COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 723 Konkoly Observatory Budapest 1972 October 11 CONTINUOUS PHOTOELECTRIC MONITORING OF EV Lac DURING THE INTERNATIONAL PATROL, SEPTEMBER 1-15, 1972 The flare star EV Lac has been monitored with the 30 cm Cassegrain reflector at the Oslo Solar Observatory of the Institute of Theoretical Astrophysics, University of Oslo. (Lambda=-0h43m02s, phi=+60d12'30", h=585 m). The observations were carried out in the international B- band with a 1P21 photomultiplier from RCA. The telescope and photometer system are described by Sivertsen (Ref. 1). During the 21.7 hours of monitoring 2 flares were observed. Detailed coverage is given in Table 1. Physical characteristics of the observed flares are given in Table 2, the quantities being presented according to proposals of Andrews et. al. (Ref. 2.). Due to the rapidly changing observing conditions we have found it necessary to prescribe a letter to each monitoring interval describing the standard fluctuations. (a),(b), and (c) refers to observing periods with sigma/I_0 <= 0.15, 0.15 0.25 are rejected. The figures present the smoothed light curves. [FIGURE 1] TABLE 1 MONITORING INTERVALS --------------------------------------------------------------------- Date Total 1972 Monitoring Sept. Monitoring intervals UT Time --------------------------------------------------------------------- 3-4 22h07m-22h28m(b),2232-2250 b, 2255-2308 (b), 2328-2345 (b), 2352-0010 (a), 0015-0053 (b), 0056-0215 (a), 0217-0225 (c), 0230-0245 (c), 3h 47m 4 2028-2034 (b), 2120-2139 (c), 2147-2151 (a), 2200-2246 (a), 2254-2303 (a), 2321-2327 (al, 2332-2336(b). 1 34 6 0000-0005(b), 0012-0025(a), 0029-0050(c), 0057-0115(a), 0121-0135(b), 0140-0224(b), 0229-0234(c), 2 00 7 0031-0036(c), 0038-0055(b), 0109-0112(b), 0114-0117(b) 0120-0138(b), 0 46 8-9 2000-2012(b), 2014-2050(b), 2100-2109(a), 2116-2141(a), 2147-2156(a), 2158-2210(a), 2215-2241(a), 2244-2254(a), 2256-0045(a), 0108-0130(a) 0134-0213(a), 0215-0227(a), 0235-0246(b) 5 32 11 1948-2023(a), 2031-2057(a), 2104-2121(b), 1 18 12-13 1952-2011(c) 2014-2027(b), 2032-2210(b), 2236-0033(b), 0033-0117(c), 0120-0132(c), 0149-0232(c). 5 46 14 2211-2223(c), 2230-2319(c), 1 01 Total 21h 44m ------------------------------------------------------------------- TABLE 2 OBSERVED FLARES ---------------------------------------------------------------------- Flare Date Max (I_f-I_0)/I_0 Deltam_B t_b t_a P_B sigma_B Air No 1972 UT mag min min min mag mass Sept ---------------------------------------------------------------------- 1 4 00h57.5m 0.50 0.44 0.33 2.66 0.57 0.09 1.19 2 12 21 41.5 0.41 0.35 0.37 3.00 0.60 0.14 1.04 ---------------------------------------------------------------------- Institute of Theoretical Astrophysics University of Oslo P.O. Box 1029, Blindern, Oslo 3. Norway. Oslo, Oct. 4, 1972 B. N. ANDERSEN B. R. PETTERSEN References: 1. Sivertsen, S.: Institute of Theoretical Astrophysics, Blindern, Oslo. Report No. 34, 1972. 2. Andrews, A.D., Chugainov, P.F., Gershberg, R.E., and Oskanian, V.S.: Comm. 27 IAU, I.B.V.S. No. 326. 1969. [From IBVS 791] ERRATA TO I.B.V.S. No.723. The UT times for EV Lac flare no. 2 presented in I.B.V.S. no.723 are 5 minutes wrong. The time interval on the light curve should run from 24h47m to 49m. In table 2 the time of maximum, Max UT, should be 21h46.5m. B.N. ANDERSEN, B.R. PETTERSEN