star        raw         B           V            R
-----------------------------------------------------------
    A

    B

    C

   CY     
------------------------------------------------------------




 difference    raw         B           V            R
------------------------------------------------------------
  (B-A)

  (C-A)
-------------------------------------------------------------




    The "best" passband is  ______________


    The shift between raw and standard magnitudes
    in this "best" passband is  

 
        ________________________________



    Applying this shift to the raw magnitude
    of CY Aqr yields a magnitude of

         mag  ___________  in the _______  passband