COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 1181 Konkoly Observatory Budapest 1976 September 23 PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR BY Dra IN 1973, 1974 Continuous photoelectric monitoring of the flare star BY Dra has been carried out at the Stephanion Observatory (lambda=-22d49'44" phi=+37d45'15") during the years 1973, 1974 using the 30-inch Cassegrain reflector of the Department of Geodetic Astronomy, University of Thessaloniki. Observations have been made with a Johnson dual channel photoelectric photometer in the B colour of the international UBV system. The telescope and photometer will be described elsewhere. Here we mention only that the transformation of our instrumental ubv system to the international UBV system is given by the following equations: V = v_0+ 0.053(b-v)_0+ 2.380, B - V = 0.858 + 1.043(b-v)_0, U - B = -1.782 + 1.020(u-b)_0. The monitoring intervals in UT as well as the total monitoring time for each night are given in the Tables Ia, Ib. Any interruption of more than one minute has been noted. In the fourth column of Tables Ia, Ib the standard deviation of random noise fluctuation sigma(mag) = 2.5 log(I_0+sigma)/I_0 for different times (UT) of the corresponding monitoring interval is given. During the 60.63 hours of monitoring time 2 flares were observed the characteristics of which are given in Table II. For each flare following characteristics (Andrews et al. 1969) are given: a) the date and universal time of flare maximum (t_b and t_a, respectively), as well as the total duration of the flare, c) the value of the ratio (I_f-I_0)/I_0 corresponding to flare maximum, where I_0 is the intensity deflection less sky background of the quiet star and I_f is the total intensity deflection less sky background of the star plus flare, d) the integrated intensity of the flare over its total duration, including pre-flares, if present, p = integral(I_f-I_0)/I_0 dt, e) the increase of the apparent magnitude of the star at flare maximum deltam(b) = 2.5log(I_f/I_0), where b is the blue magnitude of the star in the instrumental system, f) the standard deviation of random noise fluctuation sigma(mag) = 2.5 log(I_0+sigma)/I_0 during the quiet - state phase immediately preceding the beginning of the flare and g) the air mass at flare maximum. The light curves of the observed flares in the b colour are shown in Figs 1,2. M.E. CONTADAKIS, G. KAREKLIDIS, F. MAHMOUT L.N. MAVRIDIS, D. STAVRIDIS, E. ZERVAKI - ZOEROU Department of Geodetic Astronomy University of Thessaloniki References: Andrews, A.D., Chugainov, P.F., Gershberg, R.E. and Oskanian, V.S.: I.B.V.S. No. 326, 1969 T a b l e Ia. ------------------------------------------------------------------------------------------------------------------------ Total Monitoring sigma(U.T.) Date Monitoring interval (U.T.) Time ------------------------------------------------------------------------------------------------------------------------ 1973 May 19 21h19m - 21h51m, 22h04m - 22h17m, 22h19m - 22h29m, 0.01(21h49m), 0.01(22h20m), 23 02 - 23 08 , 23 11 - 23 22 , 23 30 - 23 42 , 0.01(23 20 ), 0.01(23 31 ) 23 46 - 23 54 , 23 59 - 24 00 . 1h23m 20 00 02 - 00 05 , 00 08 - 00 15 , 00 21 - 00 42 , 31 0.01(00 22 ) 24 21 32 - 21 39 , 21 40 - 21 51 , 21 54 - 22 04 , 0.02(21 41 ), 0.02(22 35 ), 22 06 - 22 07 , 22 10 - 22 22 , 22 25 - 22 48 , 0.01(23 23 ). 22 50 - 22 52 , 22 56 - 23 06 , 23 08 - 23 19 , 23 21 - 23 31 , 23 32 - 23 44 , 23 45 - 23 51 , 23 59 - 24 00 . 1 56 25 00 00 - 00 09 , 00 10 - 00 23 , 00 24 - 00 35 , 0.01(00 29 ), 0.01(01 45 ), 01 33 - 01 47 . 47 30 20 51 - 21 04 , 21 08 - 21 38 , 21 40 - 22 17 , 0.01(20 54 ), 0.01(21 25 ), 22 27 - 22 59 , 23 04 - 23 14 , 23 16 - 23 27 , 0.01(21 52 ), 0.01(22 34 ), 23 29 - 23 39 , 23 42 - 24 00 . 2 41 0.01(23 31 ), 0.01(23 54 ). 31 00 00 - 00 04 , 00 08 - 00 17 , 01 34 - 01 43 . 22 0.01(01 35 ). June 2 22 04 - 22 17 , 22 19 - 22 31 , 22 34 - 22 58 , 0.01(22 20 ), 0.01(22 48 ), 23 02 - 23 13 , 23 15 - 23 26 , 23 28 - 23 31 , 0.01(23 16 ), 0.01(23 54 ). 23 40 - 24 00 . 1 34 T a b l e Ia (Continued) --------------------------------------------------------------------------------------------------------------------------------------- June 3 00h00m - 00h03m, 00 05m - 00h07m, 01h11m - 01h19m, 0.01(01h34m) 01 22 - 01 31 , 01 32 - 01 39 . 29m 9 19 52 - 20 04 , 20 07 - 20 19 , 20 23 - 20 38 , 0.011(20 12 ), 0.010(20 31 ), 0.008(21 10 ), 20 41 - 20 48 , 20 50 - 21 05 , 21 07 - 21 19 , 0.008(21 42 ), 0.008(22 19 ), 0.006(22 35 ) 21 28 - 21 35 , 21 37 - 21 49 , 21 51 - 21 59 , 22 03 - 22 14 , 22 17 - 22 27 , 22 31 - 22 39 , 22 40 - 22 47 , 22 49 - 22 58 , 23 54 - 24 00 . 2 31 10 00 00 - 00 04 , 00 06 - 00 14 , 00 16 - 00 24 , 0.006(00 08 ), 0.006(00 48 ), 0.009(20 03 ), 00 29 - 00 35 , 00 37 - 00 45 , 00 47 - 00 54 , 0.006(20 37 ), 0.006(20 57 ), 0.006(21 39 ), 19 51 - 20 06 , 20 08 - 20 16 , 20 19 - 20 25 , 0.006(22 11 ), 0.006(22 35 ). 20 26 - 20 41 , 20 43 - 20 47 , 20 51 - 21 03 , 21 06 - 21 16 , 21 27 - 21 37 , 21 39 - 21 46 , 21 48 - 21 57 , 22 01 - 22 07 , 22 09 - 22 21 , 22 23 - 22 26 , 22 30 - 22 39 , 22 41 - 22 59v. 3 05 11 00 42 - 00 51 , 00 53 - 01 02 , 01 04 - 01 11 , 0.006(01 05 ), 0.007(20 38 ), 0.008(21 14 ), 01 13 - 01 21 , 20 20 - 20 34 , 20 36 - 20 50 , 0.007(21 48 ), 0.006(22 24 ). 0.007(22 55 ), 20 53 - 21 07 , 21 10 - 21 24 , 21 28 - 21 40 , 0.005(23 24 ). 21 44 - 21 56 , 22 06 - 22 19 , 22 21 - 22 33 , 22 39 - 22 49 , 22 53 - 23 03 , 23 06 - 23 10 , 23 13 - 23 19 , 23 20 - 23 29 , 23 32 - 23 40 . 3 05 12 01 22 - 01 30 , 01 33 - 01 42 . 17 0.005(01 28 ) 13 20 29 - 20 43 , 20 45 - 20 59 , 21 04 - 21 14 , 0.008(20 48 ), 0.006(21 11 ), 0.009(21 53 ), 21 16 - 21 23 , 21 25 - 21 29 , 21 32 - 21 46 , 0.006(22 21 ), 0.006(22 43 ), 0.008(23 22 ), 21 48 - 22 00 , 22 09 - 22 13 , 22 19 - 22 29 , 22 32 - 22 36 , 22 40 - 22 50 , 22 54 - 23 04 , 23 09 - 23 18 , 23 21 - 23 30 , 23 33 - 23 37 . 2 15 T a b l e Ia (Continued) ---------------------------------------------------------------------------------------------------------------------------------------------- June 14 01h06m - 01h14m, 01h17m - 01h24m, 01h27m - 01h36m , 24 0.006(01h29 ). 19 21 56 - 22 24 , 22 26 - 22 57 . 59 0.010(22 15 ), 0.010(22 40 ). 20 00 38 - 01 05 , 01 07 - 01 41 , 21 28 - 21 52 , 0.006(00 51 ), 0.009(01 32 ),0.008(21 35 ), 21 55 - 22 25 , 22 27 - 23 01 . 2 19 0.011(22 21 ), 0.011(22 31 ). 21 00 58 - 01 37 , 01 40 - 01 47 , 20 08 - 20 29 , 0.009(01 10 ), 0.009(20 16 ),0.007(20 49 ), 20 32 - 20 59 , 21 01 - 21 29 , 21 37 - 22 05 , 0.008(21 23 ), 0.007(22 02 ),0.008(22 22 ). 22 07 - 22 30 . 2 53 22 22 43 - 22 52 , 23 45 - 24 00 . 24 0.009(22 47 ), 0.007(23 57 ). 23 00 00 - 00 10 , 00 13 - 00 41 , 00 56 - 01 27 , 0.009(00 25 ), 0.009(01 20 ). 01 30 - 01 38 1 17 24 20 11 - 20 36 , 20 38 - 21 11 , 21 15 - 21 44 , 0.010(20 23 ), 0.011(20 44 ), 0.012(21 23 ), 22 43 - 23 03 , 1 47 0.008(22 56 ). 25 20 05 - 20 34 , 20 37 - 21 10 , 21 12 - 21 44 , 1 34 0.011(20 27 ), 0.009(20 42 ), 0.009(21 20 ). 26 21 41 - 22 09 , 22 11 - 22 43 . 1 00 0.008(21 55 ), 0.009(22 29 ). 27 20 34 - 21 02 , 21 04 - 21 16 , 21 17 - 21 34 , 0.006(20 56 ), 0.007(21 19 ), 0.007(22 03 ). 21 36 - 22 09 . 1 30 28 20 00 - 20 28 , 20 30 - 21 07 , 21 10 - 21 45 , 0.008(20 06 ), 0.010(20 54 ), 0.011(21 34 ), 21 51 - 22 22 . 2 11 0.008(22 12 ). 29 20 08 - 20 41 , 20 44 - 21 12 , 21 16 - 21 45 , 1 30 0.008(20 27 ), 0.007(21 01 ), 0.007(21 28 ). 30 19 53 - 20 19 , 20 22 - 20 53 , 20 55 - 21 29 , 21 37 - 21 55 . 1 49 0.010(19 58 ), 0.006(20 29 ), 0.008(21 00 ), 0.007(21 44 ). July 1 21 46 - 22 05 , 22 07 - 22 14 , 22 16 - 22 49 , 59 0.012(21 48 ), 0.007(22 28 ) 2 20 53 - 21 24 . 31 0.009(20 59 ). Total 42h03m T a b l e Ib --------------------------------------------------------------------------------------------------------------------------------------------- Total Monitoring sigma(U.T.) Date Monitoring interval (U.T.) Time --------------------------------------------------------------------------------------------------------------------------------------------- 1974 July 6 21h08m- 21h36m, 21h38m - 22h06m, 22h08m - 22h18m, 0.01(21h27m), 0.01(21h46 ), 23 02 - 23 32 , 23 47 - 24 00 . 1h49 0.01(23 05 ), 0.01(23 50 ). 7 00 00 - 00 18 , 00 21 - 00 44 41 0.01(00 34 ). 10 20 08 - 20 38 , 20 41 - 21 03 , 21 07 - 21 11 , 0.01(20 23 ), 0.01(20 59 ), 21 14 - 21 26 , 21 30 - 21 32 , 21 33 - 21 35 , 0.01(21 19 ). 21 39 - 21 48 . 1 21 11 20 21 - 20 50 , 20 53 - 21 19 , 21 26 - 21 41 , 0.01(20 31) , 0.01(20 57 ), 21 44 - 21 55 . 1 21 0.01(21 33 ). 14 20 42 - 21 07 , 21 09 - 21 48 , 22 13 - 22 28 , 0.01(20 50 ), 0.01(21 20 ), 22 31 - 22 44 , 23 50 - 24 00 . 1 42 0.01(22 32 ). 15 00 00 - 00 25 , 00 27 - 01 02 , 22 37 - 23 09 , 0.01(00 04 ), 0.01(00 39 ), 23 13 - 23 18 , 23 33 - 23 48 , 23 50 - 34 00 . 2 02 0.01(23 03 ), 0.01(23 35 ), 0.01(23 51 ). 16 00 00 - 00 26 , 00 31 - 00 37 , 20 23 - 20 44 , 0.01(00 33 ), 0.01(20 38 ), 0.01(21 28 ), 20 50 - 20 54 , 20 57 - 21 32 , 21 35 - 21 51 , 0.01(21 37 ). 22 00 - 22 07 . 1 55 17 20 05 - 20 33 , 20 37 - 21 10 , 21 13 - 21 36 , 0.01(20 11 ), 0.01(21 03 ), 21 38 - 21 41 . 1 27 0.01(21 17 ). 19 20 22 - 20 53 , 20 56 - 21 14 , 21 18 - 21 24 , 0.01(20 44 ), 0.01(20 59 ), 21 28 - 21 48 , 21 53 - 21 59 . 1 21 0.01(21 39 ). August 6 20 10 - 20 39 , 20 42 - 21 15 , 21 17 - 21 37 , 0.005(20 21 ), 0.004(20 44 ), 21 53 - 22 19 , 22 21 - 22 49 , 22 52 - 23 20 , 0.005(21 19 ), 0.005(22 04 ), 0.008(22 42 ), 23 32 - 23 55 , 3 07 0.007(23 02 ), 0.008(23 49 ). T a b l e Ib (Continued) ------------------------------------------------------------------------------------------------------------------------------------------- August 7 00h02m- 00h29m, 00h33m- 01h00m, 19h52m- 20h25m, 0.008(00 05 ), 0.007(00 35), 0.007(20 17), 21 17 - 21 49 . 1 42 0.006(21 21 ). Total 18h35m T a b l e II Characteristics of the Flares Observed -------------------------------------------------------------------------------------------------------------------------------------------- Date Flare 1974 U.T. t_b t_a Duration (I_f-I_0)/I_0 P deltam sigma Air No. July max. min min. max. min mag mag mass min. -------------------------------------------------------------------------------------------------------------------------------------------- 1 10 20h12.2m 0.8 1.3 2.1 0.025 0.012 0.027 0.005 1.08 2 14 22 14.2 0.6 13.3 13.9 0.310 0.720 0.300 0.010 1.04 [FIGURE 1]