Investigation on the combination of space geodetic techniques

The Space Geodesy Center (CGS) of the Italian Space Agency (ASI), located n ear Matera (Italy), hosts permanent Very Long Baseline Interferometry (VLBI ), Satellite Laser Ranging (SLR) and Global Positioning System (GPS) system s and manages the other receivers of the Italian GPS Fiducial Network. The presence of these collocated space geodetic systems in the area and the dat a analysis activities usually carried out at the CGS for each of the three techniques makes the construction of fully integrated solutions a natural o bjective. This paper describes the preliminary work carried out to assess t he consistency of the various geodetic solutions and to explore their compa tibility in order to combine the information content from the different tec hniques. The consistency of the CGS geodetic global solutions providing sit e positions and velocities is assessed, with particular attention to the Me diterranean and European areas. In addition a direct comparison between bas elines and baseline rates for the collocated european GPS and VLBI sites is made. (C) 2000 Elsevier Science Ltd, All rights reserved.