COMMISSION 27 OF THE I.A.U.
               INFORMATION BULLETIN ON VARIABLE STARS
                            Number 1458

                                                      Konkoly Observatory
                                                      Budapest
                                                      1978 August 14


              OBSERVATIONS OF CG CYGNI

BVR photoelectric observations of the eclipsing binary CG
Cyg (B.D. +34d4217) were taken during the first two weeks of
July 1978 at the Kottamia station of Helwan Observatory (Egypt). The
equipment and photometric arrangements are essentially the same as
referred to by Sadik (1978). Two stars in the neighbourhood of the
variable were selected as comparison and check stars. They are
designated (a) and (b) respectively in the field map given by Yu (1923).
The phases were computed using the light elements E = 2439425.1221
and P = 0d.6311410.
   CG Cyg has been listed by Hall (1976) in the table of short
period group of his paper on the RS CVn binaries. The spectral type
of this star is G9 V-IV (composite spectrum) and H and K emission lines
have been observed in the spectrum. The variability of the star was
discovered by A. Stanley Williams in 1905, whose visual light curve
(Williams, 1922) suggests irregularities outside of eclipses. 
Photographic observations were published by Milstein and Nicolajev (1940)
and Tsesevich (1954). The photographic light curve of CG Cyg published
by Yu (1923) shows the system to be generally brighter near the
secondary eclipse than the primary (i.e., a normal "reflection effect")
and also the system is brighter following the primary minimum than
after the secondary. UBV photoelectric data by Milone (1969a, b)
reports asymmetries in the light curve maxima which undergo some kind
of long term variation.
   Preliminary B and (B-V) curves of our observations are shown in
the diagrams below. It is remarkable that the system appears to be
brighter near the primary eclipse than near the secondary. This effect
is more pronounced in B than the V and R light curves. The observed
effect seems to contradict the normal reflection effect in close binaries;
though it is possible that it could be explained in terms of the "wave
migration" discussion of Hall. A possibly similar star is BH Vir which
has also been recently observed at Kottamia and is being examined at
the present time.


                    D.M.Z. JASSUR

                    Department of Astronomy,
                    University of Manchester,
                    Manchester, England.



References:

Hall,  D. S. 1976, Proc. of I.A.U. Coll. No. 29 (Budapest), part 1,
    p. 287, Reidel, Dordrecht. [BIBCODE 1976ASSL...60..287H ]
Milone, E F. 1969a, in Non-Periodic Phenomena in Variable Stars, L.
   Detre, ed. (Budapest: Academic Press), p. 457. [BIBCODE 1969CoKon..65..457M ]
						[CoKon No. 65]
Milone, E. F. 1969b, Inf. Bull. Var. Stars, No.. 373.
Milstein, I. P. and Nicolajev, S. P. 1940, Bull. Vses. Astr.-Geod.
   Soc. No. 6, 9.
Sadik, A. R. 1978, Inf. Bull. Var. Stars, No. 1381.
Tsesevich, V. P. 1954, Odessa Izv. 4, 255.
Williams, A. S. 1922, M.N.R.A.S., 82, 300. [BIBCODE 1922MNRAS..82..300W ]
Yu, C.-S. 1923, Ap. J., 58, 75. [BIBCODE 1923ApJ....58...75Y ]

                      [FIGURE 1]

                      [FIGURE 2]