The effects of 15th-order resonance on the orbit of Nimbus 1 rocket, 1964-52B

Over 2000 observations from 60 stations were used with the RAE computer program PROP 6 to determine accurately the orbit of Nimbus 1 rocket, 1964-52B, at 25 epochs between March and September 1970. This six-month period covered the main variations resulting from 15th-order resonance, with exact 15th-order resonance on June 5, 1970. The 25 values of orbital inclination obtained had a mean standard deviation of 0.0008 deg, the best sd being 0.0004 deg. These values, together with 16 U.S. Navy values, were analyzed to determine lumped 15th order geopotential coefficients of odd degree, for an inclination of 98.68 deg. A simultaneous fitting of the variations in inclination and eccentricity was performed to obtain lumped values for the coefficients of even degree (16, 18, 20,...). These values will be used with those from satellites with resonant orbits at other inclinations to revise existing values for individual harmonic coefficients of 15th order.