beautiful object, most normally a target of larger scopes,
NGC 7023 is imaged here with a medium focal length 6"
refractor. What makes it a suitable target
for this instrument? CCD camera power!
known as the "iris Nebula" because of the
floral shape and color, this region is surrounded by
dust. When you expose long enough with a
CCD camera, the dust begins to silouhette against the
background star light, as well as the light coming from
the strong, central star within the "iris"
itself. The result is a distinct separation of
the dust from the "space" background.
nebula is a typical reflection nebula, where the color
comes as a result of the powerful, massive, yet young,
blue-colored star resting within the dust. The
object is found slightly north of Alderamin on
the western side of the constellation Cepheus.
object is not often a visual target, though
it should be. Even through a 4" scope in
dark skies, the main reflection areas are very apparent.
With a slightly larger scope, or with a
little more power, some of the knotting in the object
Star Party 2008, near Ft. Davis, Texas
Transparency: 9.5/10 on average
Temperature: -15 and -20 degrees C on camera
Scope/Mount: Tak TOA-150
and Astrophysics AP900
Camera: SBIG STL-6303e astro
Guiding: STL external guidehead
through Tak FSQ-106
Exposure Info: LRGB
image; 160:70:20:30 minutes (5 minute subexposures for L and RGB, all unbinned)
with CCDSoft. Calibration
(darks/flats), registration, and RGB channel combine in CCDstack
(median combine). LRGB
combine, color balance, saturation, levels/curves, and noise removal/local contrast enhancement (Noel Carboni's Astronomy Tools) in Photoshop CS.
Exposure Notes: Tough
target. Hard to get enough exposure time. Green
and Blue color data was a little thin, but this is where the LRGB
technique really shines. The separate luminance fills in the
gaps for the weaker color channel data once the luminance is layered
multiple times. Earlier iterations utilize heavy noise reduction
and blurring in the weaker color channels while allowing the luminance
data to sort itself into the appropriate color locations.
Copyright(c) 2003 - 2008