IC 2118

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Observation place
New Mexico


TelescopeTakahashi FSQ 106ED, 106mm, f / 5
MountParamount ME
Imaging cameraSBIG STL 11000 regulated at -15o Celsius
Image typeLRVsB (Vs for synghetic green)
ExhibitionLuminance (10 x 10 'bin 1 × 1), RB (4 x 3' bin 2 × 2 each)
PretreatmentMaxim DL
TreatmentPhotoshop and PixInsight
Specific treatmentCreate a synthetic green image

Object description

Object typeReflection nebula "The Witch's Head nebula"
Visual magnitude8
Surface gloss17,82
Distance900 light years
Diameter52 light years
Dimension seen from Earth180 x 60 arc minutes  
IC 2118 is a very large reflective nebula of extremely low luminance in the constellation Eridanus. Seen from the Earth, its surface is 12 times larger than the Moon! It is also known, because of its profile, as the Witch's Head nebula. It is located in the constellation Eridanus, not far from the star Rigel of the constellation Orion. It is above all this star which illuminates the nebula and gives it the bluish hue. The nebula was discovered by the German-British astronomer William Herschel in 1786. It is located 900 light years from Earth and its diameter is 52 light years.  

Observations in the field of radio waves have shown that parts of the nebula contain an appreciable amount of carbon monoxide, which is indicative of regions of star formation.  
To visually see the nebula, you need an observation site without light pollution (black and gray areas). In addition, you need a large-diameter telescope to hope to see part of the nebula. This is due to the very low surface brightness of the nebula which is only magnitude 17,8.  

It is only in astrophotography that we can see and appreciate the very beautiful faint shades of the nebula in the blue tones. Even in photography, you need a site with low light pollution (green areas and less). 

In my picture, I managed to solve the nebula very well. The observation site is in Mouveau-Mexico in a site of very low light pollution (gray area), which greatly facilitated the bringing out of many details on the nebula. Even under these ideal conditions, the processing of the image was very demanding. We can very well see the Witch's Head seen in profile looking in the right direction of the image. Do you see her?  
Richard Beauregard
Sky Astro - CCD
My impression "We cannot be alone in this gigantic universe"