GRAPE software for GPS data processing: first results of ERP determination

Iskander Gayazov, Maxim Keshin, Alexander Fominov
Institute of Applied Astronomy RAS

A new software GRAPE for processing of the GPS observations has been
developed at the Institute of Applied Astronomy in the framework of
IGS related activities.  Two main working regimes of the GRAPE package
are: 1) processing GPS observations of regional campaigns on the basis
of double-differences and 2) processing the global network observations
using the triple-difference mode.  For testing the program package in
the first regime GPS observations of the BSL97 campaign were processed
and results were compared with those obtained with Bernese software.
Calculation of ERP with GRAPE has been recently started.  Observations
collected from 47 stations of the IGS global network are used to determine
X, Xdot, Y, Ydot, LOD, GPS satellite orbits and zenith path delay at the
stations.  Comparison of results with the final IGS ERP and orbits has
shown the good agreement.  Further development of the package including
capacity for combined GPS/GLONASS data processing is supposed.