This document describes a method for computing the antenna dependent amplitude and phase from the visibility data for a point source. The method can be extended to include data from extended sources for which a good source model is known.
Interpretation of the antenna dependent quantities in terms of the antenna and system temperatures is also explained. Using the antenna dependent quantities from a database with good signal-to-noise ratio, the effective system temperature valid for interferometry data can be monitored.
The equations given here are exact and are implemented in the programs antsol1 and rantsol2, which operates on the GMRT visibility database written in the native LTA format.