A New Sub-Pixel Subdivision Location Algorithm for Star Image

A new sub-pixel subdivision location algorithm for estimating the position of the star on the focal plane array is proposed. An analytical study of the optics theoretical point spread functions is presented and it is shown that the star intensity distribution is close to the Gaussian point spread function model. Based on the numerical model of the star, a Gaussian curved fitting algorithm for centroiding location of the star image is devised. Since behavior of the new sub-pixel location algorithms is influenced by the size of Gaussian window, an optimal size of calculating window is given out. In order to reduce the negative effects of noise, a weighted scheme for centroiding is considered, and it improves the accuracy of extracting the star position on the focal plane array. The simulation results show that the accuracy of the star position can reach 1/150 pixel, and the optimal size of window for calculating is 5 x 5, which is under the 10% star magnitude noise.