FIT

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

    Fit the dirty beam to obtain the clean beam parameters.

    For single fields, "FIT Plane" can be used to fit just one of  the  possible
    Frequency  dependent  beam planes. Note that the number of beam plane can be
    different from that of image channels.

    For mosaics, dirty beams can be up to 4-D, depending on Frequency and  Field
    number.   Keywords  CHANNEL  (or  equivalently PLANE) and FIELD allow to re-
    strict the fit to the specified range of  Channels  or  Field  numbers.  All
    ranges are considered

    Note that an automatic FIT is performed by all CLEAN algorithms when needed.
    The appropriate Frequency plane corresponding to each image channel is used.
    For  mosaics,  CLEAN  takes the average of the fitted beam parameters on all
    fields.

    User specified values can be used instead (see HELP FIT FixedValues).