Open Cluster Messier 18
Object Description
About one degree south of the magnificent galactic nebula M 17 les the small open star cluster Messier 18. It was discovered on 3 June 1764 by Charles Messier, who described it as a cluster of small stars surrounded by a little nebula. This impression of nebulosity is caused by numerous fine background stars, which are too faint to be resolved. Modern recordings, however, show a delicate hint of a nebula surrounding the pile, but this is far too faint for Messier to detect with his rather modest instruments.
M 18 is one of the neglected Messier objects and is often not included in lists of galactic star clusters. The distance is given as about 4900 light years. [4]
| Designation | NGC 6613 |
| Type | OCL (II3pn) |
| Right Ascension (J2000.0) | 18h 19m 58.0s |
| Declination (J2000.0) | -17° 06' 06" |
| Diameter | 7 arcmin |
| Visual magnitude | 6.9 mag |
| Metric Distance | 1.296 kpc |
| Dreyer Description | Cl, P, vlC |
| Identification, Remarks | M 18, OCL 40 |
Finder Chart
M 18 is located in the constellation Sagittarius, roughly in the middle between the Omega Nebula (M 17) and the Small Sagittarius Cloud (M 24). Connect the two stars Kaus Borealis (λ Sagittarii) and γ Scuti. Position the Telrad west of it so that the outermost Telrad circle is on the line.
