COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 750 Konkoly Observatory Budapest 1972 December 30 PHOTOELECTRIC SURVEILLANCE OF THE FLARE STARS YZ CMi, AD Leo AND EV Lac The results of the photoelectric patrolling of the dMe flare stars YZ CMi, AD Leo and EV Lac on a total of 28 nights, through a standard B filter, on a 56-cm reflector equipped with an unrefrigerated 1P21 photomultiplier, are herein reported. Tables Ia, Ib and Ic give details of the coverage of the stars. Four flares were recorded on the stars observed. Details of the flares, are given in Table II. The light curves of the flares show that while the flare of YZ CMi is reminiscent of a Type I flare in Oskanyan's classification (Oskanyan, 1969), those of AD Leo and EV Lac resemble his Type II. On a few nights the observations were taken by messers T.R. Bhatt and T.C. Tewari, to whom our thanks are due. Uttar Pradesh State Observatory, R.C. KAPOOR Manora Peak, Naini Tal, India. S.D. SINVHAL References: Erro, B.I.: 1971, Bol.Obs. Tonantzintla y Tacubaya, 6, 143. [BIBCODE 1971BITon...6..143E ] Oskanyan, V.S.: 1969, Non-periodic Phenomena in Variable Stars, Ed. L. Detre, Academic Press, Budapest 131. [BIBCODE 1969CoKon..65..131O ] Oskanyan, V.S.: 1970, I.B.V.S. No. 488. TABLE Ia COVERAGE OF YZ CMi (Times are rounded to the next minute of U.T.) ----------------------------------------------------------------- Date,1972 9 Feb. 17h15-18m, 17h21-33m, 17h35m-18h31m. 18 Feb. 17 04-24, 17 15-27, 21 Feb. 17 35-47, 17 51-18 13, 18 14-19, 18 22-41, 18 43-51, 18 53-56, 19 12-32, 19 35-43. 14 Mar. 15 06-29, 15 33-38, 15 42-58, 15 59-16 41, 16 44-17 02, 17 11-15, 17 18-22, 17 25-44, 17 46-18 09, 18 20-31, 18 34-19 04. 16 Mar. 15 02-23, 15 24-16 09, 16 11-15, 16 18-23, 16 30-52, 16 53-17 18, 17 27-18 03, 18 06-23, 18 39-19 05, 17 Mar. 15 03-16 16, 16 18-23, 16 29-17 18, 17 26-18 04, 18 06-27, 18 39-19 06, 18 Mar. 14 46-53, 14 55-15 37, 15 42-16 10, 16 17-17 04. 22 Mar. 14 14-39, 14 40-15 24, 15 26-59, 16 02-30, 16 35-45, 16 59-17 41, 17 43-18 28. 3 Apr. 15 13-15, 15 19-25, 15 28-43, 15 44-16 22, 16 28-17 02, 17 12-19, 17 20-22, 17 25-29, 17 36-39. 7 Apr. 14 46-15 38, 15 39-50, 15 52-16 18, 16 23-46, 16 48-17 07, 17 08-30. 6 May 14 57-15 31, 15 37-43. ----------------------------------------------------------------- Total Coverage: 24h30m spread over 11 nights TABLE Ib COVERAGE OF AD Leo (Times are rounded to the next minute of U.T.) ----------------------------------------------------------------------- Date,1972 11 Apr. 17h39m-18h24m, 18h25-34m, 18h36m-19h08m 19h10m-20h23m. 12 Apr. 16 12-17, 16 29-45, 16 47-17 01, 17 05-12, 17 17-53, 17 56-18 07, 18 10-23, 18 25-38, 18 39-59, 19 00-05, 19 07-18, 19 20-38, 19 39-20 08, 20 10-21. 14 Apr. 18 38-42, 18 44-49, 18 51-19 08, 19 10-16, 19 28-40, 19 41-46, 19 47-20 04, 20 05-24, 20 25-40. 3 May 14 46-52, 14 54-15 20, 15 24-35, 15 38-16 20, 16 24-48, 16 51-17 20, 17 31-18 00, 18 06-26, 18 31-49. 6 May 16 13-33. 7 May 15 37-56, 16 01-08, 16 12-36, 16 42-17 12, 17 13-35, 17 38-56, 18 00-12, 18 14-28, 18 31-35. 8 May 15 14-16 29, 16 32-34, 16 45-57, 17 04-07, 17 14-55, 17 57-18 18, 18 26-48. 9 May 16 17-23, 16 30-36, 16 38 -17 18, 17 23-39, 17 52-18 21, 18 27-19 09, 19 13-31. 10 May 15 37-39, 16 24-28, 16 32-49, 16 52-17 29, 17 33-46, 17 58-18 08, 18 09-25, 18 26-44, 18 46-56, 18 58-19 15. 12 May 14 42-44, 14 46-15 03, 15 04-21, 15 23-36. 15 May 15 21-30, 15 39-43, 15 45-51, 15 53-16 02, 16 04-21, 16 26-30. 16 May 15 15-38, 15 40-45, 16 50-17 20, 17 22-36, 17 39-46, 17 48-18 09. ---------------------------------------------------------------------- Total Coverage : 25h10m spread over 12 nights TABLE Ic COVERAGE OF EV Lac (Times rounded to the next minute of U.T.) ---------------------------------------------------------------- Date 27Oct.1971 16h29m-31m, 16h43m-53m, 16h55m-17h13m, 17 16-33, 17 35-47, 17 49-59, 18 01-14, 18 18-28, 18 30-19 03, 19 06-15, 19 16-18, 19 19-38, 19 45-49, 19 50-52. 2 Nov.1972 16 10-19, 16 20-40, 16 41-17 16, 17 17-18 03,18 05-19 02,19 03-19 41. 6 Nov.1972 16 44-17 12,17 16-27, 17 29-48, 17 52-18 43,18 59-19 30. 8 Nov.1972 15 26-15 30,16 31-18 54. 13Nov.1972 15 43-15 23,16 24-16 51,17 11-18 55. ---------------------------------------------------------------- Total Coverage : 14h33m spread over 5 nights [FIGURE 1] [FIGURE 2] [FIGURE 3] [FIGURE 4] TABLE II CHARACTERISTICS OF THE FLARES ON YZ CMi, AD Leo AND EV Lac^x --------------------------------------------------------------------------------------------------------------------------- Star Magnitude Date UTmax Flare duration Energy Excess and Before After released at energy colour t_b t_a flare max. liberated (Erro,1971) X_fm/Xs Delta_m_B sigma/Xs (10^29ergs/sec) during the P event min F(z) (10^30ergs) --------------------------------------------------------------------------------------------------------------------------- YZ CMi V=+11.20m 16 17h41m54s 1.6m 4.4m 0.61 0.52 0.006 0.67 1.51 1.75 4.37 B-V=+1.61m March 1972 AD Leo V=+9.43m 8 17h30m18s 1.0m 4.3m 0.52 0.46 0.004 0.90 2.19 7.02 24.81 B-V=+1.54m May 1972 EV Lac V=+10.09m 27 18h07m09s 1.8m 24.6m 0.30 0.26 0.022 1.41 1.28 1.02 6.80 Oct. 1971 B-V=+1.36m 13 17h44m37s 0.9m 15.4m 0.32 0.36 0.005 1.19 1.42 1.12 5.74 Nov. 1972 -------------------------------------------------------------------------------------------------------------------------- x_Based on notation proposed by Oskanyan (1970).