COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 397

                              Konkoly Observatory
                              Budapest
                              1969 November 3


            THE VARIABILITY OF BV 789

      The eclipsing binary BV 789 was found by Strohmeier
(IBVS no. 225, 1967) to have the following ephemeris:

      Min.I = JD 2425501.350 + 0.558139  E.

      Photoelectric observations were made by the author
at Cerro Tololo Inter-American Observatory in Chile on five
nights during July and August of 1969. These observations
cannot be fitted to the above ephemeris. It was found that
the period is actually nearly one day instead of somewhat
more than half a day as given in the above ephemeris. No
times of primary minimum were observed at Cerro Tololo, but
the previously observed times of minimum light yield the
following ephemeris:

      Min.I = JD 2425501.340 + 0.9972646  E.
                    +/-    5 +/-       5 p. e.

Minimum           E         O-C
    2425501.376  0        +0.036
       6899.478  1402     -0.027
       7666.370  2171     -0.031
       7685.337  2190     -0.012
       7984.509  2490     -0.020
       8045.343  2551     -0.019
       8078.286  2584     +0.015
       8391.424  2898     +0.012
       8396.426  2903     +0.027
    2431651.498  6167     +0.028
       8236.411  12770    +0.002
       8264.315  12798    -0.017
       8278.272  12812    -0.022
       8283.269  12817    -0.011
       8297.228  12831    -0.014
       8580.478  13115    +0.013
       8582.471  13117    +0.012
       8587.431  13122    -0.015
       8615.391  13150    +0.022
       8634.310  13169    -0.007
       8643.311  13178    +0.018
       8662.240  13197    -0.001
       8994.321  13530    -0.009
       9300.501  13837    +0.011
       9321.464  13858    +0.032
       9373.282  13910    -0.008
       9377.285  13914    +0.006

      BV 789 was observed together with a comparison
star, HD 187952. The magnitudes and colors of these stars
are as follows:

		  V      B-V
BV 789 (at max.) 9.56   +0.31
HD 187952        9.29   +0.38

Although the spectral types of BV 789 (HD 188297) and
HD 187952 are listed as A0 and A2, respectively, in the
Henry Draper Catalogue, their colors correspond the those
of main sequence stars with respective spectral types of
F0 and F2.
      BV 789 is practically constant in light during the
portions of its light curve outside eclipses. The secondary
minimum is about 0.07m deep in either yellow or blue light.
From the photographic data, it is assumed that the primary
minimum is at least 0.55m deep. Thus BV 789 is an Algol-type
eclipsing binary rather than a W Ursae Majoris star. Since
the period of BV 789 is very nearly equal to one day, it
will not be easy to obtain a complete light curve of this
star at only one observing site.

October 27, 1969

                        CARLSON R. CHAMBLISS
                    Georgetown College Observatory
                      Washington, D. C., U. S. A.