ORFEUS-SPAS: The Berkeley Euv Spectrometer

Abstract

ORFEUS-SPAS, the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometers, on the Astro-SPAS space platform, is a joint project of NASA and the BMFT in the Federal Republic of Germany (see Kraemer et al. 1990, this volume). The Berkeley spectrograph for this mission will obtain high-resolution (λ/△λ > 7000) spectra of point sources between 390 and 1200 Å. The Berkeley instrument incorporates a set of four novel spherically figured, varied line-space (SVLS) gratings used in a geometry that is similar to that of the classic Rowland mount to span this large wavelength interval. Two spectral detector units containing curved MCPs and delay-line anodes encode the arriving photons in digital format for telemetry. An additional optic directs the image of the source in the entrance aperture onto a sealed FUV detector which is used to track the source as it drifts during an observation, enabling a post-flight reconstruction of the spacecraft pointing vector. This in turn will allow us to define the wavelength of each recorded photon with precision.KeywordsEffective AreaDiffraction EfficiencyDiffraction GratingPrimary MirrorEntrance ApertureThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.