FIT BEAM_SIZE

    BEAM_SIZE is a Real array of size 3 containing the user-specified values for
    the  Clean beam size, with BEAM_SIZE[1] the Major axis, BEAM_SIZE[2] the Mi-
    nor axis (both in arcsec) and BEAM_SIZE[3] the Position angle  (in  degrees,
    North towards East).

    If  BEAM_SIZE[1]  and BEAM_SIZE[2] are 0, the CLEAN or FIT commands will de-
    termine the Clean beam size (available in variable  BEAM_FITTED  similar  to
    BEAM_SIZE) by adjusting the dirty beam main peak.

    If only one of BEAM_SIZE[1] and BEAM_SIZE[2] is non zero, it will be used as
    the Clean beam size for a circular beam.

    If  both  are  non  zero,  BEAM_SIZE  totally specifies the Clean beam size.
    BEAM_FITTED is thus set to the BEAM_SIZE values when used.