New extragalactic variable sources from an 8-GHz survey

Abstract

STUDIES of variable extragalactic radio sources have concentrated on sources with ‘centimetre-excess’ spectra, so that few sources without such spectra have been extensively monitored. We have used the NRAO 300-foot transit telescope at 2.7 GHz to make repeated, accurate observations of 48 sources selected by the Michigan 8-GHz survey1 without further bias towards any radio spectral type. Variability has been detected in two radio galaxies without centimetre excesses and every quasistellar source in the survey has now been observed to vary at some frequency.