The Distribution of Cosmic Radio Background Radiation

The results of a survey of cosmic radio background radiation at 250 mc using the Ohio State University 96-helix radio telescope are described. The antenna has beam widths of about 1.2° in right ascension and 8° in declination between half-power points. Radio maps, covering about 75 per cent of the sky, are presented in celestial and galactic coordinates. The greater resolving power of the antenna has revealed a number of fine features of the background radiation as well as numerous radio stars. Radio maps made at other frequencies by various groups are summarized. To present an over-all picture of the sky at different frequencies, eight maps are shown for frequencies from 64 mc to 910 mc. All maps are modified to have the same scale, coordinates and units to facilitate intercomparison. An intercomparison of these radio maps shows some consistent features of the galactic background radiation. These features may be represented by three symmetrical distributions and several unsymmetrical or irregular distributions. The symmetrical distributions are as follows: 1) a narrow belt about 3° wide lying in the galactic plane and concentrated towards the galactic center, 2) a very broad band of radiation concentrated within about 15° to 30° of galactic latitude and having its maximum near the galactic center, and 3) an approximately isotropic distribution. The first component indicates a mixture of thermal and nonthermal origin, while the other two are nonthermal.