Combination of VLBI Analysis Results

The quality and reliability of products of geodetic Very Long Baseline Interferometry (VLBI) observations, as those of any other space geodetic technique, are greatly enhanced if results of different analysis software packages with their individual models are brought together using a suitable combination process. In the framework of the Geotechnologien-project “Integration of space geodetic techniques - IERS”, tools and procedures have been developed for the combination of VLBI results taking into account the peculiarities of the VLBI observing technique. They have found their use in the routine operation of the International VLBI Service for Geodesy and Astrometry (IVS) which produces earth orientation parameters (EOP) and terrestrial reference frame (TRF) realisations from session-wise geodetic VLBI observations. The operational combination itself has several levels of latency requirements. Therefore, different types of combined EOP series based on EOP input series alone or on the full variance/covariance information of the EOP and the underlying TRF are generated.