The focal plane instrumentation of the ROSITA telescope

The X-ray astronomy satellite ROSITA is planned to perform an X-ray all sky survey in the medium energy range up to 10 keV with an imaging telescope. During the mission the whole sky will be scanned and selected areas will be observed with longer exposures. Especially cosmic X-ray sources obscured by large amounts of gas and dust like accreting black holes and active galactic nuclei as well as the hot gas of distant clusters of galaxies can be seen in this energy band. The ROSITA payload consists of an imaging X-ray telescope made of seven separate mirror modules with different viewing directions. Each module has a 27 fold nested Wolter type I mirror system. The seven mirror systems share a common X-ray camera in the focal plane with seven single frame store pnCCD detectors, each dedicated to one mirror module. The frame store pnCCD is a further development of the pnCCD detector of the EPIC camera aboard the XMM-Newton satellite. Due to the high readout frequency of the CCDs (20 s^-1) the angular resolution of the telescope is not degraded despite the scanning motion of the satellite. The CCDs are operated at a temperature of -80°C. Cooling is provided by passive radiators and thermoelectric coolers. To reduce the fluorescent X-ray background, generated by cosmic radiation in the materials of the detector housing, the CCDs are surrounded by a graded shielding. The detector performance will be checked in orbit with calibration sources. We will give an overview of the mechanical, thermal and electrical concept of the focal plane camera system.