Precision Orbit Determination of LEO Satellites Using the Software BERNESE 5.0

Currently an increasing number of LEO satellites are equipped with highly-accurate satellite-borne GPS receivers.The accuracies of orbit determination with such GPS depend on GPS satellite ephemerides and clock biases.This paper uses GPS satellite-ephemeris and clock-bias data from the CODE (Center for Orbit Determination in Europe) and calculates sets of 60-day orbits of the CHAMP and SAC-C satellites by using the Reduced-Dynamic Orbit Determination (with undifferenced GPS data).The calculated orbits are compared to the post-processed "science orbits" from the JPL and GFZ,which leads to the conclusion that the accuracies of the 3-dimensional orbital positions are within 20 cm and the accuracies of the 3-dimensional orbital velocities are appropriately 0.20 mm/s.