COMMISSION 27 OF THE I.A.U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3258

                                             Konkoly Observatory
                                             Budapest
                                             8 November 1988

                                             HU ISSN 0374 - 0676


          UBV OBSERVATIONS OF VW CEPHEI

UBV photoelectric observations of the W Ursae Majoris
type system VW Cephei (BD +75d0752) were carried out at the
Mount Laguna Observatory during three consecutive nights 5/6,
6/7 and 7/8 July, 1988. The 24-inch Smith f/20 telescope was
used with the standard U,B,V filters and thermo-electrically
cooled EMI 6256 photomultiplier. BD +75d0765 was used as a
comparison star and approximately 500 measurements were
obtained through each filter.
   Three sets of data of the light curves and fifteen times
of minimum light were determined from the observations of VW
Cep. The data reduction and standardization program for
differential photometry (Guinan et al., 1986; and a version
of the Kordylewski's "tracing - paper" method (see
Szafraniec, 1948) adopted to the IBM-PC computer graphics
(Guinan et al. 1987) were employed. The times of primary (I)
and secondary (II) minimum light of the VW Cephei for each
filter are given in Table I.
    The differential U, B, V observations of VW Cephei are
plotted against phase in Figure 1. The working ephemeris were
used :

     JD Hel Min I = 244 4176.6161 + 0.2783136 E.


                    Table I.
          Times of minima of VW Ceph

J.D. hel.2440000+     m.e.    type   filter

7348.8079           +-.0002     I      V
7348.8074           +-.0002     I      B
7348.8063           +-.0004     I      U
7348.9476           +-.0003    II      V
7348.9459           +-.0006    II      B
7348.9456           +-.0008    II      U
7349.9215           +-.0003     I      V
7349.9215           +-.0001     I      B
7349.9217           +-.0003     I      U
7350.7554           +-.0003     I      V
7350.7553           +-.0001     I      B
7350.7547           +-.0002     I      U
7350.8944           +-.0001    II      V
7350.8947           +-.0001    II      B
7350.8946           +-.0002    II      U


                        [FIGURE 1]

 Figure 1.: The differential U, B, V observations of VW Cephei
            plotted in phase.


   These light curves are almost symmetric and both the
maxima in B, V band pass are nearly equal. In the past the
light curves showed large assymmetries most noticeble in the
differences of heights of maxima (Kotarska and Glownia, 1983).
   The relative depth of primary minimum in U band pass is
significantly deeper than in B and V due in part of small
differences of stars temperatures and gravity darkening
effects. In the U light curve the maximum following secondary
minimum is slightly brighter by the order of 0.02 mag than
the corresponding maximum that follows the primary minimum.
   The analysis of the observations is underway.

Acknowledgements

    The author wishes to thank the staff of the San Diego
State University Astronomy Department for their hospitality
and granting telescope time at the Mount Laguna Observatory.
Thanks are also due to Dr. G. Mc Cook for assistance in data
reduction.


                      ZBIGNIEW GLOWNIA *

                   Department of Astronomy
                      and Astrophysics
                    Villanova University
                    Villanova, PA 19085


* Visiting Scholar
  San Diego State University
  Astronomy Department
  San Diego, CA 92182



References:

Guinan, E.F., Mc Cook, G.P., Mc Mullin J.P. 1986 in The Study of Variable Stars
   Using Small Telescopes, Cambridge, Cambridge Univ. Press. [BIBCODE 1986svss.conf...79G ]
Guinan, E.F., Najavi, S-I., Zamani-Noor, F., Boyd, P.t., Carroll, S.M. 1987,
   Inf. Bull. Var. Stars, No. 3070.
Kotarska, I., Glownia, Z. 1983, Astron. Nachr., Vol. 304, 181 [BIBCODE 1983AN....304..181K ]
Szafraniec, R. 1948, Acta Astr., Ser c , Vol. 4, 81