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.