COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      NUMBER 345

                                  Konkoly Observatory
                                  Budapest
                                  1969 April 21

  PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR AD Leo

      Continual photoelectric monitoring of the star AD
Leo was realized on the 50 cm reflector of the Byurakan
observatory during the series of co-operative observations
of this star (10-24 February 1969). The observations were
done in B approximately. The results of observations are:

       1.- Coverage
    Date           Coverage UT
of observations
15-II-1969         1730-2400
16-II-1969         0000-0015
21-II-1969         1904-1913,1930-1957,2000-2032,2035-2112,
                   2114-2200,

       2.- Total coverage 9h 16m
       3.- The limiting magnitude for these two nights was
m_lim = 14.13 (the normal B magnitude of AD Leo 10.90) and
       sigma(mag) = +4.42
       4.- No flare activity was noticed.



                          V. OSKANIAN
                 Byurakan Astrophysical Observatory




              FLARES OF AD LEONIS

      The flare star AD Leo was observed photoelectrically
for about 13 hours during the February 1969 international
campaign. The continual photoelectric monitoring was carried
out by the 24" telescope at the Konkoly Observatory using
an EMI 9502B photomultiplier, Schott 13+BG12 filter 
combination and a quartz Fabry lens.
     As comparison star we used the companion star at
1.7' N to AD Leo.
     Table 1 shows the time of monitoring.


                         Table 1.

Date               Coverage UT
of observations
1969 February 10   2104-2116,2123-2141,2150-2206,2215-2231,
                   2238-2255,2301-2317,2323-2339,2351-2400,
11                 0000-0007,0011-0027,0031-0046,0049-0106,
                   0110-0126,0130-0145,0150-0206,0210-0226,
                   0231-0245,2049-2057,2101-2116,2119-2135,
                   2138-2153,2156-2210,2213-2228,2238-2254,
                   2257-2313,2318-2331,2333-2349,2351-2400,
12                 0000-0007,0009-0025,0027-0038,0040-0101,
                   0103-0119,0121-0137,0140-0159,0201-0220,
                   0222-0237,0239-0255,0257-0315,0318-0331,
                   0348-0357
13                 2237-2253,2255-2306,
18                 2002-2018,2021-2037,2040-2112,2113-2131,
                   (2132-2148),2152-2210,2211-2224,(2225-2241)

Total coverage: 12h55m (parentheses indicate poor sky 
conditions)
          The limiting magnitude for the nights was about
m_lim = 13.2.        
          Some details of the recorded flares are summarized
in Table 2.


                       Table 2.

UT         Maximum           Duration      Integrated      Remarks
of max     intensity       before after    intensity  
           (m_f-m_0)        max.   max.
1969. Febr.
11d23h31m    0.15mag         -      -          -               (1)
18d21h05m    1.06          9 min  45 min     18 min          (2) (3)
   21h14m    0.47          2       6          0.8            (2) (4)
   22h05m    0.12          0.6     5          0.4              (2)
   22h20m    0.1           1       4          0.5              (2)

Remarks: (1) doubtful
  (2) definite
  (3) with multiple maximum
  (4) superposed on the descending branch of the one
  magnitude flare.

The light curves in intensity units are shown in the Figure.


			[FIGURE 1]

     Some measurements were also obtained in visual
spectral band. From these we can conclude a visual amplitude
of 0.45 magn. for the 1969 February 18d21h05m flare.



                          B. SZEIDL
                      Konkoly Observatory
                          Budapest