COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 210

                                      Konkoly Observatory
                                      Budapest
                                      15 July 1967


  PERIODICITY OF THE LIGHT VARIATION OF P CYGNI


P Cyg has been regularly observed at Abastumani from 1951 photoelectrically, in
B and V up to 1960 and in UBV from 1963 onwards. A periodic variation has been
revealed, the period being 0.^d500656. The light variation seems to be of the
W UMa type, with amplitudes 0.^m10 and 0.^m08 for the primary and secondary
minima, respectively. The secondary minimum is shifted relative to the median
point between two successive main minima. The heights of maxima are not equal,
the differences reach to about 0.^m03. The light curve suffers variations from
one cycle to the other, the periodic variations of eclipse character being
disturbed by irregular variations. Probably this unstability of the light
curve is responsible for the significant dispersion in the U magnitudes. The
mean light curve in V, related to the period for 1951-1960, is shown in the
Figure.


                         [FIGURE 1]


The phases are calculated according to the following elements:

Min.=J.D. 2436048.321+0.^d500656 E.


Abastumani Astrophysical Observatory
                                            N.L. MAGALASHVILI
                                            E.K. KHARADZE