Large 22-MHz array for radio astronomy

The relative merits of T- and cross-type radio telescopes are discussed. A large array used for radio astronomical studies at a frequency of 22.25 MHz ( m) is described. It is built in the form of a T with dimensions east-west and north-south. The 624 full-wave dipoles are mounted above a 65 000 m²reflecting screen. The instrument has a pencil-beam response of degrees at the zenith. A timesharing technique is used to provide simultaneous observations of 5 adjacent declinations spaced at quarter-beamwidth intervals. Observations, commenced in 1965, should provide flux density measures for 400-500 radio sources down to a limiting flux density of about W .m^-2Hz^-1. A map of the galactic background radiation from declination +90 to -20 degrees is being prepared.