A Study of Satellite Orbit Differences under IAU2000 Resolution

The IAU2000 resolution was adopted at the IAU 24th General Assembly in 2000.The new resolution has officially become effective since January ^1,2003.Compared with the old system(FK5),which was essentially derived from Newtonian Mechanics;the new system is kinematically defined by the position of the extragalactic radiosources.The two systems are mainly differenced in the definition of the pole,orientation and the models of transformation between celestial frame and terrestrial frame.As a matter of fact,implementing of the new resolution will affect the orbits of artificial satellites,whose trajectories are determined according to the ground observations.The paper describes in detail the impact on GPS orbits due to the introduction of the new models in IAU2000 resolution.GPS data on DOY 186 2005 are analyzed to find out the orbit difference between old and new models.Results show that orbits difference of GPS exhibit a periodical signal in either inertial systems or terrestrial frame,with an amplitude about 2.5 m at X,Z axis and 1 m at Y axis in inertial systems,while that is about 4mm in each axis in terrestrial system.Statistics of orbits difference show that the 3D RMS of orbits difference in inertial systems is around 3m,and the orbits difference is neglect able in terrestrial system.