Ground Calibration of Star Tracker Low Spatial Frequency Error

Abstract

The low spatial frequency error (LSFE) was an important component of the measurement error of star trackers. In order to improve the star tracker measurement accuracy better than 1 arcsecond, the calibration method of LSFE was studied. Firstly, the error composition, source and importance of ground calibration were introduced. Then, the traditional calibration and evaluation methods were described, and the problems in the application of the method to the star trackers which accuracy better than 1 arcsecond were analyzed. Then, according to the consistency of LSFE in a small range of field and the random characteristics of high spatial frequency errors (HSFE), an error separation and calibration method was proposed. Finally, the new calibration method was simulated and verified by experiments based on a sub-arcsecond precision star tracker. The Experimental results show that the calibration residual of the new method is 1.96/100 pixels, which is 38% lower than the traditional calibration method. This method is accurate, stable and reliable, and can be used for ground calibration of various space starlight measuring instrument such as star tracker and star camera.