John Herschel discovered NGC 2669 = h3140 on 11 Apr 1834 and recorded "Cluster VIII class. A L, poor, loose cl of stars, 10...13m." The position was noted as very uncertain, with the RA to the nearest (+/-) minute. There is nothing resembling even a poor cluster near his position. Dreyer credited Persian astronomer Al-Sûfi with the discovery of NGC 2669, but Al-Sûfi mentioned IC 2391 instead.

According to Archinal and Hynes in "Star Clusters", in 1930 Robert Trumpler found the most likely candidate for Herschel's missing cluster. He noted "NGC 2669 - Declination of NGC corrected by +1°.", which corresponds with ESO 165-SC5. This cluster fits JH's description though Archinal comments that several of the stars are brighter than mag 10...13. He also mentions that Harvard 3 (from Shapley's 1930 Monograph on star clusters) refers to a part of NGC 2669.

300/350mm - 14" (4/3/16 - Coonabarabran, 145x and 178x): fairly rich group of ~60 stars in a 6' or 7' region, elongated N-S. Includes a mix of brighter mag 9.5-11 stars, along with a number of faint mag 14-15 stars. A mag 9.5 star and five mag 11-12 in a 1.5' N-S string, is on the northeast side. The cluster is bounded by a striking number of very bright stars including mag 7.6 HD 75105 off the southwest side, mag 8.2 HD 75227 and mag 7.7 HD 75202 off the north side, and mag 8.6 HD 75167 off the south side (20" pair with a mag 11 star). The group spans at least 12' to 14' if you include these bright stars. Located ~55' E of IC 2391 (surrounding mag 3.6 Omicron Velorum).

Notes by Steve Gottlieb