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Exception tests the rules

Detailed observations of an intermittent ultraluminous X-ray source indicate that its emission is unlikely to be powered by mass accretion onto an intermediate-mass black hole as previously thought. See Letter p.500

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Figure 1: The host galaxy of ultraluminous X-ray source M 101 ULX-1.



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Correspondence to K. D. Kuntz.

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Kuntz, K. Exception tests the rules. Nature 503, 477–478 (2013).

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