COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 600 Konkoly Observatory Budapest 1971 December 21 PHOTOELECTRIC OBSERVATIONS OF THE FLARE STAR EV LAC DURING THE 1971, SEPTEMBER 11-27 INTERNATIONAL PATROL The preliminary results for the photoelectric observations of EV Lac carried out at the Catania Astrophysical Observatory during the observing period proposed by the IAU Working Group on Flare Stars (Andrews et al. 1971. IBVS 516), are given. The observations were made with a synchronous three colour photometer fed by a 61 cm universal type reflector. The patrol intervals in U.T. are given in Table 1. During the 20.5 hours of patrol time four flares were observed, the characteristics of which are given in Table 2. The U,B,V data were computed by means of mean transformation coefficients to the standard system. The light curves of the observed flares in the instrumental, u,b,v colours are shown in Figures 1-3. The explanation of symbols and details of the observing equipment can be found in a preceeding number of this Bulletin (Cristaldi and Rodono, 1971, IBVS 525). Catania Astrophysical Observatory, Italy December 6, 1971 S. CRISTALDI and M. RODONO Table 1. Detailed Coverage --------------------------------------------------------------------------------------- Date Total 1971 Light Coverage (U.T.) coverage 3sigma/I_o Sept. --------------------------------------------------------------------------------------- 11-12 b-v 21h02m-2109, 7m .04/.04 u-b-v 2109-2140; 2152-2213; 2233-2312; 2313-2400; 0000-0042;.0105-0242; 0244-0252; 0258-0322; 0325-0330 314 .22/.04/.04 12 u-b-v 2015-2027; 2034-2048; 2112-2137; 2157-2208; 2214-2228 74 .20/.04/,04 17 u-b-v 1912-1925 13 .19/.04/.04 18 u-v 2057-2114; 2119-2128 27 .20/ /.04 19 u-b-v 2008-2052; 2119-2251; 2255-2339 182 .19/.04/.04 20-21 u-b-v 1900-1941; 1952-2039; 0008-0050; 0114-0249; 0302-0336 253 .20/.05/.03 21-22 u-b-v 2141-2224; 2250-2303; 2309-2400; 0000-0101; 0104-0130; 0149-0152 197 .17/.04/.03 24 b-v 00h14m-0033; 0035-0054 38 .04/.03 u-b-v 0054-0132 38 .21/.04/.03 25 u-b-v 0039-0208 87 .17/.04/.03 --------------------------------------------------------------------------------------- Table 2. Characteristics of Flares ------------------------------------------------------------------------------------------------- E n e r g y t_max(U.T.) JD. 3sigma/I_0r P Air f sky no. Light September 244... d_b d_a (I_f / I-0)_max erg mass ------------------------------------------------------------------------------------------------- 1/71b b 11, 21 05.2 1206.3822 0.9 9.8 0.04 0.59 1.22 0.85 3 0 v 21 05.2 0.2 4.8 0.04 0.18 0.21 B 0.53 1.09 2.41x10^31 v 0.13 0.13 6.80x10^30 2/71a n 11, 23 28.0 1206.4814 0.4 15.0 0.22 3.10 8.18 0.84 2 0 b 23 28.1 0.7 7.0 0.04 0.45 0.98 v 23 27.8 0.1 6.0 0.04 0.11 0.20 U 2.81 7.51 2.37x10^31 B 0.40 0.88 1.94x10^31 V 0.10 0.13 6.71x10^30 3/71 u 20, 19 54.6 1215.3334 0.3 3.6 0.20 23.64 23.92 0.88 0 1 b 19 54.6 0.2 2.4 0.05 2.38 1.34 v 19 54.6 0.2 2.4 0.03 0.76 0.46 U 20.44 20.41 6.45x10^31 B 2.12 1.21 2.68x10^31 V 0.63 0.37 1.88x10^31 4/71 u 22, 00 32.6 1216.5265 0.6 2.5 0.17 1.34 1.14 0.96 0 2 b 00 32.6 0.4 1.1 0.04 0.21 0.13 v (not detectable) 0.03 U 1.23 1.05 3.35x10^30 B 0.18 0.11 2.63x10^30 --------------------------------------------------------------------------------------------------- [FIGURE 1] [FIGURE 2] [FIGURE 3]