COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1935

                                  Konkoly Observatory
                                  Budapest
                                  1981 March 11

                                  HU ISSN 0374-0676



       PHOTOELECTRIC PHOTOMETRY OF BF PAVONIS *


    BF Pavonis has been discovered by Shapley et al.
(1939). They classified it as W UMa type eclipsing binary
and gave a preliminary period of 0.170d. Such a short period
has not been confirmed for a W UMa star so far. Therefore
it has been checked photoelectrically with the two channel
photometer at the 1m ESO telescope (La Silla/Chile) in B and
V in July 1980. Comparison star has been CD-59d6951.
    It turned out that the period has to be changed to
0.3056d. With this period and by using the minimum time
       JD hel. 2444438.7611
the light curves in Figs. 1 and 2 have been plotted. They do
not show larger irregularities. It is not quite clear if the
minimum at phase 0.0 is in fact the deeper one, for the other
minimum is not completely covered by observations and there
may be minor systematic errors at its branches because of
inferior weather conditions.
    A determination of preliminary orbital elements has
been attempted. The atlas of theoretical light curves by
Anderson and Shu (1979) yields a mass ratio q approx. 0.8 and an

* Based on observations made at the European Southern Observatory 
(La Silla/Chile).

                       [FIGURE 1]

          Fig. 1   B observations of BF Pav


                       [FIGURE 2]

          Fig. 2   V observations of BF Pav


inclination i>80d. This would indicate a ratio of the radii
k~0.9. The Russell-Merrill method has been applied to the
well observed minimum at phase 0.0. It has been checked if
that minimum is a transit or an occultation. The former
possibility is in better accordance with the shape relations
but it yields a ratio of the radii k of only 0.70 (i=88d);
the latter has its best fit at k=0.82. Unless the observations 
are repeated, it can only be concluded that the ratios
of the masses and the radii are not far from unity which is
demonstrated by the unusually large amplitude of 0.9m.




                       M. HOFFMANN

                   Observatorium Hoher List
                   5568 Daun / Eifel, BRD


References:
Anderson, L., and Shu, F. H., 1979, Astrophys. J. Suppl. Ser.
          40, 667 [BIBCODE 1979ApJS...40..667A ]
Shapley, H., Boyce, E. H., and Boyd, C. D., 1939, Harvard
          Ann. 90, No. 9 [BIBCODE 1940AnHar..90..239S ]