The Details
Object
IC 2118 The Witch Head Nebula in Eridanus
Optics
Takahashi FCT-76 at f/4.5
Platform
Astro-Physics 1200 GTO
Camera
SBIG ST-10XME
Filters
Tru-Balance LRGB filter set
Date
12 January 2005
Location
Anza Borrego Desert State Park, San Diego County CA
Exposure
L 6 x 600 sec 1x1 bin; RGB 4 ea x 600 sec 2x2 bin
Software
Maxim DL/CCD, Registar, Photoshop CS
Orientation
Field of view: 02°19'17" x 01°19'30" centered on RA 05h04m45.5s
DEC -07°05'58". North angle 109.7°; east 90° CCW from north
Notes
The Witch Head is an extremely faint reflection nebula in the constellation Eridanus, The River. With a surface brightness just above the sky background of a dark sky site, this large extended object is a challenge for both visual observers and imagers alike. As the name implies, a reflection nebula is illuminated by the light from a nearby star. This illumination is caused by the starlight being reflected off particles of dust in a phenomenon known as Raleigh scattering. In the case of the Witch Head Nebula, the star responsible for the illumination is Rigel (Beta Orionis) at magnitude 0.18. Rigel lies about 2.5° away from the heart of the Witch Head in an ESE direction. Looking at the right edge of the above image you'll see what appear to be rays of light impinging on the nebula. Those rays are coming from the nearby star Cursa (Beta Eridani), which lies about 1° out from the edge of the frame.

 

 

 

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