Abstract: A new star pattern recognition algorithm without any a priori attitude knowledge is described. It uses an ordered star triplet defined by three stars and their celestial coordinates as recognizable unit, and makes up multiple units into a group. A group having maximum credibility is selected as correct recognition. By using special arrangement for the database of guidance patterns and the information provided by the recognized unit, the computation and the storage capacity of the on board star catalog are comparable with those of the traditional triangle matching. Monte Carlo experiment demonstrates that, while the magnitude uncertainty is 0.5 (3σ) and the position uncertainty is 10 arcsec (1σ), the success rate is very close to 100%.

Key words: st ar field recognition, database of guidance patter n, matching and combining of recognizable unit