IVS Working Group 2 for Product Specification and Observing Programs

After the scientific rationale is given in the introduction the Terms of Reference and the proceeding of IVS Working Group 2 are presented. Then the present status and future goals of all international activities within IVS are described. In particular the current products of IVS are described in terms of accuracy, reliability, frequency of observing sessions, temporal resolution of the parameters estimated by VLBI data analysis, time delay from observing to product, i.e. time which has passed after the end of the last session included in the VLBI solution till availability of the final products and frequency of solution (in the case of “global solutions”, when all existing or a high number of VLBI sessions are used to determine so-called global parameters). All IVS products and their potential users are covered in the report. This includes the Earth orientation parameters (EOP), the reference frames (TRF and CRF), geodynamical and geophysical parameters and physical parameters. Measures which should be taken within IVS to meet the goals defined in the first steps are presented. As most of the measures are related to the observing programs, these are the main focus for improving the current status of IVS products. The report shows that due to various requirements of the different users of IVS products the following aspects must be accomplished: significant improvement of the accuracy of VLBI products, shorter time delay from observation to availability of results, almost continuous temporal coverage by VLBI sessions. A first scenario of the IVS observing program for 2002 and 2003 considers an increase of observing time by about 30%-40% and includes sessions carried out by S2 and K4 technology. The midterm observing program for the next 4-5 years seems to be rather ambitious. However, it appears feasible if all efforts are concentrated and the necessary resources are made available.