The Radio Brightness Distributions over Four Discrete Sources of Cosmic Noise

Brightness distributions have been obtained across the four radio sources, Cygnus?A, Taurus?A, Virgo?A, and Centaurus-A, using a two-aerial interferometer of a special type in which the aerial spacing and the azimuth angle of the axis may be varied over a wide range. Radio isophotes have been constructed for three of the sources from these results, making some simple assumptions as to their form. The isophotes bear some relation to optical features of the nebulae with which the sources have been identified and their radio and optical sizes are similar. The remaining source, Cygnus?A, is unfavourably situated for observations from Sydney, and the results are less complete.