Worldwide geometric satellite triangulation

By applying the method of geometric satellite triangulation the three-dimensional positions of 45 stations distributed around the world were determined with an average positional mean error of ±4.5 m. Error theoretical investigations indicate that the result, derived in principle by interpolation into the astronomical right ascension-declination system, is essentially free of significant systematic errors. A comparison of this result of the geometric method with the corresponding result obtained by dynamic satellite geodesy from Doppler data, as computed by the Defense Mapping Agency (DMA) and the Navy, shows excellent overall agreement, with significant discrepancies in a few places on the globe. A combination solution that fully respects the covariance of the photogrammetrically derived directions leads to mass-centered station positions with an average positional mean error of ±3.7 m. The scale of the system, determined by several scalars measured on the earth's surface, suggests an equatorial radius for a best-fitting ellipsoid of 6,378,130 m.