COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS NUMBER 553 Konkoly Observatory Budapest 1971 May 24 PHOTOELECTRIC OBSERVATIONS OF YZ CMi AND AD Leo Continuous photoelectric monitoring of the flare stars YZ CMi and AD Leo was made at the Crimean Astrophysical Observatory with the 64-cm meniscus telescope in the photometric system B during the planned periods of X-ray observations of the same stars by the NASA ASE Group. The coverage, characteristics of the observed flares and their light curves are given below. A. Kulapova has collaborated these observations. ------------------------------------------------------- Star Date, 1971 Coverage (U.T.) ------------------------------------------------------- YZ CMi 19 March 1755-2110,2113-2117,2118-2119, 2121-2125,2127-2144 10 March 1716-1744,1745-2126 AD Leo 15 April 1834-1835,1836-1944,1946-2016, 2017-2053,2057-2111,2113-2145, 2147-2207,2209-2222 ------------------------------------------------------- ----------------------------------------------------------------------------------- Star Date,1971 UT_max t_b t_a (I_fl - I_0)/I_0 P F(z) minutes sigma/I_0 min. ----------------------------------------------------------------------------------- YZ CMi 19 March 17h59.0m 0.2 0.2 0.23 0.05 0.04 1.33 19 March 18 26.7 0.3 4.3 0.18 0.05 0.42 1.35 20 March 17 23.4 0.4 10.0 0.47 0.05 0.86 1,33 20 March 18 30.1 2.5 50.0 4.81 0.05 16.2 1.36 AD Leo 15 April 20 50.6 0.1 1.4 0.08 0.02 0.04 1.27 ----------------------------------------------------------------------------------- P. F. CHUGAINOV, N. I. SHAKHOVSKAYA Crimean Astrophysical Observatory [FIGURE 1]