Bright radio sources at 178 MHz : flux densities, optical identifications and the cosmological evolution of powerful radio galaxies.

A revised sample of bright radio sources at 178 MHz is defined in order to correct the biases introduced into the 3CR catalog by confusion and partial resolution. The sample is shown to be 96 percent complete to a flux-density limit of 10 Jy for sources smaller than 10 arcmin. The bias of the 3CR catalog against objects of larger angular size is also reduced. Optical identifications are presented for 96 percent of the sources, 71 percent with galaxies and 25 percent with quasars. The radio-galaxy population is found to show strong space-density evolution for luminosities in excess of approximately 10 exp 26.5 W/Hz-sr at 178 MHz (redshifts greater than or approximately equal to 0.2), while the evolutionary properties of galaxies and quasars of the same luminosity and redshift are very similar.