Positional Measurement Of Jupiter During Its Nonzero Phase

The positional observations of our solar system' planets and their satellites always have important meaning. The main purpose of the positional observation is to improve the orbital theory of the planets and their satellites and serves for the solar system space exploration.Centering of planets is normally affected by their phase effect. Therefore it is necessary to study how to effectively eliminate the phase effect for high -precision centering of planets. In this dissertation, a limb compensation algorithm which is based on the ellipse model is introduced for centering of Jupiter during its nonzero phase. The ellipse model is generated from the physical ephemeris of the Jupiter, including its phase defect, the limb and the terminator. The limb is the physical edge of the planet and the terminator is a line along the interface of the day-night. There are three main parts in this dissertation as follows.1. Determination of the location of a limb: the LOG operator and second order interpolation are used to determine the sub-pixel limb and terminator.2. Compensation of the terminator: after the judgment whether the point is on the terminator or the limb, the pixel compensation technique is performed on the terminator.3. Centering of Jupiter: an iterative fitting algorithm of ellipse-definition is used to fit the physical limb, then obtaining the Jupiter center.The algorithm is implemented with Visual C++ 6.0 platform in this paper. Moreover, we apply a method of precise estimation, namely, detecting the distance of the Jupiter's center and its satellite whose position is determined by modified moment, and then using the relationship of these data and the time to take astronomic images to evaluate the precision of edge detection algorithms. We compare our limb-fitting results with previously work which did not correct for the phase defect and discuss its accuracy. Experimental results show that the algorithm is feasible and effective.