Combined Determination of Satellite Orbit Using SLR and Pseudorange Data

The combination of SLR and GPS pseudorange data for GPS35 orbit determination is studied.The three-day orbital arcs for the GPS35 satellite are computed.When the orbit of GPS35 satellite is computed,the IERS Convention 1996 is closely followed.ITRF2000 station positions and velocities are employed,along with the IERS C04 polar motion series.The JGM-3 gravity model is employed and JPL planetary ephemeris DE403/LE403 is adopted.The IGS orbit is given in SP3 format with respect to a terrestrial reference frame and with 15-minute epochs coincident with the GPS timescale.The orbit results are given with respect to J2000 reference frame with 15-minute epochs coincident with the UTC timescale.Thus we have to convert them from J2000 to the terrestrial reference frame,at UTC epochs corresponding to the IGS ephemeris epochs.