title: Brightness-independent start-up routine for star trackers
abstract: Initial attitude acquisition by a modern star tracker is investigated here. Criteria for efficient organization of the on-board database are discussed with reference to a brightness-independent initial acquisition algorithm. Star catalog generation preprocessing is described, with emphasis on the identification of minimum star brightness for detection by a sensor based on a charge coupled device (CCD) photodetector. This is a crucial step for proper evaluation of the attainable sky coverage when selecting the stars to be included in the on-board catalog. Test results are also reported, both for reliability and accuracy, even if the former is considered to be the primary target. Probability of erroneous solution is 0.2% in the case of single runs of the procedure, while attitude determination accuracy is in the order of 0.02 degrees in the average for the computation of the inertial pointing of the boresight axis
keyphrases: brightness-independent start-up routine star trackers initial attitude acquisition on-board database star catalog generation preprocessing minimum star brightness reliability boresight axis gyroless spacecraft charge coupled device photodetector