pwitch

The Witchhead Nebula, IC2118

Reflection nebula in Eridanus

Image field of view: 1.5 x 2 degrees. (North is down)

Do you see the witch's face? Her chin is at lower right, her lips are punctuated with a red star, and her pointed nose is just above center. Rigel, the suspected illuminator of this reflection nebula, is just outside the top-right corner of the image. This nebula is a huge cloud of interstellar dust particles that reflect the light of nearby stars. The particulate scattering of light is more efficient at the shorter (blue) wavelengths of visible light, so the camera records this image in ghostly blue. Wait... did I hear an evil laugh?

This image was selected for the Astronomy Picture Of the Day, Feb. 27, 2001, was Santa Barbara Instrument Group's "Image of the Month for January, 2001" and was published in Sky and Telescope Magazine, May 2001 issue, pages 141 & 143.

The Witchhead image appears on Glinda's Bubble Ancient Voices CD.

Imaging Equipment:

Telescope: Takahashi FSQ-106N 4-element fluorite refractor at f/5

Zeiss II German Equatorial Mount

Santa Barbara Instrument Group ST-8E NABG CCD camera (1530 x 1020 pixels, 9 x 9mm, monochromatic, 16 bit, 13.8 x 9.2mm array)

CFW8 color filter wheel with IR-blocking RGB dichroic filters

Exposure Information:

Date: Saturday, January 20, 2001

Location: Joshua Tree National Park, CA

Elevation: Approx. 3500'

OAT: 0°C. CCD temp: -30°C

All exposures were shot unbinned

Total exposure time: 3.7 hours (22 exposures of 10 minutes each)

Exposures (each of two panes in the mosaic):

Blue luminance	9 exposures @ 10 minutes
Red	1 exposure @ 10 minutes
Green	1 exposure @ 10 minutes
Blue	(9 exposures @ 10 minutes, scaled)
Total exposure time	110 minutes, each of two panes

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