The Radio Spectrum of the Andromeda Nebula

Some new observations of the Andromeda nebula have been made at frequencies of 38 and 178 Mc/s. At 178 Mc/s both fan-beam and interferometric measurements have allowed a number of point sources superimposed on the nebula to be distinguished; a comparison of the number of these sources with those found in neighbouring areas of sky suggests that they are not related to the nebula. By comparing the observations at 38 and 178 Mc/s with those previously made at Jodrell Bank at 408 Mc/s, it has been possible to show that all parts of the nebula have a similar spectrum, the brightness temperature varying at ν−2.5±0.1 a figure close to that for the Galaxy.