Per Helge Andersen (Norwegian Mapping Authority, Norway)

GEOSAT is a multi-technique geodetic software that has been under
development for about 30 years [P. H. Andersen, "Multilevel arc
combination with stochastic parameters". Journal of Geodesy 01/2000;
74(7): 531 - 551]. The last couple of years the development efforts
have been headed by the Norwegian Mapping Authority, and currently the
software is being expanded to also process the latest DORIS
observation data.

The GEOSAT software can be used in the analysis of space geodetic data
by doing combined analysis of data from VLBI, SLR, GPS and DORIS at
the observation level. GEOSAT is based on factorized Kalman filters
which allow estimation of time variable parameters consistently across
the different techniques.

Analysis of DORIS data was done in the past with good results.
However, we are currently doing a major revision of the software to
support all newer types of DORIS observations and data formats. In
this presentation we will report on the current status of DORIS
analysis in GEOSAT together with the other techniques, as well as
discuss our plans for future development.