Astrometric/Geodetic (VLBA)(RDV)

Source: Notes prepared by Nancy Vandenberg, (NVI/GSFC) for RDV13 (VLBA13).

Stations participating: 20


This is the first of six bi-monthly coordinated astrometric/geodetic experiments in 1999 that use the full 10-station VLBA plus up to 10 geodetic stations currently capable of recording VLBA modes. This year's series is a continuation of the highly successful RDV series begun in 1997. These experiments are being coordinated by the geodetic VLBI programs of three agencies: USNO, NASA, and NRAO. The experiments have been designed so that the same data set may be used by each agency for its particular goals.

USNO will perform repeated imaging and correction for source structure. These sources will establish a set of core reference sources with known structure and precisely known positions. These data will provide the basis for evaluating the long term stability of the radio reference frame and the ultimate accuracy of wide angle astrometric measurements of extragalactic radio sources using VLBI.

NASA will analyze this data to determine a high accuracy terrestrial reference frame. The data will incorporate the VLBA stations into the VLBI reference frame through the inclusion of other geodetic stations for which we have long histories. The data will also produce the most accurate Earth rotation results ever produced. We will use these data to make accurate absolute measurements of UT1.

NRAO will use these sessions to provide a service to users who require high quality positions for small numbers of sources. While the quality of these results will be high, the observing and data reduction overhead required will be minimal because such sources can be incorporated into a session of the regular geodetic observations, instead of requiring special observations.


Produced by Ludwig Combrinck 19/02/99, e-mail: ludwig@ludwig.hartrao.ac.za
since 19 February 1999.