Monkey Head Nebula (NGC 2175)

NGC 2175
NGC 2175: Galactic nebula in Orion; 500 mm Cassegrain f=3625mm / f7.2; SBIG STL11K; 90+3*30 min LRGB; Bernese Highlands; © 2011 Radek Chromik


NGC 2175 was probably sighted before 1654 by the Italian astronomer Giovanni Battista Hodierna. Hodierna discovered many of the nebulae known today, but his 1654 publication was little known outside of Sicily, so it was not known by Messier, the Herschels, and Dreyer. It was only rediscovered in 1980.

In 1857, the nebula-shrouded open star cluster was rediscovered by the German astronomer Christian Bruhns. According to John L. E. Dreyer he described it as an 8th magnitude star shrouded in a nebula. On 6 February 1877, French astronomer Édouard Stephan pointed his telescope at this point in the sky and discovered «a very faint nebula between three very faint stars», which later was recorded as NGC 2174. Its coordinates and description match a bright node in the northwestern part of the nebula. NGC 2174 is often mistakenly used for the entire nebula and NGC 2175 for the open star cluster. On 11 February 1890, the French astronomer Guillaume Bigourdan recorded a «very faint, very large, diffuse nebula» whose coordinates with IC 2159 point to a southern part of the whole nebula. He mistakenly believed that the nebula NGC 2175 listed in the New General Catalogue, published two years earlier, referred to the bright node east of the star HD 42088 and corrected its right ancension in the second Index Catalogue, published in 1910. [196, 313, 315]

Physical Properties

NGC 2175 is a young star cluster and active star-forming region enveloped in an H-II region. The radio source 3C 153.1 is also located here. The distance is about 1.6 to 2.2 kpc, about 5200 to 7100 light years. [146]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
NameRADecTypebMagvMagDimDreyer DescriptionIdentification, Remarks
NGC 217406 09 00.3+20 38 26EN3.5 × 2eF, bet 3 vF stCED 67A, knot in N 2175
NGC 217506 09 38.6+20 29 18EN40 × 30* 8 m in neb (Auw No 21)LBN 854, OCL 476
NGC 2175 S06 10 54.0+20 36 36OCL5* 8 m in neb (Auw No 21)Lund 1182, near N 2175
IC 215906 09 57.0+20 25 54ENvF, vL, difCED 67B, in N 2175

Finder Chart

The galactic nebula NGC 2175 is located in the constellation of Orion, which is best visible from October to February. Turn the card upside down and you will see the monkey head in the DSS section.

Chart Monkey Head Nebula (NGC 2175)
Monkey Head Nebula (NGC 2175) in constellation Orion. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

300 mm Aperture: In the 21 mm Ethos eyepiece the nebula is invisible without O-III filter. In the O-III filter it turns out to be a large, diffuse, structureless nebula around the bright star HD 42088. — 300 mm f/4 Popp Newton, Titlis 3020 m. a.s.l., SQM 21.20, 30 October 2022, 00:20, Bernd Nies

More Objects Nearby (±15°)


146«Version 2000 of the Catalogue of Galactic Planetary Nebulae» L. Kohoutek, A&A Volume 378, Number 3, November II 2001; DOI:10.1051/0004-6361:20011162
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
196Celestial Atlas by Curtney Seligman; (2020-12-28)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)
313«A New General Catalogue of Nebulae and Clusters of Stars, being the Catalogue of the late Sir John F.W. Herschel, Bart., revised, corrected, and enlarged» Dreyer, J. L. E. (1888); Memoirs of the Royal Astronomical Society. 49: 1–237; Bibcode:1888MmRAS..49....1D
315«Second Index Catalogue of Nebulae and Clusters of Stars; containing objects found in the years 1895 to 1907, with Notes and Corrections to the New General Catalogue and to the Index Catalogue for 1888–94» Dreyer, J. L. E. (1910); Memoirs of the Royal Astronomical Society. 59: 105–198; Bibcode:1910MmRAS..59..105D