COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 810 Konkoly Observatory Budapest 1973 July 14 PHOTOELECTRIC MONITOR OF THE FLARE STARS AD Leo AND EV Lac Five flares were detected during a photoelectric monitor of the star AD Leo over a total of 22h19m spread over eight nights during the period 12 March - 4 May 1973. No flare on EV Lac could be detected over a coverage of nearly 2h between 4-6 December 1972. The details of observations are contained in Tables Ia and Ib. Table II records the flare characteristics of AD Leo which were computed using the same techniques and procedures as those employed earlier (Kapoor and Sinvhal, 1972). For all the energy calculations the quiescent state luminosity of the star was taken to be 1.25 x 10^29 erg sec^-1 100 A^-1 in the U filter and 8.2 x 10^29 erg sec^-1 100 A^-1 in the B filter with reference to Oke and Schild's (1970) calibration of alpha Lyr. The light curves of the flares, shown in Figs. 1, 3 and 4 imply that we have to do with Type II flares of Oskanyan (1969) although once again the classification is not too exact (see e.g., Kapoor and Sinvhal, 1972; Kapoor, 1973). The other flares (Figs. 2 and 5) seem to be Type I flares. Part of this work was carried out with financial assistance with PL 480 funds under Smithsonian Institution Project No. SFG-0-6425. Uttar Pradesh State Observatory R.C. KAPOOR Manora Peak, Naini Tal, India. B.B. SANWAL S.D. SINVHAL References: Kapoor, R.C., and Sinvhal, S.D., 1972, I.B.V.S. No. 750. Kapoor, R.C., 1973, I.B.V.S. No. 758. Oke, J.B. and Schild, R.E. 1970, Astrophys.J., 161, 1015. [BIBCODE 1970ApJ...161.1015O ] Oskanyan, V.S., 1969, Non-periodic Phenomena in Variable Stars Ed. L. Detre, Academic Press, Budapest, p. 131. [BIBCODE 1969CoKon..65..131O ] TABLE Ia COVERAGE OF AD Leo Date,1973 Telescope Filter Effective (Times rounded to the Coverage nearest minute of UT) 12 Mar. 56 - cm U 15h27m- 32m; 15h34m- 56m; 15 58 - 16h37m; 16 38 - 49 ; 17 01 - 50 18 27 - 31 ; 18 33 - 19 08; 19 09 - 39 ; 19 40 - 20 23. 14 Mar. 56 - cm B 18 13 - 42; 18 43 - 19 43; 20 08 - 24. 23 Mar. 56 - cm B 16 38 - 17 08; 17 09 - 14 ; 17 31 - 39; 17 44 - 48 ; 17 52 - 55; 17 59 - 18 12; 18 17 - 21; 18 42 - 50 ; 18 52 - 19 01; 19 06 - 18 ; 19 30 - 33. 25 Mar. 56 - cm B 15 22 - 29; 15 33 - 46; 15 48 - 16 10; 16 11 - 28; 16 37 - 59; 17 00 - 15; 17 20 - 36; 17 37 - 47; 17 50 - 53; 17 54 - 18 03; 18 04 - 20; 18 21 - 47; 18 48 - 19 09; 19 11 - 13; 19 14 - 17; 19 18 - 22; 19 23 - 40; 19 41 - 46. 27 Mar. 56 - cm B 15 05 - 24; 15 28 - 40; 15 41 - 54; 15 55 - 16 09; 16 10 - 14; 16 18 - 33; 16 34 - 17 15; 17 16 - 20; 17 21 - 32; 17 33 - 54; 17 55 - 18 24; 18 25 - 55; 18 56 - 19 20; 19 21 - 48; 19 49 - 20 12; 20 13 - 18; 20 20 - 33. 8 Apr. 104 - cm U 15 37 - 47; 15 50 - 59; 16 01 - 17 33; 17 35 - 18 25. 28 Apr. 104 - cm U 16 13 - 55; 16 57 - 59; 17 01 - 25; 17 30 - 19 17. 4 May 56 - cm B 15 57 - 16 00; 16 01 - 27; 16 28 - 59; 17 00 - 33; 17 34 - 18 02; 18 03 - 31; 18 33 - 19 00; 19 03 - 25; 19 27 - 36; 19 38 - 42; 19 43 - 51. Notes: 1. The flare intervals have been underlined. 2. TOTAL COVERAGE: 22h19m spread over eight nights. 3. Photomultiplier: 1P21, unrefrigerated. [FIGURE 1] TABLE Ib COVERAGE OF EV Lac Date,1972 Telescope Filter Effective (Times rounded to the Coverage nearest minute of UT) 4 Dec. 56 - cm B 16h25m- 29m; 16h32m- 59m; 17 00 - 12; 17 14 - 25. 6 Dec. 56 - cm B 15 26 - 33; 15 34 - 40; 15 42 - 16 10; 16 28 - 48 ; 16 51 - 59. Notes: 1. TOTAL COVERAGE: 2h03m spread over two nights. 2. Photomultiplier: 1P21, unrefrigerated. 3. No flare noticed. TABLE II CHARACTERISTICS OF THE FLARES ON AD LEONIS (dM4e:V=9.43m; U-V=2.61m) Date UTmax Flare Xfm+s/ Deltam sigma/X_s P (min) F (z) Energy Total 1973 duration X_s re- emission leased during tb ta at flare the flare- max. up (1029erg/s) (1030erg/s) 25 Mar. 19h02m27s 5.6m 12.5m 1.34 0.42 0.06 2.56 1.18 6.74 70.57 25 Mar. 19 36 48 2.0 6.0 1.02 0.02 0.06 0.43 1.29 4.66 11.85 8 Apr. 16 42 43 0.3 5.0 1.3 0.28 0.024 0.27 1.03 1.62 1.99 28 Apr. 17 10 06 1.38 18.05 1.46 0.41 0.038 1.99 1.24 1.82 14.93 4 May 16 29 14 0.9 3.5 1.3 0.28 0.021 0.24 1.19 5.95 6.53