M40 is “ontdekt” door Charles Messier op 24 oktober 1764 terwijl hij op zoek was naar een nevel die gezien was door de Poolse Astronoom Johannes Hevelius. Maar hij vond geen nevel, alleen deze (optische) dubbelster. Waarschijnlijk zag Hevelius het balk/ringstelsel NGC4290, maar die was te zwak voor de telescoop van Messier. Dit staat in de eerste Messier catalogus uit 1777:
“The same night on October 24-25, [1764], I searched for the nebula above the tail of the Great Bear, which is indicated in the book Figure of the Stars, second edition: it should have, in 1660, the right ascension 183d 32′ 41″, & the northern declination 60d 20′ 33″. I have found, by means of this position, two stars very near to each other & of equal brightness, about the 9th magnitude, placed at the beginning of the tail of Ursa Major: one has difficulty to distinguish them with an ordinary (nonachromatic) refractor of 6 feet [FL]. Here are their positions: right ascension, 182 deg 45′ 30″, & 59 deg 23′ 50″ northern declination.”
Opname: 14 januari 2018, 15x 300 seconden Esprit 100/QHY16200 IDAS-LP2 filter. APP/PI