IC 2118 (Witch Head Nebula)

This 3-image mosaic of the Witch Head Nebula (IC 2118) is another of my Christmas Day (according to Mountain Standard Time!) series of images taken from Chiricahua National Monument in southeastern Arizona. It covers a wider field than my previous attempt.

IC 2118 is a reflection nebula, where light is scattered by tiny particles. This so-called Rayleigh scattering is most effective for blue light, hence the color. The same mechanism is responsible for the blue daytime sky on Earth. Here, the illuminating star is Rigel in the constellation of Orion, located 2.5° to the east. Note that IC 2118 itself is located in Eridanus, which has the greatest North-South extension of all 88 constellations. Its distance is estimated at approx. 210 pc (680 light years). The image has been rotated so that South is at the top. This makes it easier to see the distinctive shape of the witch's face.

The Witch Head Nebula has a very low surface brightness, and substantial contrast stretching was necessary to see the nebula at all. To improve the signal-to-noise ratio and cover a wider field, three images were combined into a mosaic using a technique developed for the Milky Way panorama.

Instrument Vixen R200SS (8" f/4 Newtonian with coma corrector) on Losmandy G-11 mount
Guiding ST-4 autoguider
Film Kodak Supra 400 hypered
Date 26 Dec. 2002
04:03 - 04:48 UTC, 04:57 - 05:42 UTC and 06:01 - 06:46 UTC
Site Chiricahua National Monument (Faraway Ranch parking lot)
Processing Three images transformed to equidistant cylindrical projection and stacked using custom software, smoothed with bgsmooth.
Comments Temperature -10 C (14 F), high humidity

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