Bindon or George Stoney discovered NGC 595 on 2 Feb 1851 with Lord Rosse's 72" (or perhaps on the 13 Sep 1850 observation, "full of knots") and an offset measured from a star superimposed just north of the core of M33. The nebula was labeled as "2" on the diagram in the 1861 publication. No coordinates were ever measured at Birr Castle.

Guillaume Bigourdan independently discovered IC 139 = B. 131, along with numerous other HII regions and star clouds in M33, on 28 Oct 1889. Bigourdan was credited with the discovery in the IC as Dreyer had no way of confirmng Stoney's #2 was the same object.

400/500mm - 17.5" (10/25/97): fairly faint, very small, round. Stands out nicely 6' N of the center of M33. Either contains a stellar spot near the center or a faint star is superimposed. This "stellar spot" is likely B324, the brightest individual star in M33 excluding Luminous Blue Variables. B324 is an A-type supergiant with a V magnitude of 15.2. IC 142 is the first of three HII regions in the spiral arm containing IC 142, IC 143 and ending with NGC 604.

600/800mm - 24" (12/28/13): B324, a highly luminous hypergiant and the brightest individual star in M33, appeared as a 15th magnitude star at the north edge of IC 142. At 325x, it was not resolved from the general glow, but appeared as a sharp stellar point just within the glow on the north side. IC 142 is nearly collinear with a mag 13.5 star 2.1' NW and a mag 11 star 2.9' NW. Globular Cluster U49 lies 3.3' NW.

Notes by Steve Gottlieb