COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     Number 901

                                    Konkoly Observatory
                                    Budapest
                                    1974 June 24



        FLARES ON AD LEONIS AND YZ [ CANIS ] MINORIS

   Four flares on AD Leo observed during 5h25m of patrolling on
the nights of 23 and 24 December 1973 are herein reported. Another
20m of observing on 3 January 1974 recorded no flare. Details of
the observations and the flare characteristics are given in Tables 1
and 2, respectively. The latter have been computed by procedures 
adopted earlier (Kapoor and Sinvhal, IBVS 750, 1972; Kapoor et al,
IBVS 810, 1973). On the basis of the light curves (Figure 1) three
of the flares belong to Oskanjan type I while the fourth is of type
II.

                        [FIGURE 1]

   Also YZ CMi was observed for 3h59m on 21 November 1973, but
no flare was detected. Table 3 gives the details of the observations.
   Part of this investigation was done with financial assistance
under Smithsonian Institution Project No. SFG-O-6425, which is 
thankfully acknowledged.


Uttar Pradesh State Observatory,
Manora Peak, Naini Tal 263129, India.                R.C. KAPOOR

                                                     S. D. SINVHAL


                   Table 1: Coverage of AD Leo

Date         Filter   Sky conditions  Effective coverage, U.T.

23 Dec. 1973    U     Moonless;       19h05m-20h13m; 20h15m-21h31m
                      seeing, good.
24 Dec. 1973    U     Moonless;       18h23m-21h24m
                      seeing, good.
 3 Jan. 1974    B     Moonlit;        18h52m-19h12m
                      seeing, good.

Notes: 1. Times have been rounded off to the nearest minute. Total
coverage 5h45m.  2. Flare intervals are underlined. 3.Instrumentation: 
104 cm. telescope; 1P21 Photomultiplier, unrefrigerated; d.c.
amplifier; Honeywell - Brown Recorder; Time constant of the system,
1 sec. 4. Seeing (on a scale of 5) : Excellent (4-5); Good (3-4);
Fair (2-3); Poor (1-2).

                            Table 2

     Characteristics of the Flares on AD Leonis (dM4e; V=9.43m;
                           U-V=2.61m)

Date UT_max   Flare           A   B    C  P_min F(z)   Energy       Total em.
1973        duration (min.)                           released at   during the
Dec.          t_b     t_a                             flare max.   flare-up
23                                                  (10^29 erg/s) (10^30 erg/s)

19h14m54s     1.75  15.20  1.42 .38 .091 1.805 1.526    1.77         13.54
20 09 45      1.80  13.65  1.45 .40 .067 0.914 1.287    1.85          6.86
Dec.
24
18 56 16      1.25   5.10  1.34 .32 .044 0.349 1.622    1.68          2.62
20 42 02      1.37   7.00  1.36 .33 .055 0.398 1.141    1.69          2.99

A=X_{fm+s}/X_s; B=Delta(m_u); C=3*sigma/X_s

Note: X_s is the mean steady state intensity deflection above sky,
X_{f+s} that due to flare plus X_s, and X_{fm+s} the same corresponding
to flare maximum.

                            Table 3

Date, 1973   Filter   Sky condition   Effective coverage, U.T.

21 November     B     Moonless;       19h16m-20h26m; 20h29m-21h51m;
                      seeing, good.   21 56 -22 49 ; 23 05 -23 39.

                                      Total coverage: 3h59
Notes: s. Table 1