Upper Limit to Radio Emission from Nova Delphini 1967

Abstract

A NOVA (Alcock's Nova) appeared in 1967 in the constellation Delphinus1 and had a maximum brightness of 4.6 magnitudes in mid-September2. An attempt to detect radio emission from the nova at a wavelength of 4.6 cm was made on September 4, 1967, when its visual magnitude was ∼ 5.0. The observations were made with the 46 m radio telescope of the Algonquin Radio Observatory, and consisted of 100 scans across the position of the source (1950.0; α = 20h 40m 04s.2, δ = 18° 58′ 51″), resulting in a total integration time on the source of approximately 25 min. The measured flux density was 0.006 ± 0.012 flux units (1 flux unit = 10−26 W m−2 Hz−1), so the upper limit may be taken as 0.02 flux units. The confusion level, less than 0.011 flux units for this measurement (see preceding communication), was not large enough to affect seriously this upper limit.