1 UV_REF_MODEL Phase and/or amplitude reference a UV table on a nearby modeled source

        UV_REF_MODEL  does a Phase and/or Amplitude self‐calibration of a UV
    table, another observed UV table for which a correct model is known.  In
    details:

       ‐ UV_REF_MODEL self‐calibrates first  the observed visibilities of the
         modeled source  used as  reference.  The self‐calibration  is baseline
         based (i.e. it does not take into account closure relationships).
       ‐ UV_REF_MODEL   then   applies   the   gains  derived   in   previous
         self‐calibration to the visibilities of the source to be calibrated.

    It  is  STRONGLY ADVISED to self‐calibrate the phase first, then the am‐
    plitude using a longer smoothing time.  Moreover UV_REF_MODEL enables to
    subtract (part of) the input reference source, typically to provide con‐
    tinuum‐free spectral line maps.

    See also UV_REF_POINT, UV_REF_GAUSS, which does the same thing, but  us‐
    ing a point and a Gaussian source as input.

2 UV_TABLE$
        TASK\CHARACTER "UV table to be calibrated by reference" UV_TABLE$

    Input UV table to be calibrated by reference.

2 SELF$
        TASK\CHARACTER "UV table used as reference" SELF$

    UV table of the observed visibilities of the modeled source used as ref‐
    erence. In general, this is a continuum table.

2 UVMODEL$
        TASK\CHARACTER "UV Model " UVMODEL$

    UV table of the modeled visibilities of the modeled source used as  ref‐
    erence. This table must have the same format as SELF$.

2 DTIME$
        TASK\REAL"The smoothing time constant in seconds" DTIME$

    Visibilities  of the reference table will be averaged on DTIME$ time in‐
    tervals to improve signal to noise ratio before self‐calibration. Signal
    to noise MUST BE SUFFICIENT TO IMPROVE the phase or amplitude determina‐
    tions.  If DTIME$ is too short, noise will be added to the data,  rather
    than the expected improvement.  Required values are

            S/N    =  11  for 5 degree phase noise
            S/N    =  20  for 5 % amplitude correction

2 WCOL$
        TASK\INTEGER "The reference channel" WCOL$

    If  the reference UV table (SELF$) is a spectral line UV table, WCOL$ is
    the spectral channel to be used.

2 TYPE$
        TASK\CHARACTER "Type of self‐cal, Ampli, Phase, Both or None" TYPE$

    It is recommended to self‐calibrate the phase first, then the  amplitude
    using a longer smoothing time, rather than both together.  Type NONE can
    be used just to subtract a time‐smoothed continuum value from a spectral
    line table.

2 SUB$
        TASK\REAL "Fraction of the continuum source to subtract" SUB$

    Typically 1 or 0, to remove or not the continuum model.

1 ENDOFHELP































































