Observations of the Radio Source PKS 0123?01 at 5000, 408, and 80 MHz

Abstract

Observations of PKS 0123?01 (3C 40) have been made at 5000, 408, and 80 MHz with telescopes of comparable beamwidth. The value of the spectral index for the frequency intervals 5000?408 and 408?80 MHz has been calculated for a grid of points covering the source spaced at approximately half-beamwidth intervals. For both frequency intervals the spectrum of emission is found to be significantly steeper for the regions of the source furthest from the associated galaxies NGC 545?547 than for the regions nearest the galaxies. Some implications of this result are discussed. The age and energy requirements of the source have also been estimated.