MEASUREMENT TECHNIQUE. VERY LONG BASELINE INTERFEROMETRY

Abstract

In the last decade there was a large increase in the number of VLBI antennas around the world, both for radioastronomy and geodesy. This increase is connected to the dramatic improvements in their results, in particular for geodesy. In Europe a network of six antennas, spanning from Sweden to Spain and Italy, one of the world's most densely spaced VLBI networks of fixed antenna, has been operating since 1990. This network was enlarged during 1994 with the Crimea and Ny-Alesund antennas. More are under construction in Russia. The first five years of activity have produced more than 20 purely European experiments of very good quality allowing the measurements of the horizontal velocities of Italian stations with errors at the mm yr-1 level. The very latest results from Bologna solutions are presented. The future evolution of the technique at the stations and at the correlator is also presented.