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 Minor 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
determine 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.
Gildas manager
2023-06-01