Abstract: The highresolutionimage satellite is required to achieve stringent attitude determination accuracy (2.4″ (3σ) groundbased) in order to provide precise geometric accuracy. Influenced by the star sensor’s low frequency error (LFE), the conventional star sensors/gyros attitude determination system cannot achieve the precision requirement. For this reason, a new method for accurate attitude estimation with gyrobased reference time is proposed, and the satellite attitude estimates at the reference time is obtained on the ground by using the ground control points. The most relative time for achieving the required precision is limited because the effect of gyro’s bias errors and drifts is very significant in long term. Analysis and simulation results are also presented.

Key words: satellite attitude determination, attitude angular increment, rate gyro, precision