<h2>AAS  96-158</h2><h2>A FAST ON-BOARD AUTONOMOUS ATTITUDE DETERMINATION SYSTEM BASED ON A NEW STAR-ID TECHNIQUE FOR A WIDE FOV STAR TRACKER</h2><h4>D. Mortari, Universita degli Studi di Roma "La Sapienza"</h4><h2> Abstract </h2>This paper provides, for a spacecraft equipped with a wide FOV startracker, a fast and robust autonomous attitude determination system, consisting of a new star identification technique, here described, working with the fast-and-optimal attitude estimation algorithms EULER-q and QUEST-2.  Stars are directly identified within the overall large stars catalog without using the magnitude information.  The technique uses three vectors of integers, built prior to the launch, suitably devised for a fast identification of the stars pair from the angular separation.  Then, a "central-star" criterion for the correspondence identification, is introduced.  The algorithm robustness is such that it can be applied up to three true stars, after spikes are deleting, are still available.  The main characteristics of this star-ID technique are shown by plots.<br><br>