Autonomous on-orbit calibration of a star tracker

The accuracy of satellite attitude determination depends on the performance of star trackers, which can be improved by careful calibration. Star trackers are initially calibrated on ground. After the launch, because of vibrations, vacuum, thermal cycling and instrument aging, it is common to observe small shifts in calibration parameters. This paper aims to discuss an autonomous on-board calibration technique for star trackers. The approach is especially related to a set of parameters including the focal length, the principal point offset and the focal plane distortions.