Author name code: rabin
ADS astronomy entries on 2022-09-14
author:"Rabin, Douglas M." 
------------------------------------------------------------------------  

Title: First Imaging Spectroscopy of 92-115 Angstrom Solar Soft
X-rays by EUNIS: Implications for Solar Coronal Heating
Authors: Brosius, Jeffrey; Daw, Adrian; Rabin, Douglas; Landi, Enrico;
   Schmit, Donald
Bibcode: 2021AGUFMSH12B..04B
Altcode:
  The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS)
  sounding rocket waslaunched from White Sands Missile Range, NM, on
  May 18, 2021. The instrumentcomprised a pair of coaligned imaging
  spectrographs, one of which observed solarline emission in first
  order at wavelengths between 525 and 639 A, and the secondof which
  observed line emission in third order at wavelengths between 92 and
  115 Aand in first order between 277 and 345 A. Images of AR 12824,
  quiet-sun area, andoff-limb area were obtained by rastering the slits
  over the selected targets. Thisis the first time that solar imaging
  spectroscopy has been performed in the 92-115A soft X-ray range. This
  waveband was selected to (1) observe Fe XVIII 93.932 and103.948 A
  and Fe XIX 108.355 A line emission in a quiescent active region, and
  (2)explore a relatively unobserved portion of the solar electromagnetic
  spectrum. Theinstrument performed well during its 6-minute observing
  run. We report preliminaryresults on observations of Fe XVIII and Fe
  XIX in the quiescent active region, anddiscuss implications for the
  nanoflare model of solar coronal heating. EUNIS wassupported by NASA
  Heliophysics Low Cost Access to Space award 13-HTIDS13_2-0074.

Title: Distributed Space Telescopes Enabled by Constellation of
    Small Satellites
Authors: Kamalabadi, Farzad; Lightsey, E.; Rabin, Douglas; Daw,
   Adrian; D'Amico, Simone; Koenig, Adam; Chamberlin, Philip; Woods,
   Thomas; Gupta, Subhanshu; Ekici, Eylem; Sample, John; Park, Hyeongjun;
   Alexeenko, Alina; Hwang, John; Denis, Kevin; Klimchuk, James
Bibcode: 2021AGUFM.A33C..03K
Altcode:
  New pathways to high-resolution sensing and imaging for a multitude
  of high-priority scientific investigations are being realized by small
  multi-spacecraft systems. Such pathfinder mission concepts circumvent
  the limitations of conventional remote sensing/imaging systems by
  utilizing multiple baselines, synthesized apertures, diffractive
  optics, combined with computational imaging via interferometry,
  tomography, or super-resolution. Regardless of the specific scientific
  questions targeted, such small satellite constellation pathfinders
  require technological breakthroughs in precision formation flying
  and associated advances in guidance, navigation, and control;
  proximity operations and associated autonomy and robust orbit
  design with passive safety; innovations in sensor miniaturization;
  inter-satellite communication; and sophisticated computational sensing
  and reconstruction algorithms. We describe recent advances in such
  enabling technologies in the context of a scalable ultra-high-resolution
  spectral imaging mission for investigating the solar corona currently
  under development by a multi-university consortium in collaboration
  with NASA and under sponsorship by NSF.

Title: Solar Coronagraphs
Authors: Rabin, Douglas
Bibcode: 2021hai3.book..339R
Altcode:
  No abstract at ADS

Title: Photon sieves and the future of EUV imaging spectroscopy
Authors: Daw, Adrian N.; Rabin, Douglas M.; Schmit, Donald James;
   Denis, Kevin
Bibcode: 2019AAS...23412605D
Altcode:
  Large-aperture photon sieves fabricated at NASA-GSFC can provide
  diffraction-limited imaging at EUV and X-ray wavelengths, that is,
  spatial scales down to milli-arcseconds, and are also being used to
  provide monochromatic, collimated beams for the calibration of solar
  EUV instruments such as the Extreme Ultraviolet Normal Incidence
  Spectrograph (EUNIS). EUNIS is a two-channel imaging spectrograph
  with unprecedented dynamic range and broad spectral coverage (9-11 nm
  and 52-64 nm), scheduled for a sounding rocket flight in September
  2019. This will be the first time the 9-11 nm wavelength range of
  the Sun has ever been observed by an imaging spectrograph, despite
  the importance of these short EUV/soft X-ray wavelengths to observing
  the hottest (&gt;5MK) plasma in the non-flaring atmosphere, which is
  critical to understanding the energization of the solar corona. Recent
  results will be presented, and capabilities for future solar EUV
  missions will be discussed.

Title: Ultrahigh-Resolution Imaging of the Solar Corona using a
    Distributed Diffractive Telescope
Authors: Rabin, Douglas M.; Daw, Adrian N.; Denis, Kevin; Kamalabadi,
   Farzad; Klimchuk, James A.
Bibcode: 2019AAS...23410704R
Altcode:
  Several observational and theoretical considerations suggest that
  energy is often released in the solar corona on small spatial scales
  of order 100 km. It has been a longstanding goal of solar physics to
  subject this hypothesis to direct observational test. However, extreme
  ultraviolet (EUV) and soft x-ray (SXR) telescopes rarely approach
  diffraction-limited performance because conventional reflective optics
  of adequate size typically cannot be manufactured to the requisite
  figure accuracy. Diffractive optics can overcome the angular-resolution
  limitations of EUV/SXR mirrors. We describe a mission approach that
  employs diffractive optics and small satellites flying in formation
  to form a distributed solar telescope operating at EUV wavelengths.

Title: Ultrahigh-Resolution Solar Imaging with Diffractive Optics
Authors: Rabin, Douglas; Davila, Joseph M.; Daw, Adrian Nigel; Denis,
   Kevin; Shah, Neerav; Mason, Emily; Novo-Gradac, Anne-Marie; Widmyer,
   Thomas
Bibcode: 2018tess.conf40443R
Altcode:
  Extreme ultraviolet (EUV) and soft X-ray (SXR) telescopes rarely achieve
  diffraction-limited performance because conventional reflective optics
  of the required size typically cannot be manufactured to the requisite
  figure accuracy. Diffractive optics can overcome the angular-resolution
  limitations of EUV/SXR mirrors but present other design and performance
  challenges. A diffractive telescope is well-suited for probing for the
  first time the expected energy dissipation scales of the solar corona
  (&lt;100 km). We have previously described the fabrication of photon
  sieves and Fresnel zone plates as large as 80-mm clear aperture,
  as well as laboratory measurements and vibration testing. Here we
  report on the design of more efficient phase zone plates, the path
  to larger apertures, and our approach to a virtual telescope based on
  formation-flying smallsats.

Title: Building a Futuristic Telescope on the Moon - A Fun Project
    for Research, Science Teaching, and Outreach
Authors: Chen, Peter C.; Rabin, Douglas M.; Haas, J. Patrick;
   Mirel, Paul
Bibcode: 2018AAS...23136107C
Altcode:
  We present the design and demonstrate the operation of a model
  lunar observatory. While this is a research project, it is also
  intended to stimulate student interest in space science, astronomy,
  physics, chemistry, and engineering. First, we discuss the science
  objectives of a lunar observatory. The Moon is a great location for
  astronomy. Why? What science can best be done from there? What are
  exoplanets? We would like to see what planets around other stars
  look like. Why is it so difficult? What are optical interferometers
  and why do we need them? Next, we discuss the physics, chemistry,
  and engineering principles involved. The lunar environment is totally
  different from Earth. It features high vacuum, low gravity, very slow
  rotation rate, cryogenic temperatures, and dust. How can an observatory
  be designed that not only survives, but can take advantage of the
  environment? We present a “cool” solution (the model uses liquid
  nitrogen) that combines the following elements: high temperature
  superconductors, telescope mirrors made of “moondust”, novel
  telescope support system, an observatory structure made of simulated
  lunar soil, 3D printing, and methods for dust mitigation. Information
  will be provided on how similar systems can be built and what further
  refinements (e.g. voice control, precision stepper drives, autonomous
  operation, and telerobotics) can be added.

Title: Mission Concepts for High-Resolution Solar Imaging with a
    Photon Sieve
Authors: Rabin, Douglas M.; Davila, Joseph; Daw, Adrian N.; Denis,
   Kevin L.; Novo-Gradac, Anne-Marie; Shah, Neerav; Widmyer, Thomas R.
Bibcode: 2017SPD....4811006R
Altcode:
  The best EUV coronal imagers are unable to probe the expected
  energy dissipation scales of the solar corona (&lt;100 km) because
  conventional optics cannot be figured to near diffraction-limited
  accuracy at these wavelengths. Davila (2011) has proposed that a
  photon sieve, a diffractive imaging element similar to a Fresnel zone
  plate, provides a technically feasible path to the required angular
  resolution. We have produced photon sieves as large as 80 mm clear
  aperture. We discuss laboratory measurements of these devices and the
  path to larger apertures. The focal length of a sieve with high EUV
  resolution is at least 10 m. Options for solar imaging with such a
  sieve include a sounding rocket, a single spacecraft with a deployed
  boom, and two spacecraft flying in precise formation.

Title: Electron temperature maps of the low solar corona: ISCORE
    results from the total solar eclipse of 1 August 2008 in China
Authors: Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, Orville C.;
   Rabin, Douglas M.
Bibcode: 2017JGRA..122.5856R
Altcode:
  We conducted an experiment in conjunction with the total solar eclipse
  of 1 August 2008 in China to determine the thermal electron temperature
  in the low solar corona close to the solar limb. The instrument, Imaging
  Spectrograph of Coronal Electrons (ISCORE), consisted of an 8 inch f/10
  Schmidt Cassegrain telescope with a thermoelectrically cooled CCD camera
  at the focal plane. Results are electron temperatures of 1 MK at 1.08
  R<SUB>⊙</SUB> and 1.13 R<SUB>⊙</SUB> from the Sun center in the
  polar and equatorial regions, respectively. This experiment confirms
  the results of an earlier experiment conducted in conjunction with
  the total eclipse of 29 March 2006 in Libya, and results are that at
  a given coronal height the electron temperature in the polar region
  is larger than at the equatorial region. In this paper we show the
  importance of using the correct photospheric spectrum pertinent to
  the solar activity phase at the time of the experiment, which is a
  required parameter for modeling the underlying theoretical concept
  for temperature interpretation of the measured intensity ratios using
  color filters.

Title: Detecting the Beacons of Life with Exo-Life Beacon Space
    Telescope (ELBST)
Authors: Airapetian, V. S.; Danchi, W. C.; Chen, P. C.; Rabin, D. M.;
   Carpenter, K. G.; Mlynczak, M. G.
Bibcode: 2017LPICo1989.8214A
Altcode:
  We propose a new observational strategy, the “Exo-Life Beacon Space
  Telescope,” for detecting the signatures of “beacons” of life
  defined as high signal and low spectral resolution thermal emission
  from molecules associated with life signatures.

Title: Diffraction Analysis of Solar Coronagraphs
Authors: Rabin, Douglas M.; gong, qian
Bibcode: 2016SPD....4730601R
Altcode:
  The design of a solar coronagraph is predicated on controlling
  diffracted and scattered light using principles dating back to Bernard
  Lyot in the 1930’s. The existence of many successful ground-
  and space-based coronagraphs testifies to our ability to apply
  these principles in specific cases, but it is difficult to explore
  a significant range of design parameters because the calculations are
  tricky and time-consuming. Indeed, scattered light is so design-specific
  that ad hoc analysis is unavoidable once guidelines from experience
  are used to create a first-guess system of baffles and low-scatter
  surfaces. Here we describe a combination of analytic and computational
  approaches that has the potential to explore coronagraph design space
  somewhat more systematically with respect to diffracted light.

Title: Milli-Arcsecond (MAS) Imaging of the Solar Corona
Authors: Davila, Joseph M.; Oktem, Figen S.; Kamalabadi, Farzad;
   O'Neill, John; Novo-Gradac, Anne-Marie; Daw, Adrian N.; Rabin,
   Douglas M.
Bibcode: 2016SPD....47.0310D
Altcode:
  Dissipation in the solar corona is believed to occur in extremely
  thin current sheets of order 1-100 km. Emission from these hot
  but thin current sheets should be visible in coronal EUV emission
  lines. However, this spatial scale is far below the resolution
  of existing imaging instruments, so these dissipation sites have
  never been observed individually. Conventional optics cannot be
  manufactured with sufficient surface figure accuracy to obtain the
  required spatial resolution in the extreme-ultraviolet where these
  hot plasmas radiate. A photon sieve, a diffractive imaging element
  similar to a Fresnel zone plate, can be manufactured to provide a
  few milli-arcsec (MAS) resolution, with much more readily achievable
  tolerances than with conventional imaging technology. Prototype photon
  sieve elements have been fabricated and tested in the laboratory. A
  full-scale ultra-high resolution instrument will require formation
  flying and computational image deconvolution. Significant progress has
  been made in overcoming these challenges, and some recent results in
  these areas are discussed. A simple design for a sounding rocket concept
  demonstration payload is presented that obtains 80 MAS (0.080 arcsec)
  imaging with a 100 mm diameter photon sieve to image Fe XIV 334 and
  Fe XVI 335. These images will show the structure of the corona at a
  resolution never before obtained, and they will also allow a study of
  the temperature structure in the dissipation region.

Title: Evidence for Nanoflare Heating of the Solar Corona from the
    EUNIS Sounding Rocket
Authors: Brosius, J. W.; Daw, A. N.; Rabin, D. M.
Bibcode: 2015AGUFMSH31D..01B
Altcode:
  We present spatially resolved EUV spectroscopic measurements
  ofpervasive, faint Fe XIX 592.2 A line emission in AR 11726,observed
  during the 2013 April 23 flight of the Extreme UltravioletNormal
  Incidence Spectrograph (EUNIS-13) sounding rocket instrument. With
  cooled detectors, high sensitivity, and high spectralresolution,
  EUNIS-13 resolves the lines of Fe XIX at 592.2 A (formedat temperature
  T around 8.9 MK) and Fe XII at 592.6 A (T around 1.6MK). The Fe XIX
  line emission, observed over an area in excess of4920 square arcsec
  (2.58x10^9 square km, more than 60% of the activeregion), provides
  strong evidence for the nanoflare heating model ofthe solar corona. No
  GOES events occurred in the region less than 2hours before the rocket
  flight, but a microflare was observed northand east of the region with
  RHESSI and EUNIS during the flight. Theabsence of significant upward
  velocities anywhere in the region,particularly the microflare, indicates
  that the pervasive Fe XIXemission is not propelled outward from the
  microflare site, but ismost likely attributed to localized heating (due
  to reconnection,wave dissipation, or some other mechanism) consistent
  with thenanoflare heating model of the solar corona. We measure average
  FeXIX/Fe XII intensity ratios of 0.070 outside the AR core, 0.22 inarea
  of bright coronal emission (the area in which the Fe XIIintensity
  exceeds half its maximum observed value), and 0.55 in theregion's hot
  core. Using the CHIANTI atomic physics database andassuming ionization
  equilibrium, we estimate corresponding Fe XIX/FeXII emission measure
  ratios of about 0.076, 0.23 and 0.59. Theemission measure ratios must
  be viewed with caution in light oflingering uncertainties in the Fe XII
  contribution functions.EUNIS-13 was supported by the NASA Heliophysics
  Division through itsLow Cost Access to Space program.

Title: A Geomagnetic Precursor Technique for Predicting the Solar
    Activity Cycle
Authors: Sobel, E. I.; Rabin, D. M.
Bibcode: 2015AGUFMSH23A2427S
Altcode:
  The Western hemisphere has been recording sunspot numbers since Galileo
  discovered sunspots in the early 17th century, and the roughly 11-year
  solar cycle has been recognized since the 19th century. However,
  predicting the strength of any particular cycle remains a relatively
  imprecise task. This project's aim was to update and improve a
  forecasting technique based on geomagnetic precursors of future solar
  activity The model is a refinement of R. J. Thompson's 1993 paper that
  relates the number of geomagnetically disturbed days, as defined by
  the aa and Ap indices, to the sum of the sunspot number in the current
  and the previous cycle, Rn + Rn-1.[1] The method exploits the fact
  that two cycles coexist for some period on the Sun near solar minimum
  and therefore that the number of sunspots and disturbed days during
  the declining phase of one cycle gives an indication of the following
  cycle's strength. We wrote and updated IDL software procedures to define
  disturbed days with varying threshold values and graphed Rn + Rn-1
  against them. The aa threshold was derived from the Ap threshold. After
  comparing the graphs for Ap values from 20 to 50, an Ap threshold of
  30 and the corresponding aa threshold of 44 were chosen as yielding
  the best correlation. Confidence regions were computed to provide a
  quantitative uncertainty on future predictions. The 80% confidence
  region gives a range of ±40 in sunspot number. <P />[1] Thompson,
  R. J. (1993). A technique for predicting the amplitude of the solar
  cycle. Solar Physics, 148, 2, 383-388.

Title: EUNIS 2013: Unambiguous Evidence for Impulsive Coronal Heating,
    Data Available
Authors: Daw, Adrian; Brosius, Jeffrey; Haas, J. Patrick; Plummer,
   Thomas; Rabin, Douglas
Bibcode: 2015TESS....120401D
Altcode:
  The broad spectral coverage (303-370 Å, 527-635 Å) and unprecedented
  dynamic range of the Extreme Ultraviolet Normal Incidence Spectrograph
  (EUNIS) 2013 sounding rocket observations includes emission lines of
  ionization stages from He I to Fe XX, and thus a wide temperature range
  of 0.03 to 10 MK. Pervasive, faint Fe XIX 592 Å line emission was
  observed in active regions. Comparison of observed line intensities
  with calculations demonstrates that the Fe XIX emission, formed at
  temperatures around 8 MK, is evidence of the faint hot emission
  predicted by impulsive heating models of the solar corona (e.g.,
  ‘nano-flares’). The calibration and availability of the EUNIS-2013
  dataset is discussed as well.

Title: Carbon nanotube optical mirrors
Authors: Chen, Peter C.; Rabin, Douglas
Bibcode: 2015JATIS...1a4005C
Altcode:
  We report the fabrication of imaging quality optical mirrors
  with smooth surfaces using carbon nanotubes (CNT) embedded in an
  epoxy matrix. CNT/epoxy is a multifunctional composite material
  that has sensing capabilities and can be made to incorporate
  self-actuation. Moreover, as the precursor is a low density liquid,
  large and lightweight mirrors can be fabricated by processes such as
  replication, spincasting, and three-dimensional printing. Therefore,
  the technology holds promise for the development of a new generation of
  lightweight, compact "smart" telescope mirrors with figure sensing and
  active or adaptive figure control. We report on measurements made of
  optical and mechanical characteristics, active optics experiments, and
  numerical modeling. We discuss possible paths for future development.

Title: New Approaches to Externally Occulted Coronagraphs
Authors: Rabin, D. M.; Chamberlin, P. C.; Davila, J. M.; Shah, N.
Bibcode: 2014AGUFMSH53B4226R
Altcode:
  The rapidly advancing capabilities of low-cost space platforms
  prompts us to reconsider concepts for externally occulted solar
  coronagraphs. Placing the occulter on a separate platform offers
  superior diffraction control but requires an analysis of alignment
  and separation tolerances that is different from that applied to
  conventional architectures. New forms of occulter (e.g., an inflatable
  sphere or ellipsoid) have potential advantages such as low mass and
  fabrication cost, simple deployment, and less stringent demands on
  the relative alignment of the platforms. However, the diffraction
  behavior of occulters that incorporate curved surfaces (Buffington
  2000) is less explored than for edge-type occulters. We illustrate
  the new possibilities by calculating the performance of some candidate
  systems using an analytic framework adapted from radio wave propagation
  (Vogler 1985) and alignment tolerances based on a recent concept for
  a two-platform guidance, navigation, and control system.

Title: Eunis Observation of Pervasive Faint Fe XIX Line Emission
from a Solar Active Region: Evidence for Coronal Heating By Nanoflares
Authors: Brosius, J. W.; Daw, A. N.; Rabin, D. M.
Bibcode: 2014AGUFMSH13C4130B
Altcode:
  We present spatially resolved EUV spectroscopic measurements
  ofpervasive, faint Fe XIX 592.2 A line emission in an active
  regionobserved during the 2013 April 23 flight of the Extreme
  UltravioletNormal Incidence Spectrograph (EUNIS-13) sounding
  rocket instrument. With cooled detectors, high sensitivity, and
  high spectralresolution, EUNIS-13 resolves the lines of Fe XIX at
  592.2 A (formedat temperature T around 8.9 MK) and Fe XII at 592.6 A
  (T around 1.6MK). The Fe XIX line emission, observed over an area
  in excess of4920 square arcsec (2.58x10^9 square km, more than 60%
  of the activeregion), provides strong evidence for the nanoflare
  heating model ofthe solar corona. No GOES events occurred in the
  region less than 2hours before the rocket flight, but a microflare
  was observed northand east of the region with RHESSI and EUNIS during
  the flight. Theabsence of significant upward velocities anywhere in
  the region,particularly the microflare, indicates that the pervasive
  Fe XIXemission is not propelled outward from the microflare site, but
  ismost likely attributed to localized heating (due to reconnection,wave
  dissipation, or some other mechanism) consistent with thenanoflare
  heating model of the solar corona. We measure average FeXIX/Fe XII
  intensity ratios of 0.070 outside the AR core, 0.22 inarea of bright
  coronal emission (the area in which the Fe XIIintensity exceeds half
  its maximum observed value), and 0.55 in theregion's hot core. Using
  the CHIANTI atomic physics database andassuming ionization equilibrium,
  we estimate corresponding Fe XIX/FeXII emission measure ratios of about
  0.076, 0.23 and 0.59. Theemission measure ratios must be viewed with
  caution in light oflingering uncertainties in the Fe XII contribution
  functions.EUNIS-13 was supported by the NASA Heliophysics Division
  through itsLow Cost Access to Space program.

Title: Smart materials optical mirrors
Authors: Chen, Peter C.; Rabin, Douglas M.
Bibcode: 2014SPIE.9143E..50C
Altcode:
  We report the fabrication of imaging quality optical mirrors with smooth
  surfaces using carbon nanotubes embedded in an epoxy matrix. CNT/epoxy
  is a multifunctional or `smart' composite material that has sensing
  capabilities and can be made to incorporate self-actuation as
  well. Moreover, since the precursor is a low density liquid, large and
  lightweight mirrors can be fabricated by processes such as replication,
  spincasting, and 3D printing. The technology therefore holds promise
  for development of a new generation of lightweight, compact `smart'
  telescope mirrors with figure sensing and active or adaptive figure
  control. We report on measurements made of optical and mechanical
  characteristics. We discuss possible paths for future development.

Title: Pervasive Faint Fe XIX Emission from a Solar Active Region
Observed with EUNIS-13: Evidence for Nanoflare Heating
Authors: Brosius, Jeffrey W.; Daw, Adrian N.; Rabin, D. M.
Bibcode: 2014ApJ...790..112B
Altcode:
  We present spatially resolved EUV spectroscopic measurements
  of pervasive, faint Fe XIX 592.2 Å line emission in an active
  region observed during the 2013 April 23 flight of the Extreme
  Ultraviolet Normal Incidence Spectrograph (EUNIS-13) sounding
  rocket instrument. With cooled detectors, high sensitivity, and high
  spectral resolution, EUNIS-13 resolves the lines of Fe XIX at 592.2 Å
  (formed at temperature T ≈ 8.9 MK) and Fe XII at 592.6 Å (T ≈
  1.6 MK). The Fe XIX line emission, observed over an area in excess
  of 4920 arcsec<SUP>2</SUP> (2.58 × 10<SUP>9</SUP> km<SUP>2</SUP>,
  more than 60% of the active region), provides strong evidence for the
  nanoflare heating model of the solar corona. No GOES events occurred
  in the region less than 2 hr before the rocket flight, but a microflare
  was observed north and east of the region with RHESSI and EUNIS during
  the flight. The absence of significant upward velocities anywhere in
  the region, particularly the microflare, indicates that the pervasive
  Fe XIX emission is not propelled outward from the microflare site, but
  is most likely attributed to localized heating (not necessarily due
  to reconnection) consistent with the nanoflare heating model of the
  solar corona. Assuming ionization equilibrium we estimate Fe XIX/Fe
  XII emission measure ratios of ~0.076 just outside the AR core and
  ~0.59 in the core.

Title: Composite telescope technology
Authors: Chen, Peter C.; Rabin, Douglas
Bibcode: 2014SPIE.9151E..30C
Altcode:
  We report the development of optical mirrors based on polymer matrix
  composite materials. Advantages of this technology are low cost and
  versatility. By using appropriate combinations of polymers and various
  metallic and nonmetallic particles and fibers, the properties of the
  materials can be tailored to suit a wide variety of applications. We
  report the fabrication and testing of flat and curved mirrors made
  with metal powders, multiple mirrors replicated with high degree of
  uniformity from the same mandrels, cryogenic testing, mirrors made of
  ferromagnetic materials that can be actively or adaptively controlled
  by non-contact actuation, optics with very smooth surfaces made by
  replication, and by spincasting. We discuss development of a new
  generation of ultra-compact, low power active optics and 3D printing
  of athermal telescopes.

Title: Further Analysis of Active Region Thermal Structure from
    EUNIS-13
Authors: Rabin, Douglas M.; Landi, Enrico; Daw, Adrian N.; Brosius,
   Jeffrey W.
Bibcode: 2014AAS...22432339R
Altcode:
  The 2013 April 23 flight of the Extreme Ultraviolet Normal Incidence
  Spectrograph (EUNIS) sounding rocket instrument returned high-quality
  spectra in two wavelength bands, 30.0-37.0 nm and 52.7-63.5 nm, sampling
  three active regions (11723, 11724, and 11726). The spectral lines
  in these bands probe a wide temperature range, 0.03 MK to 8 MK. We
  have demonstrated that the differential emission measure (DEM) varies
  significantly between different sub-regions of AR 11726. We extend
  this analysis to ARs 11723 and 11724 and include a wider selection of
  spectral lines to delineate better the variations in thermal structure.

Title: Evidence for Impulsive Coronal Heating from EUNIS 2013
Authors: Daw, Adrian N.; Brosius, Jeffrey W.; Rabin, Douglas M.;
   Landi, Enrico; Klimchuk, James A.
Bibcode: 2014AAS...22431204D
Altcode:
  Pervasive, faint Fe XIX 592 Å line emission was observed in active
  regions by the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS)
  sounding rocket instrument on 23 April 2013. The broad spectral coverage
  (303-370 Å, 527-635 Å) and unprecedented dynamic range of the EUNIS
  observations includes emission lines of ionization stages from He I to
  Fe XX, and thus a wide temperature range of 0.03 to 10 MK. Comparison
  of observed line intensities with calculations demonstrates that the
  Fe XIX emission, formed at temperatures around 8 MK, is evidence of
  the faint hot emission predicted by impulsive heating models of the
  solar corona (such as nanoflares).

Title: EUNIS 2013 and Beyond: Resolving the AIA 94 and 131 Å
    Bandpasses
Authors: Daw, Adrian N.; Brosius, J. W.; Haas, J. P.; Landi, E.;
   Plummer, T.; Rabin, D. M.; Wang, T.
Bibcode: 2013SPD....44...10D
Altcode:
  The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding
  rocket instrument is a two-channel imaging spectrograph that observes
  the solar corona and transition region with high spectral resolution
  and a rapid cadence made possible by unprecedented sensitivity. The
  2013 flight on 23 April at 17:30 UT incorporated a new wavelength
  channel covering the range 525-630 Å, the previously-flown 300-370
  Å channel, and the first flight demonstration of cooled active
  pixel sensor (APS) arrays, resulting in high-signal-to-noise spectral
  coverage spanning a wide temperature range of 0.025 to 10 MK. Absolute
  radiometric calibration of the two channels is performed using a hollow
  cathode discharge lamp and NIST-calibrated AXUV-100G photodiode. For
  the 2013 flight, EUNIS co-observed dynamic coronal phenomena with
  DST/IBIS, SoHO/CDS, SDO/AIA and Hinode/EIS and contributes to the
  absolute radiometric calibrations of these instruments. Plans for
  future wavelength channels to cover the AIA 94 and 131 Å bandpasses
  and address the currently unresolved spectral lines (and therefore
  temperature responses) within them are presented.

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

Title: PICTURE: a sounding rocket experiment for direct imaging of
    an extrasolar planetary environment
Authors: Mendillo, Christopher B.; Hicks, Brian A.; Cook, Timothy
   A.; Bifano, Thomas G.; Content, David A.; Lane, Benjamin F.; Levine,
   B. Martin; Rabin, Douglas; Rao, Shanti R.; Samuele, Rocco; Schmidtlin,
   Edouard; Shao, Michael; Wallace, J. Kent; Chakrabarti, Supriya
Bibcode: 2012SPIE.8442E..0EM
Altcode:
  The Planetary Imaging Concept Testbed Using a Rocket Experiment
  (PICTURE 36.225 UG) was designed to directly image the exozodiacal
  dust disk of ǫ Eridani (K2V, 3.22 pc) down to an inner radius of
  1.5 AU. PICTURE carried four key enabling technologies on board
  a NASA sounding rocket at 4:25 MDT on October 8th, 2011: a 0.5 m
  light-weight primary mirror (4.5 kg), a visible nulling coronagraph
  (VNC) (600-750 nm), a 32x32 element MEMS deformable mirror and a
  milliarcsecond-class fine pointing system. Unfortunately, due to a
  telemetry failure, the PICTURE mission did not achieve scientific
  success. Nonetheless, this flight validated the flight-worthiness
  of the lightweight primary and the VNC. The fine pointing system,
  a key requirement for future planet-imaging missions, demonstrated
  5.1 mas RMS in-flight pointing stability. We describe the experiment,
  its subsystems and flight results. We outline the challenges we faced
  in developing this complex payload and our technical approaches.

Title: Underflight Calibration of SOHO/CDS and Hinode/EIS with
    EUNIS-07
Authors: Wang, Tongjiang; Thomas, Roger J.; Brosius, Jeffrey W.; Young,
   Peter R.; Rabin, Douglas M.; Davila, Joseph M.; Del Zanna, Giulio
Bibcode: 2011ApJS..197...32W
Altcode: 2011arXiv1109.6598W
  Flights of Goddard Space Flight Center's Extreme Ultraviolet
  Normal Incidence Spectrograph (EUNIS) sounding rocket in 2006
  and 2007 provided updated radiometric calibrations for Solar and
  Heliospheric Observatory/Coronal Diagnostic Spectrometer (SOHO/CDS)
  and Hinode/Extreme Ultraviolet Imaging Spectrometer (Hinode/EIS). EUNIS
  carried two independent imaging spectrographs covering wavebands of
  300-370 Å in first order and 170-205 Å in second order. After each
  flight, end-to-end radiometric calibrations of the rocket payload were
  carried out in the same facility used for pre-launch calibrations of
  CDS and EIS. During the 2007 flight, EUNIS, SOHO/CDS, and Hinode/EIS
  observed the same solar locations, allowing the EUNIS calibrations to
  be directly applied to both CDS and EIS. The measured CDS NIS 1 line
  intensities calibrated with the standard (version 4) responsivities with
  the standard long-term corrections are found to be too low by a factor
  of 1.5 due to the decrease in responsivity. The EIS calibration update
  is performed in two ways. One uses the direct calibration transfer of
  the calibrated EUNIS-07 short wavelength (SW) channel. The other uses
  the insensitive line pairs, in which one member was observed by the
  EUNIS-07 long wavelength (LW) channel and the other by EIS in either the
  LW or SW waveband. Measurements from both methods are in good agreement,
  and confirm (within the measurement uncertainties) the EIS responsivity
  measured directly before the instrument's launch. The measurements also
  suggest that the EIS responsivity decreased by a factor of about 1.2
  after the first year of operation (although the size of the measurement
  uncertainties is comparable to this decrease). The shape of the EIS SW
  response curve obtained by EUNIS-07 is consistent with the one measured
  in laboratory prior to launch. The absolute value of the quiet-Sun
  He II 304 Å intensity measured by EUNIS-07 is consistent with the
  radiance measured by CDS NIS in quiet regions near the disk center
  and the solar minimum irradiance recently obtained by CDS NIS and the
  Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment.

Title: Quantitative Evaluation of Continuous Diffractive Baffles
    for Heliospheric Imagers
Authors: Rabin, D. M.
Bibcode: 2011AGUFMSH13B1971R
Altcode:
  Wide-angle heliospheric imagers such as those carried on the SMEI and
  STEREO spacecraft require highly effective baffle systems to exclude
  diffracted light from the solar disk as well as other sources of
  stray light. Buffington (2000, Appl. Opt. 39, 2683-2686) has proposed
  replacing multi-vane baffle systems with a curved surface that can be
  thought of as the limiting case of closely spaced vanes. Buffington's
  experimental data showed that the diffractive performance of a
  continuous baffle is consistent with the limiting form expected from
  multi-vane diffraction on heuristic grounds, but a detailed prediction
  was not possible because multi-vane diffraction calculations assume
  that the diffractive edges act independently, an assumption that
  breaks down for a continuous surface. I present analytic calculations
  of diffraction from a curved surface and use them to evaluate the
  effectiveness of continuous-surface baffles for heliospheric imagers.

Title: First Solar Images Using a Photon Sieve
Authors: Daw, A. N.; Rabin, D. M.; Dunlap, L.; Vievering, J.
Bibcode: 2011AGUFMSH13B1962D
Altcode:
  The first solar images using a photon sieve were obtained in H-alpha at
  NASA Goddard Space Flight Center. The first sieve used consists of 1500
  fresnel zones comprising 15 million holes in a chrome layer on a glass
  substrate to yield a focal length of 400 mm at a wavelength of 656.3
  nm. Results of the observations are discussed, as well as the positive
  implications for the use of diffractive optics on deployable membranes
  for extremely high resolution (0.01 arcsec) imaging from space.

Title: Electron Temperatures and Flow Speeds of the Low Solar Corona:
    MACS Results from the Total Solar Eclipse of 29 March 2006 in Libya
Authors: Reginald, Nelson L.; Davila, Joseph M.; St. Cyr, O. C.; Rabin,
   Douglas M.; Guhathakurta, Madhulika; Hassler, Donald M.; Gashut, Hadi
Bibcode: 2011SoPh..270..235R
Altcode: 2011SoPh..tmp...68R; 2011SoPh..tmp...48R
  An experiment was conducted in conjunction with the total solar eclipse
  on 29 March 2006 in Libya to measure both the electron temperature
  and its flow speed simultaneously at multiple locations in the low
  solar corona by measuring the visible K-coronal spectrum. Coronal model
  spectra incorporating the effects of electron temperature and its flow
  speed were matched with the measured K-coronal spectra to interpret
  the observations. Results show electron temperatures of (1.10±0.05)
  MK, (0.70±0.08) MK, and (0.98±0.12) MK, at 1.1 R<SUB>⊙</SUB>
  from Sun center in the solar north, east and west, respectively, and
  (0.93±0.12) MK, at 1.2 R<SUB>⊙</SUB> from Sun center in the solar
  west. The corresponding outflow speeds obtained from the spectral
  fit are (103±92) km s<SUP>−1</SUP>, (0+10) km s<SUP>−1</SUP>,
  (0+10) km s<SUP>−1</SUP>, and (0+10) km s<SUP>−1</SUP>. Since
  the observations were taken only at 1.1 R<SUB>⊙</SUB> and 1.2
  R<SUB>⊙</SUB> from Sun center, these speeds, consistent with zero
  outflow, are in agreement with expectations and provide additional
  confirmation that the spectral fitting method is working. The electron
  temperature at 1.1 R<SUB>⊙</SUB> from Sun center is larger at the
  north (polar region) than the east and west (equatorial region).

Title: Coronal Bright Points and Quiet Sun Areas Observed with
    EUNIS-07 and EIS
Authors: Brosius, Jeffrey W.; Wang, T. J.; Rabin, D. M.; Thomas,
   R. J.; Landi, E.
Bibcode: 2011SPD....42.1828B
Altcode: 2011BAAS..43S.1828B
  The Extreme-Ultraviolet Normal-Incidence Spectrograph is a
  sounding rocket instrument with two independent but co-pointing
  imaging spectrographs. One spectrograph observes emission lines in a
  long-wavelength (LW) channel (300-370 A), while a second observes lines
  in a short-wavelength (SW) channel (170-205 A). The instrument was last
  flown on 6 November 2007 (EUNIS-07), when there were no active regions
  on the solar disk. After the flight, the absolute radiometric responses
  of both channels were derived from laboratory measurements obtained
  in the same facility used for pre-flight calibrations of SOHO/CDS and
  Hinode/EIS. Coordinated EUNIS-07 and EIS observations of quiet sun area
  near disk center reveal that the sensitivity of both EIS wavebands had
  diminished to 82% of their pre-launch values (Wang et al. 2011). Here
  we use the combined EUNIS-07 and EIS spectra to investigate quiet sun
  areas and small bright points observed by both instruments, as well
  as a larger, brighter bright point that was observed only by EUNIS-07.

Title: Evaluation of Diffraction by a Rounded Surface
Authors: Rabin, Douglas M.
Bibcode: 2011SPD....42.1510R
Altcode: 2011BAAS..43S.1510R
  Wide-angle heliospheric imagers such as those carried on the SMEI and
  STEREO spacecraft require highly effective baffle systems to exclude
  diffracted light from the solar disk as well as other sources of
  stray light. Buffington (2000, Appl. Opt. 39, 2683-2686) has proposed
  replacing multi-vane baffle systems with a curved surface that can be
  thought of as the limiting case of closely spaced vanes. Buffington's
  experimental data showed that the diffractive performance of a
  continuous baffle is consistent with the limiting form expected
  from multi-vane diffraction on dimensional grounds, but a detailed
  prediction was not possible because multi-vane diffraction calculations
  assume that the diffractive edges act independently, an assumption that
  breaks down for a continuous surface. I describe analytic calculations
  of diffraction from a smooth rounded surface based on the approach of
  Vogler (1985, Radio Sci. 20, 582-590).

Title: New Capabilities of the EUNIS Sounding Rocket Instrument
Authors: Daw, Adrian N.; Brosius, J.; Criscuolo, E.; Davila, J.;
   Haas, J. P.; Hilton, G.; Linard, D.; Plummer, T.; Rabin, D.; Thomas,
   R.; Varney, D.; Wang, T.
Bibcode: 2011SPD....42.1502D
Altcode: 2011BAAS..43S.1502D
  The upcoming flight of the Extreme Ultraviolet Normal Incidence
  Spectrograph (EUNIS) sounding rocket instrument, a two-channel imaging
  spectrograph that observes the solar corona and transition region
  with high spectral resolution and a rapid cadence made possible by
  unprecedented sensitivity, will incorporate a new wavelength channel
  and cooling of the active pixel sensor (APS) arrays. The new 52.4-63.0
  nm channel incorporates a Toroidal Varied Line Space (TVLS) grating
  coated with B<SUB>4</SUB>C/Ir, providing broad spectral coverage and
  a wide temperature range of 0.025 to 10 MK. The APS arrays for both
  the 52-63 nm and 30-37 nm channels will be cooled to -20 C to reduce
  dark current noise. With the resulting read-noise limited performance,
  over a dozen new diagnostic line pairs become available in the two
  wavelength channels. To our knowledge, this will be the first flight
  demonstration of cooled APS arrays. EUNIS will co-observe dynamic
  coronal phenomena with SDO/AIA and Hinode/EIS and will contribute to
  the absolute radiometric calibrations of these instruments. <P />EUNIS
  is supported by NASA through the Low Cost Access to Space Program in
  Solar and Heliospheric Physics.

Title: An Investigation of Solar Coronal Bright Points Based on EUV
    Spectra Obtained with EUNIS-07
Authors: Schaefer, R.; Brosius, J. W.; Bruhweiler, F.; Rabin, D. M.;
   Thomas, R.; Wang, T.
Bibcode: 2010AGUFMSH31C1805S
Altcode:
  The EUNIS sounding rocket instrument is a two-channel imaging
  spectrograph that observes the solar corona with a rapid cadence made
  possible by unprecedented sensitivity. The instrument was successfully
  flown on 2006 April 12 (EUNIS-06) and 2007 November 6 (EUNIS-07),
  providing hundreds of spectra in the wavelength ranges 170-205 A and
  300-370 A with sustained cadences as fast as 1.3 s. The EUNIS-07
  data have provided the first on-orbit radiometric calibration of
  Hinode's EIS and STEREO's SECCHI/EUVI. Although there were no active
  regions on the solar disk during this flight, EUNIS-07 repeatedly
  scanned across several small coronal bright points within a large
  area of quiet Sun near disk center. We fitted Gaussian profiles to
  emission lines formed at temperatures ranging from 0.05 MK to 2 MK
  (with particular attention to He II 304 A, Mg IX 368 A, and Fe XIV
  334 A) in the spatially resolved EUV spectra. The resulting line
  profile fits are used to derive a series of bright point images that
  we investigate for brightness variations on time scales of one minute,
  as well as relative Doppler velocities. Evolution of the bright points
  on time scales of hours are investigated with magnetograms from SOHO's
  MDI. EUNIS is supported by the NASA Heliophysics Division through its
  Low Cost Access to Space Program in Solar and Heliospheric Physics,
  and is scheduled to fly again in 2011. EUNIS data are freely available
  to the solar physics community. RS acknowledges support under NSF/REU
  grant ATM-00552671 to CUA. JWB is supported by NASA grant NNX10AK45G.

Title: Science Objectives for an X-Ray Microcalorimeter Observing
    the Sun
Authors: Laming, J. Martin; Adams, J.; Alexander, D.; Aschwanden, M;
   Bailey, C.; Bandler, S.; Bookbinder, J.; Bradshaw, S.; Brickhouse,
   N.; Chervenak, J.; Christe, S.; Cirtain, J.; Cranmer, S.; Deiker, S.;
   DeLuca, E.; Del Zanna, G.; Dennis, B.; Doschek, G.; Eckart, M.; Fludra,
   A.; Finkbeiner, F.; Grigis, P.; Harrison, R.; Ji, L.; Kankelborg,
   C.; Kashyap, V.; Kelly, D.; Kelley, R.; Kilbourne, C.; Klimchuk, J.;
   Ko, Y. -K.; Landi, E.; Linton, M.; Longcope, D.; Lukin, V.; Mariska,
   J.; Martinez-Galarce, D.; Mason, H.; McKenzie, D.; Osten, R.; Peres,
   G.; Pevtsov, A.; Porter, K. Phillips F. S.; Rabin, D.; Rakowski, C.;
   Raymond, J.; Reale, F.; Reeves, K.; Sadleir, J.; Savin, D.; Schmelz,
   J.; Smith, R. K.; Smith, S.; Stern, R.; Sylwester, J.; Tripathi, D.;
   Ugarte-Urra, I.; Young, P.; Warren, H.; Wood, B.
Bibcode: 2010arXiv1011.4052L
Altcode:
  We present the science case for a broadband X-ray imager with
  high-resolution spectroscopy, including simulations of X-ray spectral
  diagnostics of both active regions and solar flares. This is part of
  a trilogy of white papers discussing science, instrument (Bandler et
  al. 2010), and missions (Bookbinder et al. 2010) to exploit major
  advances recently made in transition-edge sensor (TES) detector
  technology that enable resolution better than 2 eV in an array that
  can handle high count rates. Combined with a modest X-ray mirror, this
  instrument would combine arcsecondscale imaging with high-resolution
  spectra over a field of view sufficiently large for the study of
  active regions and flares, enabling a wide range of studies such as
  the detection of microheating in active regions, ion-resolved velocity
  flows, and the presence of non-thermal electrons in hot plasmas. It
  would also enable more direct comparisons between solar and stellar
  soft X-ray spectra, a waveband in which (unusually) we currently have
  much better stellar data than we do of the Sun.

Title: Absolute Radiometric Calibration Of EUNIS, And Calibration
    Updates For Hinode/EIS And SOHO/CDS
Authors: Wang, Tongjiang; Thomas, R. J.; Brosius, J. W.; Young, P. R.;
   Rabin, D. M.; Davila, J. M.
Bibcode: 2010AAS...21640704W
Altcode: 2010BAAS...41..860W
  The Extreme-Ultraviolet Normal-Incidence Spectrograph sounding rocket
  payload was flown in 2006 (EUNIS-06) and 2007 (EUNIS-07), each time
  carrying two independent imaging spectrographs covering wave bands
  of 300-370 Angstrom in first order and 170-205 Angstrom in second
  order. For each flight, the absolute radiometric response of the EUNIS
  long-wavelength (LW) channel was directly measured in the same facility
  used for pre-flight calibrations of SOHO/CDS and Hinode/EIS. The
  wavelength range of the EUNIS LW channel overlaps that of CDS/NIS-1,
  and so can provide a direct calibration update for it. The EUNIS-06
  observation shows that the efficiency of CDS/NIS-1 has decreased by
  a factor about 1.7 compared to that of the previously implemented
  calibration. Here we present an update to the absolute calibration for
  Hinode/EIS derived with a technique that combines a direct comparison
  of line intensities observed in cospatial EUNIS-07 and EIS spectra,
  along with density- and temperature-insensitive line intensity ratios.

Title: Absolute Radiometric Calibration of the EUNIS-06 170-205
    Å Channel and Calibration Update for Coronal Diagnostic
    Spectrometer/Normal-Incidence Spectrometer
Authors: Wang, Tongjiang; Brosius, Jeffrey W.; Thomas, Roger J.;
   Rabin, Douglas M.; Davila, Joseph M.
Bibcode: 2010ApJS..186..222W
Altcode: 2009arXiv0912.2328W
  The Extreme-Ultraviolet Normal-Incidence Spectrograph sounding-rocket
  payload was flown on 2006 April 12 (EUNIS-06), carrying two independent
  imaging spectrographs covering wavebands of 300-370 Å in first order
  and 170-205 Å in second order, respectively. The absolute radiometric
  response of the EUNIS-06 long-wavelength (LW) channel was directly
  measured in the same facility used to calibrate Coronal Diagnostic
  Spectrometer (CDS) prior to the Solar and Heliospheric Observatory
  (SOHO) launch. Because the absolute calibration of the short-wavelength
  (SW) channel could not be obtained from the same lab configuration,
  we here present a technique to derive it using a combination of solar
  LW spectra and density- and temperature-insensitive line intensity
  ratios. The first step in this procedure is to use the coordinated,
  cospatial EUNIS and SOHO/CDS spectra to carry out an intensity
  calibration update for the CDS NIS-1 waveband, which shows that its
  efficiency has decreased by a factor about 1.7 compared to that of the
  previously implemented calibration. Then, theoretical insensitive line
  ratios obtained from CHIANTI allow us to determine absolute intensities
  of emission lines within the EUNIS SW bandpass from those of cospatial
  CDS/NIS-1 spectra after the EUNIS LW calibration correction. A total
  of 12 ratios derived from intensities of 5 CDS and 12 SW emission
  lines from Fe X to Fe XIII yield an instrumental response curve for
  the EUNIS-06 SW channel that matches well to a relative calibration
  which relied on combining measurements of individual optical
  components. Taking into account all potential sources of error, we
  estimate that the EUNIS-06 SW absolute calibration is accurate to ±20%.

Title: A Scalable Superconductor Bearing System For Lunar Telescopes
    And Instruments
Authors: Chen, Peter C.; Rabin, D.; Van Steenberg, M. E.
Bibcode: 2010AAS...21548102C
Altcode: 2010BAAS...42R.570C
  We report on a new concept for a telescope mount on the Moon based
  on high temperature superconductors (HTS). Lunar nights are long
  (15 days), and temperatures range from 100 K to 30 K inside shadowed
  craters. Telescopes on the Moon therefore require bearing systems that
  can position and track precisely under cryogenic conditions, over long
  time periods, preferably with no maintenance, and preferably do not
  fail with loss of power. HTS bearings, consisting of permanent magnets
  levitated over bulk superconductors, are well suited to the task. The
  components do not make physical contact, hence there is no wear. The
  levitation is passive and stable; no power is required to maintain
  position. We report on the design and laboratory demonstration of
  a prototype two-axis pointing system. Unlike previous designs, this
  new configuration is simple and easy to implement. Most importantly,
  it can be scaled to accommodate instruments ranging in size from
  decimeters (laser communication systems) to meters (solar panels,
  communication dishes, optical telescopes, optical interferometers)
  to decameters and beyond (VLA-type radio interferometer elements).

Title: Electron-Temperature Maps of the Low Solar Corona: ISCORE
    Results from the Total Solar Eclipse of 29 March 2006 in Libya
Authors: Reginald, Nelson L.; St. Cyr, O. C.; Davila, Joseph M.;
   Rabin, Douglas M.; Guhathakurta, Madhulika; Hassler, Donald M.
Bibcode: 2009SoPh..260..347R
Altcode:
  We conducted an experiment in conjunction with the total solar
  eclipse of 29 March 2006 in Libya that measured the coronal
  intensity through two filters centered at 3850 Å and 4100 Å with
  bandwidths of ≈ 40 Å. The purpose of these measurements was to
  obtain the intensity ratio through these two filters to determine
  the electron temperature. The instrument, Imaging Spectrograph of
  Coronal Electrons (ISCORE), consisted of an eight inch, f/10 Schmidt
  Cassegrain telescope with a thermoelectrically-cooled CCD camera at
  the focal plane. Results show electron temperatures of 10<SUP>5</SUP>
  K close to the limb to 3×10<SUP>6</SUP> K at 1.3R<SUB>⊙</SUB>. We
  describe this novel technique, and we compare our results to other
  relevant measurements. This technique could be easily implemented on
  a space-based platform using a coronagraph to produce global maps of
  the electron temperature of the solar corona.

Title: Transition Region Velocity Oscillations Observed by EUNIS-06
Authors: Jess, D. B.; Rabin, D. M.; Thomas, R. J.; Brosius, J. W.;
   Mathioudakis, M.; Keenan, F. P.
Bibcode: 2008ApJ...682.1363J
Altcode: 2008arXiv0804.1629J
  Spectroscopic measurements of NOAA AR 10871, obtained with the Extreme
  Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket
  instrument on 2006 April 12, reveal velocity oscillations in the He
  II 303.8 Å emission line formed at T ≈ 5 × 10<SUP>4</SUP> K. The
  oscillations appear to arise in a bright active region loop arcade
  about 25<SUP>''</SUP> wide which crosses the EUNIS slit. The period
  of these transition region oscillations is 26 +/- 4 s, coupled with
  a velocity amplitude of ±10 km s<SUP>-1</SUP>, detected over four
  complete cycles. Similar oscillations are observed in lines formed at
  temperatures up to T ≈ 4 × 10<SUP>5</SUP> K, but we find no evidence
  for the coupling of these velocity oscillations with corresponding
  phenomena in the corona. We interpret the detected oscillations as
  originating from an almost purely adiabatic plasma, and infer that
  they are generated by the resonant transmission of MHD waves through
  the lower active region atmospheres. Through the use of seismological
  techniques, we establish that the observed velocity oscillations display
  wave properties most characteristic of fast body global sausage modes.

Title: Rapid Cadence EUNIS-06 Observations of a He II Transient
    Brightening in the Quiet Sun
Authors: Brosius, Jeffrey W.; Rabin, Douglas M.; Thomas, Roger J.
Bibcode: 2008ApJ...682..630B
Altcode:
  We observed a transient brightening in the quiet Sun at rapid cadence
  (2.10 s) with the Extreme Ultraviolet Normal Incidence Spectrograph
  (EUNIS-06) sounding rocket instrument on 2006 April 12. The transient
  was visible only in He II at 303.78 Å (T ≈ 5 × 10<SUP>4</SUP> K),
  and its maximum temperature T was &lt;4 × 10<SUP>5</SUP> K. Taking
  its linear extent along the EUNIS slit to be the diameter of a circular
  feature, the transient's solar surface area was 7.8 × 10<SUP>7</SUP>
  km<SUP>2</SUP>. EUNIS observed the brightening to begin at 18:12:52
  and peak at 18:13:29 UT; coordinated observations with SOHO's EIT
  confirm that EUNIS observed the onset of the brightening. EUNIS
  spectra yield maximum and average He II intensity enhancements
  of 2.09 and 1.46, respectively, relative to the pre-event quiet
  Sun. He II line profiles from EUNIS reveal that relative upflows
  were persistent during the transient (with a maximum speed around
  20 km s<SUP>-1</SUP>) and that the upflow speed and intensity were
  positively correlated. Variations in the observed He II intensity
  and relative Doppler velocity were neither abrupt not impulsive, but
  occurred slowly compared to the EUNIS cadence. The local photospheric
  longitudinal magnetic field strength measured with SOHO's MDI revealed
  no significant variability. The transient's measured properties are
  consistent with its identification as a blinker or an elementary
  blinker, and its observed behavior suggests a formation mechanism
  involving gentle chromospheric evaporation.

Title: EUNIS-07: First Look
Authors: Rabin, D. M.; Thomas, R. J.; Brosius, J. W.
Bibcode: 2008AGUSMSP51A..07R
Altcode:
  The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding
  rocket instrument is a two-channel imaging spectrograph that observes
  the solar corona with high spectral resolution and a rapid cadence
  made possible by unprecedented sensitivity. EUNIS flew for the
  first time on 2006 April 12 (EUNIS-06), returning over 140 science
  exposures at a cadence of 2.1 s; each exposure comprises six 1K x 1K
  active pixel sensor (APS) images, three for each wavelength channel
  (170-205 Å and 300-370 Å. Analysis of EUNIS-06 data has so far shed
  new light on the nature of coronal bright points, cool transients, and
  coronal loop arcades and has enabled calibration updates for TRACE and
  SOHO's CDS and EIT. EUNIS flew successfully again on 2007 November 6
  (EUNIS-07). Because the APS arrays were operated in video rather than
  snapshot mode, a faster cadence of 1.3 s was possible (97% duty cycle),
  resulting in 276 science exposures. We present an overview of the
  EUNIS-07 spectra and describe the coordinated observing program executed
  by the Hinode Extreme ultraviolet Imaging Spectrograph (EIS) that will,
  in conjunction with the absolute radiometric calibration of EUNIS-07,
  result in the first on-orbit radiometric calibration of EIS. EUNIS data
  are freely available to the solar physics community. EUNIS is supported
  by the NASA Heliophysics Division through its Low Cost Access to Space
  Program in Solar and Heliospheric Physics.

Title: EUNIS-06 Rapid Cadence Observations of a He II Transient
    Brightening in the Quiet Sun
Authors: Brosius, J. W.; Rabin, D. M.; Thomas, R. J.
Bibcode: 2008AGUSMSP51A..06B
Altcode:
  We observed a transient brightening in the quiet Sun at rapid cadence
  (2.10 s) with the Extreme Ultraviolet Normal Incidence Spectrograph
  (EUNIS-06) sounding rocket instrument on 2006 April 12. The transient
  was visible only in He II at 303.78 Å (T ≍ 5 × 104 K), and its
  maximum temperature T was &lt; 4 × 105 K. Taking its linear extent
  along the EUNIS slit to be the diameter of a circular feature, the
  transient's solar surface area was 7.8 × 107 km2. EUNIS observed the
  brightening to begin at 18:12:52 and peak at 18:13:29 UT; coordinated
  observations with SOHO's EIT confirm that EUNIS observed the onset
  of the brightening. EUNIS spectra yield maximum and average He II
  intensity enhancements of 2.09 and 1.46, respectively, relative to
  the pre-event quiet Sun. He II line profiles from EUNIS reveal that
  relative upflows were persistent during the transient (with a maximum
  speed around 20 km s-1) and that the upflow speed and intensity were
  positively correlated. Variations in the observed He II intensity
  and relative Doppler velocity were neither abrupt not impulsive, but
  occurred slowly compared to the EUNIS cadence. The local photospheric
  magnetic flux measured with SOHO's MDI revealed no significant
  variability. The transient's measured properties are consistent with
  its identification as a blinker or an elementary blinker, and its
  observed behavior suggests a formation mechanism involving gentle
  chromospheric evaporation. The EUNIS program is supported by NASA's
  Heliophysics Division through its Low Cost Access to Space Program in
  Solar and Heliospheric Physics.

Title: EUNIS Underflight Calibrations of CDS, EIT, TRACE, EIS,
    and EUVI
Authors: Thomas, R.; Wang, T.; Rabin, D. M.; Jess, D. B.; Brosius,
   J. W.
Bibcode: 2008AGUSMSP51B..04T
Altcode:
  The Extreme-Ultraviolet Normal-Incidence Spectrograph (EUNIS) is a
  sounding rocket instrument that obtains imaged high-resolution solar
  spectra. It has now had two successful flights, on 2006 April 12 and
  2007 November 16, providing data to support underflight calibrations
  for a number of orbiting solar experiments on both occasions. A regular
  part of each campaign is the end-to-end radiometric calibration of
  the rocket payload carried out at RAL in the UK, using the same
  facility that provided pre-flight CDS and EIS calibrations. The
  measurements, traceable to primary radiometric standards, can establish
  the absolute EUNIS response within a total uncertainty of 10% over
  its full longwave bandpass of 300--370Å. During each EUNIS flight,
  coordinated observations are made of overlapping solar locations by
  all participating space experiments, and identified by subsequent
  image co-registrations, allowing the EUNIS calibrations to be applied
  to these other instruments as well. The calibration transfer is
  straightforward for wavelengths within the EUNIS LW bandpass, and is
  extended to other wavelengths by means of a series of temperature-
  and density-insensitive line-ratios, with one line of each pair in
  the calibrated band and the other in the transfer band. In this way,
  the EUNIS-06 flight is able to update the radiometric calibrations of
  CDS NIS1 (and 2nd-order NIS2 near 2x304Å), all four channels of EIT,
  and the three EUV channels of TRACE. The EUNIS-07 flight will further
  update those missions, as well as both channels of Hinode/EIS and all
  four channels of STEREO/SECCHI/EUVI. Future EUNIS flights have been
  proposed that will continue this underflight calibration service. EUNIS
  is supported by the NASA Heliophysics Division through its Low Cost
  Access to Space Program in Solar and Heliospheric Physics.

Title: Analysis of a Solar Coronal Bright Point Extreme Ultraviolet
    Spectrum from the EUNIS Sounding Rocket Instrument
Authors: Brosius, Jeffrey W.; Rabin, Douglas M.; Thomas, Roger J.;
   Landi, Enrico
Bibcode: 2008ApJ...677..781B
Altcode:
  We present a well-calibrated EUV spectrum of a solar coronal bright
  point observed with the Extreme Ultraviolet Normal Incidence
  Spectrograph (EUNIS) sounding rocket instrument on 2006 April
  12. The coronal bright point brightened around 06:30 UT during a
  period of emerging magnetic flux and remained bright at least until
  the rocket flight around 18:12 UT, while the magnetic flux merged
  and canceled. Density-sensitive line intensity ratios yield mutually
  consistent coronal electron densities (N<SUB>e</SUB> in cm<SUP>-3</SUP>)
  of log N<SUB>e</SUB> ≈ 9.4. The differential emission measure
  (DEM, in cm<SUP>-5</SUP> K<SUP>-1</SUP>) curve derived from the
  spectrum yields a peak of log DEM ≈ 20.70 at log T ≈ 6.15 and a
  local minimum of log DEM ≈ 20.15 at log T ≈ 5.35. Photospheric
  (not coronal) element abundances are required to achieve equality
  and consistency in the DEM derived from lines of Mg V, Mg VI, Mg VII,
  and Ca VII (with a low first ionization potential, or FIP) and lines
  from Ne IV and Ne V (with a high FIP) formed at transition region
  temperatures. The bright point's photospheric abundance is likely
  produced by reconnection-driven chromospheric evaporation, a process
  that is not only central to existing bright point models, but also
  consistent with measurements of relative Doppler velocities.

Title: Analysis of a Bright Point Spectrum From the Extreme
    Ultraviolet Normal Incidence Spectrograph (EUNIS) Sounding Rocket
    Instrument
Authors: Brosius, J. W.; Rabin, D. M.; Thomas, R. J.
Bibcode: 2007AGUFMSH21B..04B
Altcode:
  We present a well-calibrated spectrum of a bright point observed with
  EUNIS on 2006 April 12. Coordinated observations with SOHO's EIT and
  MDI were also obtained. The bright point brightened around 06:30 UT
  during a period of emerging magnetic flux, and remained bright at least
  until the rocket flight around 18:12 UT while the magnetic flux merged
  and canceled. Density-sensitive line intensity ratios yield mutually
  consistent coronal electron densities log Ne ~ 9.5. Based on the method
  of Landi &amp; Landini (1997), the differential emission measure (DEM)
  curve derived from the spectrum yields a peak of log DEM ~ 20.70 at log
  T ~ 6.15, and a local minimum of log DEM ~ 20.15 at log T ~ 5.35. We
  find that photospheric (not coronal) element abundances are required to
  achieve equality and consistency in the DEM derived from lines of Mg V,
  Mg VI, Mg VII, Ca VII (with a low first ionization potential, or FIP)
  and lines from Ne IV and Ne V (with a high FIP) formed at transition
  region temperatures. The bright point's photospheric abundance is
  likely produced by reconnection-driven chromospheric evaporation,
  a process that is not only central to existing bright point models
  (e.g., Priest, Parnell, &amp; Martin 1994; Longcope 1998), but also
  consistent with measurements of relative Doppler velocities (e.g.,
  ± 26 km/s for Fe XIV, ± 35 km/s for Fe XVI) previously presented by
  Brosius, Rabin, &amp; Thomas (2007). The EUNIS program is supported
  by NASA's Heliophysics Division through its Low Cost Access to Space
  Program in Solar and Heliospheric Physics. We thank the entire EUNIS
  team for the concerted effort that led to a successful first flight.

Title: Radiometric Calibration of EUNIS-06 With Theoretical Predicted
    `Insensitive' Line Ratios
Authors: Wang, T.; Brosius, J. W.; Thomas, R. J.; Rabin, D. M.
Bibcode: 2007AGUFMSH53A1049W
Altcode:
  The Extreme-Ultraviolet Normal-Incidence Spectrograph (EUNIS) is a
  sounding-rocket payload that obtains imaged high-resolution spectra
  of solar active and quiet-Sun regions, providing information about
  the corona and upper transition region. EUNIS incorporates two
  independent, co-pointing imaging spectrographs, one covering EUV
  lines between 300 and 370 Å\ seen in first order (the longwave
  [LW] channel), and a second covering lines between 170 and 205 Å\
  seen in second order (the shortwave [SW] channel). Shortly after
  the payload's initial successful flight on 2006 April 12, a complete
  end-to-end radiometric calibration of its LW bandpass was carried out
  at the Rutherford Appleton Laboratory in England. Here we develop and
  apply a technique for deriving the absolute radiometric calibration
  of its SW bandpass from these direct LW results by means of density-
  and temperature-insensitive line intensity ratios. The first step
  is to use the EUNIS LW calibration to get absolute intensities for
  EUV lines recorded from solar positions along its LW slit during the
  2006 flight. Then co-registered SOHO/CDS images taken within minutes
  of the flight are used to transfer these absolute values to solar
  locations observed by the EUNIS SW slit, spatially offset by about 1
  arcmin. Finally, theoretical `insensitive' line ratios obtained from
  CHIANTI allow us to determine absolute intensities of emission lines
  within the EUNIS SW bandpass from those observed in its LW channel. A
  total of 29 ratios composed of 11 LW and 15 SW emission lines from Fe~X
  - Fe~XIII yield an instrumental response curve that matches very well
  to a relative calibration which relied on combining measurements of
  individual optical components. The second EUNIS flight, now scheduled
  for 2007 October 30, will make coordinated observations and provide
  similar calibration updates for Hinode/EIS. We will also present some
  preliminary results from the new observations. EUNIS is supported by
  the NASA Heliophysics Division through its Low Cost Access to Space
  Program in Solar and Heliospheric Physics.

Title: Advances in Solar Coronagraphy
Authors: Rabin, D.; St. Cyr, O. C.; Davila, J. M.
Bibcode: 2007lyot.confE..18R
Altcode:
  Could Bernard Lyot have imagined the protean forms in which his most
  notable invention, the coronagraph, would appear 75 years later? Could
  he have foreseen that the most widely used solar coronagraphs would be
  based in space, or that coronagraphs would seek to image planets and
  disks around other stars? Perhaps so - he was far more than a builder
  of creative instruments. I will discuss advances in solar coronagraphy
  since Lyot's time, in both the science that drives the observations
  and the technology that sustains them.

Title: Absolute Radiometric Calibration of EUNIS-06
Authors: Thomas, Roger J.; Rabin, D. M.; Haas, J. P.; Kent, B. J.;
   Paustian, W.; Jess, D. B.
Bibcode: 2007AAS...210.2508T
Altcode: 2007BAAS...39..132T
  The Extreme-Ultraviolet Normal-Incidence Spectrometer (EUNIS) is a
  sounding-rocket payload that obtains imaged high-resolution spectra of
  individual solar features, providing information about the Sun's corona
  and upper transition region. Shortly after its successful initial
  flight last year, a complete end-to-end calibration was carried out
  to determine the instrument's absolute radiometric response over
  its longwave bandpass of 300 - 370 Å. The measurements were done
  at the Rutherford-Appleton Laboratory (RAL) in England, using the
  same vacuum facility and EUV radiation source used in the pre-flight
  calibrations of both SOHO/CDS and Hinode/EIS, as well as in three
  post-flight calibrations of our SERTS sounding rocket payload,
  the precursor to EUNIS. The unique radiation source provided by
  the Physikalisch-Technische Bundesanstalt (PTB) had been absolutely
  calibrated to a relative uncertainty of 7% (1σ) at 12 wavelengths
  covering our bandpass directly against the Berlin electron storage ring
  BESSY, which is itself a primary radiometric source standard. Scans
  of the EUNIS aperture were made to determine the instrument's absolute
  spectral sensitivity to ± 25%, considering all sources of error, and
  demonstrate that EUNIS-06 was the most sensitive solar EUV spectrometer
  flown to date. The results will be matched against prior calibrations
  which relied on combining measurements of individual optical components,
  and on comparisons with theoretically predicted 'insensitive' line
  ratios. Coordinated observations were made during the EUNIS-06 flight by
  SOHO/CDS and EIT that will allow re-calibrations of those instruments as
  well. In addition, future EUNIS flights will provide similar calibration
  updates for TRACE, Hinode/EIS, and STEREO/SECCHI/EUVI. <P />EUNIS
  is supported by the NASA Heliophysics Division through its Low Cost
  Access to Space Program in Solar and Heliospheric Physics.

Title: Forecast of the Amplitude of Solar Cycle 24 Based on the
    Disturbed Days Precursor
Authors: Rabin, Douglas M.
Bibcode: 2007AAS...210.9205R
Altcode: 2007BAAS...39..209R
  R. J. Thompson (1993, Solar Physics 148, 383) exhibited a significant
  linear relationship between the number of geomagnetically disturbed
  days (those that exceed some threshold value of the Ap or aa index) in
  a solar cycle and the sum of the peak sunspot number in that cycle and
  the next cycle. Thus, the number of disturbed days during a full cycle,
  together with the peak sunspot number in that cycle, is a predictor
  of the amplitude of the next cycle. The work reported here applies
  Thompson’s method to the current cycle. Linear relationships as
  described above are derived both for the pure aa record (1868-2006)
  and for a composite of aa (1868-1931) and Ap (1932-2006). For the
  composite record, the relationship between aa and Ap is determined
  cycle-by-cycle during the period of overlap. The method is tested
  for sensitivity to the adopted Ap (or equivalent aa) threshold. The
  highest smoothed monthly sunspot number for Cycle 24 is forecasted to
  be R<SUB>z</SUB> = 115 ± 30, where the uncertainty is conservatively
  based on the full spread of the data around the fitted line in the
  sunspot number direction. In terms of smoothed monthly 10.7-cm radio
  flux, the forecast is F10.7 = 164 ± 28.

Title: EUNIS And SOHO Observations Of A Cool Transient Brightening
    In The Quiet Sun
Authors: Brosius, Jeffrey W.; Rabin, D. M.; Thomas, R. J.
Bibcode: 2007AAS...210.2507B
Altcode: 2007BAAS...39..132B
  The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding
  rocket instrument observed a cool transient brightening in the quiet
  Sun during its first flight on 2006 April 12. The brightening appeared
  in emission from He II, formed at temperatures around 50,000 K (log
  T = 4.7), but was not evident in emission from ions formed at greater
  temperatures, including Mg VI (log T = 5.6), Mg IX (log T = 6.0), and
  Fe XIV (log T = 6.3). Of these and other lines in the EUNIS spectra,
  only lines from He II and Mg IX were strong enough in the quiet Sun
  to measure relative Doppler velocities during this transient; He II
  revealed continuous upflows around 15 km/s while Mg IX revealed no
  significant velocities. The average He II intensity enhancement factor
  observed with EUNIS was 1.34, and its maximum was 1.84. Coordinated
  observations with SOHO's EIT reveal a source area of 3.3x10^7 km^2,
  in which the average He II intensity enhancement factor was 1.39 and
  its maximum was 1.81; the transient did not appear in EIT's hotter
  wavebands. Variations in the local magnetic field strength measured with
  SOHO's MDI were marginal. The EUNIS program is supported by NASA through
  its Low Cost Access to Space Program in Solar and Heliospheric Physics.

Title: Doppler Velocities Measured in Coronal Emission Lines from
    a Bright Point Observed with the EUNIS Sounding Rocket
Authors: Brosius, Jeffrey W.; Rabin, Douglas M.; Thomas, Roger J.
Bibcode: 2007ApJ...656L..41B
Altcode:
  Spectroscopic measurements of a coronal bright point obtained with
  the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding
  rocket instrument on 2006 April 12 show both upflows and downflows in
  all five of the best observed emission lines. Relative velocities on
  opposite sides of the feature were found to be +/-15 km s<SUP>-1</SUP>
  in the line of He II 303.8 Å (formed at T~5×10<SUP>4</SUP> K),
  +/-14 km s<SUP>-1</SUP> in Mg IX 368.1 Å (T~9.5×10<SUP>5</SUP> K),
  +/-26 km s<SUP>-1</SUP> in Fe XIV 334.2 Å (T~2.0×10<SUP>6</SUP>
  K), and +/-35 km s<SUP>-1</SUP> in both Fe XVI 335.4 and 360.8 Å
  (T~2.5×10<SUP>6</SUP> K). The latter are the hottest lines for which
  Doppler velocities have been reported in a bright point. Photospheric
  longitudinal magnetograms reveal that the photospheric magnetic
  fields underlying the bright point were canceling during the EUNIS
  observation. Based on existing bright point models, this suggests that
  the observed hot flows were associated with magnetic reconnection.

Title: Preliminary EUNIS-06 EUV Spectral Catalog
Authors: Thomas, Roger J.; Rabin, D. M.
Bibcode: 2006SPD....37.0105T
Altcode: 2006BAAS...38..216T
  The recent 2006 April 12 flight of NASA/GSFC's sounding rocket payload,
  the EUV Normal-Incidence Spectrograph (EUNIS-06), produced 145 spectral
  images in each of two optical channels with passbands of 170--205 Å
  and 300--370 Å, respectively. These spectra are spatially resolved
  along slit lengths of about 660 arcsec covering portions of NOAA Active
  Region 10871 at S07E28, as well as quiet areas near disk center. We
  present here examples of spatial variations recorded in some of the
  stronger lines, along with a preliminary catalog of all spectral lines
  found by averaging the complete data set.EUNIS is supported by the NASA
  Heliophysics Division's Solar &amp; Heliospheric Physics Supporting
  Research and Technology and Low Cost Access to Space Program.

Title: First Results from EUNIS-06
Authors: Rabin, Douglas M.; Thomas, R. J.; Davila, J. M.
Bibcode: 2006SPD....37.0106R
Altcode: 2006BAAS...38..216R
  The Extreme Ultraviolet Normal-Incidence Spectrograph (EUNIS) sounding
  rocket experiment successfully completed its first flight on 12
  April 2006 from White Sands Missile Range, obtaining 145 science
  images in each of two wavelength channels. EUNIS is designed to
  investigate the energetics of the solar corona and hotter transition
  region through high-resolution imaging spectroscopy with a rapid
  (2-3 second) cadence. The two independent optical systems of EUNIS
  simultaneously record spectra over two passbands (170-205 Å and
  300-370 Å), each spatially resolved along slit lengths of about
  660 arcsec. The longwave channel includes He II 304 Å and strong
  lines from Fe XI-XVI. The shortwave passband has a sequence of very
  strong Fe IX-XIII lines. Together, the EUNIS telescopes furnish a wide
  range of temperature and density diagnostics and enables underflight
  calibration of instrumental passbands on the SOHO, TRACE, Solar-B,
  and STEREO missions. <P />We present an overview of the science images
  from the first flight with emphasis on transient phenomena. The target
  was active region NOAA 10871 and adjacent quiet areas. Spectra were
  recorded with exposure times as short as 0.1 s, demonstrating that EUNIS
  is the most sensitive solar EUV spectrograph in operation, with over 100
  times the throughput of its predecessor, the Solar Extreme ultraviolet
  Research Telescope and Spectrograph (SERTS). <P />EUNIS is supported
  by the NASA Heliophysics Division's Solar &amp; Heliospheric Physics
  Supporting Research and Technology and Low Cost Access to Space Program.

Title: Component Radiometric Calibrations of the EUV Normal-Incidence
    Spectrograph (EUNIS)
Authors: Thomas, R. J.; Rabin, D. M.
Bibcode: 2005AAS...20711111T
Altcode: 2005BAAS...37.1343T
  The EUV Normal-Incidence Spectrograph (EUNIS) is a sounding rocket
  experiment that will investigate the energetics of the solar corona and
  hotter transition region through high-resolution imaging spectroscopy
  with a rapid (2 s) cadence. EUNIS features independent optical
  systems to record spatially co-aligned spectra simultaneously over
  its two bandpasses of 170--205 and 300--370 Å. All the components
  in the detection chain have been characterized, including multilayer
  telescope mirrors, lithographic slits, multilayer diffraction gratings,
  microchannel-plate intensifiers, and active-pixel sensors. The results
  demonstrate that EUNIS is the most sensitive solar EUV spectrograph
  in existence. Its first flight is scheduled for 2005 November. EUNIS
  is supported by NASA RTOP 432-03-31.

Title: First Results From EUNIS 2005
Authors: Rabin, D. M.; Thomas, R. J.; Davila, J. M.; Brosius, J. W.;
   Swartz, M.; Jordan, S. D.
Bibcode: 2005AGUFMSH41B1122R
Altcode:
  The Extreme Ultraviolet Normal-Incidence Spectrograph (EUNIS) is
  a sounding rocket experiment to investigate the energetics of the
  solar corona and hotter transition region through high-resolution
  imaging spectroscopy with a rapid (2 second) cadence. Pre-flight
  characterization of throughput has demonstrated that EUNIS is the
  most sensitive solar EUV spectrograph in existence, having over
  100 times the throughput of its predecessor, the Solar Extreme
  ultraviolet Research Telescope and Spectrograph (SERTS). We report
  initial results from the first flight in November 2005 from White
  Sands Missile Range. The main scientific goal of the first EUNIS
  flight is to extend the investigation of transient phenomena, such as
  nanoflares and blinkers, to shorter timescales than has been possible
  with previous EUV spectrographs. The two independent optical systems
  of EUNIS record spatially co-aligned spectra over two passbands
  (170--205 Å and 300--370 Å) simultaneously with spectral resolution
  of 60 mÅ or 120 mÅ, respectively. The longwave passband includes
  He II 304 Å and strong lines from Fe XI--XVI. The shortwave passband
  has a sequence of very strong Fe IX--XIII lines. Together, the EUNIS
  telescopes furnish a wide range of temperature and density diagnostics
  and enable underflight calibration of instrumental passbands on the
  SOHO, TRACE, Solar-B, and STEREO missions.

Title: Measured Pre-Flight Performance of the Extreme Ultraviolet
    Normal Incidence Spectrograph (EUNIS)
Authors: Thomas, R. J.; Rabin, D. M.; Nowak, M. D.; Gum, J. S.; Seely,
   J. F.; Seshadri, S.; Siegmund, O. H.
Bibcode: 2005AGUSMSP43A..06T
Altcode:
  The Extreme Ultraviolet Normal-Incidence Spectrograph (EUNIS) is a
  sounding rocket experiment that will investigate the energetics of
  the solar corona and hotter transition region through high-resolution
  imaging spectroscopy with a rapid (2 s) cadence. EUNIS features
  independent optical systems to record spatially co-aligned spectra over
  the two bandpasses 170--205 Å and 300--370 Å simultaneously. All
  the components in the detection chain have been characterized,
  including multilayer telescope mirrors, lithographic slits, multilayer
  diffraction gratings, microchannel plate intensifiers, and active pixel
  sensors. The results demonstrate that EUNIS is the most sensitive
  solar EUV spectrograph in existence. Its first flight is scheduled
  for 2005 August.

Title: Coronal Heating, Spicules, and SolarB
Authors: Moore, R. L.; Falconer, D. A.; Porter, J. G.; Hathaway,
   D. H.; Yamauchi, Y.; Rabin, D. M.
Bibcode: 2004ASPC..325..283M
Altcode:
  We summarize certain observations of coronal luminosity, network
  magnetic flux, spicules, and macrospicules. These observations together
  imply that in quiet regions that are not influenced by active regions
  the coronal heating comes from magnetic activity in the edges of the
  network flux, possibly from explosions of sheared core fields around
  granule-sized inclusions of opposite-polarity flux. This scenario can
  be tested by SolarB.

Title: The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS)
Authors: Rabin, D.; Davila, J.; Thomas, R. J.; Engler, C.; Irish,
   S.; Keski-Kuha, R.; Novello, J.; Nowak, M.; Payne, L.; Rodriguez, I.;
   Saha, T.; Scott, R.; Swartz, M.; Trimble, M.; White, L.; Seshadri, S.
Bibcode: 2003SPD....34.2007R
Altcode: 2003BAAS...35..845R
  EUNIS is a high-efficiency extreme ultraviolet spectrometer that
  is expected to fly for the first time in 2004 as a sounding rocket
  payload. Using two independent optical systems, EUNIS will probe
  the structure and dynamics of the inner solar corona high spectral
  resolution in two wavelength regions: 17-21 nm with 3.5 pm resolution
  and 30-37 nm with 7 pm resolution. The long wavelength channel includes
  He II 30.4 nm and strong lines from Fe XI-XVI; the short wavelength
  channel includes strong lines of Fe IX-XIII. Angular resolution of
  2 arcsec is maintained along a slit covering a full solar radius. <P
  />EUNIS will have 100 times the throughput of the highly successful
  SERTS payloads that have preceded it. There are only two reflections in
  each optical channel, from the superpolished, off-axis paraboloidal
  primary and the toroidal grating. Each optical element is coated
  with a high-efficiency multilayer coating optimized for its spectral
  bandpass. The detector in each channel is a microchannel plate image
  intensifier fiber-coupled to three 1K x 1K active pixel sensors. <P
  />EUNIS will obtain spectra with a cadence as short as 1 sec, allowing
  unprecedented studies of the physical properties of evolving and
  transient structures. Diagnostics of wave heating and reconnection wil
  be studied at heights above 2 solar radii, in the wind acceleration
  region. The broad spectral coverage and high spectral resolution will
  provide superior temperature and density diagnostics and will enable
  underflight calibration of several orbital instruments, including
  SOHO/CDS and EIT, TRACE, Solar-B/EIS, and STEREO/EUVI. <P />EUNIS
  is supported by NASA through the Low Cost Access to Space Program in
  Solar and Heliospheric Physics.

Title: SUMI - The Solar Ultraviolet Magnetograph Investigation
Authors: Porter, J. G.; West, E. A.; Davis, J. M.; Gary, G. A.; Noble,
   M. W.; Thomas, R. J.; Rabin, D. M.; Uitenbroek, H.
Bibcode: 2003SPD....34.2015P
Altcode: 2003BAAS...35..847P
  Solar physics has been successful in characterizing the full vector
  magnetic field in the photosphere, where the ratio of gas pressure to
  magnetic pressure (β ) is greater than 1. However, at higher levels
  in the atmosphere, where β is much less than 1 and flares and CMEs
  are believed to be triggered, observations are difficult, severely
  limiting the understanding of these processes. In response to this
  situation, we are developing SUMI (the Solar Ultraviolet Magnetograph
  Investigation) a unique instrument designed to measure the circular
  and linear polarization of upper chromospheric Mg II lines (280 nm) and
  circular polarization of transition region C IV lines (155 nm). To date
  the telescope mirrors have been built, tested and coated with dielectric
  stacks designed to reflect only the wavelengths of interest. We have
  also developed a unique UV polarimeter and completed the design of a
  high-resolution spectrograph that uses dual toroidal varied-line-space
  (TVLS) gratings. Incorporating measurements of those components
  developed so far, the revised estimate of the system throughput exceeds
  our original estimate by more than an order of magnitude. A sounding
  rocket flight is anticipated in 2006. Our objectives and progress
  are detailed in this presentation. <P />This work is supported by
  NASA SR&amp;T.

Title: SHARPI: Solar High Angular Resolution Photometric Imager
Authors: Rabin, D.; Davila, J.; Content, D.; Keski-Kuha, R.;
   Michael, S.
Bibcode: 2002AAS...200.5606R
Altcode: 2002BAAS...34..735R
  Observing the lower solar atmosphere with enough linear resolution (&lt;
  100 km) to study individual magnetic flux tubes and other features on
  scales comparable to the photon mean free path remains a challenging and
  elusive goal. Space-borne instruments based on conventional heavy optics
  proved to be too expensive, and adaptive optics on the ground made slow
  progress for many years. Yet, the scientific case for high-resolution
  imaging and magnetography has only become more compelling over the last
  ten years. Today, ground-based adaptive optics is a promising approach
  for small fields of view at visible wavelengths. Space experiments
  will need to employ lightweight optics and low-cost platforms. The
  Sunrise balloon experiment is one example. We describe a concept for
  a sounding rocket experiment that will achieve 0.1-arcsecond imaging
  using a lightweight, ultraprecise 55-cm mirror in the far ultraviolet
  (160 nm continuum, Lyman alpha, and possibly C IV 155 nm). The f/1.2
  parabolic primary mirror is entering the final stages of production. The
  mirror is a ULE honeycomb design with front and back face sheets. The
  front sheet will be figured to 6.3 nm rms with microroughness 1 nm
  or better. For the initial proof of concept, we describe a no-frills,
  high-cadence imager aboard a Black Brant sounding rocket. Development
  of lightweight UV/EUV optics at Goddard Space Flight Center has been
  supported by the GSFC Internal Research and Development program.

Title: Observed properties of the solar cycle dynamo
Authors: Rabin, Douglas
Bibcode: 2002ocnd.confE..32R
Altcode:
  No abstract at ADS

Title: The New Solar Corona
Authors: Aschwanden, Markus J.; Poland, Arthur I.; Rabin, Douglas M.
Bibcode: 2001ARA&A..39..175A
Altcode:
  We focus on new observational capabilities (Yohkoh, SoHO,
  TRACE), observations, modeling approaches, and insights into
  physical processes of the solar corona. The most impressive new
  results and problems discussed in this article can be appreciated
  from the movies available on the Annual Reviews website and at
  http://www.lmsal.com/pub/araa/araa.html. "The Sun is new each
  day." Heraclites (ca 530-475 BC) "Everything flows." Heraclites (ca
  530-475 BC)

Title: Overview of the Solar Ultraviolet Magnetograph Investigation
Authors: West, Edward A.; Porter, Jason G.; Davis, John M.; Gary,
   G. Allen; Rabin, Douglas M.; Thomas, Roger J.; Davila, Joseph M.
Bibcode: 2000SPIE.4139..350W
Altcode:
  Traditional magnetographs measure the solar magnetic field at the
  visible 'surface' of the Sun, the photosphere. The Solar Ultraviolet
  Magnetograph Investigation (SUMI) is a hardware development study
  for an instrument to measure the solar magnetic field higher in the
  atmosphere, in the upper chromosphere and in the transition region at
  the base of the corona. The magnetic pressure at these levels is much
  stronger than the gas pressure (in contrast to the situation at the
  photosphere), so the field controls the structure and dynamics of the
  atmosphere. Rapid changes in the magnetic structure of the atmosphere
  become possible at this height, with the release of energy. Measurements
  of the vector magnetic field in this region will significantly improve
  our understanding of the physical processes heating the Sun's upper
  atmosphere and driving transient phenomena such as flares and coronal
  mass ejections. The instrument will incorporate new technologies to
  achieve the polarization efficiencies required to measure the magnetic
  splitting of lines in the VUV an UV (C<SUB>IV</SUB> at 1550 angstrom and
  Mg<SUB>II</SUB> at 2800 angstrom). We describe the scientific goals,
  the optical components that are being developed for a sounding rocket
  program, and the SUMI baseline design.

Title: Chromosphere: Fibrils
Authors: Rabin, D.
Bibcode: 2000eaa..bookE2004R
Altcode:
  Fibrils are dark, elongated, curvilinear patterns in the CHROMOSPHERE
  as seen through a filter that isolates the Hα spectral absorption
  line of hydrogen. Well-developed fibrils occur in and around SOLAR
  ACTIVE REGIONS (figure 1) and SOLAR FILAMENT CHANNELS....

Title: The Spatial Distribution of Molecules in Sunspots
Authors: Rabin, D. M.; Clark, T. A.; Bergman, M. W.
Bibcode: 2000SPD....31.0118R
Altcode: 2000BAAS...32..804R
  We report preliminary results from a program to map the concentration
  of H<SUB>2</SUB>O, OH, and SiO in the atmospheres of sunspots using
  imaging infrared spectroscopy. The water molecule is confined to
  the inner core of the umbra, whereas OH can sometimes be detected
  in the penumbra. Plots of line depth against continuum intensity
  show an abrupt onset of absorption at a different intensity for
  each molecule. A larger sample is needed to decide to what extent
  such features are characteristic. Evershed flow is seen in OH in the
  penumbra of spots near the limb, with typical outward velocities of
  1-2 km s<SUP>-1</SUP>. Spatial imaging of molecular concentrations in
  sunspots should eventually provide new diagnostics for the temperature
  structure of the umbral atmosphere, as yet poorly determined. This work
  has been supported by the University of Calgary and by the National
  Science Foundation through its support of NSO/NOAO.

Title: SUMI: The Solar Ultraviolet Magnetograph
Authors: Davis, J. M.; Porter, J. G.; Gary, G. A.; West, E. A.; Rabin,
   D. M.; Thomas, R. J.; Davila, J. M.
Bibcode: 2000SPD....31.0299D
Altcode: 2000BAAS...32..828D
  A major focus of solar physics is the measurement of the temporal
  and spatial variability of solar magnetic fields from the photosphere
  into the lower corona, together with the study of how their behavior
  produces the dynamic phenomena in this region such as flares and
  CMEs. Considerable success has been achieved in the characterization of
  the full vector field in the photosphere, where β , the ratio of the
  gas pressure to the magnetic pressure, is gtrsim1. At higher levels
  in the atmosphere where β &lt;&lt;1, the magnetic field (through
  the Lorentz force) controls the structure and dynamics of the solar
  atmosphere, and rapid changes in structure with release of energy
  become possible. However, observations of the field at these higher
  levels have proven to be difficult, placing a serious limitation on our
  understanding of the physical processes occurring there. This poster
  will discuss the Solar Ultraviolet Magnetograph Investigation (SUMI),
  a hardware development study for an instrument capable of measuring
  the polarization in ultraviolet lines of C IV and Mg II formed in the
  transition region and upper chromosphere. We are currently developing
  optical technologies necessary to build an instrument that will
  achieve a major advance in performance over that of earlier attempts
  (e.g., SMM/UVSP). Initially configured as a sounding rocket payload,
  such a UV magnetograph would allow us to make exploratory measurements
  extending the observation of solar magnetic fields into new and dynamic
  regimes. This work is supported by NASA through the SEC Program in
  Solar Physics and the program for Technology Development for Explorer
  Missions and Sofia.

Title: Synoptic Solar Physics -- 18th NSO/Sacramento Peak Summer
    Workshop
Authors: Balasubramaniam, K. S.; Harvey, Jack; Rabin, D.
Bibcode: 1998ASPC..140.....B
Altcode: 1998ssp..conf.....H
  No abstract at ADS

Title: The Solar Magnetic Field in Three Dimensions
Authors: Rabin, Douglas
Bibcode: 1997SoPh..174..281R
Altcode:
  Historically, our understanding of the solar magnetic field has been
  shaped by an interplay between theoretical ideas about the subsurface
  dynamo and precise measurements of magnetic flux at the level of the
  photosphere. Today we have an unprecedented ability to measure, or to
  infer from measurements, properties of the magnetic field at every level
  from the solar interior to interplanetary space, although photospheric
  observations still lead the way in completeness and precision. I review
  the state of our capabilities to measure or calculate the magnetic
  field and suggest that the next major goal should be to follow specific
  magnetic structures in space and time from before they emerge until
  they can no longer be detected at any level.

Title: Toward Zeeman Magnetometry in the Corona: Line-of-Sight Effects
Authors: Rabin, D.
Bibcode: 1997SPD....28.0144R
Altcode: 1997BAAS...29..887R
  One of the motivations for a large-aperture ground-based coronagraph
  is the possibility of measuring magnetic flux in the solar corona
  using the Zeeman sensitivity (Lande g = 1.5) of emission lines such
  as Fe XIV 530.3 nm, Fe X 637.4 nm, and Fe XIII 1074.7 nm. However,
  because the corona is optically thin, it is necessary to consider the
  effects of superposition along the line-of-sight on the interpretation
  of a detected Zeeman signal. Simple models are used to explore and
  illustrate the likely importance of line-of-sight confusion.

Title: F. Espenak and J. Anderson, Total Solar Eclipse of 1999 August
    11, NASA Reference Publication 1398
Authors: Rabin, Douglas
Bibcode: 1997EM&P...76..123R
Altcode:
  No abstract at ADS

Title: Microflaring in Sheared Core Magnetic Fields and Episodic
    Heating in Large Coronal Loops
Authors: Porter, J. G.; Falconer, D. A.; Moore, R. L.; Harvey, K. L.;
   Rabin, D. M.; Shimizu, T.
Bibcode: 1996AAS...188.7018P
Altcode: 1996BAAS...28..941P
  We have previously reported that large, outstandingly-bright coronal
  loops within an active region or stemming from an active region have
  one end rooted around a magnetic island of included polarity that is
  itself a site of locally enhanced coronal heating (X-ray bright point)
  [Porter et al 1996, in Proceedings of the Yohkoh Solar/Stellar IAU
  Symposium, ed. Y. Uchida, T. Kosugi, H.S. Hudson (Kluwer: Dordrecht), in
  press]. This suggests that exceptional magnetic structure in and around
  the magnetic island fosters magnetic activity, such as microflaring,
  that results in the enhanced coronal heating in both the compact core
  field around the island and in the body of large loops that extend
  from this site. We have also reported that enhanced coronal heating
  in active regions goes hand-in-hand with strong magnetic shear in
  the core magnetic fields along polarity neutral lines (Falconer et al
  1995, BAAS, 27(2), 976). Here, by combining MSFC vector magnetograms
  with an NSO full-disk magnetogram and Yohkoh SXT coronal images, we
  examine the incidence of sheared core fields, enhanced coronal heating,
  and microflaring in two active regions having several good examples
  of enhanced extended coronal loops. It appears that the localized
  microflaring activity in sheared core fields is basically similar
  whether the core field is on the neutral line around an island of
  included polarity or on the main neutral line of an entire bipolar
  active region. This suggests that the enhanced coronal heating in an
  extended loop stemming from near a polarity inversion line requires a
  special field configuration at its foot to plug it into the activity at
  the neutral line, rather than a different kind of activity in the core
  field on the neutral line. We also examine whether the waxing and waning
  of the coronal brightness of extended loops shows any correlation with
  the vigor or frequency of microflaring at the feet. This research was
  supported by the Solar Physics Branch of NASA's Office of Space Science.

Title: NIM-2 -- A Near Infrared Imaging Vector Magnetograph
Authors: Rabin, D.; Keller, C.; Jaksha, D.
Bibcode: 1996AAS...188.6706R
Altcode: 1996BAAS...28R.934R
  NIM-1 is a spectrograph-based Stokes polarimeter for measuring the
  strength and orientation of magnetic fields in the solar photosphere
  using two Zeeman-sensitive Fe I lines (g = 3 and g_geff = 1.53) near
  1565 nm. NIM-2, now under construction, also uses these spectral
  lines but is based on a high-resolution Fabry-Perot etalon. NIM-2
  will eliminate the image scanning and consequent spatial distortions
  of NIM-1 and will be compact and light enough to serve as a prototype
  for balloon or space instruments. The Queensgate etalon will provide a
  spectral resolving power of 10(5) over a 1-nm free spectral range. The
  initial detector will be the 256(2) InSb array shared with NIM-1, but
  NIM-2 is designed to accommodate a 512(2) or 1024(2) ``Aladdin'' InSb
  array. The data system, also shared with NIM-1, is being upgraded to
  handle the faster switching speed ( ~ 8 ms) of improved liquid-crystal
  variable retarders. NOAO is operated for the NSF by the Association of
  Universities for Research in Astronomy. Near-infrared magnetometry at
  NSO is supported by the the NASA Space Physics Division through the
  SR&amp;T program in solar physics.

Title: Observations of Solar Carbon Monoxide with an Imaging Infrared
    Spectrograph. I. Thermal Bifurcation Revisited
Authors: Ayres, Thomas R.; Rabin, Douglas
Bibcode: 1996ApJ...460.1042A
Altcode:
  We describe long-slit spectroscopy of the solar 4.7 μm carbon monoxide
  (CO) Δυ = 1 bands at the Main spectrograph of the NSO McMath-Pierce
  telescope. We utilized stigmatic imaging of the temperature-
  and velocity-sensitive CO absorptions to map quiet regions near
  disk center and at the extreme limb. At Sun center the dominant
  long-lived spatial structures are small-scale hot spots associated
  with fragments of the supergranulation network seen in cotemporal Ca
  II filtergrams. Oscillatory thermal and velocity fluctuations of the
  global p-mode interference pattern are a pervasive feature of the
  maps, but the rms amplitudes (≍70 K and ≍240 m s<SUP>-1</SUP>)
  are perturbations on a relatively unstructured outer photosphere. We
  occasionally see small-scale transient cooling episodes longer lived
  than the p-mode wavepackets that might be overshooting granules
  or rising magnetic flux ropes. The events are too rare, however,
  to influence the global properties of the CO fundamental bands. <P
  />Seeing-selected frames of the off-limb CO emissions show a typical
  extension of 0".6 for the strongest lines, with little variation along
  the limb. The off-limb extensions indicate the presence of cool gas
  up to 350 km above the "T<SUB>min</SUB>" of popular reference models
  of the solar chromosphere. <P />We carried out two-dimensional model
  atmosphere simulations to study the effects of thermal inhomogeneities
  on the disk-center, extreme-limb, and off-limb behavior of the CO
  lines. The models are spherically symmetric, static, and in LTE. Our
  data favor a scenario in which the bulk of the low chromosphere
  below the base of the magnetic "canopy" is in reality a "COmosphere"
  dominated by gas colder than the minimum temperature in conventional
  models. <P />The moderate-scale (≍5"), mild thermal perturbations
  of the p-mode pattern have little influence on the CO Δυ = 1
  spectra. Small-scale (≍1") hot regions embedded in a cool average
  atmosphere are strongly "shadowed" at the extreme limb. The shadowing
  is of little consequence, however, because the atmosphere already is
  dominated by the cool component. The opposite scenario-small-scale
  cold regions in a warm average produce effective shadowing at the
  limb for granule-size (≍1"-2") dark points only if the covering
  fraction is relatively large (f &amp;#8819 0.2). That scenario is
  ruled out: it predicts high-contrast dark spots at disk center,
  contrary to our observations. We also argue against the possibility
  of shadowing by even smaller, subresolution (≍0"3) cold spots with
  f &amp;#8819 0.1. <P />We show that multistep reactions, rather than
  direct radiative associations, dominate the gas-phase chemistry of
  CO molecules under conditions typical of the outer photosphere. The
  CO formation and radiative cooling timescales are fast enough that
  low-temperature plasma conditions can be restored following disruption
  by a localized heating event such as a Ca II K<SUB>2v</SUB> "flash." In
  cool giant stars, the chemical formation timescales are much longer than
  in dwarfs like the Sun. Nevertheless, the density dependence is such
  that the molecular cooling proceeds proportionately more rapidly than
  the gas dynamics, ensuring an even more important role for autocatalyzed
  "thermal bifurcation."

Title: Magnetic Roots of Enhanced High Coronal Loops
Authors: Porter, J. C.; Falconer, D. A.; Moore, R. L.; Harvey, K. L.;
   Rabin, D. M.; Shimizu, T.
Bibcode: 1996mpsa.conf..429P
Altcode: 1996IAUCo.153..429P
  No abstract at ADS

Title: Line-of-sight magnetic flux imbalances caused by electric
    currents
Authors: Gary, G. Allen; Rabin, Douglas
Bibcode: 1995SoPh..157..185G
Altcode: 1995SoPh..157..185A
  Several physical and observational effects may contribute to the
  significant imbalances of magnetic flux that are often observed in
  active regions. We consider an effect not previously treated: the
  influence of electric currents in the photosphere. Electric currents can
  cause a line-of-sight flux imbalance because of the directionality of
  the magnetic field they produce. Currents associated with magnetic flux
  tubes produce larger imbalances than do smoothly-varying distributions
  of flux and current. We estimate the magnitude of this effect for
  current densities, total currents, and magnetic geometry consistent
  with observations. The expected imbalances lie approximately in
  the range 0-15%, depending on the character of the current-carrying
  fields and the angle from which they are viewed. Observationally,
  current-induced flux imbalances could be indicated by a statistical
  dependence of the imbalance on angular distance from disk center. A
  general study of magnetic flux balance in active regions is needed to
  determine the relative importance of other - probably larger -effects
  such as dilute flux (too weak to measure or rendered invisible by
  radiative transfer effects), merging with weak background fields,
  and long-range connections between active regions.

Title: Photospheric Origins of Enhanced High Coronal Loops
Authors: Porter, J. G.; Falconer, D. A.; Moore, R. L.; Harvey, K. L.;
   Rabin, D. M.
Bibcode: 1995SPD....26..704P
Altcode: 1995BAAS...27..966P
  No abstract at ADS

Title: Eclipse Measurements of the Distribution of CO Emission Above
    the Solar Limb
Authors: Clark, T. A.; Lindsey, C.; Rabin, D. M.; Livingston, W. C.
Bibcode: 1995itsa.conf..133C
Altcode:
  No abstract at ADS

Title: The Next Generation of Near-Infrared Solar Magnetographs
    (Abstract only)
Authors: Rabin, D.
Bibcode: 1995itsa.conf...87R
Altcode:
  No abstract at ADS

Title: Scaling of Solar Magnetic Fields
Authors: Ruzmaikin, A.; Cadavid, C.; Lawrence, J.; Rabin, D.; Lin,
   H. -S.
Bibcode: 1995itsa.conf..375R
Altcode:
  No abstract at ADS

Title: Stokes Polarimetry with the Near Infrared Magnetograph ---
    Telescope Polarization Effects
Authors: Rabin, D.
Bibcode: 1994AAS...18512302R
Altcode: 1994BAAS...26.1522R
  NIM produces spatial images of magnetic field properties in the
  low photosphere from polarized spectra of the g = 3 line Fe I
  6388.64 cm^{-1} (1.5648 \micron). Designed initially for circular
  polarimetry, NIM can now acquire full Stokes information. I discuss
  the approximate polarization transfer (Mueller) matrix for NIM as
  used at the McMath-Pierce Telescope and compare it with the transfer
  matrix at visible wavelengths. Although telescope polarization
  effects are generally smaller in the infrared, in one respect the
  infrared requires careful treatment. In the visible, the net linear
  polarization due to the Zeeman effect is often small enough compared to
  circular polarization that linear-to-circular instrumental crosstalk
  is unimportant. In the infrared, the Zeeman components are usually so
  strongly split that the linearly polarized Stokes components (Q and U)
  are comparable in magnitude to the circular component (V). This work
  has been supported by the NASA SR&amp;T program in solar physics.

Title: Eclipse Observations of the Extreme Solar Limb Profile of HI
    Pfund beta Emission.
Authors: Clark, T. A.; Lindsey, C. A.; Rabin, D. M.; Livingston, W. C.
Bibcode: 1994AAS...185.4412C
Altcode: 1994BAAS...26.1378C
  A region of the infrared solar spectrum (2147.7 - 2150.1 cm(-1)
  ) around the HI Pfund beta line (2148.79 cm(-1) ) was monitored
  through 3 eclipse "contacts" with the Amber InSb array on the Main
  spectrograph on the McMath-Pierce telescope during the 10 May 1994
  partial solar eclipse over Kitt Peak National Observatory to produce
  limb profiles of intensity and line width to an angular resolution
  of 0.15 arc second. This line is broad (FWHM = 0.9 cm(-1) and shallow
  (5.7%) in absorption at disk center but shows a narrow emission core
  above the continuum envelope at 2 arc seconds inside the limb which
  remains visible out to 4.5 arc seconds beyond the continuum limb. The
  Pfund beta peak intensity appears to follow the continuum profile at
  the limb but then intensifies again to reach a peak at about 1000 km
  above the limb in a manner similar to that of the HeI D3 line. The line
  width becomes narrower with height above the limb, reaching a FWHM of
  0.22 cm(-1) at several arc seconds above the limb. These profiles will
  be discussed in relation to those of other HI lines above the solar
  limb. This work was supported by NSERC of Canada and by NSO, Tucson.

Title: Imaging spectroscopy of the solar CO lines at 4.67 microns
Authors: Uitenbroek, Han; Noyes, R. W.; Rabin, Douglas
Bibcode: 1994ApJ...432L..67U
Altcode:
  We analyze spatially and temporally resolved spectra of the fundamental
  vibration-rotation transitions of carbon monoxide (CO) in the solar
  spectrum at 4.67 micrometers. Our observations imply that, in the quiet
  Sun, spatial variations in CO intensity are largely dynamical in nature,
  reinforcing the suggestion that dynamical effects play a key role in
  the formation of the dark CO cores. Time sequences of resolved spectra
  exhibit mainly 3 minute power in line-core intensity but mainly a 5
  minute period in Doppler shift. The weak 7-6 R68 line shows normal
  Evershed flow in the penumbra of a sunspot; we find evidence for the
  onset of inverse Evershed flow in the strong 3-2 R14 line. Spectra at
  the limb indicate that 3-2 R14 emission extends approximately 360 km
  beyond the continuum limb.

Title: A Magnetic Field Strength vs. Temperature Relation in Sunspots
Authors: Kopp, G.; Rabin, D.
Bibcode: 1994IAUS..154..477K
Altcode:
  No abstract at ADS

Title: Near Infrared Imaging Magnetometry
Authors: Rabin, D.
Bibcode: 1994IAUS..154..449R
Altcode:
  No abstract at ADS

Title: Infrared solar physics: proceedings of the 154th Symposium
    of the International Astronomical Union, held in Tucson, Arizona,
    U.S.A., March 2-6, 1992.
Authors: Rabin, D. M.; Jefferies, John T.; Lindsey, C.
Bibcode: 1994IAUS..154.....R
Altcode:
  No abstract at ADS

Title: Recent array-detector Observations of the solar CO Fundamental
    vibration--rotation Transitions at 4.67 microns
Authors: Uitenbroek, H.; Noyes, R. W.; Rabin, D.
Bibcode: 1993AAS...183.5902U
Altcode: 1993BAAS...25.1386U
  We present recent observations of lines of the fundamental
  vibration--rotation transitions of carbon monoxide (CO) in the solar
  atmosphere obtained with the 256(2) infrared array detector at the
  McMath telescope on Kitt Peak. Standard, plane parallel, solar models
  have these lines form in LTE around the temperature minimum region;
  they should be indicative of electron temperatures there. However,
  matching observed line profiles in a standard solar model requires
  temperatures as low as 3700 K which are not confirmed by any other
  spectral diagnostic. We investigate whether this discrepancy can be
  solved by invoking spatial inhomogeneities or temporal variations
  or a combination of both. To this end we obtained series of
  spectra-spectroheliograms at different positions on the disk as well
  as time series of slit-spectra at a single position. The former type
  of observations allow us to study spatial inhomogeneities in stronger
  and weaker lines and the IR continuum at 4.6 microns and to distinguish
  between variations due to the 5-minute oscillations and the more steady
  patterns due to magnetic fields by comparing heliograms taken several
  minutes apart. We also obtained spectra with the slit crossing the limb
  giving us a more rigid registration of the intensity variations above
  the limb as compared to previous single-detector measurements. Early
  analysis shows that high and low excitation lines behave differently
  at the limb which may bear information on the temperature structure
  of the atmosphere just above the minimum.

Title: A Magnetograph Comparison Workshop
Authors: Jones, H.; Bogart, R.; Canfield, R.; Chapman, G.; Henney,
   C.; Kopp, G.; Lites, B.; Mickey, D.; Montgomery, R.; Pillet, V.;
   Rabin, D.; Ulrich, R.; Walton, S.
Bibcode: 1993BAAS...25.1216J
Altcode:
  No abstract at ADS

Title: Intercomparison of Seven Magnetographs
Authors: Walton, S. R.; Bogart, R. S.; Chapman, G. A.; Henney, C.;
   Jones, H.; Kopp, G.; Lites, B.; Mickey, D.; Montgomery, R.; Pillet,
   V.; Rabin, D.
Bibcode: 1993BAAS...25.1205W
Altcode:
  No abstract at ADS

Title: Measurement of p-Mode Energy Propagation in the Quiet Solar
    Photosphere
Authors: Fontenla, J. M.; Rabin, D.; Hathaway, D. H.; Moore, R. L.
Bibcode: 1993ApJ...405..787F
Altcode:
  We have measured and analyzed the p-mode oscillations in the profile
  of the Mg I 4571 A line in a quiet region near disk center. The
  oscillations are found to be mostly standing waves, in agreement with
  previous work. However, a small propagating component is measured, and
  we determine the direction, magnitude, and vertical variation of the
  energy propagation. The work integral indicates an upward energy flow of
  about 2 x 10 exp 7 ergs/sq cm/s at a height of 50 km above the base of
  the photosphere for waves with frequencies of 2-16 mHz. This energy flow
  decreases exponentially with height and drops below 10 exp 5 ergs/sq
  cm/s in the uppermost photosphere. The energy flow leaving the upper
  photosphere is at least an order of magnitude too small to constitute a
  significant source of heating for the chromosphere. However, the p-mode
  damping in the lower photosphere approaches levels large enough to
  account for the measured p-mode line widths. The relative amplitudes
  and phases of the thermodynamic quantities indicate that the p-mode
  are neither adiabatic nor isothermal in the photosphere.

Title: Siphon Flow Across the Magnetic Neutral-Line of an Active
    Region
Authors: Solanki, S. K.; Ruedi, I.; Rabin, D.
Bibcode: 1993ASPC...46..534S
Altcode: 1993IAUCo.141..534S; 1993mvfs.conf..534S
  No abstract at ADS

Title: NIM --- A Near Infrared Magnetograph
Authors: Rabin, D.; Jaksha, D.; Kopp, G.; Mahaffey, C.
Bibcode: 1992AAS...181.8101R
Altcode: 1992BAAS...24.1251R
  \newcommand{\micron}{microns} \newcommand{\kayser}{cm(-1)
  } \newcommand{\NIM}{NIM} We describe a new instrument for mapping
  magnetic field strength in the active solar photosphere. \NIM\ is a
  Stokes spectropolarimeter that exploits the high Zeeman sensitivity of
  the line Fe I 6388.64 \kayser\ (15648.5 Angstroms, e\:(7D_1) -- 3d(6) 4s
  5p\:(7D^) o_1, Lande g = 3.00, chi_e = 5.36 eV) to measure vec {B}. For
  |B| ga 850 G, the magnitude of the field is derived, without adjustable
  parameters, from the complete splitting of the Zeeman components. The
  relative strengths of the Stokes components indicate the direction of
  the field. The absolute strength of the polarized signal depends on
  the areal filling factor, inclination, continuum contrast, and line
  strength of the magnetic flux tubes within the angular resolution
  element. \NIM\ comprises the following subsystems: precision image
  scanner liquid crystal polarization modulators and control electronics
  slit spectrograph transfer and minification optics 128 times 128 InSb
  infrared array camera computer for data acquisition and user interface
  \NIM\ builds up a two-dimensional array of polarized spectra by scanning
  the solar image across the spectrograph slit. The spatial and spectral
  sampling frequencies are 1.0 arcsec or 0.5 arcsec per pixel (depending
  on which telescope is used) and 0.025 \kayser\ per pixel. At each slit
  position, 8 polarization pairs for each Stokes parameter (e.g., +/- V)
  are acquired at 7 Hz, averaged, and recorded in FITS format. A 128 times
  128 arcsec(2) map is acquired in about 20 minutes. \NIM\ is available
  to NSO visiting observers at the McMath-Pierce Telescope on Kitt Peak.

Title: Solar infrared presensitization photography
Authors: Geary, Joseph M.; Rabin, Douglas
Bibcode: 1992OptEn..31.2694G
Altcode:
  Infrared presensitization photography (IRPP) is used to acquire images
  of the solar disk in the 1 to 2 micrometers regime. This is the first
  time IRPP has been employed at such short IR wavelengths, used against
  a thermal (instead of a laser) source, and applied to astronomy. The
  experiments demonstrate the feasibility of IRPP for solar imaging,
  but the image quality needs improvement for solar research.

Title: A Photometric Study of Faculae and Sunspots Between 1.2-MICRONS
    and 1.6-MICRONS
Authors: Moran, T.; Foukal, P.; Rabin, D.
Bibcode: 1992SoPh..142...35M
Altcode:
  We investigate further the interpretation of dark magnetic faculae
  observed in previous imaging of the solar photosphere at 1.63 μm. We
  show that their contrast at 1.63 μm increases with magnetic flux
  beyond a threshold value of Φ ∼ 2 × 10<SUP>18</SUP> Mx and blends
  smoothly with the contrast vs flux relation measured at this wavelength
  for larger structures of sunspot size. Not all facular structures that
  are bright in Ca K are dark at 1.63 μm, apparently because their
  magnetic flux is not large enough. After correction for blurring,
  the contrast of the dark faculae observed near the disc center at
  1.63 μm is approximately 4%. But our observations at 1.23 μm,
  which probe slightly higher photospheric levels, do not show these
  dark faculae. These results indicate that magnetic flux tubes of
  diameter as small as 500 km significantly inhibit convective heat
  flow to the photosphere, much as do sunspot flux tubes of much larger
  diameter. They also suggest that, in even smaller flux tubes, the
  inhibition becomes rapidly less significant. Finally, we show that the
  sunspot-size dependence of umbral infrared contrast versus wavelength
  that we observe can probably be explained in terms of instrumental
  blurring. Observations with lower scattered light will be required
  to determine whether a real decrease of contrast with diameter also
  plays a role.

Title: A Relation Between Magnetic Field Strength and Temperature
    in Sunspots
Authors: Kopp, Greg; Rabin, Douglas
Bibcode: 1992SoPh..141..253K
Altcode:
  We present Stokes I Zeeman splitting measurements of sunspots using the
  highly sensitive (g = 3) Fe I line at λ = 1.5649 μm. The splittings
  are compared with simultaneous intensity measurements in the adjacent
  continuum. The relation between magnetic field strength and temperature
  has a characteristic, nonlinear shape in all the spots studied. In the
  umbra, there is an approximately linear relation between B<SUP>2</SUP>
  and T<SUB>b</SUB>, consistent with magnetohydrostatic equilibrium in
  a nearly vertical field. A distinct flattening of the B<SUP>2</SUP> vs
  T<SUB>b</SUB>relationship in the inner penumbra may be due to changes
  in the lateral pressure balance as the magnetic field becomes more
  horizontal; spatially unresolved intensity inhomogeneities may also
  influence the observed relation.

Title: Pervasive Variability in the Quiet Solar Transition Region
Authors: Rabin, Douglas; Dowdy, James F., Jr.
Bibcode: 1992ApJ...398..665R
Altcode:
  Extreme UV spectroheliograms from an experimental time series are
  employed to investigate the nature of the quiet solar transition
  region with respect to temporal variability. A statistical treatment
  is developed to analyze the fraction of spatial elements that yield
  intensity variations significantly higher than the signal noise. The
  EUV intensity in every spatial resolution varies on a time scale
  of minutes by about 10-30 percent, and the fractional amplitude of
  the temporal variations is found to be nearly independent of mean
  intensity. The paper concludes that the quiet solar transition region
  is probably generated and modulated by small-scale magnetic activity,
  since the temporal variability in the transition region is spatially
  uniform and rather pervasive.

Title: Infrared lines as probes of solar magnetic features. IV -
    Discovery of a siphon flow
Authors: Rueedi, I.; Solanki, S. K.; Rabin, D.
Bibcode: 1992A&A...261L..21R
Altcode:
  Spectra of two neighboring IR lines, Fe I 15648.5 A and Fe I 15652.9 A,
  are analyzed. The spectra were obtained with an IR array detector in
  active region plages with the entrance slit of the spectrograph placed
  across the polarity-inversion (neutral) line. Near the neutral line the
  positive polarity field is weaker (about 1200 G) and shows an upflow
  of up to 2 km/s, while the negative polarity field is stronger (about
  1500 G) and exhibits a downflow of up to 1 km/s. This configuration
  corresponds to the expected signature of a siphon flow along a loop
  connecting flux tubes across the neutral line.

Title: Spatially Extended Measurements of Magnetic Field Strength
    in Solar Plages
Authors: Rabin, Douglas
Bibcode: 1992ApJ...391..832R
Altcode:
  The study determines magnetic field strengths along one spatial
  dimension of a plage region from circularly polarized (Stokes V) spectra
  of a highly Zeeman-sensitive iron line at 6388.6/cm (1.565 micron). The
  measured fields are found to lie primarily in the range 1200-1700
  G. The mean formal precision for a single determination is +/-65 G. More
  than 90 percent of the magnetic flux is kilogauss-strength fields. The
  field strength is coherently organized on spatial scales from 1 arcmin
  to the limit of angular resolution (2 arcsec). It is inferred from
  the amplitude of the V signal that the spatial filling factor of the
  strong-field elements can approach 0.5 within a 2-arcsec resolution
  element. Magnetic field strength and amplitude are correlated in the
  sense that locations with stronger mean fields have larger V amplitudes,
  but the relationship shows more scatter than can be explained by errors
  in measurement. The individual sigma-components of the V profile are
  broader than an average quiet-sun line profile would produce by an
  amount corresponding to 625 G or 4.1 km/s; Zeeman broadening due to
  a range of magnetic field strength within the resolution element is
  proposed as the likely explanation.

Title: A True-Field Magnetogram in a Solar Plage Region
Authors: Rabin, Douglas
Bibcode: 1992ApJ...390L.103R
Altcode:
  The Near-Infrared Magnetograph is used to make the first 2D image of
  true magnetic field strength in the solar photosphere. The magnitude
  of the magnetic field vector is derived with a typical formal
  precision of + or - 75 G (2 sigma) from circularly polarized spectra
  of a highly Zeeman-sensitive iron line at 6388.6/cm. The true-field
  map demonstrates that the properties of 'kilogauss' flux tubes vary
  coherently on a variety of spatial scales within the 1-arcmin field of
  view. The measured fields span the range 1000-1700 G. The amplitude
  of the polarized signal implies that the spatial filling factor of
  the flux tubes can approach 0.3 at the seeing-limited resolution of 2
  arcsec. Magnetic field strength and magnetic flux are statistically
  related in the sense that weak-field areas are weak-flux areas, but
  strong fields are present in both strong-flux and weak-flux areas. This
  implies a degree of independence in the relationship between the
  filling factor of flux tubes and their individual properties, such as
  field strength, pressure, and temperature.

Title: Infrared Determinations of Magnetic Profiles in Sunspots
Authors: Kopp, G.; Kuhn, J.; Lin, H.; Rabin, D.
Bibcode: 1992AAS...180.1202K
Altcode: 1992BAAS...24R.747K
  We present measurements of a sunspot using unpolarized observations of
  the magnetically-sensitive (Lande g=3) Fe I line at lambda =1.5649
  microns (6388.6 cm(-1) ). We compare the magnetic field profile
  from this fairly symmetric spot with model profiles. Splittings
  in this infrared line are nearly a factor of 3 greater than in a
  comparable visible line, since Zeeman splitting as a fraction of
  linewidth increases linearly with wavelength. The infrared is also
  less affected by stray light than the visible, because the intensity
  contrast is reduced, decreasing the effects of stray light, and because
  instrumental scatter is lower in the infrared. The combination of the
  magnetic and stray light advantages of the infrared and the recent
  availability of ``large'' infrared arrays has made possible more
  sensitive determinations of the magnetic field profile throughout
  sunspots. From observations of several sunspots, we find that the
  magnetic field strength, determined in the strong field regime, is not
  a smooth function of radius from spot center, and that single radial
  parameter models do not accurately describe the observed spots.

Title: Solar infrared presensitization photography
Authors: Geary, Joseph M.; Rabin, Douglas
Bibcode: 1992SPIE.1638...63G
Altcode:
  Infrared presensitization photography (IRPP) is used to acquire images
  of the solar disk in the 1 to 2 micrometers regime. This is the first
  time IRPP has been employed at such short IR wavelengths, used against
  a thermal (instead of a laser) source, and applied to astronomy. The
  experiments demonstrate the feasibility of IRPP for solar imaging,
  but the image quality needs improvement for solar research.

Title: Magnetic Field Strength; Continuum Intensity Measurements of
    Sunspots at 1.56 microns
Authors: Kopp, M. G.; Rabin, D.
Bibcode: 1992ASPC...26..246K
Altcode: 1992csss....7..246K
  No abstract at ADS

Title: Fine-Scale Magnetic Fields in the Solar Photosphere (Invited
    Review)
Authors: Rabin, D.
Bibcode: 1992ASPC...26..201R
Altcode: 1992csss....7..201R
  No abstract at ADS

Title: Energy Balance in Coronal Funnels
Authors: Rabin, Douglas
Bibcode: 1991ApJ...383..407R
Altcode:
  The energy balance in magnetic flux tubes is examined semianalytically
  for the case in which thermal conduction balances radiation or in which
  enthalpy transport occurs. Different values are considered for areal
  constriction, shape, length, and maximum temperature. The overall
  energy budget of the solar corona is not significantly affected by
  magnetic constriction. A bowl-shaped funnel with a constriction factor
  of 4 describes the empirical differential-emission measure for log-T
  values between approximately 5.3 and 6.0. Loop-scaling relationships
  are derived for the full range of models to illustrate the dependence
  of the constant of proportionality on the properties of the magnetic
  constriction. Constriction can reduce the total energy requirement of
  the funnel by a factor of 5 and not affect the differential emission
  in flow-dominated models.

Title: A True-Field Magnetogram
Authors: Rabin, D.; Cole, L.; Jaksha, D.; Iwata, K.
Bibcode: 1991BAAS...23.1030R
Altcode:
  No abstract at ADS

Title: Zeeman Splitting and Continuum Measurements of Sunspots at
    1.56 μm
Authors: Kopp, G.; Rabin, D.; Lindsey, C.
Bibcode: 1991BAAS...23.1055K
Altcode:
  No abstract at ADS

Title: Plage magnetic field strengths from near-infrared spectra.
Authors: Rabin, D.; Jaksha, D.; Plymate, C.; Wagner, J.; Iwata, K.
Bibcode: 1991sopo.work..361R
Altcode:
  The authors have measured magnetic field strenghts in a small sample
  of plages from Stokes V spectra of two Zeeman-sensitive iron lines
  near 6388 cm<SUP>-1</SUP>(1.565 μm). The detected fields are strong
  (≡10<SUP>3</SUP>gauss), but their strength varies significantly from
  feature to feature. The individual σ-components are broader than
  an average quiet-Sun line profile; if this broadening is primarily
  magnetic, there is typically about a 20% range in field strength within
  a 2-arcsecond resolution element. These observations represent the
  first stage of a project to build a near-infrared magnetograph that
  will produce two-dimensional maps of local magnetic field strength in
  the low photosphere.

Title: The solar activity cycle.
Authors: Rabin, Douglas M.; DeVore, C. R.; Sheeley, Neil R., Jr.;
   Harvey, Karen L.; Hoeksema, J. T.
Bibcode: 1991sia..book..781R
Altcode:
  Study of the solar cycle is entering a new era dominated by objective,
  precise measurements of magnetic, velocity and radiation fields over the
  surface of the Sun. This review emphasizes observations of photospheric
  magnetic flux during cycle 21 (1976 - 1986) and how these measurements
  have been used to model the cyclic variability of the heliospheric
  magnetic field. Indices of solar activity are discussed in terms of
  their potential to figure in theoretical or empirical models. Other
  recent data, such as measurements of large-scale surface flows and
  information on the Sun's internal rotation from helioseismology, as
  well as the magnetic flux observations, are considered in the context
  of Babcock's phenomenological model of the solar cycle: can this model
  still serve? Is there anything better to replace it?

Title: Solar IR presensitization photography
Authors: Geary, Joseph M.; Rabin, Douglas; Lindmayer, Joseph
Bibcode: 1990SPIE.1235..181G
Altcode:
  The principles involved in the IR presensitization photography (IRPP)
  are discussed, and the feasibility of using IRPP in solar IR astronomy
  is investigated. Images of the solar disk were acquired in the 1-
  to 2-micron regime, demonstrating that IRPP is a feasible technique
  for solar imaging. However, in order to use IRPP images for solar
  research, the image quality needs improvement in terms of resolution
  and photometric accuracy.

Title: Infrared Imaging of Faculae at the Deepest Photospheric Layers
Authors: Foukal, P.; Little, R.; Graves, J.; Rabin, D.; Lynch, D.
Bibcode: 1990ApJ...353..712F
Altcode:
  The NOAO 58 x 62 InSb array and the National Solar Observatory McMath
  telescope are used to image the deepest photospheric layers of three
  active regions at the 1.63-micron opacity minimum. The faculae are
  darker than the photosphere, with a measured contrast of at least 2
  percent at positions on the disk with mu = 0.75-1.0. Near the limb,
  they are brighter than the photosphere, as in the visible. At mu =
  0.5-0.75, they are difficult to detect at 1.63 micron. The observation
  that faculae and their immediate surroundings exhibit a clear deficit
  of brightness temperature near disk center at 1.63 micron seems to
  rule out the hillock model put forward to explain their center-to-limb
  contrast variation.

Title: Magnetic Loops in the Chromospheric Network
Authors: Moore, R. L.; Rabin, D. M.; Dowdy, J. F., Jr.
Bibcode: 1990BAAS...22..815M
Altcode:
  No abstract at ADS

Title: Measurement of Dissipation or Pumping of P-Modes in the
    Solar Photosphere
Authors: Fontenla, J. M.; Hathaway, D. H.; Rabin, D.; Moore, R.
Bibcode: 1990BAAS...22..856F
Altcode:
  No abstract at ADS

Title: Spatially Resolved Measurements of Magnetic Field Strength
    Outside Sunspots
Authors: Rabin, D. M.
Bibcode: 1990BAAS...22..840R
Altcode:
  No abstract at ADS

Title: Infrared Imaging of Faculae at the Deepest Photospheric Layers
Authors: Foukal, P.; Little, R.; Graves, B.; Rabin, D.; Lynch, D.
Bibcode: 1989BAAS...21..828F
Altcode:
  No abstract at ADS

Title: Ubiquity of magnetic Loops in the Chromospheric Network
Authors: Moore, R. L.; Rabin, D. M.; Dowdy, J. F., Jr.
Bibcode: 1989BAAS...21..864M
Altcode:
  No abstract at ADS

Title: Measuring Sunspot Magnetic Fields with the Infrared Line
    Fe Iλ15649
Authors: Rabin, D. M.; Graves, J. E.
Bibcode: 1989BAAS...21R.854R
Altcode:
  No abstract at ADS

Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
   C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
   MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
   D. M.; Shine, R. A.
Bibcode: 1989epos.conf..303D
Altcode:
  The work of this team addressed the question of the response and
  relationship of the flare chromosphere and transition region to the
  hot coronal loops that reach temperatures of about 10<SUP>7</SUP>K
  and higher. Flare related phenomena such as surges and sprays were
  also discussed. The team members debate three main topics: 1) whether
  the blue-shifted components of X-ray spectral lines are signatures of
  "chromospheric evaporation"; 2) whether the excess line broadening of UV
  and X-ray lines is accounted for by "convective velocity distribution"
  in evaporation; and 3) whether most chromospheric heating is driven by
  electron beams. These debates illustrated the strengths and weaknesses
  of our current observations and theories.

Title: A Three-Dimensional View of the DQ Herculis Nova Shell
Authors: Barden, S. C.; Rabin, D. M.; Wade, R. A.
Bibcode: 1988BAAS...20R1052B
Altcode: 1988BAAS...20Z1052B
  No abstract at ADS

Title: Observed Magnetic Structure and Activity in the Quiet Solar
    Atmosphere
Authors: Moore, R. L.; Dowdy, J. F., Jr.; Rabin, D. M.
Bibcode: 1988BAAS...20.1009M
Altcode:
  No abstract at ADS

Title: How Quiet is Quiet?-Movies of the Quiet Sun in EUV Emission
    Lines
Authors: Rabin, D. M.; Dowdy, J. F., Jr.; Withbroe, G. L.
Bibcode: 1988BAAS...20.1009R
Altcode:
  No abstract at ADS

Title: 10.7 cm solar radio flux and the magnetic complexity of
    active regions.
Authors: Wilson, Robert M.; Rabin, Douglas; Moore, Ronald L.
Bibcode: 1987SoPh..111..279W
Altcode:
  During sunspot cycles 20 and 21, the maximum in smoothed 10.7-cm solar
  radio flux occurred about 1.5 yr after the maximum smoothed sunspot
  number, whereas during cycles 18 and 19 no lag was observed. Thus,
  although 10.7-cm radio flux and Zürich suspot number are highly
  correlated, they are not interchangeable, especially near solar
  maximum. The 10.7-cm flux more closely follows the number of sunspots
  visible on the solar disk, while the Zürich sunspot number more
  closely follows the number of sunspot groups. The number of sunspots
  in an active region is one measure of the complexity of the magnetic
  structure of the region, and the coincidence in the maxima of radio
  flux and number of sunspots apparently reflects higher radio emission
  from active regions of greater magnetic complexity. The presence
  of a lag between sunspot-number maximum and radio-flux maximum in
  some cycles but not in others argues that some aspect of the average
  magnetic complexity near solar maximum must vary from cycle to cycle. A
  speculative possibility is that the radio-flux lag discriminates between
  long-period and short-period cycles, being another indicator that the
  solar cycle switches between long-period and short-period modes.

Title: Thermal Conduction in Magnetic Funnels
Authors: Rabin, D. M.
Bibcode: 1987BAAS...19..940R
Altcode:
  No abstract at ADS

Title: The prominence-corona interface and its relationship to the
    chromosphere-corona transition.
Authors: Rabin, Douglas
Bibcode: 1986NASCP2442..135R
Altcode: 1986copp.nasa..135R
  The classical model of the chromosphere-corona transition does not
  account for the observed behavior of the differential emission measure
  for T approx. less than 100,000 K. Several models have been proposed
  to resolve this discrepancy in physically different ways. Because
  the observed differential emission measure at the prominence-corona
  interface is on average nearly the same as in the chromosphere-corona
  transition, prominences offer a fresh testing ground for models tailored
  to the chromosphere-corona transition. The researcher considered three
  such models and concluded that none extends in a natural way to the
  environment of prominences. The researcher advanced a simple idea
  involving thermal conduction both along and across the magnetic field
  from the corona into cool threads.

Title: The Prominence-Corona Interface
Authors: Rabin, D. M.
Bibcode: 1986BAAS...18..991R
Altcode:
  No abstract at ADS

Title: On the Magnetic Structure of the Quiet Transition Region
Authors: Dowdy, J. F., Jr.; Rabin, D.; Moore, R. L.
Bibcode: 1986SoPh..105...35D
Altcode:
  Existing models of the quiet chromosphere-corona transition region
  predict a distribution of emission measure over temperature that agrees
  with observation for T ≳ 10<SUP>5</SUP> K. These `network' models
  assume that all magnetic field lines that emerge from the photosphere
  extend into and are in thermal contact with the corona. We show
  that the observed fine-scale structure of the photospheric magnetic
  network instead suggests a two-component picture in which magnetic
  funnels that open into the corona emerge from only a fraction of the
  network. The gas that makes up the hotter transition region is mostly
  contained within these funnels, as in standard models, but, because
  the funnels are more constricted in our picture, the heat flowing
  into the cooler transition region from the corona is reduced by up
  to an order of magnitude. The remainder of the network is occupied
  by a population of low-lying loops with lengths ≲ 10<SUP>4</SUP>
  km. We propose that the cooler transition region is mainly located
  within such loops, which are magnetically insulated from the corona
  and must, therefore, be heated internally. The fine-scale structure
  of ultraviolet spectroheliograms is consistent with this proposal,
  and theoretical models of internally heated loops can explain the
  behavior of the emission measure below T ≈ 10<SUP>5</SUP> K.

Title: Bimodality of the solar cycle
Authors: Rabin, D.; Wilson, R. M.; Moore, R. L.
Bibcode: 1986GeoRL..13..352R
Altcode:
  For sunspot cycles 1-20 (1755-1976), all cycles occurred in strings
  (two to six cycles in length) during which the period remained longer
  or shorter than the sample mean period. These strings have coincided
  with long-term trends of growth or decay in the amplitude of the
  cycle. In six out of six cases, the period of the cycle has switched
  from long to short (or the reverse) in coincidence with turning points
  in the long-term trend. This suggests that the solar dynamo has two
  modes with different mean periods. In the short-period mode, the
  amplitude of the cycle grows; in the long-period mode, the amplitude
  decays. The transition between modes has occurred at irregular
  intervals. A persistence of the long-period mode would eventually
  produce a grand minimum such as the Maunder minimum; a persistence
  of the short-period mode would produce a grand maximum. Unless the
  present interval between transitions turns out to be shorter than any
  previously observed interval, the present cycle (cycle 21) is part of a
  long-period, decaying trend and will be of longer-than-average duration
  (&gt;133 months).

Title: Chromospheric explosions.
Authors: Doschek, G. A.; Antiochos, S. K.; Antonucci, E.; Cheng,
   C. -C.; Culhane, J. L.; Fisher, G. H.; Jordan, C.; Leibacher, J. W.;
   MacNiece, P.; McWhirter, R. W. P.; Moore, R. L.; Rabin, D. M.; Rust,
   D. M.; Shine, R. A.
Bibcode: 1986NASCP2439....4D
Altcode:
  The work of this team addressed the question of the response and
  relationship of the flare chromosphere and transition region to the
  hot coronal loops that reach temperatures of about 10<SUP>7</SUP>K
  and higher. Flare related phenomena such as surges and sprays are
  also discussed. The team members debated three main topics: 1. whether
  the blue-shifted components of X-ray spectral lines are signatures of
  "chromospheric evaporation"; 2. whether the excess line broadening of UV
  and X-ray lines is accounted for by "convective velocity distribution"
  in evaporation; and 3. whether most chromospheric heating is driven
  by electron beams.

Title: Measurement and interpretation of magnetic shear in solar
    active regions
Authors: Hagyard, M. J.; Rabin, D. M.
Bibcode: 1986AdSpR...6f...7H
Altcode: 1986AdSpR...6....7H
  In this paper we summarize and synthesize the results on the role of
  magnetic shear in the flare process that have been derived from the
  series of Flare Buildup Study Workshops in the Solar Maximum Analysis
  program. With emphasis on observations, we discuss the mechanisms that
  seem to produce the sheared magnetic configurations observed in flaring
  active regions. The spatial and temporal correlations of this shear with
  the onset of solar flares are determined from quantitative analyses of
  measurements of the vector magnetic field. The question of why some
  areas of sheared magnetic fields are the sites of flares and others
  are not is investigated observationally. We conclude by synthesizing
  these findings with current theoretical models of stressed magnetic
  fields that lead to the eruption of a flare.

Title: Evidence for submergencew of magnetic flux in a growing
    active region
Authors: Rabin, D. M.; Moore, R. L.; Hagyard, M. J.
Bibcode: 1985svmf.nasa..437R
Altcode:
  In NOAA Active Region 2372 (April 1980), 4 x 10 to the 20th power
  maxwell of magnetic flux concentrated within a 30" circular area
  disappeared overnight. Vector magnetograms show that all components of
  the magnetic field weakened together. If the field had weakened through
  diffusion or fluid flow, 80% of the original flux would still have been
  detected by the magnetograph within a suitably enlarged area. In fact
  there was at least a threefold decrease in detected flux. Evidently,
  magnetic field was removed from the photosphere. Since the disappearing
  flux was located in a region of low magnetic shear and low activity,
  it is unlikely that the field dissipated through reconnection. The most
  likely possibility is that flux submerged. Observations suggest that
  even in the growth phase of active regions, submergence is a strong
  process comparable in magnitude to emergence.

Title: Sunspots.
Authors: Moore, R.; Rabin, D.
Bibcode: 1985ARA&A..23..239M
Altcode:
  It is pointed out that the sun provides a close-up view of many
  astrophysically important phenomena, nearly all connected with the
  causes and effects of solar magnetic fields. The present article
  provides a review of the role of sunspots in a number of new areas
  of research. Connections with other solar phenomena are examined,
  taking into account flares, the solar magnetic cycle, global flows,
  luminosity variation, and global oscillations. A selective review of
  the structure and dynamic phenomena observed within sunspots is also
  presented. It is found that sunspots are usually contorted during the
  growth phase of an active region as magnetic field rapidly emerges
  and sunspots form, coalesce, and move past or even through each
  other. Attention is given to structure and flows, oscillations and
  waves, and plans for future studies.

Title: Evidence for submergence of magnetic flux in a growing
    active region.
Authors: Rabin, D. M.; Moore, R. L.; Hagyard, M. J.
Bibcode: 1985NASCP2374..437R
Altcode:
  No abstract at ADS

Title: Graphic displays of vector magnetograph data.
Authors: Rabin, D. M.; West, E. A.
Bibcode: 1985NASCP2374..454R
Altcode:
  The authors summarize their experience with graphic displays that
  have proved useful in dealing with vector magnetograph data in three
  settings: real-time control, analysis, and final presentation. Among
  the topics discussed are: flexible, implicit data-scaling; geometrical
  transformations; methods of comparing fields (e.g., transverse
  vs. longitudinal; observed vs. computed; one time vs. another);
  displaying the magnitude and direction of the transverse field;
  minimizing the display time of serial graphics devices; graphic file
  structure; and graphic interaction with operators and observers.

Title: A case for submergence of magnetic flux in a solar active
    region
Authors: Rabin, D.; Moore, R.; Hagyard, M. J.
Bibcode: 1984ApJ...287..404R
Altcode:
  In NOAA Active Region 2372 (April 1980), 4 x 10 to the 20th maxwells
  of magnetic flux concentrated in an area 30 arcsec across disappeared
  overnight. Vector magnetograms show that all components of the magnetic
  field weakened together. If the field had weakened through diffusion
  or fluid flow, 90 percent of the original flux would still have been
  detected by the magnetograph within a suitably enlarged area. In fact
  there was a threefold decrease in detected flux. Evidently, magnetic
  field was removed from the photosphere. Since the disappearing flux
  was located in a region of low magnetic shear and low activity in
  H-alpha and Ly-alpha, it is unlikely that the field dissipated through
  reconnection. It is argued that the most likely possibility is that
  flux submerged. The observations suggest that even during the growth
  phase of active regions, submergence is a strong process comparable
  in magnitude to emergence.

Title: Heating the sun's lower transition region with fine-scale
    electric currents
Authors: Rabin, D.; Moore, R.
Bibcode: 1984ApJ...285..359R
Altcode:
  This paper discusses the hypothesis that the lower transition region is
  locally heated by the dissipation of electric currents. It proposes a
  model based on ohmic heating by filamentary electric currents that flow
  along the magnetic field. The current filaments must be of fine scale,
  with a narrow dimension in the range 1 cm to 1 km, and the ambient
  magnetic field must be greater than about 10 gauss. An ensemble
  of filamentary currents that agree in sign across the horizontal
  scale of a photospheric granule can generate enough heat to match
  observations without the need for anomalous resistivity. Thermal
  conduction perpendicular to the axis of a current filament produces
  a distribution of emission measure over temperature that is in good
  agreement with observations.

Title: Bimodality of the Solar Cycle
Authors: Rabin, D. M.; Moore, R. L.; Wilson, R. M.
Bibcode: 1984BAAS...16Q.993R
Altcode:
  No abstract at ADS

Title: Sunspot Oscillations and the Short-Period Cutoff for Global
    p-Mode Oscillations
Authors: Moore, R.; Rabin, D.
Bibcode: 1984BAAS...16..978M
Altcode:
  No abstract at ADS

Title: Photospheric Electric Current and Transition Region Brightness
    Within an Active Region
Authors: Deloach, A. C.; Hagyard, M. J.; Rabin, D.; Moore, R. L.;
   Smith, B. J., Jr.; West, E. A.; Tandberg-Hanssen, E.
Bibcode: 1984SoPh...91..235D
Altcode:
  Distributions of vertical electric current density (J<SUB>z</SUB>)
  calculated from vector measurements of the photospheric magnetic
  field are compared with ultraviolet spectroheliograms to investigate
  whether resistive heating is an important source of enhanced emission
  in the transition region. The photospheric magnetic fields in Active
  Region 2372 were measured on 6 and 7 April, 1980 with the MSFC vector
  magnetograph; ultraviolet wavelength spectroheliograms (Lα and Nv
  1239 Å) were obtained with the UVSP experiment aboard the Solar
  Maximum Mission satellite. Spatial registration of the J<SUB>z</SUB>
  (5 arc sec resolution) and UV (3 arc sec resolution) maps indicates that
  the maximum current density is cospatial with a minor but persistent UV
  enhancement, but there is little detected current associated with other
  nearby bright areas. We conclude that although resistive heating may be
  important in the transition region, the currents responsible for the
  heating are largely unresolved in our measurements and have no simple
  correlation with the residual current measured on 5 arc sec scales.

Title: On the Formation of Magnetic Shear: Clues from a Well-Observed
    Active Region
Authors: Moore, R. L.; Rabin, D. M.
Bibcode: 1984BAAS...16..528M
Altcode:
  No abstract at ADS

Title: A Case for Submergence of Magnetic Flux in a Solar Active
    Region
Authors: Rabin, D. M.; Moore, R. L.
Bibcode: 1984BAAS...16..528R
Altcode:
  No abstract at ADS

Title: On Heating the Lower Transition Region with Fine-Scale Currents
Authors: Rabin, D. M.; Moore, R. L.
Bibcode: 1983BAAS...15..700R
Altcode:
  No abstract at ADS

Title: Analysis of integrated spectra of red star clusters in the
    Magellanic Clouds.
Authors: Rabin, D.
Bibcode: 1982ApJ...261...85R
Altcode:
  The present investigation has the objective to demonstrate that
  integrated spectra can play an important role in the quantitative
  analysis of the ages and abundances of star clusters. In particular,
  it is shown that by comparing the strength of the Balmer lines with
  the strength of a metallic feature, and guided by a sequence of model
  star clusters and the empirical sequence of Galactic globular clusters,
  one may infer age differences between fairly old clusters, for each
  of which a color-magnitude study to extremely faint magnitudes would
  be necessary to approach the main sequence. Most Magellanic Cloud
  clusters are younger than Galactic globulars and lack a developed
  horizontal branch.

Title: Structure of the Lower Transition Zone in an Active Region
Authors: Rabin, D. M.; Moore, R. L.
Bibcode: 1982BAAS...14..925R
Altcode:
  No abstract at ADS

Title: Book-Review - Carbon Stars
Authors: Alksne, Z. K.; Klaunieks, Y. Y.; Baumert, J. H.; Rabin, D.
Bibcode: 1982JBAA...92Q.153A
Altcode:
  No abstract at ADS

Title: Studies of Stellar Populations: Star Clusters in M31, the
    Galaxy and the Magellanic Clouds.
Authors: Rabin, D. M.
Bibcode: 1981PhDT.........2R
Altcode: 1981PhDT.......114R
  Medium resolution spectra of the integrated light of star clusters in
  our own Galaxy and in three nearby systems M31 and the two Magellanic
  Clouds are described. Since only integrated properties will normally be
  observable for clusters in more distant galaxies, or for the galaxies
  themselves, it is important to develop quantitative techniques which
  relate features of the integrated light to physical characteristics
  such as age and chemical composition. Here, digital spectra, are
  analyzed both internally, as multivariate data sets, and externally by
  comparison with evolutionary models of star clusters and with detailed
  observations of nearby clusters.

Title: Studies of stellar population: star clusters in M31, the
    galaxy and the Magellanic clouds
Authors: Rabin, Douglas Mark
Bibcode: 1981PhDT.......129R
Altcode:
  No abstract at ADS

Title: Studies of stellar populations: Star clusters in M31. The
    galaxy and the Magellanic Clouds
Authors: Rabin, Douglas Mark
Bibcode: 1981ssps.book.....R
Altcode:
  No abstract at ADS

Title: Coronal holes, the height of the chromosphere,and the origin
    of spicules.
Authors: Rabin, D.; Moore, R. L.
Bibcode: 1980ApJ...241..394R
Altcode:
  Analysis of 650 microphotometric scans across the solar limb reveals
  that the H(alpha) chromosphere is slightly taller inside coronal holes
  than in quiet regions outside holes. The change in height occurs as
  a step at the hole boundaries; this suggests that the increase with
  latitude in the average height of spicules found by Lippincott and
  by Athay was the average result of upward steps at the polar hole
  boundaries rather than a gradual latitude trend. It is estimated that
  the power consumed by spicules is of the same order as that returning
  by conduction from the corona, but the bulk of the spicules (which
  sets the height of the chromosphere) shows almost no response. It is
  concluded that spicules are not caused by heat conduction from the
  corona but are driven from below, suggesting that spicules are more
  closely connected with the heating of the corona than with its cooling.

Title: Polar Coronal Holes and the Variation with Latitude of the
    Height of the Hα Chromosphere.
Authors: Rabin, D. M.; Moore, R. L.
Bibcode: 1978BAAS...10..430R
Altcode:
  No abstract at ADS

