Also known as the Monkey head Nebula
Open Cluster NGC 2175 (also known as
OCL 476 or
Cr 84) is an
open cluster in the
Orion constellation, embedded in a diffusion nebula. It was discovered by
Giovanni Batista Hodierna before 1654 and independently discovered by
Karl Christian Bruhns in 1857. NGC 2175 is at a distance of about 6,350
light years away from
Earth.
The nebula surrounding it is
Sharpless catalog Sh 2-252.
There is some equivocation in the use of the identifiers
NGC 2174 and NGC 2175. These may apply to the entire nebula, to its brightest knot, or to the star cluster it includes. Burnham's
Celestial Handbook lists the entire nebula as 2174/2175 and does not mention the star cluster.
[1] The NGC Project (working from the original descriptive notes) assigns NGC 2174 to the prominent knot at J2000 06h 09m 23.7s, +20° 39′ 34″ and NGC 2175 to the entire nebula, and by extension to the star cluster.
[2] Simbad uses NGC 2174 for the nebula and NGC 2175 for the star cluster.
[3][4]WIKI