Galactic Radio Emission Below 16·5 MHz and the Galactic Emission Measure

Abstract

New maps of the distribution of the galactic background radio emission are given for wave frequencies of 2�1,3�7,4�7,5�5,8�3,13 and 16�5 MHz. The angular resolutions of the observations were 7.5�, 6.8�, 3 � � 10�, 4.5�, 3.0�, 1.9� and 1.5� respectively. A map of the quantity ?? in galactic coordinates is obtained from an analysis of the changes in the radio brightness distributions with frequency. For an assumed electron kinetic temperature of 104 K, the emission measure is found to vary from 3�9 cm -6 pc near the south galactic pole to 140 cm -6 pc near the equator.