Messier 40 (M40), also known as Winnecke 4 (WNC 4), is a double star located in the constellation Ursa Major, the Great Bear.
M40 lies at a distance of 510 light years from Earth. It is one of the few Messier objects that are not deep sky objects, but were catalogued by mistake. It was not listed in the New General Catalogue (NGC).
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