Determining Gains and Polarimetric Properties - GPCAL

Task gpcal is the main workhorse of the Miriad calibration system, although it is only particularly useful if you have measured all four polarisation products (XX, YY, XY and YX). It has a plethora of options to turn on and off various solvers. Most of these will be irrelevant to normal use - particularly when calibrating a source, such as 1934-638, which is known to be unpolarised. However it does not determine a bandpass function. So, if you have not averaged you data into a channel-0 dataset, you should precede gpcal with mfcal - gpcal will normally apply any bandpass function it finds with the dataset before it performs it real work.

Do not be intimidated by the number of options - we give you advice on which ones to use in the following chapter. We now discuss the various inputs.

Miriad manager