High Precision Measurement And Research For Position Of Saturnian Nearby Faint Satellites

It has always been of importance to measure positions of planets and their satellites in our solar system. The main purpose of measurement is to improve the orbit theories of these planets and to server for the solar space exploration.The focus of this paper is measuring the position of those faint satellites nearby Saturn, not Saturn itself. However, precision research result of Saturn should be provided for measuring these satellites' positions. Peng et al put forward an algorithm based on a threshold. By using this method, we can get good measurement results of Saturn. Based on this result, the author tried his best to measure positions of those satellites near Saturn.For most of natural satellites, their distances to their primary planets, and their differences of magnitude are both great, which cause it difficult to measure the position of natural satellites. The measurement result of center of faint satellite will be offset to main star, impact measurement accuracy by using any conventional digital centering algorithm.To solve this problem, we try to do the following: (1) Remove the halo of Saturn's ring, to get more opportunity to measure its nearby faint satellites. (2) Under the condition of removing halo of Saturn's ring, using a polynomial to fit background gray of the region, using Gaussian fitting method to measure faint satellites' position. (3) Analyze the convergence of Gauss fit function with different order polynomial, and ultimately find an appropriate Gaussian fitting form.In order to research functions' convergence better, we use two different functions to fit for the background of Gauss function respectively according to whether wipe off ring of Saturn's halo In the process of system's implementation. The results of experiments prove that: In the case of wiping off Saturn's ring, Gauss function can be convergent quickly, the dimension of polynomial of background reach to 2 can get good result. .In other case, the fit function can be convergent too, but the step of background fit function should reach to 4 always...