The IDS Central Bureau
initiated in November 2001 an
that originally focused only on sets of station coordinates derived from
the June 2001 observations of the Spot2, Spot4 and Topex/Poseidon satellites.
were received from six Analysis Centers,
while three other expressed interest to participate at a later time.
The content of the responses was larger than expected, in several ways:
the data span covers several years, as compared to the single month requested,
and the products span not only sets of stations coordinates, but also
times series of the Earth's orientation parameters and of the geocenter
location and orbits.