Documentation on uvsub

Task: uvsub
Purpose: Subtract point source models from visibilities
Categories: uv analysis

        UVSUB reads a file containing point source models and subtracts
        them from the visibilities.  The models can be for a subset of
        the channels, but the output file will contain all the input
        channels.

Key: vis
        The name of the input uv data sets. No default.

Key: line
        Standard Linetype. This assumes only a single spectral
        window is processed.

Key: model
        A text file containing the models. Each row should contain
        four columns giving

          VELOCITY    FLUX DENSITY    X OFFSET      Y OFFSET

        The velocity must be in Km/s (radio definition), with the same
        rest standard as the data-set. The flux density is in Jy and the
        offsets in radians are from the phase centre in the convention 

             offset = point source location - phase centre

        Lines beginning with a "#" are ignored.

Key: out
       The name of the output uv data set. No default.