COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 529


					Konkoly Observatory
                          	        Budapest
                          	        1971 March 8



           AD LEONIS, FEBRUARY 15-21, 1971


      A continual photoelectric monitoring of the flare
star AD Leo was done with the 91 cm reflector of the Okayama
Station from 15 to 21 February 1971.
      During the 29.4 hours of monitoring in the magnitude
B, 2 flares were observed as shown in the following table:


-------------------------------------------------------------
Date       Time of       Time of           Flares Duration
1971    Monitoring(UT)   Max.(UT)  Deltam(B)  P         sigma
                                             min.  min. mag.
-------------------------------------------------------------
Feb.15  11h42m-20h00m                                    0.01
16       17 00-18 16                                     0.02
17       10 36-16 19     11h39.7m  0.13mag   0.1   0.5   0.02
18       10 43-19 30     13 02.6   0.97      2.7  26     0.01
19       17 36-20 02                                     0.03
20       14 47-17 41                                     0.02
-------------------------------------------------------------



Deltam(B)  =   2.5 log [(I_0+f)_max / I_0]

P          =   Integral(I_0+f - I_0)/I_0 * dt

sigma(mag) =   2.5 log (I_0 + sigma)/I_0



Tokyo Astronomical Observatory
25 February 1971.



                               K. OSAWA
                               K. ICHIMURA