COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                      Number 1903

                                     Konkoly Observatory
                                     Budapest
                                     1981 January 5

                                     HU ISSN 0374-0676


                    GY CYGNI



    This star was estimated on Sonneberg Sky patrol plates
 made during the years 1966-1980. The light curve shows apparent
 non periodic waves with clear maxima and minima. The middle cycle


                         [FIGURE 1]

Fig.1. Middle lightcurve from parallel photographic observation
       series in mpg and mpv.

duration is about 300d+-50d. Probable there exists a secondary
light variation with a period of 4000^d and an amplitude of
0.5 mag.(mpv).           
	The observed amplitude   of the total light variation is
10.6-11.8 (mpg) and 9.5-10.7 (mpv). The colour index is  about
(mpg-mpv)=+1.1m.
It is possible that the star is a semiregular type  variable 
of type SR b.
    Its spectral type M 7p determined by Jaschek et al. (1) 
contradicts the observed colour. From the estimated luminosity of
the star we can find a distance r=(1.0+-0.8)kpc. The interstellar
extinction with A_v=0.2m-0.7m, which is effective in this distance,
increases the discrepancy between the colour index and spectral
type.
    The peculiarities in the spectrum of this variable pointed
out by Wachmann (2,3) call for a detailed spectrographic 
investigation.





                        DIETMAR BOHME
                        4851 Nessa 11
                        PSF 93
                        DDR





References:
(1) Jaschek, C., Conde, H. and de Sierra, A.C., La Plata, Ser.
         Astr. 28. 2,  1964 [BIBCODE 1964PLPla..28....1J ]
(2) Wachmann, A.A., Astron. Nachr. 255, 369, 1935 [BIBCODE 1935AN....255..341W ]
(3) Wachmann, A.A., Astron. Nachr. 236, 280, 1929 [BIBCODE 1929AN....236..279W ]