COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 746

                                 Konkoly Observatory
                                 Budapest
                                 1972 December 21


     EPOCHS OF PHOTOELECTRIC MINIMA OF Y CYGNI



   This report concerns the Japanese contribution to the
international campaign of photoelectric observations of the
eclipsing variable Y Cyg in 1971 and 1972 for the epochs of
the minima given by Commission 42 of the IAU during the
Brighton meeting. Y Cyg is a binary system with apsidal 
motion, and accurate epochs of the light minima would provide
with important data for study of the latter motion. Photoelectric 
observations were carried out with the 20 cm refractor 
BV) at the Education Centre of Kanagawa Prefecture, the
25 cm reflector UBV at the Akita University, the 20 cm
refractor BV at the Education Centre of Saga Prefecture
and the 91 cm reflector UBV at the Dodaira Station of Tokyo
Astronomical Observatory. In the observations BD +34d4196
 O'Connell 1971 was used as comparison star. The following
eleven epochs of minima were obtained from these observations:



-------------------------------------------------------------------------
Date       JD hel.       min    E     (O-C)1   (O-C)2 Observer*  Observatory
           2441...                                               **
1971                        
-------------------------------------------------------------------------
Aug.28     192.2044      odd  10565  +0.1277  +0.0040 H,S;Kt,Oz   A;D
Sep.15     210.1848      odd  10571  +0.1301  +0.0069 H,S;Kt,Oz   A;D
1972
July 18    517.0692      even 10674  -0.1098  -0.0095 Og          K
July 24    523.0605      even 10676  -0.1112  -0.0111 Og,O, K     K
Aug. 8     538.0430      even 10681  -0.1103  -0.0108 Og,O, K     K
Aug.14     544.0353      even 10683  -0.1107  -0.0113 Og,O, K     K
Sep. 4     565.0145      even 10690  -0.1058  -0.0071 H, S        A
Sep.10     571.007       even 10692  -0.1060  -0.0075 H, S        A
Oct. 4     594.9784      even 10700  -0.1053  -0.0076 Kg          S
Oct.13     603.9644      even 10703  -0.1083  -0.0109 Kg          S
Oct.16     606.9599      even 10704  -0.1091  -0.0118 Kg          S
------------------------------------------------------------------------



*Observers: H=Hayasaka, S=Sato, Kt=Kitamura, Oz=Okozaki,
           Og=Ogata, O=Oba, K=Koreeda, Kg=Koga.
**Observatories: K=Kanagawa (20 cm refractor), A=Akita (25 cm
                reflector), S=Saga (20 cm refractor), D=Dodaira
                (91 cm reflector).



   In  calculating the O-C value for each  minimum we used
Dugan's formulae (1931).



Min  I   (even)   = JD 2409534.3195
                                       +2.9963331d.E 
Min II    (odd)   = JD 2409535.8175    



+ 0.1380 Sin (0.06266deg.E)
                         -0.0074 Sin 2(0.06266deg.E).
- 0.1380 Sin (0.06266deg.E)



On the nights of August 28 and September 15 in 1971, 
simultaneous observations were made at Dodaira and Akita and 
therefore the epochs of minimum listed  for these two nights are the
mean values. In the table the (O-C)1 -values were calculated
with the linear formulae, while the (O-C)2 -values were calculated 
with the full formulae.



      H. OGATA, Education Centre of
              Kanagawa Prefecture,
      T. HAYASAKA and N. SATO, Akita University,
      M. KOGA, Education Centre of Saga
            Prefecture and
      M. KITAMURA, Tokyo Astronomical Observatory.



References:

O'Connell, D.J.K. 1971, IBVS No. 542.
Dugan, R.S. 1931, Contr.Princeton Univ.Obs., No. 12. [BIBCODE 1931CoPri..12....1D ]