Dirk Behrend

Data Handling within the International VLBI Service

The International VLBI Service for Geodesy and Astrometry (IVS) is a globally operating service that coordinates and performs Very Long Baseline Interferometry (VLBI) activities through its constituent components. The VLBI activities are associated with the creation, provision, dissemination, and archiving of relevant VLBI data and products. The data and products are stored in dedicated IVS components called ‘Data Centers.’ The three Primary Data Centers provide identical data holdings. We give a brief overview of the organizational structure of the IVS and describe the general data flow among the various IVS components from preparing observational plans to creating the final products.

IVS High Accurate Products for the Maintenance of the Global Reference Frames as Contribution to GGOS

VLBI provides highly accurate and unique products for the realization and maintenance of the celestial and terrestrial reference frames, ICRF and ITRF, as well as for the Earth Orientation Parameters. In 2001 the products were reviewed with respect to obtaining highest accuracy and to improving the observing sessions in order to make best use of the resources which are made available by the IVS member institutions. Since 2002 improved observing sessions were coordinated by the IVS aiming at fast turn-around products for EOP and better products for TRF and CRF. The number of observations increased by more than 30% from 2002 to 2004. New products, e. g. the troposphere zenith path delay, are now being generated. Concerns about the aging technology, which has been used for the past three decades, and about radio interference problems that decrease the number of useable observations, led to the establishment of IVS Working Group 3. The working group was asked to examine current and future requirements for geodetic VLBI, including all components from antennas to analysis, and to create recommendations for a new generation of VLBI systems. The results are summarized in a vision paper, VLB12010 (Niell et al., 2005), which is recommended for coordination of new developments in VLBI and for plans to invest in new components by member institutions. This paper reviews IVS activities of recent years and gives a perspective about new developments for meeting future requirements, which are set up by GGOS.