Gordon A. Grant

Determination of Orbital Characteristics of an Earth Satellite from Single-Station Radio-Transit Observations

MERIDIAN transit radio observations have been made of the Satellite 1958α by means of a modified Minitrack Mark II interferometer located at the Sohio Research Laboratories east of Cleveland, Ohio (lat. 41° 26.3′ N., long. 81° 32′ W.). Because of the generally low altitude of the satellite at this station, the horizontal dipoles were replaced with commercial Yagi antennas, following a suggestion of G. W. Swenson, jun., of the University of Illinois. The completed system acts as a compound interferometer in that two pairs of Yagis are separated by 2.5 wavelengths from each other and 55 wave-lengths from the other two pairs. This was done to minimize lobe ambiguities. The antenna system deviates about 0.3 deg. from the true east–west base-line as determined by solar transit observations. The receiving system consists of a low-noise preamplifier, triple -conversion receiver, WWV time-marking circuit and a dual-channel recorder which was kindly loaned by the Brush Instrument Co. More than 120 transits have been observed to date. Fifty-six transits between Feb. 15 and Feb. 27 were selected for further analysis, as the multiple interferometer was in operation during that time.