High-resolution UV spectrograph for sounding rocket measurement of planetary emission line profiles

We have constructed a high resolution imaging spectrograph for use as a payload in a sounding rocket experiment. The spectrograph employs a modified Ebert-Fastie design using a LiF pre-dispersing prism and a replica of the E1 echelle grating developed for the Space Telescope Imaging Spectrograph. The instrument has a 5 arcmin long adjustable width entrance aperture with two secondary apertures separated from the primary by ± 2 arcmin. The secondary apertures are intended for simultaneous measurement of the sky background. The spectrograph has been optimized for measurement of the 224^the order of Ly-α at a resolution of .04 angstrom. The detector system is a two dimensional photon counting device employing a microchannel plate intensifier and a wedge and strip anode read out. The spectrograph is used as a focal plane instrument of the Jupiter Telescope, a Cassegrain telescope constructed exclusively for use as a sounding rocket payload. The Jupiter Telescope is self pointed, employing image motion compensation to achieve 2-3 arcsec image quality. The telescope and spectrograph were launched from the White Sands Missile Range (WSMR) on May 4, 1991 to observe the H Ly-α line profile spatially resolved across the disk of Jupiter in the North-South (polar) and East-West (equatorial) directions, and to measure the H Ly-α emission line profile from interplanetary hydrogen associated with the local interstellar medium.