21:T4c3,The microchannel plate, delay line, detectors developed for the far ultraviolet spectroscopic explorer mission to be launched in 1998 are described. The two FUSE detectors have a large format (approximately equals 184 mm by 10 mm split into two 88.5 by 10 mm segments), with high spatial resolution (less than 20 micrometers by 50 micrometers FWHM, greater than 9000 by 200 resolution elements) and good linearity (plus or minus 25 micrometers), high image stability, and counting rates in excess of 4 by 10⁴ events sec^-1. KBr opaque photocathodes have been employed to provide quantum detection efficiencies of 30 - 40% in the 900 - 1200 angstrom range. Microchannel plates with 10 micrometer pores and an 80:1 pore length to diameter ratio, with a 95 mm by 20 mm format have been used in a Z stack configuration to provide the photon amplification (gain approximately equals 2 by 10⁷). These show narrow pulse height distributions (less than 35% FWHM) even with uniform flood illumination, and good background levels (less than 0.3 event cm^-2sec^-1). Flat field images are demanded by the microchannel plate multifiber boundary fixed pattern noise and are stable.22:T464,The Berkeley spectrograph aboard the ORFEUS telescope made its second flight on the 14-day ORFEUS-SPAS II mission of the Space Shuttle Columbia in November/December 1996. Approximately half of the available observing time was dedicated to the Berkeley spectrograph, which was used by both Principal and Guest Investigators. The spectrograph's full bandpass is 390-1218 A; here we discuss its in-flight performance at far-ultraviolet (FUV) wavelengths, where most of the observations were performed. The instrument's effective area peaks at 8.9 +/- 0.5 cm^2 near 1020 A, and the mean spectral resolution is 95 km/s FWHM for point sources. Over most of the spectral range, the typical night-time background event rate in each spectral resolution element was about 0.003/s. Simultaneous background observations of an adjacent blank field were provided through a secondary, off-axis aperture. The Berkeley spectrograph's unique combination of sensitivity and resolution provided valuable observations of approximately 105 distinct astronomical targets, ranging in distance from the earth's own moon to some of the brightest AGN.23:T820,

	Year	Citations

Abstract

References