George Johnstone Stoney, Lord Rosse's assistant, discovered NGC 3180 on 25 Jan 1851. His description of NGC 3184 states "is triple, neby perhaps extends round them all as far as the * north." The 1 Feb 1856 description states: "The neby connecting the 3 principal knots is vvF but I have no doubt of its existence." R.J. Mitchell sketched the the spiral structure on 1 Feb 1856 (fig 13, Plate XXVII in the 1861 publication) and highlighted two brighter knots or sections of the western spiral arm.

900/1200mm - 48" (4/4/11): A small HII knot with a stellar core was visible 1.8' NW of the nucleus of NGC 3184. This small knot is within a larger, slightly brighter portion of the long, sweeping arm (shown on the sketch at Birr Castle) that wraps around the core of NGC 3184 on the south side before winding north on the west side and ending near NGC 3180.

Notes by Steve Gottlieb