You should now have a program source dataset containing the
appropriate calibration solutions.
The antenna gain solutions have been derived
from observations of a phase
calibrator, near the program source, taken typically for 2 minutes every
fifteen minutes or so. The program source antenna gains are derived
by interpolating and extrapolating these gain solutions.
Although these can often be skipped, there are a few steps
that you might consider doing to improve the interpolation process.
The Interpolation Process