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Winnecke 4

GenitiveUrsae Majoris
Right Ascension12h 23m 4s
Declination+57° 59' 28"
Brightest StarHD 238107
Optimum VisibilityApril (Usually visible from northern latitudes)
NotesM40 is unique in the Messier Catalogue as a simple optical double star (though it falls within a field of galaxies, and was perhaps catalogued incorrectly in place of one of these). The two stars of M40, HD 238107 and HD 238108, are in fact unrelated, and lie more than 200 light years from one another.