Utilization of satellite‐satellite tracking data for determination of the geocentric gravitational constant GM

Range rate tracking of Geos 3 through the ATS 6 satellite has been used, along with ground tracking of Geos 3, to estimate the geocentric gravitational constant. Using multiple half‐day arcs, a GM of 398,600.36±0.12 km3/s2 was estimated using the GEM 10 gravity model, based on a speed of light of 299,792.458 km/s. Tracking station coordinates were simultaneously adjusted, leaving geopotential model error as the dominant error source. Base lines between the adjusted NASA laser sites show better than 15‐cm agreement with multiple short arc Geos 3 solutions.