TELESCOPE BAFFLE PERFORMANCE FOR LYMAN FAR-ULTRAVIOLET SPECTROGRAPHICEXPLORER

The Lyman Far Ultraviolet Spectrographic Explorer telescope is a Wolte r type II glancing incidence design with an aperture of 64 cm. Because the spacescraft is required to guide on stars fainter than m(v) = 16, a visible light baffle is necessary to protect the field of view from the stray light that results from out-of-field bright sources. Such a baffle system is described here. Total point-source transmittances ar e computed for incident beams in the range 0-70-degrees. Estimates for background brightness on the detector are made for the contribution f rom direct sunlight and earthshine. Scattering from the black surfaces of the baffle, the vanes, and diffraction at the structure's edges ar e taken into consideration.