Abstract: | The orbit of Cosmos 268 rocket (1969-20B) has been determined at 28 epochs during its 342-day life, with the aid of the PROP5 orbit refinement program. All available observations were used, including 16 from the Hewitt camera at Malvern, 28 from the 200-mm camera at Meudon, 56 from the kinetheodolite at the Cape Observatory, 700 visual observations from volunteer observers, 500 US Navy observations and 200 British radar observations. The orbits are of very good accuracy for such a high-drag satellite, most of the values of inclination having standard deviations less than 0.002°. The most accurate orbits are those utilizing photographic observations, and the best of these has standard deviations of 0.00001 in eccentricity and 0.0001° in inclination. The values of inclination obtained, after correction to allow for the effects of other perturbing forces, have been analysed to determine zonal wind speeds in the upper atmosphere at heights a little above perigee (230–250 km) averaged over latitudes up to about 25°. The results show a clear distinction between the wind at night (21 to 03 hr local time), which is west-to-east with an average speed of 140 ± 50 m/sec, and the wind by day (08 to 17 hr), which is east-to-west with an average speed of 110 ± 50 m/sec. |