FEATHER_RANGE

          Real FEATHER_RANGE[2]

      FEATHER_RANGE[2]  defines a region of "overlapping" UV spacings over which
    the ratio of LOWres and HIGHres visibilities can be  checked.  If  the  flux
    scale  is  correct,  this  ratio  should  be  1.   FEATHER_RANGE defaults to
    FEATHER_RADIUS/1.15 and FEATHER_RADIUS*1.15.

      The computed ratio is only a guide, and not  used  in  the  algorithm.   A
    proper definition of FEATHER_RANGE requires knowledge of the initial UV cov-
    erage  of  the  HIGHres and LOWres data sets. If FEATHER_RANGE is too large,
    the computed ratio has no real meaning.