COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1019

                                  Konkoly Observatory
                                  Budapest
                                  1975 July 8



      PHOTOELECTRIC TIMES OF MINIMA OF RZ CAS


Photoelectric observations of RZ Cassiopeiae were made in 1973 and
1974 with the 16-inch Boller and Chivens f/18 Cassegrain telescope
operated by the University of Montana's Department of Physics and
Astronomy on the 6500-foot peak of Blue Mountain near Missoula, 
Montana. The telescope is equipped with a Johnson-type single-channel
photometer containing an EMI 6256B photomultiplier behind a Corning
3384 V-band filter. The photomultiplier signal is fed through a DC
amplifier to a voltage-to-frequency converter, whose output is 
integrated by an electronic counter for ten seconds.
The stars SAO 12386 and HR 791 were used as the comparison and check
stars, respectively. Each observation consisted of three ten-second
integrations. Observations were made at the rate of about one per
minute in the vicinity of minimum light. The heliocentric times of
the observed minima determined by the chord bisection method are given
in the table, along with the epoch numbers E, the O-C values computed
from the GCVS (1969) ephemeris, and the duration of constant light
(to +-0.003m) during minimum light.


-----------------------------------------------------------------------------
Hel. JD of Minimum             E        O-C        Duration of constant light
-----------------------------------------------------------------------------
 2,441,954.8561               4025     -0.0025d           7 minutes
 2,442,339.7265               4347     -0.0017            8 minutes
-----------------------------------------------------------------------------


Further observations of this system are planned in conjunction with
a dynamical analysis of the O-C curve. A preliminary analysis supports
the hypothesis that RZ Cas has two dark companions with orbital 
revolution periods of about 23 years and 705 years (1975).




                T.E. MARGRAVE, M.A. LUKES,
                J.H. DOOLITTLE, R.S. EVENSKAAS,
                J.W. MacDONALD, and N.D. MURRAY

                    Blue Mountain Observatory
                    University of Montana
                    Missoula, Montana 59801



References

Kukarkin, B.V. et al., General Cataloue of Variable Stars, Vol. 1, 1969.
Margrave, T.E., Doolittle, J.H., and Evenskaas, R.S.,Proceedings of the
      Montana Academy of Sciences, 1975 (in press).