COMMISSION 27 OF THE I. A. U.
             INFORMATION BULLETIN ON VARIABLE STARS
                          Number 3640

                                                 Konkoly Observatory
                                                 Budapest
                                                 17 July 1991

                                                 HU ISSN 0374 - 0676


     OBSERVATIONS OF THE SUSPECTED VARIABLE STAR TAU CASSIOPEIAE


This paper represents a continuation of previous photoelectric observations of
the suspected variable star tau Cassiopeiae (Leiker et al., 1989,1988). Tau
Cassiopeiae (tau Cas, HR 9008, HD 223165, SAO 35763, K1 III, V = 4.87 m) was
observed by Leiker, Hoff, and Caruso at the Oak Ridge Observatory in Harvard,
MA from September 1990 through February 1991. A 0.4 meter Cassegrain telescope
and a STARLIGHT-1 photon counting photometer with standard B and V filters was
used. This is the same photometer that was used in our previous work.

Tau Cas is listed in the New Catalogue of Suspected Variable Stars as a
possible variable star (Kholopov et al, 1982). Previous observations of tau Cas
made at University of Northern Iowa indicate that it may be a variable star
(Leiker and Hoff, 1988, 1989). HR 9010 (HD 223173, SAO 35761, K3 II, V = 5.51 m,
B-V =1.65) was used as the comparison star. The delta magnitudes were obtained
in the sense of tau Cas - HR 9010 and are not corrected for color or
extinction. Table I lists the mean delta magnitudes obtained for tau Cas. 
Each mean and standard deviation was calculated from three delta magnitudes.
Standard deviation was calculated in the usual manner. See also Figures 1 and
2.

Table I. Tau Cas delta V and delta B magnitudes obtained by Leiker, Hoff, and
Caruso

HJD          Delta Vm  sigma       HJD    Delta Bm  sigma

2448108.8    -0.659   0.017   2448108.8    -1.149   0.024
2448116.6    -0.663   0.022
2448130.6    -0.683   0.002   2448130.6    -1.191   0.007
2448131.7    -0.745   0.047   2448131.8    -1.203   0.010
2448153.59   -0.690   0.016   2448153.6    -1.195   0.002
2448155.56   -0.687   0.002   2448155.58   -1.182   0.017
2448162.58   -0.695   0.014
                              2448169.76   -1.184   0.011
2448180.72   -0.674   0.016   2448180.76   -1.201   0.014
2448189.54   -0.679   0.005   2448189.52   -1.204   0.008
2448192.64   -0.676   0.003   2448192.63   -1.180   0.025
2448196.55   -0.682   0.004   2448196.56   -1.186   0.001
2448204.69   -0.683   0.004   2448204.68   -1.189   0.002
2448285.52   -0.681   0.015   2448285.53   -1.182   0.026
2448289.54   -0.703   0.007

The authors wish to acknowledge the Smithsonian Astrophysical Observatory and
Dr. Robert P. Stefanik for the use of the 0.4-M telescope at the Oak Ridge
Observatory, Harvard, MA. They would also like to thank Dr. Thomas A. Hockey
and the University of Northern Iowa for the use of a photoelectric photometer.

                              [FIGURE 1]

 Figure 1. Delta V magnitudes of tau Cas obtained by Leiker, Hoff, and Caruso

                              [FIGURE 2]

 Figure 2. Delta B magnitudes of tau Cas obtained by Leiker, Hoff, and Caruso



                         P. STEVEN LEIKER
                         DARREL B. HOFF
                         Harvard-Smithsonian
                         Center for Astrophysics
                         60 Garden St.
                         Cambridge, MA 02138
                         USA

                         JOSEPH R. CARUSO
                         Oak Ridge Observatory
                         Harvard, MA 01451
                         USA

References:

Kholopov, P. N., et al.: 1982. New catalogue of suspected variable stars.
        Moscow: Publishing Office (Nauka). [BIBCODE 1982ncss.book.....K ]
Leiker, P. S., & Hoff, D. B., & Tuttle, M. M.: 1989, IBVS No. 3341.
Leiker, P. S., & Hoff, D. B.: 1988, IBVS No. 3176.