HIGH-RESOLUTION ULTRAVIOLET SPECTROGRAPH FOR SOUNDING ROCKET MEASUREMENTS OF PLANETARY EMISSION-LINE PROFILES

We constructed a high-resolution imaging spectrograph for use as a pay load in a sounding rocket experiment. The spectrograph employs a modif ied Ebert-Fastie design with a LiF objective prism and a replica of an El echelle grating developed for the Space Telescope Imaging Spectrog raph. The instrument has a 5-arcmin-long adjustable width entrance ape rture with two identical secondary apertures separated from the primar y by +/- 2 arcmin. The secondary apertures are intended for simultaneo us measurement of the sky background. The spectrograph has been optimi zed for measurement of the 221st order of Lyman-alpha at a resolution of 0.03 to 0.04 angstrom. The detector system is a two-dimensional pho ton counting device that employs a microchannel plate intensifier and a wedge and strip anode readout. The spectrograph is used as a focal p lane instrument of the Jupiter Telescope, a Cassegrain telescope const ructed exclusively for use as a sounding rocket payload. The Jupiter T elescope is self-pointed, employing image motion compensation to achie ve 2- to 3-arc sec image quality. The telescope/spectrograph payload w as launched from the White Sands Missile Range on May 4, 1991, to obse rve the H Lyman-alpha. line profile spatially resolved across the disk of Jupiter in the North-South (polar) and East-West (equatorial) dire ctions, and to measure the H Lyman-alpha emission line profile from in terplanetary hydrogen associated with the local insterstellar medium.