COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       NUMBER 682

                                          Konkoly Observatory
                                          Budapest
                                          1972 May 25


PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR AD Leo DURING THE 1972, FEBRUARY
9-22 INTERNATIONAL PATROL


The preliminary results of the AD Leo photoelectric observations carried out
at the Catania Astrophysical Observatory during the 1972 campaign proposed by
the IAU Working Group on Flare Stars (I.B.V.S. No. 605) are here reported.

The observations were performed by a symultaneous three colour photometer
equipped with an EMI 6256 A (S13) photomultiplier and the Schott filter
combinations: UG1/1(U), BG12/1+GG13/2(B), GG14/2(V). The above photometric
equipment was fed by a 61 cm quasi-cassegrain universal type reflector.

Adopting averaged coefficients, transformation equations from the Catania
photometric system to the standard UBV were applied.

In Table 1 the intervals of effective coverage, which give a total of 4.2
patrol hours, and in Table 2 the characteristics of the observed flare are
given. The flare light curve is shown in the accompanying Figure.

The explanation of symbols and additional details both on the observing
equipment and the Catania photometric system can be found in Cristaldi S. and
Rodono M., Astron. and Astrophys. Suppl. (in press).

C. Lo Presti and F. Spinella have collaborated to the present work.


May 15, 1972

S. CRISTALDI and M. RODONO'
Catania Astrophysical Observatory
Italy

Table 1: Detailed coverage of 1972, February 19-20 observations

                                                Total        3sigma/I_0
Light       Coverage UT                        coverage

UBV   23h10m-2315; 2319-2330; 0010-0032;
      0034-0153; 0205-0301; 0303-0400;
      0411-0433.                                4.2h        .13/.03/.02

Table 2: Characteristics of the observed flare
Date: 1972 Febr. 20, Air mass: 1.19, Feature: double, Sky: clear, moonless.

Light t_max UT    JD_hel      d_b   d_a  3sigma/I_0(I_f/I_0)  Energy
                                                             ---------
                                                   max.    P_min.   erg

U   01h25.8m   2441367.5652  1.2m  17.1m   0.12   1.22    5.88  0.38x10^32
B   01 25.9       1367.5653  1.3    6.0    0.03   0.17    0.49  0.22x10^32
V   01 25.5       1367.5650  0.9    6.0    0.02   0.03    0.14  0.14x10^32


                          [FIGURE 1]