COMMISSION 27 OF THE I.A.U.
                   INFORMATION BULLETIN ON VARIABLE STARS
                               Number 2913

                                                         Konkoly Observatory
                                                         Budapest
                                                         8 July 1986

                                                         HU ISSN 0374 - 0676


                      UBV PHOTOMETRY OF HR 8752. II

HR 8752 (=HD 217476=V509 Cas) is a highly luminous G-type hypergiant.
Recent photoelectric photometry was done by Halbedel (1985, 1986) and
Zsoldos and Olah (1985).
   This paper presents observations made between December 1984 and
January 1986 with the 50-cm and 1-m telescopes of Konkoly Observatory in
Piszkéstetô. The comparison star was HR 8761 (V=6.20, B-V=1.50 and U-B=1.53).
It did not show any variation during the last three years (Halbedel, 1986).
Reductions and transformations into the UBV system were made by the usual
way. The observations are listed in Table I.


                Table I

     J.D.        V       B-V      U-B

2446038.355    4.885    1.295    0.985
   6039.276    4.882    1.292
   6181.590    4.983    1.340
   6182.560    4.990    1.360    1.012
   6196.577    4.947    1.395
   6198.553    4.968    1.383    1.049
   6228.536    4.947    1.354    1.094
   6276.554    4.843    1.271    1.081
   6281.392    4.840    1.252    1.042
       .548    4.836    1.251    1.030
   6283.468    4.826    1.241    0.975
   6299.397    4.801    1.197
   6300.438    4.793    1.202    0.942
   6301.485    4.795    1.213    1.011
   6302.467    4.792    1.204    0.985
   6303.471    4.791    1.205    1.020
   6311.527    4.772    1.200    0.981
   6315.427    4.785    1.191
   6318.478    4.777    1.199
   6319.395    4.776    1.200
   6327.444    4.738    1.184
   6364.418    4.804    1.235    1.046
   6452.253    4.956    1.322    1.115


                          [FIGURE 1]

   Figure 1: Light and colour curves of HR 8752 in 1984-85. Symbols:
             plus signs - Halbedel (1985), crosses - Halbedel (1986),
             dots - Zsoldos and Olah (1985), circles - present paper.


   Figure 1 shows the light and colour curves since 1984 (for the light
curve between 1979 and 1985 see Zsoldos and Olah (1985)). Period analysis by
neither the Lafler-Kinman nor the Deeming method yielded any period, though
a characteristic timescale of about 1 year is present. The cycle length
seems to become shorter, this, however, is not certain because of the small
number of observed cycles.
   HR 8752 shows alternating brighter and fainter maxima (see Figure 1
here and that in Zsoldos and Olah (1985)). This may be the result of the
interaction of pulsation and mass loss in the star (Zsoldos, 1986). Further
photometric and spectroscopic observations are needed to have a better
understanding of the behaviour of HR 8752.
   I wish to thank Dr. K. Olah, Mr. A. Mizser and Mr. I. Toth for
obtaining some of the observations presented here.


                            E. ZSOLDOS
                        Konkoly Observatory
                      Budapest XII., P.O. Box 67
                         H - 1525, Hungary



References:

Halbedel, E., 1985, I.B.V.S. No. 2718.
Halbedel, E., 1986, I.B.V.S. No. 2876.
Zsoldos, E., 1986, in preparation. [BIBCODE 1987IAUS..122..465Z ]
Zsoldos, E., Olah, K., 1985, I.B.V.S. No. 2715.