The relation of the European datum to a geocentric reference system

Over 31,000 precision reduced optical observations of GEOS-I and II in 70 two-day orbital arcs have been used at Goddard Space Flight Center (GSFC) in a dynamical solution to determine center-of-mass coordinates for 15 tracking stations on the European Datum. Comparisons with the results obtained at Centre National d’Etudes Spatiales (CNES) give agreement of about 1.5 ppm for chord lengths. After considering a scale correction to the European Datum (ED) of 1950 to account for the absence of geoid heights at the time of its reduction, agreement to a few ppm between the CNES/GSFC and the ED chords is obtained. However, a small systematic difference between survey and satellite results remains for stations in south-eastern France and Switzerland. Presented at the International Union of Geodesy and Geophysics Meeting in Moscow, U.S.S.R., August 1971.