Status of the international GPS service in terms of co-location and local ties

The IGS network today consists of 364 stations managed by about, 100 different agencies worldwide. The RINEX observations are contributed to the IGS Data Centers, which permanently archive the data and make it freely available to all users. The primary customer of the data set is the IGS Analysis Centers, which acquire the data for generation of precise GPS products such as ephemerides, clocks, earth orientation parameters, and station position and velocities.