Basic Information 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.  Each model applies either to a
        single spectral channel, or to all channels (continuum mode).
        The output file contains all of the input channels whether
        modified or not.
 

Key: vis
        The name of the input visibility data sets (no default).

Key: line
        Standard Linetype: 'channel' (default) and 'velocity' are
        recognized.  Do 'help line' for more information.  uvsub assumes
        that only a single spectral window is processed.

Key: model
        The name of a text file containing the models (no default).
        Each row must contain four columns which depend on the line type
        specified.  For line = 'channel':
 
          CHAN No.    FLUX DENSITY    X OFFSET      Y OFFSET
 
        A channel number of zero is recognized as applying to all
        channels (i.e. continuum).  Otherwise, it is an error for the
        channel number to lie outside the range in the data.
 
        The flux density is in Jy and the offsets, true angular
        distances in radians, are measured from the phase centre in the
        sense
 
          offset = point source location - phase centre
 
        For line = 'velocity', the channel number is replaced by
        velocity:
 
          VELOCITY    FLUX DENSITY    X OFFSET      Y OFFSET
 
        The velocity must be in km/s, radio definition, i.e.
 
          v = c (f0 - f) / f0,
 
        with the same rest standard as the data-set.  The model
        visibility will be subtracted from the channel closest to this
        velocity.  Note that a rest frequency (f0) must be set in the
        input visibility dataset in order to convert between velocity
        and channel number (i.e. frequency).
 
        Lines beginning with "#" are ignored.

Key: out
        The name of the output visibility data set (no default).
 
Revision: 1.8, 2018/12/04 06:36:14 UTC