Development and testing of the eROSITA mirror modules

MPE will provide the X-ray Survey Telescope eROSITA for the Russian Spektrum-Roentgen-Gamma Mission. The mirror system consists of a compact bundle of seven co-aligned mirror modules with a focal length of 1600 mm and 54 nested mirror shells each. The 61 arcmin field-of-view (FoV) will yield a high grasp of about 1000 cm²deg² around 1 keV. An angular resolution of 15 arcsec HEW on-axis (resulting in an average angular resolution of ~26 arcsec HEW over the field-of-view and ~30 arcsec including all optical and spacecraft error contributions) will help distinguish point sources from extended emission of galaxy clusters which are relevant for cosmological studies. During a four year allsky survey eROSITA will generate a new rich database of X-ray sources. In a second phase of the mission eROSITA will also perform pointed observations.

After a mirror development program the integration of flight mirror modules started in early 2011. Currently, the manufacturing of flight modules is ongoing and some of the partially integrated ones have already been X-ray tested. Calibration of completed mirror modules will start end of 2012. Parallel to the X-ray mirrors we have developed an X-ray baffle to suppress stray light from single reflections. It consists of precisely shaped and welded concentric Invar foils which will be mounted on top of each mirror module and aligned by optical means.

We report on the design and the mirror development program including the X-ray baffle and present the latest results from X-ray measurements.