Design and development of the eROSITA x-ray mirrors

MPE will provide the X-ray Survey Telescope eROSITA [5] for the Russian Spektrum-Roentgen-Gamma Mission [4] to be launched in 2011. The design of the X-ray mirror system is based on that of ABRIXAS: The bundle of 7 mirror modules with the short focal length of 1600 mm makes it still a compact instrument while, however, its sensitivity in terms of effective area, field-of-view, and angular resolution shall be largely enhanced with respect to ABRIXAS. The number of nested mirror shells increases from 27 to 54 compared to ABRIXAS thus enhancing the effective area in the soft band by a factor of six. The angular resolution is targeted to be 15 arc seconds half-energy width (HEW) on-axis resulting in an average HEW of 26 arc seconds over the 61 arc minutes field-of-view (FoV). The instrument's high grasp of about 1000 cm²deg² in the soft spectral range and still 10 cm²deg² at 10 keV combined with a survey duration of 4 years will generate a new rich database of X-ray sources over the whole sky. As the 7 mirror modules are co-aligned eROSITA is also able to perform pointed observations.