Geopotential harmonics of order 15 and 30, from analysis of the orbit of satellite 1971-10B

The Cosmos satellite 1971-10B passed through exact 15th-order resonance on March 30, 1981, and orbital parameters were determined at 52 epochs from 3500 observations using the orbit refinement program PROP, between 1980 September and 1981 October. The variations in inclination and eccentricity during this time were analyzed, and 6 lumped 15th-order harmonic coefficients and two 30th-order coefficients were evaluated. The 15th-order coefficients are the best yet obtained for an orbital inclination near 65 deg; previously there were no 30th-order coefficients available at this inclination. The lumped coefficients were used to test the Goddard Earth Model GEM 10B; there is good agreement for 7 of the 8 coefficients.