The SPEKTROSAT mission

SPEKTROSAT, the follow-up mission to ROSAT will be equipped with a transmission grating spectrometer with a spectral resolution of 0.2 A over the wavelength range between 6 and 300 A. Third-order aberrations are minimized by a mounting of the grating elements according to the Rowland-torus geometry. The ROSAT mirror system will be slightly changed by a redesign of the optical stops in order to reduce the field of view. The Focal Instrumentation has to be modified for a better match with the spectroscopic requirements. Since SPEKTROSAT is almost identical to ROSAT, this concept offers a large amount of science at relatively low costs. Its limiting line sensitivity will be about 20 times better than that of the EINSTEIN-OGS.