COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 338


                                   Konkoly Observatory
                                   Budapest
                                   1969 March 29



     PHOTOELECTRIC OBSERVATIONS OF UV Cet AND YZ CMi


      This is a report on photoelectric observations of
the flare stars UV Cet and YZ CMi made as a Part of 
cooperative programmes in the periods of 14-28 October 1968
and 11-25 January 1969.
      Simultaneous registrations in the wave-length 
intervals 3300-3640, 4140-4290 and 5100-5300 A were obtained
with a three-channel photometer at the 70-cm reflector. The
data given below refer only to the interval 4140-4290 A.
      The time intervals covered by observations are 
included in Table I. Brackets denote uncertain observations.
The total coverage for UV Cet is equal to 24.2 hours and
for YZ CMi to 34.0 hours. Table II contains the flare
characteristics according to the proposals given earlier
(1). The quantity Delta m_lim is found by the formula

             Delta m_lim = -2.5 log 3 sigma / I_0

and the integrated intensity P by the formula

	 P = integral I_0+f-I_0/I_0  dt.


The light curves of flares (Figs. 1,2) have the relative 
intensities (I_0+f - I_0)/I_0 as ordinates and Universal Times as
abscissae.


                          P.F. CHUGAINOV
                   Crimean Astrophysical Observatory

[References]

(1) A.D. Andrews, P.F. Chugainov, R.E. Gershberg, V.S. Oskanjan
               I.B.V.S. No 326, 1969

		     [FIGURE 1]
		     [FIGURE 2]


                                             Table I.

Star     Date             Coverage (UT)
UV Cet   October 22 1968  18h40m-24h00m
         23               00h00m-01h00m,18h40m-24h00m
         24               00h00m-00h29m,18h48m-19h37m,
                          19h39m-22h59m
         25               18h59m-20h31m
         26               18h22m-21h01m,21h23m-22h14m,
                          22h29m-23h00m
         27               17h45m-20h02m
YZ CMi January  13 1969   22h20m-23h45m,23h54m-24h002m
         14               00h00m-02h20m
         15               (17h37m-18h17m),18h17m-19h39m,
                          19h43m-19h49m,20h08m-20h2m,
                          (20h26m-21h13m),21h22m-22h40m,
                          (22h40m-23h42m)
         17               19h29m-20h19m,20h28m-24h00m,
         18               00h00m-02h00m,(17h33m-18h00m),
                          18h00m-18h43m,18h52m-19h15m
                          19h25m-20h49m,20h53m-22h05m
                          (22h05m-22h55m),22h55m-24h00m
         19               00h03m-00h09m,21h28m-22h28m
         22               17h10m-23h07m,(23h07m-23h24m),
                          23h24m-24h00m
         23               00h00m-01h15m


                                                Table II.

         Date and UT       Durations             
Star     of flare           before                    Integrated      Air
         maximum             and       Delta m  Delta m intensity       mass 
                             after              lim    minutes
                            maximum,               
                            minutes
                           t_b    t_a
UV Cet   Oct.24 19h39.2m    ?      5    1.63    0.68     3.6         2.43
         Oct.26 20h28.0    5.4    33    2.54    0.52    90.2         2.20
YZ CMi   Jan.14 01h13.5    1.0     2    0.28    0.15     0.40        1.98
         Jan.15 20h17.5   (3.5)    7    0.40    0.20     1.20        1.42
         Jan.17 20h16.6    0.4     4    1.07    0.17     1.44        1.40
         Jan.18 18h13.8    1.6    21    1.53    0.26    15.2         1.99
         Jan.22 22h21.9    0.3    0.4   0.31    0.15     0.10        1.37