NGC 7023 (Iris Nebula)

NGC 7023
All Images Copyright Steve Cannistra

Please click here or on image for a higher resolution view.

Magnitude:  7.1
Size: about 18'
Distance: 1,300 light years
RA: 21h 00m 30s
Dec: 68 degrees 10' 00"

The Iris Nebula (NGC 7023) is located in the constellation Cepheus and is a beautiful example of a reflection nebula.  The young, central star (designated HD 200775) is only about 5,000 years old, and its blue light is preferentially scattered by the surrounding dust (resulting in the characteristic blue color of the reflection nebula).  However, on higher magnification, areas of red emission can be observed flanking the central star, a result of ultraviolet radiation that excites Ha emission within this region.  Finally, the entire region is filled with a dense, chocolate-brown dust that obscures light from stars behind the nebula.   Therefore, this region is comprised of all three main nebulosities:  reflection, emission, and dark, much like the Cocoon Nebula.

Photographic Details:

Date:  October 5, 2004
Takahashi Sky 90 at f4.5 with field flattener/focal reducer, on the G11 Losmandy Mount.
Autoguider:  SBIG STV with e-finder.
Camera:  SXV-H9
Astronomik Type II Clear, R, G, B filter set.
Exposures:  LRGB.  17 x 5' for Clear filter (luminance); 5 x 4' each for R and G (unbinned); 8 x 4' each B (unbinned).
Conditions:  Temperature 36 degrees F; above average transparency; above average seeing; calm; a glorious night.
No darks, flats, or bias frames used.  Alignment done in ImagesPlus.  Sigma combined using RC Sigma Reject Plug-in for MaximDL.  DDP was performed in ImagesPlus (IP).  Subsequent levels and curves adjustments in Photoshop CS (16 bit format). 
L was combined with RGB using the technique of Luminance Corrected RGB.  Seeing those chocolate-brown regions of opaque dust appear during the RGB combine was awe-inspiring and great fun!

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