COMMISSIONS 27 AND 42 OF THE IAU
              INFORMATION BULLETIN ON VARIABLE STARS
                           Number 4041

                                                Konkoly Observatory
                                                Budapest
                                                22 June 1994

                                                HU ISSN 0374 - 0676


              PHOTOELECTRIC PHOTOMETRY OF VW CEPHEI IN 1993

  VW Cephei (HD 197433; BD+75d752) is a short period (P=0.27831347d), W Ursae
Majoris-type eclipsing binary with components of spectral types G5V+K0V. VW Cep
has been monitored at the Villanova University Observatory since 1978. Asymmetries
in the light curve have been interpreted as arising from the presence of cool starspots,
located chiefly on the photosphere of the larger, more massive component of the system
(Bradstreet and Guinan, 1990).
  The data were acquired over six nights: July 17, 18, 21, 23, 31, 1993 UT using the
38-cm Cassegrain telescope at the Villanova University Observatory. This telescope is
equipped with a photoelectric photometer that uses a refrigerated EMI 9558 photocell.
Differential magnitudes were computed from observations made with the intermediate-
band Stromgren y filter (lambda=5500A, FWHM=350A) and in the intermediate-band Halpha
filter (lambda=6585A, FWHM=280A). A total of nearly 600 observations were secured in both
band-passes. An integration time of 20 seconds was used for each observation. The
observing sequence used was the usual sky-comparison-variable-comparison-sky routine;
BD+76d809 (m_v=7.6, F2) was the comparison star.
  The yellow and red light curves, shown in Figure 1, were formed from the observations
using the ephemeris given by Hill (1989):

       T_minI (HJD) = HJD 2437469.3939 - 0.27831347d x E                  (1)
                                  +/-7         +/-6


                              [FIGURE 1]

           Figure 1. Yellow and red light curves of VW Cep.


  The light levels of the extrema are listed in Table 1. They are given in terms of delta
magnitude (variable minus comparison) and are relative to the comparison star.


                    Table 1
                    Yellow Deltam(v-c)  Halpha Deltam(v-c)
Primary Minimum    	+0.597		    +0.303
Maximum I          	+0.205		    -0.070
Secondary Minimum   	+0.506		    +0.232
Maximum II         	+0.249 	            -0.031

  As shown in Figure 1 and Table I, the light curves are asymmetrical in which the
Maximum I (0.25P) is brighter than the corresponding Maximum II (0.75P) by approx. 0.04
magnitude in each filter. This is probably due to the presence of spots at the 0.75 phase.
  The times of the minimum light were calculated using the nights of July 17 and July
18, 1993 UT, in which the eclipses were completely observed. The times of mid-eclipses
were found using a parabolic least squares fit to the data in each filter. Table 2 lists
the type of minimum, the time of minimum (times in each filter in terms of heliocentric
Julian Date averaged from both filters), the number of cycles elapsed (E), and the (O-C)
residual in days from equation 1.


                        Table 2
                          HJD 2449100+             E       (O-C)
Primary   (07/17/93 UT)     85.6369    		42097.0   +0.0809d
Primary   (07/18/93 UT)     86.7501    		42101.0   +0.0808
Secondary (07/18/93 UT)     86.6141   		42100.5   +0.0840



                        Brian P. ABBOTT
                        Department of Astronomy
                        & Astrophysics
                        Villanova University
                        Villanova, PA 19085
                        USA

                        Donald J. RUMIGNANI
                        Department of Applied
                        Mathematics
                        Hofstra University
                        Hempstead, NY 11550
                        USA



References:

Bradstreet, D. H. and Guinan, E. F., 1990, in "Active Close Binaries", ed. C. Ibanoglu
   (Kluwer, Netherlands), p. 467
Hill, G., 1989, Astronomy and Astrophysics, 218, 141 [BIBCODE 1989A&A...218..141H ]