SIMBAD references

A generally accepted hypothesis is that much of the variability (e.g. outbursts) observed in the compact radio sources can be explained as due to propagation of shocks in relativistic jets. In order to compare the predictions of the shock models with observations, we define the maximum amplitude of outbursts at 8.0, 14.5, 22, 37 GHz. Also the time delays between frequencies are calculated. In the analysis we use both data from University of Michigan monitoring program and our own Metsaehovi data. In some cases also our 90 GHz data from the SEST telescope has been used. Our results fit together well with general ideas of shock models, but the specific models need some modifications.