COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                    Number 3125

                                        Konkoly Observatory
                                        Budapest
                                        28 December 1987

                                        HU ISSN 0374-0676



                PHOTOELECTRIC TIMES OF MINIMA
                 OF FOUR ECLIPSING BINARIES


  We made differential photoelectric measurements during November and 
December of 1987 with the new 40 cm f/14 Cassegrain reflector at the Baja 
Observatory. The telescope was made in the Astronomical Observatory of the Odessa
University (USSR) and is connected with a Starlight-1 stellar photometer made
in USA, by the firm Thorn EMI, The latter is employed in the standard UBV system.
The transformation coefficients of our telescope-photometer system are as 
follows:

epsilon = -0.014+/-0.063, mu = 1.263+/-0.041, psi = 0.953+/-0.068


The comparison stars were as follows:

for OO Aql :   BD+8 4220,
    RZ Cas :   BD+69 171
    VW Cep :   BD+75 765,
    AG Per :   BD+32 714

  The times of minima were obtained by least-squares parabolic fitting to the
measured points near the centre of minima. Table I contains the Heliocentric
Julian Date, and the O-C residuals obtained by different ephemerides.

                       Table I
Star     N    Filter   J.D.Hel.     E         O-C I     O-C II
                       -2400000
OO Aql   45   V        47058.3422   16664     -0.0032   +0.0313
OO Aql   65   V        47060.3709   16668     -0.0017   +0.0328
RZ Cas   45   B,V      47118.3364   24901     -0.0545   +0.0086
RZ Cas   39   B,V      47142.2418   24921     -0.0541   +0.0091
VW Cep   36   V        47142.4445   10725.5   -0.0318
VW Cep   36   B        47142.4452   10725.5   -0.0311
AG Per   49   V        47118.4458   2684      +0.0160   -0.0117

  The value of N means the number of measured points used in the parabolic
fit. Column E gives the number of cycles have elapsed since the epoch taken
into account in the calculations of O-C. The O-C residuals O-CI and O-CII
are computed using the following references:
  
  Star           References
         for O-CI        for O-CII

OO Aql   GCVS 1987       Demircan and Gudur, 1981.
RZ Cas   Parenago, 1952  Herceg and Friboes - Conde, 1974
VW Cep   SAC 58
AG Per   SAC 58          Gudur, 1984

  The first residual of OO Aql may be considered of less weight as compared
with the second one. In the case of AG Per the O-CII value was calculated
taking into account also a sinusoidal term (Gudur, 1984), but for the others
it was done by only the linear term. AG Per has shown a slight fluctuation of
the brightness near the light minimum, and so does, but more strongly, OO Aql
and VW Cep. So, the uncertainties of their minima times are increased somewhat
owing to this fact. RZ Cas seems to show a distinct period increase.


  T. HEGEDUS
Baja Observatory
Baja, P.O.Box 766.
  HUNGARY





References:
Demircan, O. and Gudur, N., Photometric and Spectroscopic Binary Systems,
  413-439, D.Reidel Publ. Co., 1981, [BIBCODE 1981psbs.conf..413D ]
Gudur, N., 1984,I.B.V.S. 2644.
Herczeg, T., and Friboes-Conde, 1974, Astr. and Ap. 30, 259, [BIBCODE 1974A&A....30..259H ]
Parenago, P.P., 1952, Variable Stars 9, 125,
Rudnicki, K., 1987, Supplemento ad Annuario Cracoviense, No. 58, Krakow.