SN 1993 J
This image shows the region around the spiral galaxy M81 observed with the ROSAT PSPC in 1992 and 1993. SN 1993J (the 10th or 'Jth' supernova observed in 1993 and marked by the arrow) lies in the lower left side of the image. You can see that briefly the supernova outshines the entire galaxy in the X-ray band of the spectrum.
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