Slitless spectrometers can provide both spatial and spectral information of extended objects, such as the Sun, in a single snapshot. The data, however, require unfolding of overlapping spatial and spectral information. Thanks to advances in computer processing speeds, there have been several techniques developed to complete the spatial/spectral unfolding, unlocking the full capability of slitless spectrometers for solar observations. The goal of this talk is to give an overview of the capability of such instruments and demonstrate their usefulness in the next decade of solar observatories and beyond.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a sounding rocket mission that completed a successful flight from the White Sands Missile Range on July 30, 2021. MaGIXS captured spatially resolved soft X-ray spectra from portions of two solar active regions during its roughly 5-minute flight. The instrument was originally designed as a grazing incidence slit spectrograph but flew in a slit-less configuration that produced overlapping spectroheliograms. For the second flight, MaGIXS-2, the instrument has been reconfigured to a more simplified optical layout that reuses the Wolter-I telescope and blazed varied-line space reflective grating. The field stop at the telescope focal plane and the finite conjugate spectrometer mirror pair have been removed – the telescope now directly feeds the grating. Additionally, an identical but new 2k x 1k CCD camera has been built for this flight. The MaGIXS-2 data product will again be overlapping spectroheliograms of at least one solar active region, but with improved resolution, a larger field of view and increased effective area. Here we present the updated instrument layout, the expected performance, the integration and calibration approach, and proposed future improvements, including the implementation of additional complimentary spectral diagnostics.
FURST is a sounding rocket mission designed to acquire the first high quality, full-disk, UV Solar spectra in the range of 1200 - 1800 ̊A. The instrument uses a set of cylindrical optical elements, acting in place of a slit, to collect light from the entire solar disk in combination with a Rowland circle spectrometer, to generate high resolution spectra, ≥2 ×104λ/∆λ, without scanning a slit over the spatial extent of the Sun. The instrument requires absolute radiometric and spectral calibration before and after flight in order to analyze data products and meet science goals. We present an update on the portable calibration system designed to meet ambitious calibration requirements. The system consists of a vacuum chamber, a Pt hollow cathode lamp, collimating optics and NIST calibrated photodiodes. Absolute radiometric calibration of ≤15% and wavelength calibration corresponding to ±3km/s is expected.
The Full-sun Ultraviolet Rocket SpecTrograph (FURST) is a sounding rocket designed to acquire the first full-disk integrated high resolution vacuum ultraviolet (VUV) spectra of the Sun. The data enable analysis of the Sun comparable to stellar spectra measured by astronomical instruments such as those on board the Hubble Space Telescope. The mission is jointly operated by teams at Montana State University (MSU), developing the instrument, and Marshall Space Flight Center (MSFC), developing the camera and calibration systems, and is scheduled to launch from White Sands Missile Range, New Mexico, in 2022. This mission requires the development of a pre- and post-launch calibration plan for absolute radiometric and wavelength calibration to reliably generate Hubble analogue spectra. Absolute radiometric calibration, though initially planned to be performed at the National Institute for Standards and Technology (NIST) calibration facilities, is now planned to be completed with a portable VUV calibration system provided by MSFC, due to instrument incompatibilities with NIST infrastructure. The portable calibration system is developed to provide absolute wavelength calibration and track changes in calibration over the duration of the mission. The portable calibration system is composed mainly of a VUV collimator equipped with an extreme ultraviolet line source and calibrated photodiodes. The calibration system is developed to accommodate both repeatable wavelength and radiometric testing of the FURST instrument at various test sites before and after launch. Presented here are the requirements, design, and implementation of this portable calibration system with a focus on those features most significant to radiometric measurements.
Chromospheric LAyer Spectro-Polarimeter (CLASP2) was a sounding rocket experiment, which is a follow-up mission to the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP1) in 2015. To measure the magnetic fields in the upper solar atmosphere in a highly quantitative manner, CLASP2 changes the target wavelengths from the hydrogen Ly-α line (121.567 nm) to Mg II lines near 280 nm. We reused the main structure and most of the optical components in the CLASP1 instrument, which reduced the turnaround time and cost. We added a magnifying optical system to maintain the wavelength resolution, even at the longer wavelength of CLASP2. Here, we describe the optical design and performance of the CLASP2 instrument.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed and built to observe X-ray emissions from the Sun’s atmosphere in the 6–24Å (0.5–2.0keV) range while achieving high spectral and spatial resolution along a 8-arcminute long slit. We describe the alignment process and discuss the results achieved for assembling the Telescope Mirror Assembly (TMA) and the Spectrometer Optics Assembly (SOA) prior to final integration into the MaGIXS instrument. The MaGIXS mirrors are full shell, electroformed nickel replicated on highly polished mandrels at the Marshall Space Flight Center (MSFC). The TMA carries a single shell, Wolter Type-1 mirror pair (primary and secondary) formed on a common mandrel. The SOA includes a matched pair of identical parabolic mirrors and a planar varied-line spacing (VLS) diffraction grating. We performed the subassembly alignment and mounting at the Smithsonian Astrophysical Observatory (SAO) using metrology and precision positioning systems constructed around the Centroid Detector Assembly (CDA), originally built for the alignment of the Chandra mirror shells. The MaGIXS instrument launch has been postponed until 2021 due to the COVID-19 pandemic.
Recently NASA Marshall Space Flight Center has made good progress in employing computer numerical control (CNC) polishing techniques on electroless nickel mandrels, as part of our replicated grazing incidence optics program. CNC polishing has afforded the ability to deterministically refine mandrel figure, therefore improving mirror performance. The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a MSFC-led sounding rocket instrument that comprises some of the first mirrors produced at MSFC using this polishing technique. Here we present the predicted mirror performance obtained from metrology, after completion of CNC polishing, as well as the results of X-ray tests performed on the MaGIXS telescope mirror before, and after mounting.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed to obtain spatially resolved soft X-ray spectra of the solar atmosphere in the 6–24 Å (0.5–2.0 keV) range. The instrument consists of a single shell Wolter Type-I telescope, a slit, and a spectrometer comprising a matched pair of grazing incidence parabolic mirrors and a planar varied-line space diffraction grating. The instrument is designed to achieve a 50 mÅ spectral resolution and 5 arcsecond spatial resolution along a ±4-arcminute long slit, and launch is planned for 2019. We report on the status and our approaches for fabrication and alignment for this novel optical system. The telescope and spectrometer mirrors are replicated nickel shells, and are currently being fabricated at the NASA Marshall Space Flight Center. The diffraction grating is currently under development by the Massachusetts Institute of Technology (MIT); because of the strong line spacing variation across the grating, it will be fabricated through e-beam lithography.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument designed to obtain spatially resolved soft X-ray spectra of the solar atmosphere in the 6–24 Å (0.5–2.0 keV) range. The instrument consists of a single shell Wolter Type-I telescope, a slit, and a spectrometer comprising a matched pair of grazing incidence parabolic mirrors and a planar varied-line space diffraction grating. The instrument is designed to achieve a 50 mÅ spectral resolution and 5 arcsecond spatial resolution along a ±4-arcminute long slit, and launch is planned for 2019. We report on the status and our approaches for fabrication and alignment for this novel optical system. The telescope and spectrometer mirrors are replicated nickel shells, and are currently being fabricated at the NASA Marshall Space Flight Center. The diffraction grating is currently under development by the Massachusetts Institute of Technology (MIT); because of the strong line spacing variation across the grating, it will be fabricated through e-beam lithography.
The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS) is a NASA sounding rocket instrument that is designed to observe soft X-ray emissions from 24 - 6.0 Å (0.5 - 2.0 keV energies) in the solar atmosphere. For the first time, high-temperature, low-emission plasma will be observed directly with 5 arcsecond spatial resolution and 22 mÅ spectral resolution. The unique optical design consists of a Wolter - I telescope and a 3-optic grazing- incidence spectrometer. The spectrometer utilizes a finite conjugate mirror pair and a blazed planar, varied line spaced grating, which is directly printed on a silicon substrate using e-beam lithography. The grating design is being finalized and the grating will be fabricated by the Massachusetts Institute of Technology (MIT) and Izentis LLC. Marshall Space Flight Center (MSFC) is producing the nickel replicated telescope and spectrometer mirrors using the same facilities and techniques as those developed for the ART-XC and FOXSI mirrors. The Smithsonian Astrophysical Observatory (SAO) will mount and align the optical sub-assemblies based on previous experience with similar instruments, such as the Hinode X-Ray Telescope (XRT). The telescope and spectrometer assembly will be aligned in visible light through the implementation of a theodolite and reference mirrors, in addition to the centroid detector assembly (CDA) - a device designed to align the AXAF-I nested mirrors. Focusing of the telescope and spectrometer will be achieved using the X-ray source in the Stray Light Facility (SLF) at MSFC. We present results from an alignment sensitivity analysis performed on the on the system and we also discuss the method for aligning and focusing MaGIXS.
G. Giono, Y. Katsukawa, R. Ishikawa, N. Narukage, R. Kano, M. Kubo, S. Ishikawa, T. Bando, H. Hara, Y. Suematsu, A. Winebarger, K. Kobayashi, F. Auchère, J. Trujillo Bueno
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The instrument main scientific goal is to achieve polarization measurement of the Lyman-α line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. The optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly-α profiles. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-α is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.
The sounding rocket Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) was launched on September 3rd, 2015, and successfully detected (with a polarization accuracy of 0.1 %) the linear polarization signals (Stokes Q and U) that scattering processes were predicted to produce in the hydrogen Lyman-alpha line (Lyα; 121.567 nm). Via the Hanle effect, this unique data set may provide novel information about the magnetic structure and energetics in the upper solar chromosphere. The CLASP instrument was safely recovered without any damage and we have recently proposed to dedicate its second flight to observe the four Stokes profiles in the spectral region of the Mg II h and k lines around 280 nm; in these lines the polarization signals result from scattering processes and the Hanle and Zeeman effects. Here we describe the modifications needed to develop this new instrument called the "Chromospheric LAyer SpectroPolarimeter" (CLASP2).
The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras were built and tested for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint MSFC, National Astronomical Observatory of Japan (NAOJ), Instituto de Astrofisica de Canarias (IAC) and Institut D'Astrophysique Spatiale (IAS) sounding rocket mission. The CLASP camera design includes a frame-transfer e2v CCD57-10 512 × 512 detector, dual channel analog readout and an internally mounted cold block. At the flight CCD temperature of -20C, the CLASP cameras exceeded the low-noise performance requirements (≤ 25 e− read noise and ≤ 10 e− /sec/pixel dark current), in addition to maintaining a stable gain of ≈ 2.0 e−/DN. The e2v CCD57-10 detectors were coated with Lumogen-E to improve quantum efficiency (QE) at the Lyman- wavelength. A vacuum ultra-violet (VUV) monochromator and a NIST calibrated photodiode were employed to measure the QE of each camera. Three flight cameras and one engineering camera were tested in a high-vacuum chamber, which was configured to operate several tests intended to verify the QE, gain, read noise and dark current of the CCD. We present and discuss the QE measurements performed on the CLASP cameras. We also discuss the high-vacuum system outfitted for testing of UV, EUV and X-ray science cameras at MSFC.
The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-α and to detect the Hanle effect in the line core. Due to the nature of Lyman-α polarizationin the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1% in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1% polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. The CLASP cameras were designed to operate with ≤ 10 e-/pixel/second dark current, ≤ 25 e- read noise, a gain of 2.0 +- 0.5 and ≤ 1.0% residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument currently under development at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. CLASP’s optics are composed of a Cassegrain telescope and a spectro-polarimeter which are designed to achieve an unprecedentedly accurate polarization measurement of the Ly-α line at 121.6nm emitted from the solar upper-chromosphere and transition region. CLASP’s first flight is scheduled for August 2015. Reaching such accuracy requires a careful alignment of the optical elements to optimize the image quality at 121.6 nm. However Ly-α is absorbed by air and therefore the optics alignment has to be done under vacuum condition which makes any experiment difficult. To bypass this issue, we proposed to align the telescope and the spectrograph separately in visible light. Hence we present our alignment procedure for both telescope and spectro-polarimeter. We will explain details about the telescope preliminary alignment before mirrors coating, which was done in April 2014, present the telescope combined optical performance and compare them to CLASP tolerance. Then we will present details about an experiment designed to confirm our alignment procedure for the CLASP spectro-polarimeter. We will discuss the resulting image quality achieved during this experiment and the lessons learned.
Ken Kobayashi, Jonathan Cirtain, Amy Winebarger, Sabrina Savage, Leon Golub, Kelly Korreck, Sergey Kuzin, Robert Walsh, Craig DeForest, Bart DePontieu, Alan Title, William Podgorski, Ryouhei Kano, Noriyuki Narukage, Javier Trujillo-Bueno
We present an overview of solar sounding rocket instruments developed jointly by NASA Marshall Space Flight Center
and the University of Alabama in Huntsville. The High Resolution Coronal Imager (Hi-C) is an EUV (19.3 nm) imaging
telescope which was flown successfully in July 2012. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a
Lyman Alpha (121.6 nm) spectropolarimeter developed jointly with the National Astronomical Observatory of Japan and
scheduled for launch in 2015. The Marshall Grazing Incidence X-ray Spectrograph is a soft X-ray (0.5-1.2 keV) stigmatic
spectrograph designed to achieve 5 arcsecond spatial resolution along the slit.
NASA/MSFC and SAO have developed a High Resolution EUV Solar Coronal Imaging telescope (Hi-C). The scientific objective of the mission is to determine, at higher spatial resolution than previously available, the geometric configuration and topology of the structures making up the inner corona. The Hi-C telescope launched on a rocket in early July 2012. It acts as a technology pathfinder for future satellite based missions. Key technology features of the Hi-C telescope are: (1) A 23.9 meter focal length, allowing for 0.1 arc-second pixels (2) Extremely high quality optics (3) Single wavelength multi-layer coating over the entire surface of each optic (4) Low distortion approach to mounting the primary into the telescope. The low distortion approach to mounting the primary mirror into the telescope is discussed in this paper. In previous solar EUV telescopes (TRACE, AIA, IRIS) the primary mirror is first bonded into a flexured mirror cell that is then bolted into the telescope. Techniques for bonding the mirror into the mirror cell have been well developed. If done properly, these techniques produce minimal distortion in the optic. Experience has shown, however, that bolting of the cell into the telescope produces distortions, typically in the form of astigmatism. The magnitude of the astigmatism may be acceptable for lower resolution missions, but as we approach ever higher resolutions, these astigmatisms contribute significantly to the error budget. In the Hi-C mission the mirror mounting hardware was completely assembled into the telescope tube prior to bonding the mirror to the mount. This final operation was done with the telescope tube vertical and the primary mirror surface facing up. This approach minimizes the "bolt-up" distortions typically seen, thus improving resolution.
One of the biggest challenges in heliophysics is to decipher the magnetic structure of the solar chromosphere.
The importance of measuring the chromospheric magnetic field is due to both the key role the chromosphere
plays in energizing and structuring the outer solar atmosphere and the inability of extrapolation of photospheric
fields to adequately describe this key boundary region. Over the last few years, significant progress has been
made in the spectral line formation of UV lines as well as the MHD modeling of the solar atmosphere. It is
found that the Hanle effect in the Lyman-alpha line (121.567 nm) is a most promising diagnostic tool for weaker
magnetic fields in the chromosphere and transition region. Based on this groundbreaking research, we propose
the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) to NASA as a sounding rocket experiment, for
making the first measurement of the linear polarization produced by scattering processes and the Hanle effect
in the Lyman-alpha line (121.567 nm), and making the first exploration of the magnetic field in the upper
chromosphere and transition region of the Sun. The CLASP instrument consists of a Cassegrain telescope, a
rotating 1/2-wave plate, a dual-beam spectrograph assembly with a grating working as a beam splitter, and
an identical pair of reflective polarization analyzers each equipped with a CCD camera. We propose to launch
CLASP in December 2014.
This paper will describe a new Extreme Ultraviolet (EUV) test facility that is being developed at the Marshall Space
Flight Center (MSFC) to test EUV telescopes. Two flight programs, Hi-C, the high resolution coronal imager (a
sounding rocket program), and SUVI, the Solar Ultraviolet Imager (GOES-R), set the requirements for this new facility.
This paper will discuss those requirements, the EUV source characteristics, the wavelength resolution that is expected
and the vacuum chambers (Stray Light Facility, Xray Calibration Facility and the NSSTC EUV test chamber) where this
facility will be used.
The Marshall Grazing Incidence X-ray Spectrograph (MaGIXS) is a proposed sounding rocket experiment designed to observe
spatially resolved soft X-ray spectra of the solar corona for the first time. The instrument is a purely grazing-incidence
design, consisting of aWolter Type-1 sector telescope and a slit spectrograph. The telescope mirror is a monolithic Zerodur
mirror with both the parabolic and hyperbolic surfaces. The spectrograph comprises a pair of paraboloid mirrors acting as
a collimator and reimaging mirror, and a planar varied-line-space grating, with reflective surfaces operate at a graze angle
of 2 degrees. This produces a flat spectrum on a detector covering a wavelength range of 6-24Å (0.5-1.2 keV). The design
achieves 20 mÅ spectral resolution (10 mÅ /pixel) and 5 arcsec spatial resolution (2.5 arcsec / pixel) over an 8-arcminute
long slit. The spectrograph is currently being fabricated as a laboratory prototype. A flight candidate telescope mirror is
also under development.
A sounding-rocket program called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is proposed to be
launched in the summer of 2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567 nm), aiming to detect
the linear polarization signal produced by scattering processes and the Hanle effect for the first time. The polarimeter of
CLASP consists of a rotating half-waveplate, a beam splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is
used for these optical components, because MgF2 exhibits birefringent property and high transparency at ultraviolet
wavelength.
The development and comprehensive testing program of the optical components of the polarimeter is underway using the
synchrotron beamline at the Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first objective is deriving
the optical constants of MgF2 by the measurement of the reflectance and transmittance against oblique incident angles for
the s-polarized and the p-polarized light. The ordinary refractive index and extinction coefficient along the ordinary and
extraordinary axes are derived with a least-square fitting in such a way that the reflectance and transmittance satisfy the
Kramers-Krönig relation. The reflection at the Brewster's Angle of MgF2 plate is confirmed to become a good polarization
analyzer at Ly-alpha. The second objective is the retardation measurement of a zeroth-order waveplate made of MgF2. The
retardation of a waveplate is determined by observing the modulation amplitude that comes out of a waveplate and a
polarization analyzer. We tested a waveplate with the thickness difference of 14.57 um. The 14.57 um waveplate worked as
a half-waveplate at 121.74 nm. We derived that a waveplate with the thickness difference of 15.71 um will work as a
half-waveplate at Ly-alpha wavelength.
We developed a prototype of CLASP polarimeter using the MgF2 half-waveplate and polarization analyzers, and
succeeded in obtaining the modulation patterns that are consistent with the theoretical prediction. We confirm that the
performance of the prototype is optimized for measuring linear polarization signal with the least effect of the crosstalk
from the circular polarization.
This paper will describe the scientific goals of our sounding rocket program, the Solar Ultraviolet Magnetograph
Investigation (SUMI). This paper will present a brief description of the optics that were developed to meet SUMI's
scientific goals, discuss the spectral, spatial and polarization characteristics of SUMI's optics, describe SUMI's flight
which was launched 7/30/2010, and discuss what we have learned from that flight.
The solar chromosphere is an important boundary, through which all of the plasma, magnetic fields and energy in the
corona and solar wind are supplied. Since the Zeeman splitting is typically smaller than the Doppler line broadening in
the chromosphere and transition region, it is not effective to explore weak magnetic fields. However, this is not the case
for the Hanle effect, when we have an instrument with high polarization sensitivity (~ 0.1%). "Chromospheric Lyman-
Alpha SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect linear polarization produced by the
Hanle effect in Lyman-alpha line (121.567 nm) and to make the first direct measurement of magnetic fields in the upper
chromosphere and lower transition region. To achieve the high sensitivity of ~ 0.1% within a rocket flight (5 minutes) in
Lyman-alpha line, which is easily absorbed by materials, we design the optical system mainly with reflections. The
CLASP consists of a classical Cassegrain telescope, a polarimeter and a spectrometer. The polarimeter consists of a
rotating 1/2-wave plate and two reflecting polarization analyzers. One of the analyzer also works as a polarization beam
splitter to give us two orthogonal linear polarizations simultaneously. The CLASP is planned to be launched in 2014
summer.
This paper will describe the Marshall Space Flight Center's Solar Ultraviolet Magnetograph (SUMI) sounding rocket
program, with emphasis on the polarization characteristics of the VUV optics and their spectral, spatial and polarization
resolution. SUMI's first flight (7/30/2010) met all of its mission success criteria and this paper will describe the data
that was acquired with emphasis on the MgII linear polarization measurements.
We present the design for a stigmatic grazing incidence X-ray spectrograph designed for solar coronal observations. The
spectrograph is composed of a slit, a pair of paraboloid mirrors and a plano varied-line-space grating. All reflective surfaces
of the spectrograph operate at an angle of incidence of 88 degrees, and covers a wavelength range of 0.6 to 2.4nm (0.5 to
2.0keV). The design achieves 1.5pm spectral resolution and 15 μm spatial resolution over a 2.5mmlong slit. The current
spectrograph design is intended for a sounding rocket experiment, and designed to fit inside a NASA sounding rocket
payload behind a 1.1m focal length Wolter Type-1 telescope. This combination will have a 2.5arcsec spatial resolution
and a 8 arcminute slit length. We are currently fabricating a laboratory prototype of the spectrograph to demonstrate the
performance and establish the alignment procedures for a flight model.
KEYWORDS: Ultraviolet radiation, Spectral calibration, Solar processes, Aerospace engineering, Current controlled current source, Rockets, UV optics, Polarization, Magnetism, Sun
This paper describes the scientific goals of a sounding rocket program called the Solar Ultraviolet Magnetograph Investigation (SUMI), presents a brief description of the optics that were developed to meet those goals and discusses the spectral, spatial and polarization characteristics of SUMI's Toroidal Variable-Line-Space (TVLS) gratings, which are critical to SUMI's measurements of the magnetic field in the Sun's transition region.
Toroidal variable-line-space (VLS) gratings are very important in the design of an efficient VUV solar telescope that will measure the CIV (155nm) and MgII (280nm) emissions lines in the Sun's transition region. In 1983 Kita and Harada described spherical VLS gratings but the technology to commercially fabricate these devices is a recent development, especially for toroidal surfaces. This paper will describe why this technology is important in the development of the Solar Ultraviolet Magnetograph Investigation (SUMI) sounding rocket program (the good), the delays due to the conversion between the TVLS grating design and the optical fabrication (the bad), and finally the optical testing, alignment and tolerancing of the gratings (the ugly).
KEYWORDS: Magnetism, Polarization, Vacuum ultraviolet, Solar processes, Coronagraphy, Interferometers, Doppler effect, 3D modeling, Remote sensing, Current controlled current source
Marshall Space Flight Center's (MSFC) is developing a Vacuum Ultraviolet (VUV) Fabry-Pérot Interferometer that will be launched on a sounding rocket for high throughput, high-cadence, extended field of view CIV (155nm) measurements. These measurements will provide (i) Dopplergrams for studies of waves, oscillations, explosive events, and mass motions through the transition region, and, (ii), polarization measurements to study the magnetic field in the transition region. This paper will describe the scientific goals of the instrument, a brief description of the optics and the polarization characteristics of the VUV Fabry Pérot.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph
Investigation (SUMI) and the unique optical components that have been developed to meet those objectives. A sounding
rocket payload has been developed to test the feasibility of magnetic field measurements in the Sun's transition region.
The optics have been optimized for simultaneous measurements of two magnetic sensitive lines formed in the transition
region (CIV at 1550 Å and MgII at 2800 Å). This paper will concentrate on the polarization properties SUMI's toroidal
varied-line-space (TVLS) gratings and its system level testing as we prepare to launch in the Summer of 2008.
We present measurements of toroidal variable-line-space (TVLS) gratings for the Solar Ultraviolet Magnetograph
Investigation (SUMI), currently being developed at the National Space Science and Technology Center (NSSTC).
SUMI is a spectro-polarimeter designed to measure magnetic fields in the solar chromosphere by observing two UV
emission lines sensitive to magnetic fields, the CIV line at 155nm and the MgII line at 280nm. The instrument uses a
pair of TVLS gratings, to observe both linear polarizations simultaneously. Efficiency measurements were done on
bare aluminum gratings and aluminum/MgF2 coated gratings, at both linear polarizations.
KEYWORDS: Magnetism, Mirrors, Polarization, Space telescopes, Solar processes, Telescopes, Spatial resolution, Sun, Optical coatings, Signal to noise ratio
The Magnetic Transition Region Probe is a space telescope designed to measure the magnetic field at several heights and temperatures in the solar atmosphere, providing observations spanning the chromospheric region where the field is expected to become force free. The primary goal is to provide an early warning system (hours to days) for solar energetic particle events that pose a serious hazard to astronauts in deep space and to understand the source regions of these particles. The required magnetic field data consist of simultaneous circular and linear polarization measurements in several spectral lines over the wavelength range from 150 to 855 nm. Because the observations are photon limited an optical telescope with a large (>18m2) collecting area is required. To keep the heat dissipation problem manageable we have chosen to implement MTRAP with six separate Gregorian telescopes, each with ~ 3 m2 collecting area, that are brought to a common focus. The necessary large field of view (5 × 5 arcmin2) and high angular resolution (0.025 arcsec pixels) require large detector arrays and, because of the requirements on signal to noise (103), pixels with large full well depths to reduce the readout time and improve the temporal resolution. The optical and engineering considerations that have gone into the development of a concept that meets MTRAP's requirements are described.
This paper will describe the Vacuum Ultraviolet (VUV) polarization testing of the Solar Ultraviolet Magnetograph (SUMI) optics. SUMI is being develop for a sounding rocket payload to prove the feasibility of making magnetic field measurements in the transition region. This paper will cover the polarization properties of the VUV calibration polarizers, the instrumental polarization of the VUV chamber, SUMI's toroidal varied-line-space gratings and the SUMI polarimeter.
This paper will describe the objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. A sounding rocket payload is being developed to test the feasibility of magnetic field measurements in the Sun's transition region. The optics have been optimized for simultaneous measurements of two magnetic lines formed in the transition region (CIV at 1550Å and MgII at 2800Å). Finally, this paper will concentrate on the polarization properties of the SUMI polarimeter and toroidal variable-line-space gratings.
Extremely stable pointing of the telescope is required for images on the CCD cameras to accurately measure the nature of magnetic field on the sun. An image stabilization system is installed to the Solar Optical Telescope onboard SOLAR-B, which stabilizes images on the focal plane CCD detectors in the frequency range lower than about 20Hz. The system consists of a correlation tracker and a piezo-based tip-tilt mirror with servo control electronics. The correlation tracker is a high speed CCD camera with a correlation algorithm on the flight computer, producing a pointing error from series of solar granule images. Servo control electronics drives three piezo actuators in the tip-tilt mirror. A unique function in the servo control electronics can put sine wave form signals in the servo loop, allowing us to diagnose the transfer function of the servo loop even on orbit. The image stabilization system has been jointly developed by collaboration of National Astronomical Observatory of Japan/Mitsubishi Electronic Corp. and Lockheed Martin Advanced Technology Center Solar and Astrophysics Laboratory. Flight model was fabricated in summer 2003, and we measured the system performance of the flight model on a laboratory environment in September 2003, confirming that the servo stability within 0-20 Hz bandwidth is 0.001-0.002 arcsec rms level on the sun.
We present the design and initial flight results of a balloon-borne hard X-ray detector system for observing high-resolution spectra of solar flares. The instrument is designed to achieve a 3 keV energy resolution over the energy range of 15-120 keV. The instrument uses sixteen 10×10×0.5mm cadmium telluride (CdTe) detectors with indium electrodes that act as Schottky barriers. Pre-flight tests confirmed that all detectors exceeded the target 3 keV resolution. The detector system is designed to optimize radiative cooling in order to achieve the operating temperature of 0°C without refrigeration mechanisms. The first flight took place on August 29, 2001 and while no major flares were observed, the instrument operation was verified and a detector temperature of -13° C was achieved. The second flight took place on May 24, 1974 and during the 8 hours of level flight at an altitude of 41km, we succeeded in observing a class M1.1 solar flare.
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