Analysis of the variation in inclination of Intercosmos 13 Rocket, 1975-22B

The orbit of Intercosmos 13 rocket (1975-22B) has been determined at 103 epochs between 30 April 1975 and 10 April 1980 from almost 7000 observations. One hundred and three values of inclination have been determined and corrections incoporated for the effects due to zonal harmonic, lunisolar and tesseral harmonic perturbations, precession, and solid Earth tides. The modified data have been analysed to yield values of the atmospheric rotation rate, Λ rev day −1, viz. Λ = 0.94 ± 0.10 at an average height of 322 ± 6 km and Λ = 1.27 ± 0.02 at 288 km. Analysis of the inclination near 14th-order resonance has indicated lumped harmonic values 10 9 C 1.0 1.4 = − 76.13 ± 12.47, 10 9 S 1,0 14 = − 29.89 ± 32.64, 10 9 C −1.2 14 = − 63.11 ± 15.44 10 9 S −1.2 14 = − 32.52 ± 26.96, for inclination 82.952°.