On hourly orbit determination

Abstract

We present here our hourly orbit product and we compare it to other near real-time (NRT) reliable orbits. The comparisons are based on satellite position differences with respect to the final IGS orbits. Experience shows that the use of predicted precise orbits in the NRT processing mode is usually problematic due to poorly determined arcs of only a few satellites. Thus, evaluation of satellite orbits is necessary. Nevertheless, we can find a decreased quality of some arcs also in ultra-rapid products, but the magnitude is significantly lower here. Reducing the predictions to 1–2 hours only, our hourly orbits improve especially the along-track satellite positions.