- This paper describes, for a spacecraft equipped with a wide Field-Of-View (FOV) startracker, a fast and robust autonomous attitude determination system, consisting of a new star identification technique, here developed, working with a mixed EULER-q/QUEST-2 attitude estimation algorithm, presented in . The stars identification is based on the stars angular separation. Stars are directly identified within an overall large stars catalog without using the magnitude information. A first proposed star-pair-ID technique is based on a best fitting criterion while a second faster one uses three vectors of integers. A proposed "reference-star" criterion is then used for star-matching identification. The algorithm robustness is such that, after spikes being deleted, at least three true stars are still available. An overall software block diagram of the proposed system is depicted. Extensive tests have been performed and the results are shown by plots.