Continuous precise ephemerides for Beidou-2 maneuvered satellites based on a new thrust force model

Beidou geostationary earth orbit (GEO) and inclined geosynchronous orbit (IGSO) satellites are frequently maneuvered to keep them in the designed orbits by thrust forces. As the thrust forces are generally unknown, precise satellite orbits are difficult to be determined during maneuver periods. At present, precise ephemerides are not available or not complete for the satellite on the day of maneuver, and sometimes even the day after. This study aims to provide continuous precise orbit for Beidou-2 satellites during the maneuver period through better modeling of the thrust forces. We firstly present a thrust model based on the thrust behavior of Beidou-2 satellites detected in our previous study. Then, for the maneuvered satellite, the precise orbit is determined by estimating the extra thrust model parameters, together with other orbit parameters of initial satellite state and solar radiation pressure (SRP). Using observations from the Multi-GNSS Experiment (MGEX) network in Sep and Oct 2017, we have detected 10 GEO in-plane, 1 GEO and 3 IGSO out-of-plane maneuvers among the 5 GEO and 6 IGSO satellites; precise orbit determination (POD) is conducted for all the GEO in-plane and IGSO maneuvered satellites. The accuracy of our recovered orbit has been evaluated by comparing to a concatenation of the dynamic orbit before/after the maneuver and kinematic orbit during the maneuver. The RMSs of orbit differences before/after maneuvers are about 0.30, 2.34 and 0.42 m in the radial, along-track, and cross-track (RAC) directions for GEOs, and 0.33, 0.62 and 0.26 m for IGSOs. A similar level of accuracy has also been achieved during maneuvers as shown by the orbit differences and the stable POD residuals during the whole maneuver day. The recovered orbit accuracy is comparable to that of the normal Beidou-2 precise ephemerides from International GNSS Service (IGS) analysis centers (WHU/GFZ).