COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       NUMBER 268

                                      Konkoly Observatory
                                      Budapest
                                      1968 April 19


                FLARE ACTIVITY UF YZ CMi


According to the proposal of the "Working group on flare stars" of the IAU
Commission No 27 two series of continual observations of the star YZ CMi have
been realized at the Burakan Observatory. The observations were done in the B
colour during the periods 1968 Jan. 22/Feb. 6 and 1968 Feb. 21/March 7 with
the 20" Cassegrain telescope. The results of these observations are given in
the table.

Date   Observing time    Coverage  delta m  Time of  Duration     Remarks
1968       UT                                max.    of flares
                                              UT     after max.
22.I  19^h15^m-20^h02^m
      20  07  -20  48     1^28^m
25.I  20  33  -23  33     3 00      0,12?  21^h55^m    1 min
                                    0,16?  22  04      1 min      1)
26.I  18  10  -21  22     3 12      0,36   19  17      9,5 min
 4.II 18  43  -22  17     3 34      0,46   20  36.2   38,5 min
                                    1,12   21  13.4   47,3 min
 5.II 20  33  -23  08     2 35
 6.II 19  53  -22  40     2 47
22.II 16  39  -20  40     4 01      0,16   17  45.5    6,5 min
23.II 16  45  -22  00     5 15      0,33   16  51.3    1 min      2)
24.II 16  30  -21  00     4 30      3,21   16  51.5    cca
                                                       4 hours
                   Total 30 22

1) The measurements are not very reliable and must be checked with other
   observations.

2) Until 17^h20^m UT the star was about 0,1 magnitude brighter than before the
   flare.

Six reliable and two suspected flares were observed during a total coverage of
30^h22^m. The mean frequency of flare appearance calculated from these data
is:

a) one event per 5^h04^m if considering the reliable flares only, or

b) one event per 3^h48^m if taking into account the suspected flares as well.

The figure shows the smoothed light-curve of the strongest flare observed
during these two series (24-II-1968). It should be noted, that on this evening
the brightness of the star was already for about one magnitude above the normal
one, as we started with our observations.


                          [FIGURE 1]


V.S. OSKANIAN
Burakan Astrophysical Observatory
Armenian SSR, USSR