COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                      Number 3153


                                    Konkoly Observatory
                                    Budapest
                                    4 March 1988

                                    HU ISSN 0374-0676


       PHOTOELECTRIC MINIMA TIMES OF THE BINARY STAR V508 Oph

  The eclipsing binary BD+ 13 3496 ( V 508 Oph ) is a peculiar short period
variable star. Its variability was firstly detected by Hoffmeister in 1935 and
it was classified as W UMa type by Jacchia (1936). Karetnikov obtained photographic
and photovisual light curves of V508 Oph in 1963 and 1977, respectively;
while Rovithis and Rovithis-Livaniou (1983) obtained the first BV photoelectric
observations of it. Recently, UBV light curves for the system were published by
Lapasset (1985) and a spectroscopic analysis was made by Lu (1986),
  Because of its peculiarity (unequal amplitudes of its light curves in the
different colours) this star was re-observed during 1986. Our photoelectric
observations were made using the two-beam, multi-mode, nebular-stellar photometer
attached to the 48-inch Cassegrain reflector at Kryonerion Astronomical Station
of the National Observatory of Athens. The B and V filters used are in close
accordance to the standard ones and reduction of the observations was made in
the usual way (Hardie, 1962).
  From our observations two primary and four secondary minima times were derived
using Kwee and Van Woerden's method (1956). These moments are presented in Table I
the successive columns of which give: the Hel. JD, the (O-C) values and 
the type of minima.

                    Table I

   Hel.J.D.     (O-C)Kuk  (O-C)Kar  (O-C)Lap  (O-C)Kho  Min.

   2440000.+
   6668.4185    +0.0174d  +0.0067d  -0.0014d  +0.0041   II
   6671.3510    +0.0191   +0.0085   +0.0003   +0.0049   I
   6674.4526    +0.0176   +0.0070   -0.0012   +0.0043   I
   6675.3150    +0.0180   +0.0074   -0.0008   +0.0048   II
   6677.3836    +0.0179   +0.0072   -0.0010   +0.0046   II
   6678.4182    +0.0181   +0.0075   -0.0008   +0.0048   II

In the residuals the C values have been calculated using Kukarkin's et al.
(1976), Karetnikov's (1977), Lapasset's (1985), and Kholopov's et al, (1985)
ephemeris formulae, respectively.


P. ROVITHIS

Astronomical Institute
National, Observatory
of Athens, Athens
Greece

H. ROVITHIS-LIVANIOU

Section of Astrophysics
Astronomy and Mechanics
Athens University
Athens 157 83 Zografos
Greece


References

Hardie, R.H.: 1962, in W.A. Hiltner (ed.), Stars and Stellar Systems Vol. II,
  "Astronomical Techniques", University of Chicago Press, Chicago
Hoffmeister, C.: 1935, Astron. Nachr: 255, 405. [BIBCODE 1935AN....255..401H ]
Jacchia, L.: 1936, Astron. Nachr. 261, 212. [BIBCODE 1936AN....261..211J ]
Karetnikov, V.G.: 1963, Perem. Zvezdy 14, 348. [BIBCODE 1963PZ.....14..348K ]
Karetnikov, V.G.: 1977, Perem. Zvezdy Suppl. 3, 247. [BIBCODE 1977PZP.....3..247K ]
Kholopov, P.N. et al.: 1985, Fourth Edition to the General Catalogue of Variable
  Stars
Kukarkin, B.V. et al.: 1976, Third Edition to the General Catalogue of Variable
  Stars
Kwee, K.K. and Van Woerden, H.: 1956, Bull. Astron. Inst, Neth. 12, 327. [BIBCODE 1956BAN....12..327K ]
Lapasset, E.: 1985, I.B.V.S. No 2828.
Lu, W.: 1986, Publ. Astron. Soc. Pacific, 98, 577. [BIBCODE 1986PASP...98..577L ]
Rovithis, P., and Rovithis-Livaniou, H.: 1983, Astrophys. Space Sci. 96, 283. [BIBCODE 1983Ap&SS..96..283R ]