1. A method of autonomous acquisition of spacecraft attitude comprising the steps of: using a star tracker to observe a first set of stars at a first instant in time; forming a set of candidate star triplets from the first set of stars; pattern matching each candidate star triplet to an on-board star catalog to determine a set of pattern matches; forming a set having a plurality of spacecraft attitudes based on the pattern matches; and performing a rejection method on the set of spacecraft attitudes to eliminate certain spacecraft attitudes from the set of spacecraft attitudes.