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.