COMMISSION 27 OF THE I. A. U
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 266

                                     Konkoly Observatory
                                     Budapest
                                     1968 April 6


   PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR YZ CMi


The working group on UV Ceti type stars (I.A.U. Commission 27) has organized
co-operative observations of the flare star YZ CMi during two observing
periods:  January 22- February 6 and February 21 - March 7, 1968. This paper
contains the results of photoelectric observations obtained at the Crimean
Astrophysical Observatory.

During the first period observations were made with the 64 cm telescope in the
V-band and during the second one with the 70 cm reflector in the B-band. Three
flares of the star were observed. Table 1 contains the times of the beginning
and end of observations, times of maxima of the flares, their amplitudes and
durations. Light curves of the flares are shown in Fig. 1. The quantity i is
the ratio of excess radiation to the normal radiation of the star, i.e.

i=I/I_normal

Table 1

         Beginning           Time of   delta    Duration
Date    and end time         max. of     m      of flare,    Notes
           U.T.              flare,             minutes
                              U.T.
Jan.24  19^h08^m-23^h05^m
Jan.31  18  09  -20  24      19^h58^m   0.28     4
Feb. 1  16  27  -19  24      18  21     0.15     5
Feb. 3  16  31  - 0  00      22  49     0.16     9
Feb.23  19  07  -20  02
Feb.24  20  13  -22  19                                      Clouds sometimes
Feb.27  19  59  -23  00                                      - " -
Feb.28  20  48  -22  37                                      - " -
Mar. 3  17  02  -20  02


                          [FIGURE 1]


                                          P.F. CHUGAINOV
Crimean Astrophysical
Observatory
March 26, 1968