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13 October 1986 The ROSAT Star Tracker
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A high precision star tracker has been developed as part of the attitude measurement and control system of the German Roentgen-Satellit ("ROSAT"). A Peltier cooled CCD array in the focal plane of an 82 mm refractive lens is used to measure the position of up to 3 stars within a field of view (FOV) of 5.9° x 4.4°. The position of a fourth reference star provided by the telescope of the satellite as an alignment control can be monitored simultaneously. The CCD readout data are reduced by a fast preprocessor; subsequently a microprocessor com-putes the exact star position by pixel interpolation using a centroiding algorithm. Optical performance tests on the engineering model have demonstrated the capability to track stars of my = +6.5 with an accuracy of 2 arcsec and a noise equivalent angle of less than 1 arcsec with an update period of 1 sec. In scan mode the stars can be tracked with an accuracy of less than 10 arcsec at a scan rate of 5 arcmin/sec. The environmental tests of the system were completed in October 1985.
© (1986) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gunter Lange, Bernhard MoBbacher, and David Purll "The ROSAT Star Tracker", Proc. SPIE 0627, Instrumentation in Astronomy VI, (13 October 1986);


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