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Proceedings Paper

Performance of the Multi-Spectral Solar Telescope Array VI: performance and characteristics of the photographic films
Author(s): Richard B. Hoover; Arthur B. C. Walker II; Craig Edward DeForest; Maxwell J. Allen; Joakim F. Lindblom
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Paper Abstract

The Multi-Spectral Solar Telescope Array (MSSTA) is a sounding rocket-borne observatory designed to produce ultra-high resolution full-disk images of the Sun. The MSSTA utilizes an array of Ritchey-Chretien, Cassegrain, and Herschelian normal incidence multilayer x-ray/EUV telescopes and thin film interference-coated FUV telescopes to produce narrow band solar images at selected wavelengths in this broad region of the electromagnetic spectrum. This mission places extremely strenuous requirements upon the imaging detector. The desire for ultra-high resolution images of the solar disk and corona out to 1.5 R demands an information storage capacity which can at the present time be met only by the highest quality photographic emulsions. Furthermore, there exists a tremendous range in intensity levels and contrast of solar x-ray/EUV/FUV emission features. The MSSTA imaging detectors must have the ability to record extremely bright, high contrast features associated with flares and active regions without saturating, whicle still maintaining the capability of capturing very faint, low contrast structures in coronal holes, polar coronal plumes, network structures and faint ioops in the corona. This very difficult requirement established the need for very wide latitude photographic emulsions so that these diverse features can be imaged at appropriate density levels within the range of exposure times that can be accommodated on a sounding rocket mission. Furthermore, the films selected for the MSSTA flight must be sensitive over a very broad and difficult portion of the electromagnetic spectrum. The payload must be evacuated prior to launch to preserve the integrity of the delicate EUV filters. Hence, the films chosen must also have low-outgassing rates and possess the ability to be unspooled from the reel and transported through conventional film cameras while dry, after exposure to high vacuum, without experiencing the degradation to the images which can result from electrostatic discharges. In this paper we describe the performance and characteristics required of photographic films for solar observations in the soft x-ray/EUV and FUV wavelength regimes. We discuss the properties of the important new emulsions that have been selected for flight on the Multi-Spectral Solar Telescope Array. We also present exciting and important new data on the response characteristics of a tabular grain Experimental XUV 100 film and an uncoated Experimental Spectroscopic 649 emulsion based upon measurements of these films at the SURF II synchrotron facility of the National Institute of Standards and Technology and at the Space Sciences Laboratory of the University of California, Berkeley.

Paper Details

Date Published: 1 February 1991
PDF: 14 pages
Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991); doi: 10.1117/12.23191
Show Author Affiliations
Richard B. Hoover, NASA/Marshall Space Flight Ctr. (United States)
Arthur B. C. Walker II, Stanford Univ. (United States)
Craig Edward DeForest, Stanford Univ. (United States)
Maxwell J. Allen, Stanford Univ. (United States)
Joakim F. Lindblom, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 1343:
X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography

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