NGC 7023 (Iris Nebula)
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.
Date: September 10, 2005
FS-102 at f6 with TOA-130 focal reducer, on the G11 Losmandy
Autoguider: SBIG STV with
Camera: Maxcam CM10.
Type II RGB filter set; IDAS-LPS filter).
Exposures: Luminance filter, 24
Red filter, 7 x 8'; Green filter, 5 x 8'; Blue filter, 10 x 8'
unbinned). Total exposure: 6.1 hours.
Conditions: Temperature 75 degrees F, dropping to 50
transparency, average seeing; calm; clear.
This is an LRGB image (192:56:40:80
minutes). Subs were
debloomed with Ron Wodaski's
Debloomer software, calibrated in Maxim and aligned in Registar.
Sigma combined using RC Sigma Reject, followed by DDP
in ImagesPlus (IP). Further processing in Photoshop CS (16
note: Graphics on this website
may not be reproduced without author permission.
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