M39 · open cluster

Messier 39

Messier 39 or M39, also known as NGC 7092, is an open cluster of stars in the constellation of Cygnus, sometimes referred to as the Pyramid Cluster.

RA21h 31m 48sDec+48° 26' 17"

Image: Chuck Ayoub. CC0, via Wikimedia Commons.

Identity & coordinates

Identification

Primary designation: M39
All designations: M39 · NGC 7092
Object type: Open Cluster
Constellation: Cygnus
Best viewing: Summer · Autumn

Coordinates & physical

Right ascension (J2000): 21h 31m 48s
Declination (J2000): +48° 26' 17"
Apparent magnitude (V): —
Distance: —

III

Visibility tonight

The science

Messier 39 or M39, also known as NGC 7092, is an open cluster of stars in the constellation of Cygnus, sometimes referred to as the Pyramid Cluster. It is positioned two degrees south of the star Pi Cygni and around 9° east-northeast of Deneb. The cluster was discovered by Guillaume Le Gentil in 1749, then Charles Messier added it to his catalogue in 1764. When observed in a small telescope at low power the cluster shows around two dozen members but is best observed with binoculars. It has a total integrated magnitude (brightness) of 4.6 and spans an angular diameter of 29 arcminutes – about the size of the full Moon. It is centered about 1,010 light-years away.

Summary adapted from Wikipedia · CC-BY-SA-4.0