
Authors: Collados, M.; Martinez Pillet, V.; Ruiz Cobo, B.; del Toro
   Iniesta, J. C.; Vazquez, M.
Bibcode: 1994A&A...291..622C
Altcode:
  We confirm recent results about the differences in temperature
  and magnetic field strength between the umbra of large and small
  sunspots. Five Stokes I- and V-spectra from the darkest cores of
  three different umbrae have been analysed with the inversion code
  of the radiative transfer equation by Ruiz Cobo &amp; del Toro
  Iniesta (1992). The run with depth of temperature, magnetic field
  (strength and inclination) and velocity along the line of sight are
  obtained. The larger sunspots turn out to be cooler and possesing
  a larger magnetic field strength, practically throughout the whole
  atmosphere. Neither significant gradients of the line-of-sight velocity,
  nor of the magnetic field inclination, are detected in any of the
  spots analysed. Two model atmospheres are given corresponding to hot
  (small) and cool (large) sunspots. The models are, to a large extent,
  free from effects of penumbral/photospheric stray-light because it is
  nearly absent in the large spots and because in the small one, where
  it is important for the Stokes I-profile, only Stokes V is considered
  to obtain the model atmosphere. These are the first umbral models in
  the literature for which a simultaneous determination of the magnetic
  field and thermodynamic stratifications is presented. The implications
  of these stratifications for the energy transport in sunspot umbrae
  are discussed.

Title: On the Temperature and Velocity through the Photosphere of
    a Sunspot Penumbra
Authors: del Toro Iniesta, J. C.; Tarbell, T. D.; Ruiz Cobo, B.
Bibcode: 1994ApJ...436..400D
Altcode:
  We investigate the structure in depth of a sunspot penumbra by means
  of the inversion code of the radiative transfer equation proposed
  by Ruiz Cobo &amp; del Toro Iniesta (1992), applied to a set of
  filtergrams of a sunspot, scanning the Fe I line at 5576.1 A, with
  a sampling interval of 30 mA, from -120 to 120 mA from line center
  (data previously analyzed by Title et al. 1993). The temperature
  structure of this penumbra is obtained for each of the 801 pixels
  selected (0.32 sec x 0.32 sec). On the average, the temperatures seem
  to decrease as we move inward, but the differences are of the order
  of the rms values (approximately equal 100-200 K) at a given distance
  to sunspot center. The outer parts of the penumbra have also a bigger
  curvature in the T versus log tau<SUB>5</SUB> relation than the inner
  parts. We realize, however, that these differences might be influenced
  by possible stray light effects. Compared to the quiet Sun, penumbral
  temperatures are cooler at deep layers and hotter at high layers. A mean
  penumbral model atmosphere is presented. The asymmetries observed in the
  intensity profile (the line is magnetically insensitive) are deduced
  to be produced by strong gradients of the line-of-sight velocity that
  sharply vary spatially along slices of almost constant distance to
  sunspot center. These variations suggest that such gradients are not
  only needed to explain the broadband circular polarization observed
  in sunspots (see Sanchez Almeida &amp; Lites 1992) but are a main
  characteristic of the fine-scale penumbra. The results are compatible
  with an Evershed flow present everywhere, but its gradient with depth
  turns out to vary so that the flow seems to be mainly concentrated in
  some penumbral fibrils when studied through Dopplergrams. Finally,
  as by-products of this study, we put constraints to the practical
  usefulness of the Eddington-Barbier relation, and we explain the values
  of the Fourier Dopplergrams to be carrying information of layers around
  the centroid of the generalized response function of Dopplergrams to
  velocity fluctuations.

Title: On the sensitivity of Stokes profiles to physical quantities.
Authors: Ruiz Cobo, B.; del Toro Iniesta, J. C.
Bibcode: 1994A&A...283..129R
Altcode: 1994A&A...283..129C
  A thorough analysis of the sensitivities of the four Stokes profiles to
  the physical quantities involved in the local thermodynamic equilibrium
  (LTE) line formation is presented. We point out the ambiguities
  on the definition of a mean depth of formation of a given spectral
  line and on the use of Contribution Functions for the ascription of a
  measure to a given depth in the atmosphere. Response Functions behave
  like partial derivatives of the Stokes spectrum at a given depth
  of the atmosphere. They provide the sensitivities of the observed
  spectrum to the physical quantities characterizing the state of the
  atmosphere. After a theoretical generalization of any measured parameter
  over the spectrum, we extend the concept of Response Functions for such
  parameters; in detail are discussed the properties and sensitivities
  of the equivalent width, the Stokes V peaks distance, the line-ratio
  method, and the centre of gravity method. Of particualr interest are
  the following results : (1) a constant and longitudinal magnetic field
  can desaturate a spectral line with a Zeeman pattern other than a pure
  Zeeman triplet; (2) saturation is readily understood as a consequence
  of an enhencement of the photon supply; and (3) methods to measure
  magnetic field strength are sensitive to temperature variations,
  mostly if a field strength gradient is present through the photosphere.

Title: Vertical Stratification of a Sunspot Penumbra
Authors: del Toro Iniesta, J. C.; Tarbell, T. D.; Ruiz Cobo, B.
Bibcode: 1993BAAS...25Q1221D
Altcode:
  No abstract at ADS

Title: Inversion of Stokes Profiles
Authors: Ruiz Cobo, B.; del Toro Iniesta, J. C.
Bibcode: 1992ApJ...398..375R
Altcode:
  An inversion code of Stokes line profiles is presented. It allows
  the recovery of the stratification of the temperature, the magnetic
  field vector, and the line of sight velocity through the atmosphere,
  and the micro- and macroturbulence velocities - which are assumed
  to be constant with depth. It is based on the response functions,
  which enter a Marquardt nonlinear least-squares algorithm in a natural
  way. Response functions are calculated at the same time as the full
  radiative transfer equation for polarized light is integrated. This
  enables us to obtain values of many free parameters in a reasonable
  computation time. Many numerical experiments have been performed in
  order to check the behavior of the code. These experiments reveal the
  high stability, accuracy, and uniqueness of the results, even when
  simulated observations present signal-to-noise ratios of the order of
  the lowest acceptable values in real observations.

Title: From Filtergrams to Physical Atmospheric Magnitudes: A
    Prospective Diagnostic
Authors: del Toro Iniesta, J. C.; Tarbell, T.; Ruiz Cobo, B.
Bibcode: 1992AAS...181.8115D
Altcode: 1992BAAS...24.1255D
  No abstract at ADS

Title: Spectropolarimetry of active regions.
Authors: Del Toro Iniesta, J. C.; Martínez Pillet, V.; Vázquez, M.
Bibcode: 1991sopo.work..224D
Altcode:
  A circular analyzer has been used at the focal plane of a telescope in
  days of absence of instrumental polarization to simultaneously record
  I±V spectrograms at two different wavelength ranges: ≡6300 Å and
  ≡3930 - 3970 Å. The observations have been analyzed within two,
  also different, frames: on the one hand, an empirical relationship
  between brightness temperature and the magnetic field strength has been
  found for sunspot umbrae, which allows a determination of the Wilson
  depression; on the other, estimates of the chromospheric longitudinal
  component of the magnetic field (magnetic flux if the filling factor
  is not unity) in two umbrae, in a penumbra, and in a plage have been
  found by using profiles of the resonance lines H and K of Ca II. A
  ratio of order 2 - 3 between the longitudinal components of the field
  at the chromospheric height of formation of the Ca II lines and the
  photospheric height of formation of the 6302.5 Å Fe I line is also
  found in umbrae.

Title: Circular Polarization of the CA II H and K Lines in Solar
    Quiet and Active Regions
Authors: Martinez Pillet, V.; Garcia Lopez, R. J.; del Toro Iniesta,
   J. C.; Rebolo, R.; Vazquez, M.; Beckman, J. E.; Char, S.
Bibcode: 1990ApJ...361L..81M
Altcode:
  A representative set of profiles is presented for the Ca II H resonace
  line in Stokes V and I, for the quiet sun, plages, sunspot umbrae,
  and a flare, as well as one example of the Ca II K line in a sunspot
  penumbra. The degree of polarization is highest in the spots and zero
  in the quiet sun, within error limits. The V profile asymmetries are,
  however, highest in the flare. The spectra of the Ca II K line are
  used to obtain a linear relation between V(lambda) and -dI/d(lambda)
  and a value for B(parallel) of 820 + or - 40 G using the weak-field
  approximation.

Title: Numerical Test of a New V-Profile Inversion Technique
Authors: Ruiz Cobo, B.; del Toro Iniesta, J. C.; Collados, M.;
   Sanchez Almeida, J.
Bibcode: 1990Ap&SS.170..113R
Altcode:
  The diagnostic method proposed by Landi Degl'Innocenti and Landolfi
  (1982), based on the observation of circular polarization, has been
  generalized to derive the thermodynamic properties of unresolved
  magnetic elements in the solar atmosphere. The final aim is to derive
  the height dependence of several parameters of the flux tube atmosphere
  (such as temperature, magnetic field and velocity distributions,
  macroturbulence and filling factor). We have used a perturbation
  method based on the concept of response functions for the Stokes
  profiles introduced by Landi Degl'Innocenti and Landi Degl'Innocenti
  (1977). We present here the preliminary results of invertingV-profiles
  by an iterative standard least-squares technique, which allows to find
  the magnetic 1-D atmosphere consistent with simulated data.

Title: Facular points and small-scale magnetic elements
Authors: del Toro Iniesta, J. C.; Collados, M.; Sanchez Almeida, J.;
   Martinez Pillet, V.; Ruiz Cobo, B.
Bibcode: 1990Ap&SS.170....9D
Altcode:
  We present spectroscopic observations, with high spatial resolution, of
  Ca ii K bright points very near the disc centre. Magnetic concentrations
  have been detected in these network (facular) points by only using
  intensity profiles of the well-known pair of lines Fe i5250.22 Å and
  5247.06 Å. No brightening of these structures with respect to the quiet
  photosphere can be ascertained within an accuracy threshold of 1.2%.

Title: Velocity Fields Associated with the Magnetic Component of
    Solar Faculae
Authors: Sanchez Almeida, J.; Collados, M.; del Toro Iniesta, J. C.
Bibcode: 1990Ap&SS.170...31S
Altcode:
  The StokesV asymmetries observed in solar faculae can be interpreted
  by invoking the presence of magnetic and velocity fields variations
  along the line-of-sight. By means of a perturbative approach, we
  develop the theoretical dependence on magnetic and velocity fields
  of the StokesV profile around its zero-crossing point. We find that
  the empirical curves of growth for theV zero-crossing point and the
  slope, as well as the curve of growth for the integral (previously
  derived by Sánchez Almeidaet al., 1989, through the same approach),
  are reproduced quite well with a single atmosphere which assumes such
  simultaneous variations. The depth dependence of the fields that give
  the best fit in our model presents several striking properties which
  cannot be released without totally compromising the goodness of the
  fit. Namely, the magnetic field strength increases towards the observer
  while the downflowing velocity field decreases. Both variations must
  occur co-spatially, in the same atmospheric layers. This fact seems to
  contradict theoretical models for the fanning out parts of magnetic
  concentrations which foresee a sharp separation between a static
  magnetic layer and a deep zone with velocity fields. We discuss a
  possible solution of such contradiction in terms of a finite optical
  thickness of the boundary layer between zones with and without magnetic
  field in faculae.

Title: Are small-scale magnetic concentrations spatially coincident
    with bright facular points?
Authors: del Toro Iniesta, J. C.; Collados, M.; Sanchez Almeida, J.;
   Martinez Pillet, V.; Ruiz Cobo, B.
Bibcode: 1990A&A...233..570D
Altcode:
  The usually assumed identification of small-scale magnetic
  concentrations with bright facular or network points on the photosphere
  is observationally checked by using high spatial resolution spectra
  of Ca II K bright points very near the disk center. The detection of
  spatially unresolved magnetic structures is made via a new differential
  analysis of the well-known pair of Fe I lines 5247.06 A and 5250.22
  A; these concentrations are present in the central part of a line
  weakening zone, which is of some 2 arcsec wide. No continuum intensity
  enhancement with respect to the quiet photosphere can be ascertained of
  these structures, within an accuracy threshold of 1.2 percent. In spite
  of this, magnetic concentrations brighter than the quiet photosphere
  are compatible with the observations, but if so, they must be narrower
  than 0.2 arcsec.

Title: Spectropolarimetry of solar faculae - High spatial resolution
    results
Authors: del Toro Iniesta, J. C.; Collados, M.; Sanchez Almeida, J.;
   Semel, M.
Bibcode: 1990A&A...227..591D
Altcode:
  A new method to measure the magnetic field strength of small-scale
  solar magnetic concentrations is presented. It is based on the center
  of gravity method (Semel, 1967), is independent of radiative transfer
  calculations and only observable parameters are needed. This method
  also provides parameters like filling factor (area fraction occupied by
  the tubes), continuum intensity contrast between flux tubes and their
  surroundings, in a two-component model scheme. The method is applied
  to spectropolarimetric high spatial resolution data. Local variations
  of the above parameters inside single faculae are found. This result
  suggests some indications about flux tube evolution. A comparison with
  low spatial resolution results is also made.

Title: On the generation of the net circular polarization observed
    in solar faculae
Authors: Sanchez Almeida, J.; Collados, M.; del Toro Iniesta, J. C.
Bibcode: 1989A&A...222..311S
Altcode:
  The net circular polarization observed in solar faculae (Stenflo et
  al., 1984) follows a law expected from the combination of velocity
  and magnetic field gradients in the photosphere. To show this, the
  theoretical curve of growth (net circular polarization produced by
  a single line versus its absorption coefficient) predicted by this
  mechanism is developed. An empirical curve of growth with more than
  80 Fe I lines is also constructed. The agreement between theory and
  observation seems to point toward this mechanism as responsible for
  circular polarization in faculae at the disk center.

Title: Les facules solaires ou comment observer l'invisible.
Authors: Sanchez Almeida, J.; Collados, M.; Del Toro Iniesta, J. C.
Bibcode: 1989Rech...20..810S
Altcode: 1989Rech...20..810A
  No abstract at ADS

Title: An explanation for the Stokes V asymmetry in solar faculae
Authors: Sanchez Almeida, J.; Collados, M.; del Toro Iniesta, J. C.
Bibcode: 1988A&A...201L..37S
Altcode:
  The asymmetry in the Stokes V profile observed in solar faculae
  can be explained by assuming that the magnetic field increases with
  height while downflow speed decreases. The MHD compatibility of such
  solution is briefly discussed together with an observational test for
  that possibility.

Title: Magnetic field strength in solar flux tubes - A model
    atmosphere independent determination
Authors: Sanchez Almeida, J.; Collados, M.; del Toro Iniesta, J. C.;
   Solanki, S. K.
Bibcode: 1988A&A...196..266S
Altcode:
  The "line ratio method" (Stenflo, 1973) has been extensively used in
  the past to carry out measurements of the magnetic field strength in
  spatially unresolved magnetic flux concentrations. The authors present
  here a new variant of this technique, which is particularly simple as
  it does not depend on any radiative transfer calculations and thus the
  assumption of a model atmosphere is not required. General properties
  of the transfer equation lead to a relationship between the circular
  polarization generated by two lines which are identical except for
  their Landé factors. This can be used to directly determine the field
  strength from the measured line profiles. In order to test the method
  the authors have applied it to experimental data. A comparison with
  the traditional line ratio method is shown.

Title: Photometry of sunspot penumbrae
Authors: Collados, M.; del Toro Iniesta, J. C.; Vazquez, M.
Bibcode: 1988A&A...195..315C
Altcode:
  The authors present the results of a statistical analysis of the
  penumbra of sunspots. The intensity distribution, and several
  parameters derived from it, is analysed at different heliocentric
  angles and positions on the spot. It has revealed, on the one hand,
  that a two-component model is compatible with the observations and
  that both components lie at the same height, and on the other, that
  the penumbral asymmetry found by Collados et al. (1987) is confirmed
  under a photometrical point of view, the western penumbra being slightly
  shorter than the eastern one.

Title: On the Age Dependence of the Asymmetry of Penumbrae of Sunspots
Authors: Collados, M.; del Toro Iniesta, J. C.; Vazquez, M.; Woehl, H.
Bibcode: 1988SoPh..117..199C
Altcode:
  The age dependence of the recently described asymmetry of penumbrae
  of large stable sunspots was analyzed. Young sunspots showed shorter
  eastern penumbrae, which differed by a maximum of ± 10 % from their
  mean width. For older sunspots the western penumbrae became smaller
  than the mean penumbra reaching differences of 20 % for spots of two
  months age.

Title: A Statistical Study of the Geometrical Wilson Effect
Authors: Collados, M.; del Toro Iniesta, J. C.; Vazquez, M.
Bibcode: 1987SoPh..112..281C
Altcode:
  An analysis has been carried out of the centre-to-limb variation of the
  apparent sizes of the umbra, penumbra and whole spot. It has revealed
  that the umbral size decreases with height. We have interpreted this
  result in terms of the penumbral geometrical height scale. A value
  of 230 km, which is larger than that of the photosphere or the umbra,
  explains the observed decrease. An intrinsic asymmetry in the penumbra
  of old sunspots has also been found, the western penumbra being slightly
  shorter that the rest of the penumbra. This explains why the inverse
  Wilson effect is present, preferentially, in the western hemisphere,
  as found in previous investigations. A comparison with other works is
  also made.

Title: Observations of the Magnetic Fine Structure of a Facula
Authors: del Toro Iniesta, J. C.; Semel, M.; Collados, M.
Bibcode: 1987rfsm.conf..122D
Altcode:
  No abstract at ADS

Title: Continuum intensity and magnetic flux of solar fluxtubes.
Authors: Del Toro Iniesta, J. C.; Semel, M.; Collados, M.; Sánchez
   Almeida, J.
Bibcode: 1987PAICz..66..265D
Altcode: 1987eram....1..265D
  The continuum contrast between fluxtubes and their quiet background,
  and the magnetic flux carried by these magnetic elements, have been
  determined at different points of a solar facula, in the frame of a
  two-component model from spectropolarimetric observations of 1arcsec
  spatial resolution. Local spatial variations of these two parameters
  have been obtained.

Title: The Wilson Effect in Sunspots
Authors: Collados, M.; del Toro Iniesta, J. C.; Vázquez, M.
Bibcode: 1987rfsm.conf..183C
Altcode:
  An analysis of the center to limb variation of the geometrical
  properties of spots has been carried out. It has revealed that spots do
  not have a symmetrical behaviour with respect to the centre of solar
  disk. Thus, the Wilson effect is not zero at δ = 0°, but at δ ≡
  45°W. Moreover, the inverse Wilson effect is the general rule in that
  interval, while the normal phenomenon is maximum at a heliocentric
  angle of 40° - 50°E.

Title: Intensity profiles in fluxtubes.
Authors: Sanches Almeida, J.; Collados, M.; del Toro Iniesta, J. C.;
   Solanki, S. K.
Bibcode: 1987PAICz..66..261S
Altcode: 1987eram....1..261S
  Spectroscopic analysis of the light coming from an atmosphere is a
  powerful tool for revealing its properties. The problem when using
  conventional spectroscopy for solar fluxtubes is their unresolved
  character: magnetic and non-magnetic regions of a plage have to be
  observed as a whole. With the aim of obtaining the true intensity
  spectrum of an unresolved tube, the authors have developed a simple
  method which can reconstruct the intensity generated in the magnetic
  component. Only observed parameters are used: intensity and circular
  polarization in the plage and intensity in the quiet photosphere.

Title: The Intensity Distribution in Sunspot Penumbras
Authors: Collados, M.; del Toro Iniesta, J. C.; Vázquez, M.
Bibcode: 1987rfsm.conf..214C
Altcode:
  The intensity distribution of the penumbra at different stages of
  evolution has been analyzed. The results have been different for both
  evolved and primitive penumbras. While the former present almost
  symmetrical, single-peaked histograms, the same does not occur for
  the latter, their distributions being, preferentially, asymmetrical
  or double-peaked. These results are interpreted in terms of bright
  and dark elements. Thus, an evolutionary process has been proposed to
  explain the diverse characteristics found at the different stages.

Title: Observations of the magnetic fine structure of a facula.
Authors: Del Toro Iniesta, J. C.; Semel, M.; Collados, M.
Bibcode: 1987rfsm.conf..127D
Altcode:
  Simultaneous spectropolarimetric observations of a facula have
  been carried out in 10 spectral lines with a spatial resolution of
  1arcsec. Local variations of the magnetic field strength and the filling
  factor of fluxtubes were obtained. The analysis of the velocities inside
  fluxtubes shows that positive and negative Doppler shifts are present,
  at the same time, at different points of the facula.

