document: Brightness-independent start-up routine for star trackers 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 -LRB- CCD -RRB- 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
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