M39

M39 = NGC7092 ( 21h 32.3m +48°26´, 4.6 mag. )
This large open cluster in Cygnus was discovered by LeGentil in 1750 but Aristotle mentioned it in 325 B.C. Messier observed it on October 24, 1764. It is about 950 ly away and measures 7 ly across.

M39 (NGC 7092) is large and scattered and equally unspectacular; a group of faint (seventh magnitude) stars forming a rough triangle. It is nine degrees ENE of alpha Cygni.

M39 cannonM39 lens mountM3 (album)
M3 (Cape Town)M3 37 mm gunM3 Communications Group, Inc
M3 Grease GunM3 Half-trackM3 Lee ...

M29 (open cluster)
M39 (open cluster)
Deneb, along with Altair and Vega form the well-known Summer Triangle.
Another famous object in Cygnus is Cygnus X-1, a black hole candidate.

Located in the constellation Cygnus, M39 is a very loose cluster of about 30 stars. It lies only 800 light-years from Earth, which makes it one of the closest open clusters in the sky.

Orion Arm: The Orion Nebula M42 is located in our Arm. Celestial Objects 1000 LY to 100 LY from the Sun: M39, M44, M45. Celestial Objects 100 LY to 16LY From the Sun. Celestial Objects less than 16 LY from the Sun: List of nearest stars ...

The lens mount is an important issue for compatibility between cameras and lenses; each major camera manufacturer typically has their own lens mount which is incompatible with others; notable exceptions are the Leica M39 lens mount for rangefinders, ...

About nine degrees east and a bit north of alpha Cyg is the open star cluster M39 located. Only about 50 stars belong to this quite large cluster which has therefore a somewhat loose appearance.

See also: Cluster, Open, Cygnus, Deneb, Sky