IC 1396

All Images Copyright Steve Cannistra

Please click here or on image for a medium-size view (35%).
Please click here for a larger-size view (45%).
Please click here for the hydrogen alpha version of this image.

Magnitude:  Unknown.
Size: Roughly 3 degrees across.
Distance: 2,450 light years
RA: 21h 39m 31s (J2000)
Dec: 57degrees 29' 59" (J2000)

IC1396 is a large emission nebula in Cepheus.  The above image was obtained using two different kinds of narrowband filters:  one that passes light emitted from singly ionized hydrogen (HII), and another that passes light from doubly ionized oxygen (OIII).  Both hydrogen and oxygen are ionized as a result of UV irradiation from the central star HD206267.  Radiation from this star has cleared out a central portion from the nebula and has also blown away gas and dust radially, resulting in a variety of dark globules that roughly point towards the center. 
These are called "cometary globules" in recognition of their overall shape, which consists of a head followed by a tail of dust that is being blown backwards by HD206267's solar wind.  The most conspicuous globule is 1396A, also known as the "Elephant Trunk," which contains a subtle reflection nebula vdb142.   Other cometary globules can be appreciated in the 60% size hydrogen alpha version of this image.  Although the dark gas and dust are opaque to visible light, infrared light passes through this region easily, permitting a view of the inner workings of the Elephant Trunk.  Please click here for an infrared view of this area taken through the Space InfraRed Telescope Facility (SIRTF), now known as the Spitzer Space Telescope.   Please be sure to check out the larger sized images for greater detail.  Rob Gendler has an excellent description of IC1396 on his website.

Photographic Details:
Date Posted:  June 9, 2007
Scope:  Takahashi FSQ106 at f5 on the G11 Losmandy Mount.
Autoguider:  SBIG ST-402 with e-finder.
Camera:  STL11K -20C.

Baader 7 nm Ha filter; Baader 8.5 nm OIII filter.
Exposures:  Ha, 10 x 20'; OIII, 8 X 15' (unbinned, image scale 3.5"/pixel).  Total exposure 5.3 hours.
Post-processing:  Calibrated, astrometric aligned, and Sigma Clip combined in Maxim, followed by DDP in ImagesPlus (IP).  Further processing in Photoshop CS (16 bit format).  The Ha and OIII images were combined using my Bicolor Technique.

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