COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 3237

                                                         Konkoly Observatory
                                                         Budapest
                                                         15 September 1988

                                                         HU ISSN 0374 - 0676


       THE FIRST PHOTOELECTRIC LIGHT CURVE OF V456 OPHIUCHI

The detached eclipsing binary V456 Oph (=BD +08d3814) seems to be observed
first photographically by Kapko in 1949 (see the 1958 and 1969 editions of the
General Catalogue of Variable Stars), Kapko found that the photographic light
curve is of Algol type with partial eclipses (d=0), and the range of light
variation being m_ph=10m.2-10m.7 at the primary minimum and 10.2m-10.5m at
the secondary minimum. The GCVS 1958, 1969 gave the light elements as

          Min I = Hel. J.D. 2428422.341 + 1.015986d E.

   No other observations of this neglected binary system have appeared in the
literature until 1973 when one of us (O.D.) observed the primary and secondary
eclipses of the system in BV filters (c.f. Kizilirmak and Pohl, 1974, 1975).
The minimum times were delayed, with respect to the given ephemeris, by about
four hours. Times of eclipse minima were determined as

          Prim. Min. = Hel. J.D. 2441897.534 and 2441951.383
           Sec. Min. = Hel. J.D. 2442239.410

   Such a big delay in the eclipse minima suggests an increase in the orbital
period of the system. The new period is estimated roughly as P=1.0159989d.
Such a delay in the eclipse minima could also be caused by the probable errors
in the light elements given by Kapko, because his photographic observations
could not be as accurate as the present observations. However, Diethelm
(1981) reported the new light elements as

          Min I = Hel. J.D. 2441897.532 + 1.0159996d E

which were determined by using mostly our observations. The GCVS 1985 cited
Diethelm's light elements for V456 Oph, and noted a variable period.
   We included V456 Oph in our program and observed it id BV filters on
twelve night between May 20 and July 19, 1988. Thus, we secured the first
whole photoelectric light curves of the system in two colours. The differential
observations were made with respect to the comparison star BD +08d3824 by
checking against the nearby check stars BD +05d3813 and BD +08d3809. The 


                              [FIGURE 1]

comparison was found to be constant during the observations. The observations
were made by using an EMI 9789 photomultiplier attached to the Maksutov
telescope of the Ankara University Observatory. 365 differential observations
have been secured in each colour. The observations were corrected for 
differential extinction and are shown in Figure 1. The phases were calculated by
using the above cited Diethelm's light elements.
   We thank to G. Kahraman, for the generous help during the observations. The
period and light curve analysis of the system is in progress and will be
published elsewhere in the future.


                O. DEMIRCAN
                 E. DERMAN
                 S. SELAM

        Ankara University Observatory
           Astronomy Department
         06 100 Besevler, Ankara
                 Turkey



References:

Kizilirmak, A., Pohl, E., 1974, IBVS No. 937.
Kizilirmak, A., Pohl, E., 1975, IBVS No. 1053.
Diethelm, R., 1981, BBSAG Bull. No. 57.