The Galactic background radiation from 0.2 to 13.8 MHz

Abstract

The radio frequency receivers of the WAVES instrument on the WIND spacecraft are used to determine the direction of maximum intensity of the Galactic noise background in the frequency range 0.2 to 13.8 MHz. The observations are made with dipole antennas spinning in the ecliptic plane, hence provide information on the large scale distribution of intensity. The main results are: (1) the direction of maximum brightness at the higher frequencies is close to that of the Galactic center, (2) in an intermediate range around 3-4 MHz the brightness appears isotropic, and (3) at frequencies of 3 MHz and lower the maximum brightness is at the ecliptic longitude nearest the Galactic poles. On the basis of previous observations these results are not unexpected, but this is the first time that a precise spectrum has been made over this large frequency range.