COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3382

                                         Konkoly Observatory
                                         Budapest
                                         9 October 1989

                                         HU ISSN 0374 - 0676


          1989 BV PHOTOELECTRIC OBSERVATIONS OF BW Dra


BW Dra is a W UMa - type eclipsing system. Together with its companion, BV
Dra, they form the visual binary ADS 9535. BW Dra is a short period variable
and it was observed from 20 May through 29 May 1989 with the 1.2m Kryonerion
telescope and a single channel photon counting photometer described by
Dapergolas and Korakitis (1987). The photometer employs a high gain 9789QB
phototube and conventional BV filters. Its output is fed directly to a
microcomputer enabling rapid data access.

The data reduction method is the standard one. The comparison star is the BD
+62d1395 and the accuracy of the observations is +-0.02 mag.

Table I lists the dates of observations and phases covered, whereas Figures 1
and 2 summarize the results for B and V colours.

       Table I

Date            Phase

20 May 1989   .92   .23
              .43   .64
21 May 1989   .49   .24
25 May 1989   .95   .88
29 May 1989   .78   .25

In Table II the times of minima and the O-C values are listed for the V and B
bands respectively. Times of minima are calculated using the method described
by Kwee and van Woerden (1956) whereas the O-C values determined from the
linear ephemeris T=2442572.538d + 0.2921671d E (Geyer et al., 1982).

From the Figures presented here it can be seen that BW Dra has symmetric light
curves.

Considering all the O-C values found in literature (Wood (1970), Yamasaki
(1979), Geyer et al. (1982), Rovithis and Rovithis-Livaniou (1987)), and those
presented here it can be seen that there are large deviations which might be
due to the variability of the individual light curves of the binary.


                                [FIGURE 1]
                                [FIGURE 2]


                    Table II

                V COLOUR               B COLOUR
Type of     Heliocentric   (O-C)     Heliocentric   (O-C)
minima       Jul. Day      phase      Jul. Day      phase

Primary     2447667.3488   0.003     2447667.3498   0.007
                +-0.0004  +-.001         +-0.0007  +-.002
Secondary   2447667.4988   0.516     2447667.4968   0.510
                +-0.0010  +-.003         +-0.0004  +-.001
Primary     2447668.5180   0.005     2447668.5175   0.003
                +-0.0002  +-.001         +-0.0004  +-.001
Primary     2447672.3171   0.008     2447672.3162   0.005
                +-0.0004  +-.001         +-0.0003  +-.001
Secondary   2447672.4611   0.501     2447672.4609   0.504
                +-0.0002  +-.001         +-0.0004  +-.002

From Figures 1 and 2 it can be also seen that the differences between the
depths of the primary and the secondary minima are equal for both colours (~0.1
mag). The depth of the minima is variable up to 0.05 mag as it was reported
previously by Geyer et al. (1982).


A. DAPERGOLAS and E. KONTIZAS    M. KONTIZAS
National Observatory of Athens   University of Athens
Astronomical Institute           Laboratory of Astrophysics
P.O. Box 20048                   Panepistimiopolis
GR Athens 118-10                 GR Athens 151-71
Greece                           Greece

References:

Dapergolas, A. and Korakitis, R.: 1987, Publ. Nat. Obs. of Athens, Ser II,
   No. 28.
Geyer, E.H., Hoffmann, M. and Karimie, M.T.: 1982, Astron. Astrophys. Suppl. 
   Ser., 48, 85. [BIBCODE 1982A&AS...48...85G ]
Kwee, K.K. and van Woerden, H.: 1956, Bull. Astr. Inst. Netherlands, 12, 327. [BIBCODE 1956BAN....12..327K ]
Rovithis, P. and Rovithis-Livaniou, H.: 1987, Astron. Astrophys. Suppl. Ser.,
   70, 63. [BIBCODE 1987A&AS...70...63R ]
Wood, D.B.: 1970, Bull. American Astron. Soc., 2, 357. [BIBCODE 1970BAAS....2Q.357W ]
Yamasaki, A.: 1979, Astrophys. Space Sci., 60, 173. [BIBCODE 1979Ap&SS..60..173Y ]