A Radio Survey of the Galactic Plane at a Frequency of 408 Mc/s. I. The Discrete Sources

Abstract

Part of the galactic plane has been surveyed at 408 Mc/s using the 250 ft radio telescope at Jodrell Bank. The results are compared with the Sydney 85 Mc/s survey and the Leiden 1390 Mc/s survey in order to group the discrete sources of radio emisson according to their spectral index. Of fifty-one sources, thirty-six are found to have a spectral index consistent with the assumption that they radiate thermally, and fifteen, including the source at the galactic centre, have a non-thermal spectral index. Most of the sources lie within 1/4° of the new galactic plane, and are thought to be at distances of several kiloparsecs. Some of the thermal sources are a few degrees from the galactic plane, and probably less than one kiloparsec from the Sun. The continuum background emission from the galactic disk is discussed in a second paper.