James Dunlop discovered D 333 = h3577 on 8 May 1826 and described "a group of small stars with faint nebula. There is rather a gathering of the nebulous matter, about 10 arcseconds diameter, near the north side." His position was 10' west of center. JH observed this cluster on 9 Jul 1834 and logged, "cluster VII. Pretty rich, stars 11..13th mag, irregular, scattered,10' diameter, rather more comp M." JH credited Dunlop with the discovery.

300/350mm - 14" (4/3/16 - Coonabarabran, 178x): this cluster appears to extend 7' to 8' in diameter but the eye-catching portion is a small, distinctive group of similar mag stars on the west side, forming an striking oval ring or loop. Within this 2.5' curving chain are roughly two dozen, mostly mag 12.5-13.5 stars and the interior of the loop is nearly devoid of stars. A mag 10.7 star is a couple of arcminutes east. Roughly 50 additional stars are in the surrounding portion of cluster, for a total of ~75 stars. A mag 9.3 star (HD 129144) is 5' S.

Notes by Steve Gottlieb