NGC 2404

NGC 2404 is a massive H II region inside NGC 2403, a spiral galaxy in Camelopardalis. It was discovered on February 2, 1886 by Gulliaume Bigourdan. NGC 2404 is approximately 940 ly in diameter, making it one of the largest H II regions so far known. It is the largest H II region in NGC 2403, and lies at the outskirts of the galaxy, making for a striking similarity with NGC 604 in M33, both in size and location in the host galaxy. This H II region contains 30-40 Wolf-Rayet stars,^[5] and unlike the Tarantula Nebula, but similar to NGC 604, NGC 2404's open cluster is probably much less compact, so it probably looks like a large stellar association. This H II region is probably only a few million years old.

NGC 2404

Emission nebula
H II region
NGC 2404 is the giant H II region to the left
Observation data: J2000 epoch
Right ascension	07h 36m 51.4s[1]
Declination	+65° 36′ 09″[1]
Distance	9,650,000 ly   (2,960,000[2] pc)
Apparent magnitude (V)	+16.9
Apparent dimensions (V)	20 arcsecs[3]
Constellation	Camelopardalis
Physical characteristics
Radius	470 (estimated)[4] ly
Absolute magnitude (V)	-14.5
Notable features	Massive H II region, the largest one in NGC 2403.
See also: Lists of nebulae