Abstract: Most studies of star image location of star sensors are limited in static state conditions at present, however, the star spot is moving during exposure as a result of satellite rotation, thus influencing the location accuracy of the star image center. In this paper the accuracy of star image center location in dynamic state is analyzed for active pixel sensor (APS) based star sensors. First of all, sources of the location errors produced by the centroid algorithm are analyzed, a dynamic accuracy estimation method is proposed, and corresponding formulas are deduced. Then choice of the calculation window and the exposure time influencing the dynamic accuracy is analyzed based on given APS star sensor parameters. Finally, corresponding simulations are made to validate the conclusions.

Key words: dynamic accuracy, star image center, APS-based star senor, centroid algorithm