FIT /JVM_FACTOR

        [CLEAN\]FIT [Plane] | [CHANNEL First Last] [FIELD First Last]
      [/THRESHOLD Value] /JVM_FACTOR [NoCircle]

    This  option  instructs the FIT command to estimate the so-called JvM factor
    (from Jorsater  van Moorsel 1995), which is the ratio of Clean beam area  to
    Dirty beam area.  The value is returned into the BEAM_JVM variable.

    The  Dirty  beam  area is an ill-defined quantity (if no Zero spacing is in-
    cluded, the Dirty beam area tends toward Zero when a sufficiently large area
    is included). It is defined here by integrating only up to the first null of
    the Dirty beam.

    In case of Dirty beams presenting shoulders around the main beam, this ratio
    may be used to adjust the contribution of residuals to the  CLEAN  image  so
    that  the  flux  is  better preserved.  For well-behaved beams, it should be
    quite close to 1.

    NoCircle is an argument which, if present,  indicates  that  the  Clean  and
    Dirty  beam  should not be circularized to derive the factor; this should be
    reserved for debugging.