This paper gives an account of the radar observations of the Russian earth satellites I and II and of the carrier rocket of satellite I, which have been made with the 250 ft. radio telescope at the Jodrell Bank Experimental Station. When the first satellite was launched on 4 October 1957, the radio telescope was still in an incomplete state. The instrument had already been tested in early August on the reception of the extragalactic radio emissions, but had never been used as a radar instrument. Emergency arrangements were made to connect it with the existing radar installations working in other parts of the establishment. By the night of 9 October the equipment was available for testing and with the telescope in automatic motion on the moon satisfactory lunar echoes were obtained. The first radar contacts with the rocket and satellite were obtained during the evening of 11 October. The present paper is confined to a discussion of the results up to the date of burn-up of the carrier rocket of satellite I on 1 December 1957 2. Equipment The essential features of the radio telescope have been described by Lovell (1956, 1957
a
). On the frequencies used in the present work (36 and 120 Mc/s) the calculated beam widths and power gains are 8° to half power and 600 on 36 Mc/s, and 2.5° to half power and 6500 on 120 Mc/s. These values have not yet been established by experiment, but the equivalent measured values on frequencies of 160 and 408 Mc/s are very close to the calculated figures. Hence, it is unlikely that the values quoted for 36 and 120 Mc/s are in error. On each frequency the primary feed was a dipole with reflector, mounted at the focal point so that there was cross-polarization between the two feeds.
Radar observations of the moon at 10-cm wavelength