The H II emission nebula NGC 2174 ("Monkey head nebula") and the open star cluster NGC 2175 in the constellation Orion
on December 5 / 6, 2015. The ionized hydrogen cloud NGC 2174 is 6400 light-years from Earth and was discovered by the French astronomer Édouard Jean-Marie Stephan in 1877.
The star cluster NGC 2175 is associated with the nebula (and thus is also 6400 light-years from Earth) and was probably discovered before 1654 by Italian astronomer Giovanni
Battista Hodierna and re-discovered by German astronomer Karl Christian Bruhns in 1857. It's not quite clear which NGC number belongs to the nebula (and even to what part
of the nebula) and which number belongs to the star cluster (source: Wikipedia).
Twenty-four exposures of approximately 3 minutes at ISO 800 with no dark frame subtraction were stacked with Deep Sky Stacker
(resulting in a 1 h 20 min exposure) and further processed in Photoshop.
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Equipment: Canon EOS 450D Baader modified camera, TeleVue Paracorr Type II coma corrector,
16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform,
Lacerta MGEN autoguider, Lacerta off axis system (field of view comparison:
image of the moon with the same equipment).
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