BEAM_PATCH

    The  dirty  beam  patch  to  be  used  for the minor cycles in CLARK and MRC
    method.  It should be large enough to avoid doing too many major cycles, but
    has practically no influence on the result.  This size should  be  specified
    in  pixel  units.  Reasonable values are between N/8 and N/4, where N is the
    number of map pixels in the same dimension.  If set to N,  the  CLARK  algo-
    rithm becomes identical to the HOGBOM algorithm.