The SPEAR instrument and on-orbit performance

Abstract

The SPEAR ( or "FIMS") instrumentation has been used to conduct the first large-scale spectral mapping of diffuse cosmic far-ultraviolet (FUV; 900 - 1750 angstrom) emission, including important diagnostics of interstellar hot (10(4) - 10(6) K) and photoionized plasmas, H-2, and dust-scattered starlight. The instrumentation's performance has allowed for the unprecedented detection of astrophysical diffuse FUV emission lines. A spectral resolution of lambda/Delta lambda similar to 550 and an imaging resolution of 5' is achieved on-orbit in the Short (900 - 1150 angstrom) and Long (1350-1750 angstrom) bandpass channels within their respective 4.degrees 0 x 4.'6 and 7.degrees 4 x 4'.3 fields of view. We describe the SPEAR imaging spectrographs, their performance, and the nature and handling of their data.