Analysis of earth limb viewing from the Upper Atmospheric Research Satellite

The Upper Atmospheric Research Satellite (UARS) is a multi-instrumented satellite which will examine the earth's upper atmosphere. One of the instruments onboard UARS is a Cryogenic Limb Array Etalon Spectrometer (CLAES) developed at the Lockheed Research Laboratory to measure atmospheric infrared emissions. This paper addresses the Sun-Orbit-CLAES viewing geometry during the two year mission. Orbit averages and monthly averages are computed. In particular, the problem of viewing through a partially illuminated atmospheric shell is solved. For this transition situation, part of the look vector is in sunlight while the remainder is in the earth's shadow.