Practical relativistic clock synchronization for high-accuracy space astrometry

Future high-accuracy space astrometry missions, such as Gaia and SIM, will need a time-tagging of observations consistent with General Relativity nowadays used as standard background for global data processing scheme. In this work, we are focusing on the realization of the onboard time scale. The onboard clock, being not ideal and consequently tainted with systematic biases, has to be carefully calibrated to the ideal relativistic proper time of the satellite. We present here a modeling of this essential step to provide a reliable relation between the onboard time and TCB, a time scale suitable for global data processing.