COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1896

                                  Konkoly Observatory
                                  Budapest
                                  1980 December 22

                                  HU ISSN 0374-0676



    PHOTOGRAPHIC OBSERVATIONS OF 1980 ECLIPSE OF CI CYGNI


   Photographs were taken with two cameras, focal lengths 50
and 130 cm, with two emulsions, Tri X and 103a-O. The former was
exposed with the yellow-green filter which gives the brightness
very close to visual magnitude.
   The results between J.D. 2444300 and 4500 are shown in
Fig. 1, in which the upper curve is photovisual and the lower
curve is photographic.


                       [FIGURE 1]


   Fig.1. m_pv(upper) and m_pg(lower) light curves of CI Cyg.
        Arrows are estimated dates of minimum.


   The depth of the minimum was very shallow compared, with the
previous minima, being only 0.4m in visual region and 0.7m in photographic 
region, probably because the eclipse occurred when the
hot component was near the faintest stage. The minimum magnitudes
in both regions are in good agreement with the 1975 and 1977-78
eclipses observed by Belyakina (1976, 1979).
   The times of middle of eclipse are estimated and shown by
arrows in the Figure. They are on J.D. 2444395 for photovisual
curve, and 4394 for photographic curve. Together with the observations 
by Belyakina in the last two minima, the period 855d
seems to be fairly correct. From the present observations, D and
d were estimated as 133d and 72d respectively, though the estimations 
were not less difficult due to the irregular variations
of short period throughout the eclipse.
    The detailed results will be published elsewhere.




                          MASAAKI HURUHATA
                        Hodozawa 88, Gotemba-shi
                            412 Japan




References:

Belyakina, T.S., 1976, I.B.V.S. No. 1169
Belyakina, T.S., 1979, I.B.V.S. No. 1602