Error analysis of CCD-based point source centroid computation under the background light.

The CCD-based point source centroid computation (PSCC) error under the background light is analyzed integrally in theory, numerical simulation and experiment. Furthermore, a comprehensive formula of the PSCC error caused by the diversified error sources is put forward. The optimum threshold to reduce the effects of all the error sources to a minimum is selected. The best threshold level is N(B) +3sigma(B), where N(B) is the average value of the error sources and sigma(B) is the mean-square value of the fluctuation of the error sources. The simulation and experiment results are in great accordance with the theoretical analysis.