  We present results from the first intensive monitoring campaign of a sample
of Compact Symmetric Objects (CSOs). We observed seven CSOs at 8.5 GHz over a
period of eight months, with an average spacing between observations of 2.7
days. Our results show that, as predicted, the flux densities of the CSOs are
extremely stable; the mean RMS variability of the sample was 0.7% in flux
density. The low variability of the CSOs makes them excellent flux density
calibrators at this frequency. We recommend that at least four CSOs be included
in any VLA monitoring campaign which requires precise epoch-to-epoch
calibration, such as those to measure gravitational lens time delays. The CSO
data enable the correction of small systematic errors in the primary flux
calibration.
