BRITDOC: 1982 DOPPLER CAMPAIGN RESULTS

Abstract

BRITDOC, the British Radio Interferometric, Terrestrial and Doppler Observation Campaign, was conceived in March 1981 by a group of radio astronomers from Jodrell Bank and geodesists from Nottingham University, working in cooperation with the Ordnance Survey. The main aim was to establish a terrestrial geodetic network connecting the major radio telescope sites in Great Britain, capable of CERI (Connected Element Radio Interferometry) or VLBI (Very Long Baseline Interferometry), and the new SLR (Satellite Laser Ranging) facility at the Royal Greenwich Observatory. It was proposed to carry out simultaneous satellite-Doppler and radio interferometry observations, followed by a combined rigorous adjustment and a full statistical error analysis of the space derived and terrestrial measurements, in order to obtain an indication of the relative observational accuracies of the various techniques involved. In the long term, it was projected that this (potentially) very accurate network would be used to test and calibrate existing and new space oriented geodetic observation systems (e.g. NAVSTAR GPS), and to develop techniques for the monitoring of local crustal movements by geodetic measurements. In the first instance (Phase 1), the BRITDOC network would be based on five of the MERLIN array of radio telescopes at Jodrell Bank, the geodetic measurements connecting these to OSSN 80 (the Ordnance Survey Scientific Network 1980), and simultaneous CERI and satellite-Doppler observations. Later on, it is projected to incorporate inertial survey data, and to extend the network as far. as the Cambridge array of radio telescopes, the SLR at RGO, and eventually across the Channel to similar installations in Western Europe. The satellite-Doppler observations and the CERI measurements in Phase 1 of BRITDOC were carried out during February and March of 1982, and the terrestrial observations followed during the summer of 1982. The latter are still being pre-processed at the Ordnance Survey in readiness for the simultaneous adjustment with the CERI and Doppler derived data. This paper deals exclusively with the satellite-Doppler observations carried out during Phase 1 of BRITDOC. The planning and execution of the field campaign is discussed in §2, and details of data processing are given in §3. This is followed by the results and their interpretation in §4, and the paper is concluded in §5.