A method of orbit computation taking into account the earthʹs oblateness

The Laplace method is a typical method of orbit computation for short arcs in the model of two-body problem. If the angular measurement is as accurate as 10−4 – 10−5 (2″ – 20″ ), then the oblateness of the Earth should be considered in the computation. In this paper, the theory and procedure of an improved Laplace method is given together with numerical examples. Besides orbit computation with multiple measurements, the method discussed in this paper is an efficient way to improve the accuracy of orbit computation, in general. It is the more useful the larger the oblateness.