Heinrich d'Arrest discovered NGC 1642 on 29 Dec 1861 with an 11" refractor at Copenhagen. His single position is accurate. He mentioned the nebula formed a right triangle with two mag 18 stars following, though the two stars are probably mag 14-15.

300/350mm - 13.1" (11/29/86): fairly faint, fairly small, slightly elongated, fairly diffuse, slightly brighter small core.

600/800mm - 24" (12/22/14): moderately bright and large, round, ~1.2' diameter, fairly sharply concentrated with a very small, bright core. Surrounded by a number of 14th and 15th magnitude stars! A mag 10.4 star lies 3.7' W.

UGC 3141 (double system) lies 8.4' NNE and appeared faint to fairly faint, fairly small, round, 30" diameter, low surface brightness, no core or zones.

Notes by Steve Gottlieb