aka NGC 6613, is an open cluster of stars in the constellation Sagittarius.
It was discovered by Charles Messier in 1764. M18 is situated between the Omega Nebula (M17) and the Small Sagittarius Star Cloud (M24).

This is a sparse cluster with a linear diameter of 8.04 pc, a radius of 7.3 pc, and is centrally concentrated with core radius of 0.012 pc. and a visual magnitude of 8.65.[4]

Messier 18 is 1,296 pc[2] from the Earth and 6,830 pc from the Galactic Centre.