COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 3291

                                                         Konkoly Observatory
                                                         Budapest
                                                         16 February 1989

                                                         HU ISSN 0374 - 0676


          TIMES OF MINIMA AND THE LIGHT CURVE OF VW CEPHEI

We made differential B and V photoelectric observations of the W UMa type
eclipsing binary system VW Cephei during six nights (from 24 July to 7 August
1988) at the Baja Observatory with the 40 cm Cassegrain telescope. The
comparison star was BD +75d765. Times of minima and the full light curve was
determined.
   The times of minima were calculated by a least squares parabolic fitting
program. The following ephemeris was used (Kreiner and Winiarski, 1981):

     Min I (Hel.J.D.) = 2444157.4131 + 0.27831460d E

   The moments of minima are listed in Table I.
   The full light curves in B and V bands are shown in Figure 1. It can be
seen that the scatter of the measured points near the maximum after the primary 
minimum is larger than near the other maximum or any minima. This fact
indicates that the light curve is strongly asymmetric in contradiction with
Glownia's (1988) note.


Table I. Times of minima of VW Cephei


Hel.JD -2400000  type   filter

7367.4545          I      V
7367.4543          I      B
7368.4292         II      V
7368.4287         II      B
7368.5664          I      V
7368.5649          I      B
7374.4117          I      V
7374.4122          I      B
7374.5510         II      V
7374.5516         II      B
7375.3878         II      V
7375.3877         II      B
7379.5610         II      V
7379.5610         II      B
7380.3960         II      V
7380.3960         II      B
7380.5340          I      V
7380.5338          I      B


                             [FIGURE 1]

              Figure 1. The light curves of VW Cephei

   The light curves obtained in different nights show that the heights of
the maxima are different (Delta h~0.05 mag) and this difference was varying during
our observational period (see also Kreiner and Winiarski, 1981; Kotarska and
Glownia, 1983). This behaviour may be explained by the starspot model described
by Yamasaki (1982) or Bradstreet and Guinan (1988). The large scatter near
the mentioned maximum may be caused by the large surface activity of the
components.
   The list of the individual observations can be requested from the author.
The author wishes to express his thanks to T. Hegedus for his help and advice
in the measurements and the data reduction.


                 J. VINKO

             JATE University
           Department of Physics
             Szeged, Dom ter 9.
              H-6720, Hungary



References:

Bradstreet, D.H., Guinan, E.F. 1988, In: "A Decade of UV Astronomy with IUE",
   ESA SP-281, vol. 1, 303. [BIBCODE 1988ESASP.281a.303B ]
Glownia, Z. 1988, Inf. Bull. Var. Stars, No. 3258.
Kotarska, I., Glownia, Z. 1983, Astron. Nachr., 304, No. 4, 181. [BIBCODE 1983AN....304..181K ]
Kreiner, J.M. Winiarski M. 1981, Acta Astr. 31, No. 3, 351. [BIBCODE 1981AcA....31..351K ]
Yamasaki, A. 1982, In. Binary and Multiple Stars as Tracers of Stellar
   Evolution", eds. Z. Kopal and J. Rahe, p. 305. [BIBCODE 1982ASSL...98..305Y ]