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   PR # 11058
    SN1993J is the brightest supernova ever observed since 1972 except SN
    1987A. ASCA and ROSAT already detected X-rays from SN1993J only about
    10 days after the outburst. The optical light curve is quite unusual,
    showing two maxima and gradually decreasing. It is argued that radio-
    isotope 56Co and/or a newly born pulsar might be currently powering
    the light curve. If so, X-rays originated from nuclear gamma lines of
    56Co and/or from the pulsar could be contributing to the currently
    observed X-rays or would be observed in near future. X-rays from hot
    plasma produced by collision of supernova ejecta with circumstellar
    matter can also be an origin of X-rays. Continuous X-ray monitoring
    of SN1993J is very important and is rather duty of X-ray astronomy
   satellites currently working.
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