Dr. XU Guochang, senior scientist in GeoForschungsZentrum Potsdam of Germany, paid a visit to National Time Service Center, Chinese Academy of Sciences (NTSC, CAS) at the invitation of CAS Key Laboratory on Precision Navigation Positioning and Timing Technology (LPNPTT) on October 26, 2010.

Dr. XU delivered a report titled “A general introduction of the study from the satellite theory to n-body problems in the solar system” during his visit. He particularly analyzed the impact of the gravitational field of the earth on satellite perturbation and presented a simplified equation of motion. The audience had a heated discussion with Dr. XU at the end of the report.

Dr. XU is interested in studying the theory, algorithms and applicationsof GPS/Galileoa. His major publications include GPS ---- Theory, Algorithms and Applications(2003) and MFGsoft, Multi Functional GPS/(Galileo) Software (2004). He is now a visiting professor in LPNPTT.