Guillaume Bigourdan discovered NGC 2404 = Big. 28, a superassociation/HII region in NGC 2403, on 2 Feb 1886 with the 12.4-inch refractor of Paris Observatory. The NGC position, based on Bigoudan's original published position in list I, is in error but Bigourdan later measured and published an accurate position in his five volume (3000 pages) compilation (Annales de l'Observatoire de Paris). RNGC classifies the number as nonexistent (Type 7), although Type 35 (diffuse nebula in galaxy) would be more appropriate.

300/350mm - 13" extremely small emission "knot" at the east end of NGC 2403.

400/500mm - 17.5" (2/22/87): this is a prominent knot (superassociation) located at the end of the northern spiral arm of NGC 2403. Appears fairly faint, small, round, clearly nonstellar.

600/800mm - 24" (2/24/20): brightest HII complex in NGC 2404. At 375x appeared fairly bright, slightly elongated or irregular, ~15" diameter.

900/1200mm - 48" (4/15/10): The supergiant HII complex NGC 2404 (perhaps 2000 light-years across) is located 1.7' ENE of the core and 1.5' NNW of a superimposed mag 10.5 star. It appeared as a very bright, irregular, 20" knot. At the relatively low power of 330x, I quickly logged 8 HII knots in the galaxy (see description of NGC 2403).

Notes by Steve Gottlieb