Philippe de Chéseaux discovered IC 4665 in 1745-46. Although his list of nebulae was presented to the Académie des Sciences in 1746 it was not generally known until published by Bigourdan in 1892. John Bode independently discovered the cluster around 1782 and as well as Caroline Herschel on 31 Jul 1783. Solon Bailey also found the cluster on a photographic plate in 1896 using a 1" (f/13) Cook lens at the Arequipa station. The discovery was reported in the 1908 "A Catalogue of Bright Clusters and Nebulae" (Annals of Harvard College Observatory, Vol LX, No. VIII) and Bailey was credited with the discovery in the IC.

200/250mm - 8" (5/80): very bright, very large, overfills 100x field (40'), scattered, includes ∑2212 = 8.5/9.0 at 3". Naked-eye cluster with averted vision (1.3° NNE of mag 2.8 Beta Oph) and bright and resolved in 10x50 binoculars.

Notes by Steve Gottlieb