Open Cluster Messier 39

Messier 39
Messier 39: Section of the STScI Digitized Sky Survey [147]


This large, loose star cluster was already discovered by Aristotle in 325 BC. Noticed as a meteoric appearing object. Charles Messier took it on October 24, 1764 as the 39th item in his list. [4, 196]

Physical Properties

The star cluster is of the Trumpler type III2p and has around 30 members, scattered over about 0.5° According to the H-R diagram of the cluster, practically all members are on the main sequence, except for the brightest pair, which are at the beginning of the evolution to the giant stage. The cluster is probably younger than M 44 but older than the Pleiades. The distance is about 310 pc. [4, 145]

«Revised New General Catalogue and Index Catalogue» Dr. Wolfgang Steinicke, 2021 [277]
DesignationNGC 7092
TypeOCL (III2p)
Right Ascension21h 31m 52.0s
Declination+48° 25' 30"
Diameter31.00 arcmin
Visual magnitude4.6 mag
Dreyer DescriptionCl, vL, vP, vlC, st 7…10
IdentificationM 39, OCL 211

Finder Chart

The star cluster is in the constellation Cygnus. The best observation time is from March to December.

Chart Messier 39
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]


4«Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System» by Robert Burnham; Dover Publications, Inc.; Voume I: ISBN 0-486-23567-X; Volume II: ISBN 0-486-23568-8; Volume III: ISBN 0-486-23673-0
145SIMBAD astronomical database;
147Aladin Lite; (2020-12-23)
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
196Celestial Atlas by Curtney Seligman; (2020-12-28)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)