Messier 23

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title: "Messier 23" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["open-clusters", "orion–cygnus-arm", "sagittarius-(constellation)", "messier-objects", "ngc-objects", "astronomical-objects-discovered-in-1764", "discoveries-by-charles-messier"] description: "Open cluster in Sagittarius" topic_path: "general/open-clusters" source: "https://en.wikipedia.org/wiki/Messier_23" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Open cluster in Sagittarius ::

::data[format=table title="Infobox open cluster"]

Field	Value
name	Messier 23
image	M23 Open Star Cluster.png
caption	Open cluster Messier 23 in Sagittarius
epoch	J2000
ra
dec
dist_ly	628 pc
appmag_v	5.5
size_v
mass_msol	1,206
radius_ly	8 ly
age
constellation	Sagittarius
names	M23, NGC 6494, Cr 356, C 1753-190
::

| name = Messier 23 | image = M23 Open Star Cluster.png | caption = Open cluster Messier 23 in Sagittarius | epoch = J2000 | ra = | dec = | dist_ly = 628 pc | appmag_v = 5.5 | size_v = | mass_msol = 1,206 | radius_ly = 8 ly | age = | constellation = Sagittarius | notes = | names = M23, NGC 6494, Cr 356, C 1753-190

Messier 23, also known as NGC 6494, is an open cluster of stars in the northwest of the southern constellation of Sagittarius. It was discovered by Charles Messier in 1764. It can be found in good conditions with binoculars or a modestly sized telescope. It is in front of "an extensive gas and dust network", which there may be no inter-association. It is within 5° the sun's position (namely in mid-December) so can be occulted by the moon.

The cluster is centered about 2,050 light years away. Estimates for the number of its members range from 169 up to 414, with a directly-counted mass of ; by application of the virial theorem. The cluster is around 330 million years old with a near-solar metallicity of [Fe/H] = −0.04. The brightest component (lucida) is of magnitude 9.3. Five of the cluster members are candidate red giants, while orange variable VV Sgr in the far south, is a candidate asymptotic giant branch star.

A 6th-magnitude star, shown in the top-right corner, figures in the far north-west as a foreground star – HD 163245 (HR 6679). Its parallax shift is , having taken into account proper motion, which means it is about 101 pc away.

Gallery

File:M23map.png|Map showing the location of M23 File:M23 Eguivar.jpg|Open cluster Messier 23 in Sagittarius

References

1. {{Cite Gaia DR2. 4119588770476941312
2. "M 23".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::