NED object is 3C 231; Reference is 1974MNRAS.168..491H

   Fig.1. The contours of brightness temperature in M82 at 5 GHz. The contour
 interval is 141 K and the first contour represents a temperature of 42 K. The
 solid region, A, reaches a level of 23 contours. The half-power beam width is
 indicated by the shaded ellipse.