COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2371 Konkoly Observatory Budapest 19 July 1983 HU ISSN 0374-0676 PHOTOELECTRIC OBSERVATIONS OF epsilon AURIGAE DURING THE INGRESS UBV photoelectric observations reported here were made by members of JAPOA (Japan Amateur Photoelectric Observers Association) during the period of October 1982 to March 1983 covering the ingress. Being in co-operation with the international campaign of this remarkable binary star (e.g., Campaign Letters by Hopkins and Stencel 1982), several Japanese amateur astronomers participated in the UBV observations with their own telescopes furnished with photoelectric photometers. The observers and used telescopes are as follows: Observer Place Telescope T. Abe Niigata 30-cm reflector S. Ohmori Kanagawa 20-cm refractor T. Ohki and Fukushima 20-cm reflector H. Yoshinari [FIGURE 1] Light curves of Epsilon Aurigae Table I UBV Photoelectric Observations of Epsilon Aurigae ---------------------------------------------------------- Date(UT) Hel.JD U.mag B.mag V.mag Observer 2440000+ ---------------------------------------------------------- 1982 Sep.24 5239.15 4.452 4.067 3.529 OY Sep.28 5241.19 4.460 4.102 3.499 OY Oct. 3 5246.131 4.417 4.084 3.518 Ab .141 4.417 4.075 3.524 Ab Oct. 7 5250.089 4.427 4.116 3.518 Ab .101 4.450 4.125 3.563 Ab Oct.12 5255.15 4.465 4.096 3.552 OY Oct.13 5256.126 4.451 4.119 3.577 Ab .16 4.450 4.113 3.559 OY .173 4.458 4.115 3.566 Ab Oct.16 5259.14 4.477 4.088 3.576 OY Oct.18 5261.14 4.452 4.114 3.565 OY Oct.20 5263.118 4.125 3.586 Om .121 4.122 3.587 Om Oct.20 .17 4.473 4.119 3.585 OY Oct.22 5065.107 4.495 4.127 3.582 Ab .116 4.497 4.129 3.580 Ab .17 4.497 4.128 3.589 OY Oct.26 5269.12 4.481 4.132 3.596 OY Oct.27 5270.18 4.495 4.147 3.601 OY Oct.29 5272.089 4.490 4.156 3.614 Ab .150 4.592 4.158 3.619 Ab Nov. 3 5277.036 4.540 4.200 3.659 Ab .046 4.542 4.188 3.649 Ab Nov.12 5286.239 4.244 3.691 Om .242 4.249 3.691 Om Nov.13 5287.08 4.623 4.264 3.712 OY Nov.18 5292.06 4.742 3.738 OY Nov.30 5304.153 4.367 3.787 Om .164 4.374 3.800 Om Dec. 8 5312.13 4.731 4.373 3.804 OY Dec.14 5318.17 4.742 4.390 3.803 OY 1983 Jan.11 5345.08 4.715 4.333 3.793 OY Feb. 2 5375.002 4.361 3.810 Om .006 4.362 3.820 Om Feb. 4 5370.00 4.737 4.363 3.816 OY Feb.14 5380.01 4.705 4.354 3.813 OY Feb.15 5381.10 4.724 4.365 3.835 OY Feb.28 5394.959 4.380 3.829 Om .968 4.381 3.825 Om Mar. 5 5399.03 4.739 4.392 3.854 OY Mar. 9 5402.99 4.714 4.363 3.837 OY Mar.11 5405.953 4.378 3.827 Om .958 4.359 3.825 Om Mar.14 5408.933 4.351 3.917 Om .936 4.348 3.814 Om ---------------------------------------------------------- Abbreviation: T. Abe=Ab, S. Ohmori=Om, T. Ohki and H. Yoshinari=OY Actual observations were carried out differentially with respect to lambda Aur as the primary comparison star and standard stars of Johnson were also observed on each night to make it possible to reduce the individual observations to the standard UBV magnitudes. The observed nights are altogether thirty. The results of the observations are all listed in Table I and they are also plotted in Figure 1. From the figure, we can estimate the magnitudes in UBV of the bottom level to be U=4.74, B=4.28 and V=3.74, respectively. The epoch of the second contact can be estimated to be about JD 2445306, which is found to be 9 days earlier than predicted by Gyldenkerne (1970). Photometric reductions to the standard UBV system were carefully made by Ohmori with his computer PC 8801. The participated members of JAPOA would like to express their hearty thanks to Prof. M. Kitamura of Tokyo Astronomical Observatory for his encouragement and generous guidance. JAPOA (Japan Amateur Photoelectric Observers Association) c/o Geology Section Education Centre of Kanagawa Prefecture, Fujisawa City, Fujisawa 4210, Kanagawa, 251 Japan References: Gyldenkerne, K. 1970, Vistas in astronomy, Vol. 12, 199 [BIBCODE 1970VA.....12..199G ] Hopkins, J.L. and Stencel, R.E., 1982, Campaign letters for epsilon Aur 1982-84 eclipse