COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 953 Konkoly Observatory Budapest 1974 December 23 PHOTOELECTRIC OBSERVATIONS OF RW TAURI The eclipsing binary RW Tauri was observed by the author on two nights at the Fernbank Science Center Observatory for the purpose of obtaining times of primary minimum. These observations were made with the 91 cm Cassegrain reflector and an EMI 6256s photomultiplier. Because of the rapid light variations, only the yellow filter of the standard UBV system was used. All observations were made with respect to a twelfth magnitude comparison star located 1' north of RW Tauri as shown in Fig. 1. The magnitude difference in the sense variable minus comparison and the corresponding Julian dates are given in the table. The observations of universal date 21. November, 1974, are plotted in Fig. 2. The residual light that is evident just after second contact and just before third contact is due to luminous ring around the B component as explained by Grant (Ap.J. 129, 62, 1959). The method of Hertzsprung (BAN 4, 178, 1928) was used to calculate the time of minimum of 21 November, 1974. Only the ascending branch was observed on 17 March, 1974, and a tracing paper method [FIGURE 1] [FIGURE 2] was used for this time of minimum calculation. The times of minimum are given as: 17 March, 1974 JD(Hel) 2442123.498 21 November, 1974 JD(Hel) 2442372.6902 The (O-C)'s as calculated from Grant's period are -0.066 and -- -0.0704 respectively. OBSERVATIONS OF RW TAURI IN YELLOW LIGHT JD (Hel) V-C JD (Hel) V-C JD (Hel) V-C 2442000+ 2142000+ 2442000+ 123.5551 -2.310 123.6370 -3.620 272.7270 -1.235 .5567 -2.348 .6397 -3.638 .7283 -1.332 .5596 -2.441 123.6411 -3.675 .7320 -1.557 .5610 -2.480 372.6437 -1.803 .7330 -1.613 .5646 -2.640 .6452 -1.750 .7354 -1.763 .5659 -2.714 .6462 -1.690 .7366 -1.840 .5700 -2.751 .6497 -1.481 .7390 -1.969 .5713 -2.772 .6511 -1.391 .7403 -2.035 .5755 -2.822 .6591 -1.154 .7424 -2.119 .5769 -2.877 .6559 -1.107 .7441 -2.177 .5814 -3.026 .6582 -0.852 .7467 -2.275 .5826 -3.030 .6599 -0.703 .7483 -2.334 .5850 -3.064 .6634 -0.584 .7520 -2.465 .5863 -3.095 .6646 -0.566 .7537 -2.514 .5887 -3.125 .6677 -0.550 .7567 -2.605 .5901 -3.167 .6692 -0.546 .7589 -2.662 .5928 -3.164 .6722 -0.538 .7618 -2.731 .5940 -3.179 .6737 -0.541 .7629 -2.762 .5967 -3.213 .6768 -0.519 .7657 -2.838 .5979 -3.244 .6801 -0.507 .7669 -2.879 .6001 -3.246 .6816 -0.510 .7695 -2.933 .6013 -3.261 .6882 -0.518 .7709 -2.965 .6037 -3.320 .6897 -0.517 .7721 -2.987 .6050 -3.330 .6923 -0.515 .7751 -3.045 .6074 -3.373 .6938 -0.524 .7764 -3.066 .6086 -3.386 .6970 -0.535 .7776 -3.079 .6111 -3.431 .6989 -0.545 .7802 -3.112 .6123 -3.438 .7019 -0.521 .7814 -3.140 .6159 -3.482 .7036 -0.530 .7826 -3.158 .6173 -3.505 .7067 -0.528 .7854 -3.226 .6200 -3.544 .7082 -0.531 .7865 -3.245 .6213 -3.552 .7110 -0.531 .7878 -3.261 .6239 -3.596 .7127 -0.521 .7905 -3.289 .6250 -3.615 .7156 -0.554 .7916 -3.305 .6278 -3.679 .7173 -0.573 .7928 -3.316 .6290 -3.712 .7196 -0.673 .7961 -3.364 .6317 -3.687 .7210 -0.730 .7972 -3.367 .6329 -3.642 .7232 -0.906 .7985 -3.391 .6356 -3.628 .7246 -1.043 RICHARD M. WILLIAMON Fernbank Science Center Observatory Atlanta, GA 30307