Maxwell J. Allen

Multi-Spectral Solar Telescope Array

The development of multilayer optics has profound implications for soft x-ray/extreme ultraviolet (XUV) astronomy. During the October 1987 flight of the Stanford/Marshall Space Flight Center Rocket X-Ray Spectroheliograph, narrow wavelength band, low scatter soft x-ray/extreme ultraviolet spectroheliograms were obtained with ~ 1 arcsec spatial resolution at ? ~ 173 A (Fe IX, Fe X) and at ? - 256 A (He II Ly-?). Although the Cassegrain telescopes used in this experiment were small (63.5 mm diameter) and utilized spherical rather than paraboloidal/hyperboloidal mirrors, the images produced exceed in quality any XUV spectroheliograms previously obtained with either normal or grazing incidence techniques. We describe a new rocket spectroheliograph instrument, the MultiSpectral Solar Telescope Array (MSSTA), that is currently being prepared for launch in August 1990. This instrument will utilize true Ritchey-Chretien optics of 127 mm diameter and parabolic Herschelian optics of 40 mm diameter, which will allow spectroheliograms to be obtained over the soft x-ray/extreme ultraviolet/far ultraviolet spectral range (40 to 1550 A). The performance of this new instrument should definitely demonstrate the unique combination of ultrahigh spatial resolution and spectral differentiation that multilayer optics afford for astronomical observations. The MSSTA will also represent the first astronomical use of an important new optical device, the multilayer grating. The MSSTA should obtain unprecedented information regarding the structure and dynamics of the solar atmosphere in the temperature range 104 to 107 K.

Multi-Spectral Solar Telescope Array II: soft x-ray EUV reflectivity of the multilayer mirrors

We have developed seven compact soft x-ray/EUV (XUV) multilayer- coated and two compact FUV interference-film-coated Cassegrain and Ritchey-Chretien telescopes for a rocket-borne observatory, the Multi-Spectral Solar Telescope Array. We report here on extensive measurements of the efficiency and spectral band pass of the XUV telescopes carried out at the Stanford Synchrotron Radiation Laboratory.

Chromospheric and Coronal Structure of Polar Plumes. 1; Magnetic Structure and Radiative Energy Balance

The Multi-Spectral Solar Telescope Array (MSSTA), a rocket-borne solar observatory, was successfully launched from White Sands Missile Range, New Mexico, on May 13, 1991 at 19:05 UT. The telescope systems onboard the MSSTA obtained several full disk solar images in narrow bandpasses centered around strong soft X-ray, EUV, and FUV emission lines. Each telescope was designed to be sensitive to the coronal plasmas at a particular temperature, for seven temperatures ranging from 20000 K to 4000000 K. We report here on the images obtained during the initial flight of the MSSTA, and on the chromospheric and coronal structure of polar plumes observed over both poles of the Sun. We have also co-aligned the MSSTA images with Kitt Peak magnetograms taken on the same day. We are able to positively identify the magnetic structures underlying the polar plumes we analyze as unipolar. We discuss the plume observations and present a radiative energy balance model derived from them.

EUV/FUV response characteristics of photographic films for the Multi-Spectral Solar Telescope Array

The photographic film employed by NASAs Multi-Spectral Solar Telescope Array must have high-to-ultrahigh resolution; since the spacecraft bearing the telescope must be evacuated to prevent the failure of delicate EUV and soft X-ray filters due to acoustic vibration during launch, the films must also have very low outgassing rates. An account is presently given of the properties of important new emulsions selected for flight, together with response-characteristics data for the experimental XUV 100 film and an uncoated Spectroscopic 649 emulsion.

Multi-spectral solar telescope array V; Temperature diagnostic response to the optically thin solar plasma

The authors have developed compact soft x-ray, extreme ultraviolet (EUV), and far-ultraviolet (FUV) multilayer coated telescopes for the study of the solar chromosphere, corona, and corona/solar wind interface. Because these systems operate at short wavelengths ({approximately}40 {angstrom} {lt} {lambda} {lt} 1550 {angstrom}), the modest apertures of 40 to 127 mm allow observations at very high angular resolution (0.1 to 0.7 arcsec). In addition to permitting traditional normal incidence optical configurations to be used at soft x-ray/EUV wavelengths, multilayer coatings also allow a narrow wavelength band ({lambda}/{Delta}{lambda} {approximately} 15 {minus}100) to be selected for imaging. The resulting telescopes provide a very powerful and flexible diagnostic instrument for the study of both the fine-scale structure of the chromosphere/corona interface and the large-scale structure of the corona and corona/solar wind interface. In previous papers, the authors have described a new solar rocket payload, the Multi-spectral Solar Telescope Array (MSSTA), which is composed of 17 of these compact telescopes. In this paper, the authors report on the ability of the MSSTA payload to obtain temperature diagnostic information about the optically thin solar plasma. The authors also discuss applications of this information to studies of coronal structure.

Performance of the multilayer-coated mirrors for the MultiSpectral Solar Telescope Array

The Multi-Spectral Solar Telescope Array, a rocket-borne solar observatory, was successfully flown in May, 1991, obtaining solar images in eight XUV and FUV bands with 12 compact multilayer telescopes. We report on recent measurements of the performance of multilayer coated mirrors for the Multi Spectral Solar Telescope Array, carried out at the Stanford Synchrotron Radiation Laboratory.

Performance of compact multilayer coated telescopes at soft X-ray/EUV and far ultraviolet wavelengths

We have developed compact soft x-ray/EUV (XUV) and farultraviolet (FUV) multilayer coated telescopes for the study of the solar chromosphere corona, and corona/solar wind interface. Because they operate at short wavelengths (~40 < ? < 1550 A), the modest apertures of 40 to 127 mm allow observations at very high angular resolution (0.1 to 0.7 arcsec). In addition to permitting traditional normal incidence optical configurations such as Cassegrain, Ritchey-Chretien, and Herschelian to be used at XUV wavelengths, multilayer coatings also allow a narrow wavelength band (?/?? ~30 to 100) to be selected for imaging. The resuIting telescopes provide a very powerful and flexible diagnostic instrument for the study of both the fine scale structure of the chromosphere/ corona interface and the large scale structure of the corona and corona/ solar wind interface. In previous papers we described a new solar rocket payload, the Multi-Spectral Solar Telescope Array (MSSTA), composed of 17 of these compact telescopes. In this paper we report on the performance of the seven MSSTA Ritchey-Chretien telescopes.

Solar observations with the multispectral solar telescope array

The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne solar observatory which was succesfully launched on May 13, 1991, from the White Sands Missile Range, NM. Ultrahigh resolution, full-disk solar X-ray, EUV, and FUV images were obtained with the MSSTA Herschelian, Cassegrain, and Ritchey-Chretien telescopes. We describe the payload and provide some preliminary scientific results from the flight.

Tin–polyimide and indium–polyimide thin-film composites as soft x-ray bandpass filters

A tin-polyimide and an indium-polyimide soft x-ray bandpass filter were fabricated with thicknesses of 1400 and 1750 A for the metal and polyimide components, respectively. The transmission of each filter was measured at the Stanford Synchrotron Radiation Laboratory. The transmission of the tin-polyimide filter was found to be ~40% for radiation with wavelengths between 60 and 80 A. The transmission of the indium-polyimide filter was greater than 40% between 70 and 90 A. The indium was ~5% more transmissive than the tin and attained a maximum transmission of ~48% at 76 A. Such filters have potential applications to soft x-ray telescopes that operate in this region. They might also be of interest to investigators who work with x-ray microscopes that image live biological specimens in the 23-44-A water window.

The Stanford/Msfc Multi-Spectral Solar Telescope Array

The development of multilayer optics has profound implications for soft x-ray/EUV (XUV) astronomy. During the October 1987 flight of the Stanford/MSFC Rocket X-Ray Spectroheliograph, narrow wavelength band low scatter soft x-ray/EUV spectroheliograms were obtained with 1 arc second spatial resolution at λ~ 173 A (Fe IX, Fe X) and at X, 256 A (He II). Although the Cassegrain telescopes used in this experiment were small (63.5 mm diameter) and utilized spherical rather than paraboloidal/hyperboloidal mirrors, the images produced exceed in quality any XUV spectroheliograms previously obtained with either normal or grazing incidence techniques. We describe a new rocket spectroheliograph instrument, the Multi-Spectral Solar Telescope Array (MSSTA), that is currently being prepared for launch in September 1989. This instrument will utilize true Ritchey-Chretien optics of 127 mm diameter and parabolic Herschelian optics of 40 mm diameter, which will allow spectroheliograms to be obtained over the soft x-ray/EUV/VUV spectral range (40 Å - 1550 Å). The performance of this new instrument should definitely demonstrate the unique combination of ultra-high spatial resolution and spectral differentiation which multilayer optics afford for astronomical observations. The MSSTA will also represent the first astronomical use of an important new optical device, the multilayer grating. The MSSTA should obtain unprecedented information regarding the structure and dynamics of the solar atmosphere in the temperature range 104 K to 107 K.