The purpose of this paper is to determinate the precise orbits for satellites in LEO (Low Earth Orbit) using GPS data with less than four visible GPS Satellites. It is able to estimate kinematic positions of satellites in LEO, because they can track about 10 GPS satellites at once. However if a LEO satellite has a mission to point the sun or an inertially fixed point, the number of GPS data occasionally decreases to one. In this paper, we consider the situation using less than four GPS data. Least Square method was used to estimate the parameters for the Precise Orbit Determination (POD).

Keywords: LEO, POD