Nature 330, 230 - 231 (19 November 1987); doi:10.1038/330230a0

Discovery of an unusual hard X-ray source in the region of supernova 1987A

T. Dotani^*, K. Hayashida^*, H. Inoue^*, M. Itoh^*, K. Koyama^*, F. Makino^*, K. Mitsuda^*, T. Murakami^*, M. Oda^*, Y. Ogawara^*, S. Takano^*, Y. Tanaka^*, A. Yoshida^*, K. Makishima^†, T. Ohashi^†, N. Kawai^‡, M. Matsuoka^‡, R. Hoshi^§, S. Hayakawa, T. Kii, H. Kunieda, F. Nagase, Y. Tawara, I. Hatsukade^¶, S. Kitamoto^¶, S. Miyamoto^¶, H. Tsunemi^¶, K. Yamashita^¶, M. Nakagawa^£, M. Yamauchi^£, M. J. L. Turner^**, K. A. Pounds^**, H. D. Thomas^**, G. C. Stewart^**, A. M. Cruise^††, B. E. Patchett^†† & D. H. Reading^††

^*Institute of Space and Astronautical Science, Komaba, Meguro-ku, Tokyo, Japan
^†Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan
^‡Institute of Physical and Chemical Research, Wako, Saitama, Japan
^§Department of Physics, Rikkyo University, Nishi-Ikebukuro, Toshima-ku, Tokyo, Japan
Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya, Japan
^¶Department of Physics, Osaka University, Toyonaka, Japan
^£Department of Physics, Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka, Japan
^**Department of Physics, University of Leicester, Leicester LEI 7RH, UK
^††Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK

We have discovered a new hard X-ray source near supernova 1987 A, in the Large Magellanic Cloud, from the X-ray astronomy satellite Ginga. The present error box of 0.2^° 0.3^° includes the supernova. The energy spectrum is very hard above 10 keV and unusual for any of the known classes of X-ray source. The flux in the range 10–30 keV as of 2–3 September is ~510^–11ergcm^–2 s^–1. The source intensity increased steadily throughout July, August and early September, but an observation in late September revealed no further increase. The positional agreement, a steady brightening and an unusual hard spectrum support the identification of the source as SN1987A.

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