Geodetic Surveying with Quasar Radio Interferometry

Abstract

Geodetic Surveying with. Quasar Radio Interferometry A. STOLZ et alFrom 20 April to 3 May, 1982, five Australian radio-telescopes were linked for the first time and operated in synchronism to form a single radio-telescope. The link-up was the culmination of two years ofintensive effort and co-operation to co-ordinate telescope modifications and overcome the logistic problems ofun~ertakillg such an experiment. The five telescopes are sited at the NASA Deep Sydney, and the LANDSAT tracking station at Alice Springs. The simultaneous but independent operation of two or more widely separated telescopes is called Long-Baseline Interferometry. This experiment was set up to provide high-resolution radio maps of distant Southern Hemisphere quasars and galaxies. However, the experiment is of great interest to surveyors, since it also provides a means of making accurate position difference and distance measurements. It is expected, for instance, that the distance between the telescopes at Parkes and Tidbinbilla will be measured to an accuracy of 10 cm while the distances from the Tidbinbilla telescope to those at Hobart and Alice Springs will be determined to an accuracy of 1 to 2 metres. The experiment is described in this paper.The basic principles of the VLBI technique are also reviewed in general terms.