On the variability of some Parkes radio sources.

A statistical analysis of the variability of 68 pointing radio sources at 2700 and 5000 MHz is presented. All of the sources in the analysis were originally observed over a period of at least a few years. A criterion for defining variability was developed on the basis of the standard error in individual flux measurements. On the basis of the variability criterion, it is shown that: (1) 12 sources (20 percent of the total) were not variable; (2) six sources (10 percent of the total) were less variable at 5000 MHz than at 2700 MHz; and (3) about one-third of the sources had the same variability as the radio sources identified at 2695 and 8085 MHz in the variability analysis of Altschuler and Wardle (1976). No evidence was found to indicate a correlation between the variability values and the redshift z. A complete list of the sources used in the analysis is provided.