CCD star tracker has developed rapidly for various space application since 1970's. This paper describes design consideration

system construction

and operation princple of XG-1 CCD star tracker developed in CIOFM.In the system a single-chip computer is used to control CCD integration time and threshold selection. Due to centroiding algorithm is adopted the subpixel accuracy is obtained.The test results given in the end of this paper show that stationary accuracy of the star tracker is better than 2 arcsec (rms) and the stars with magnitude of 6.4 can be tracked steadily.