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).