10.8-GHz flux density variations among a complete sample of sources from the NRAO-Bonn 84 survey

The authors have measured the 10.8-GHz flux densities of 285 radio sources at 14 epochs between January 1979 and November 1982. For the subset of 258 objects constituting a complex flux-density-limited sample selected at 5 GHz, it is found that at least 45% vary within ten years. About nine-tenths of the steep spectrum (α ≤ -0.5) sources do not vary, whereas about two-thirds of the flat spectrum sources do. Quasars are much more likely to vary than either galaxies or empty field sources. Most objects from the S4 catalog identified with empty fields are galaxies beyond the plate limit.