XIII. Extra-galactic radio-frequency radiation

Abstract

It has been shown previously that radio-frequency radiation is being received on the earth from the extra-galactic nebula N.G.C. 224 (M. 31). This paper reports some initial attempts to extend the measurements of extra-galactic radio radiation on a wavelength of 1·89 m. A radio survey has been made of three bright nebulae (in addition to N.G.C. 224) and three radio sources have been associated with them. The radio intensity to be expected from eight of the major clusters of nebulae has been calculated and two of the clusters have been surveyed and identified with radio sources. For a selected region of sky an attempt has been made to predict the irregularities in the radio isophotes corresponding to large scale irregularities in the distribution of extra-galactic nebulae. These predictions have been compared with radio observations of the region, and it is shown that there is a correlation between the radio isophotes and the distribution of extra-galactic nebulae. A preliminary examination has been made of the relation between the apparent photographic magnitude and the apparent radio magnitude of nebulae. The results suggest that there is a definite relationship and that the apparent photographic magnitude increases more rapidly than the apparent radio magnitude.