UV_STAT Casa

        CASA  and  GILDAS  handle  the weighting scheme slightly differently and
    with different conventions for the Robust parameter values.

    CASA uses only Briggs weighting, while IMAGER offers  the  Briggs  weighting
    scheme  (obtained  for  MAP_ROBUST  <  0) and a different, more progressive,
    weighting (obtained for MAP_ROBUST > 0).

    For MAP_ROBUST < 0, the corresponding CASA Briggs value can be  obtained  by
    adding 2.

    In  addition,  CASA  apparently  uses a default value for the size of the UV
    cell in Briggs weighting which is about the dish diameter(*).  If MAP_UVCELL
    is 0, IMAGER will use the same default value.  Otherwise,  IMAGER  will  use
    the specified user input.

    (*)  The  default value quoted before is valid for a single field.  However,
    the documentation is unclear in this respect and suggests that the  UV  cell
    size  depends  on the imaged field size. This would be strange, though. What
    happens for mosaics is even less clear.