The Spectrum of the Galactic Radio Emission: I. Observations of Low Resolving Power

Abstract

A new series of observations made at wavelengths of 0.75 m, 17 m, 7.9 m and 11.4 m has been used to determine the spectrum of the general galactic radio emission; in these observations no attempt was made to investigate the emission which is concentrated to within a few degrees of the galactic plane. The measurements at the larger wavelengths were made with scaled aerials of similar radiation patterns but at 0.75 m, where the effect of an uncertainty in the ground radiation is more important, an instrument of higher resolving power was employed. At each wavelength the sky brightness was established by reference to a resistance heated to different temperatures. Spectra have been determined separately for the emission from the galactic halo and for the general emission from the galactic disk in the direction of the anti-centre. There are small, but possibly significant, differences between the two spectra. In each case the spectrum has a marked curvature—the temperature spectral index β in the relationship T ∝ λ ^β is smaller at the longer wave-lengths. The observations have also allowed a new determination of the intensity of the integrated extra-galactic radiation to be made.