Comparison of a radio interferometric differential baseline measurement with conventional geodesy

(Accepted for publication March 24, 1978) ABSTRACT: Niell, A.E., Ong, K.M., MacDoran, P.F., Resch, G.M., Morabito, D.D., Claflin, E.S. and Dracup, J.F., 1979. Comparison of a radio interferometric differential baseline measurement with conventional geodesy. In: C.A. Whitten, R. Green and B.K. Meade (Editors), Recent Crustal Movements, 1977. Tectonophysics, 52: 49-58. The ARIES (Astronomical Radio Interferometric Earth Surveying) 9-m transportable station has been deployed at two sites selected to be intervisible. By observing on approximately 380-km baselines from ARIES to the 40-m telescope of the Owens Valley Radio Observatory, we derived the three-dimensional position of each site relative to the OVRO telescope. By differencing the components of the positions of the two sites, we obtained the vector from Malibu to Palos Verdes — a 42-km path across Santa Monica Bay in southern California — with an estimated accuracy of better than 10 cm. The National Geodetic Survey has directly measured both the intersite distance and azimuth by conventional first-order horizontal geodetic control methods. The two techniques differ by 6 + 10 cm in baseline length, and 0.5 + 1.2 arc sec in azimuth (corresponding to 10 + 20 cm).