Time transfer by laser link between China and France

To advance from milli-arcsecond to micro-arcsecond astrometry, time keeping capability and its comparison among different stations need to be improved and enhanced. The T2L2 (Time transfer by laser link) experiment under development at OCA and CNES to be launched in 2008 on Jason-2, allows the synchronization of remote clocks on Earth. It is based on the propagation of light pulses in space which is better controlled than propagation of radio waves. In this paper, characteristics are presented for both a common view and non-common view T2L2 comparisons of clocks between China and France.