NGC 2174 (Sh2-252, Monkey Head Nebula) in the constellation Orion

1800 px

© Velimir Popov & Emil Ivanov 2020

There is some ambiguity in the use of NGC 2174 and NGC 2175 identifiers. The following information will clarify this issue:

NGC 2174 is an H II emission nebula (Sh2-252) located in the constellation Orion. The prominent HII region Sh2-252 was originally catalogued by Sharpless (1959), who related it to an emission nebula (NGC 2174) and a loose stellar distribution (NGC 2175). Currently, NGC 2174 refers to the whole HII region, while NGC 2175 refers to a possible young open cluster (OC) or a stellar group of scattered stars in the nebula.

(Bonatto, C.; Bica, E., 2011).

Latest investigations reveals existence of the six young clusters associated with that large, diffuse H II region NGC 2174. Their designations are Sh2-252A, Sh2-252C, Sh2-252E, NGC2175s, Teutsch 136 and one possible young open cluster or stellar group NGC2175. The distance from the Sun to this single star-forming complex is 1.4 kpc or 4566 ly (Bonatto & Bica 2011). All these clusters have an estimated age of 5 Myr or less, consistent with the age of the primary ionizing source, the O6.5 V star HD 42088 (Garnier & Lortet-Zuckermann 1971; Felli et al. 1977; Jose et al. 2012).

Image details:

Charts and image details obtained from


Center of field RA 06:09:46.856 (h:m:s)
Center of field DE +20:30:58.319 (deg:m:s)
Size 35.6 x 35.6 (arcmin)
Pixel scale: 1.04 (arcsec/pixel)
Orientation: Up is 1.83 degrees E of N
Optic(s): RC” Astrograph @ f/5
Mount: ASA DDM85 Premium
Camera: ATIK 4000 M
Filters: Astronomik Ha, OIII filters; SII Astronomik filters
Dates/Times: January 2013 - January 2014
Location: IRIDA Observatory, BG, longitude: E 24 44' 18", latitude: N 41 41' 42"
Exp. Details: Ha: 13x20 min, OIII: 8x20 min, SII: 15x20 min
  Total 720 min (12 hrs)
More details: Bias, dark, and flat frames reduction
Processing: PixInsight / PS
Copyright: Velimir Popov and Emil Ivanov 2013 - 2020. All Rights Reserved
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