Right Ascension	12 : 22.4 (h:m)
Declination	+58 : 05 (deg:m)
Distance	0.51 (kly)
Visual Brightness	8.4 (mag)
Apparent Dimension	0.8 (arc min)
Discovered by	John Helevius        1660

This faint double star was found by Charles Messier when he was searching for a nebula which was - erroneously - reported by the 17th-century observer Johann Hevelius in this vicinity. As Messier had measured the position of these stars, he gave them a number in his catalog. This fact gives some suggestion on how this catalog was compiled: Messier collected positions while he was cataloging the star clusters and nebula which could be taken for comets. M40 was apparently the last one he recorded when he was busy in checking the reports available to him in 1764.

This "object" or actually pair of stars is called Winnecke 4 because it was rediscovered in 1863 by A. Winnecke at Pulkova Observatory in Russia.

Messier observed M40 on October 24th, 1764 "Two stars very close to one another...."

Close by: 70 Ursa Majoris 1/2 degree SW (49" away).

Courtesy www.seds.org