It was discovered by Charles Messier on June 5, 1764[6] and added to his catalogue of comet-like objects that same year.

[7] The cluster is located 4.5° WSW of Theta Ophiuchi and is just visible as a fuzzy point of light using 50 mm (2.0 in) binoculars.

Using a telescope with a 25.4 cm (10.0 in) aperture, the cluster shows an oval appearance with a 3′ × 4′ core and a 5′ × 7′ halo.

[7] This flattening may not accurately reflect the physical shape of the cluster because the emitted light is being strongly absorbed along the eastern edge.

[10] Observations made during the ROSAT mission failed to reveal any low-intensity X-ray sources.