COMMISSION 27 OF THE I. A. U.
              INFORMATION BULLETIN ON VARIABLE STARS
          		   NUMBER 848


					Konkoly Observatory
					Budapest
					1973 November 26


		A FLARE ON AD LEONIS


A flare has been recorded on the dMe star AD Leo during
an effective photoelectric covering of about 4.3 hours on the
nights of June 1 and 3, 1973. Details of observations and findings 
are contained in Tables I and II respectively. The flare
characteristics have been calculated along the lines of Kapoor
and Sinvhal (1972) and Kapoor et al. (1973).

				Table I
			Coverage of AD Leo
		(56-cm reflector, standard B filter)

Date, 	1973(U.T.) 			Effective Coverage
June 1 					15h33m - 16 08,16 11 - 42,
					16 43 - 17 24, 17 26 - 18 32.
June 3 					16 42 - 17 12, 17 13 - 17 34.
					17 38 - 18 15.

Notes: 1. Times have been rounded off to the nearest minute.
2. Total Coverage: 4h20m.
3. Flare interval is underlined.
4. Photomultiplier: 1P21, unrefrigerated; d.c. amplifier;
Honeywell Brown Recorder; time constant
of the system: 1 sec.

                        [FIGURE 1]

The flare light curve, shown in fig. 1, seems difficult to fit in 
any of the standard Oskanyan Types. One could regard it as a rapid
succession of two Type I flares.

                         Table II 
Characteristics of Flares of June 1, 1973

UT_max                                   : I :       		16h37m24s

                                     	  II :     		16 38 42
Total duration of the flare              :   	                7.4 min.
	      
X_fm + s/X_s                             : I :       	        1.39
                                   	   II:     		2.11
Delta m_B                                : I :       	        0.36m
                                    	 : II:     		0.81m
sigma                                    : 		        0.314
Confidence level 3sigma/X_s              : 	                0.11
P                                    	 :		        1.31 min
F (z)                                    : I :    		1.91
                                     	   II:     		1.92

Energies released at flare maxima	 : I :	6.39 x 10^29  erg sec^-1
                                 	 : II:	9.71 x 10^29  erg sec^-1
Total emission during the
events                                   :		3.71 x 10^31 ergs.
	
Note: X_s is the average steady state intensity deflection minus
sky and X_f+s that due to flare plus X_s minus sky; X_fm+s
corresponds to flare maximum.

    Part of this work was done with financial assistance by
funds under the Smithsonian Institution Project No. SFG-O-6425.

Uttar Pradesh State Observatory,
Manora Peak, Naini Tal, India.


                               R.C. KAPOOR



References:
Kapoor, R.C., and Sinvhal, S.D., 1972, I.B.V.S. No. 750.
Kapoor, R.C., Sanwal, B.B., and Sinvhal, S.D., 1973, I.B.V.S. No. 810.