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.