- The Iris Nebula
Nebula in Cepheus
Instrument: 12.5" f/5 Home made Newtonian
Platform: Astrophysics 1200 QMD
CCD Camera: SBIG 10XME NABG with Enhanced Water Cooling
Guider: SBIG ST4
Exposure: LRGB = 240:40:40:40 (RGB not binned)
RGB Combine Ratio: 1: 1.05: 1.11
Filters: AstroDon RGB Tricolor
Location: Payson, Arizona
Elevation: 5150 ft.
Sky: Seeing FWHM = 8.5 arcsec (Maxim DL - 10min subframe), Transparency 8/10
Outside Temperature: 35 F
CCD Temperature: -30 C
Processing Tools: Maxim DL, Gralaks Sigma, Photoshop, PixInsight, Starizona Debloomer.
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nebulosity sits in a sea of dark nebula. So dense is the absorption
here that nearly all the stars in this field are considerably
reddened, and finding a guide star was a real challenge! The
"Iris Nebula" as it is named resembles a blue human
eye. Several key features here to take note of. The dust is illuminated
very faintly by starlight from the nearby Milkyway stars. It
appears brownish in color, and has openings allowing the stars
to shine from behind. Such a structure to the right of the bright
nebula is the "Star Window", the clarity of which determines
the depth and quality of an image of this object.
While the bright
nebulosity is NGC7023 which is about 15 arcminutes in diameter,
the surrounding dark cloud is LBN487. Most amusingly, the star
cluster inside the "Star Window" actually has a designation,
Cr427 and is listed as 13.8 magnitude and 4 arcminutes in size.
Now thats a faint star cluster!
This is an LRGB
image, with 4h of luminance data and 2h of RGB. A negative image
masked Screen layer was applied to the L channel data to bring
up the dim outer nebulosity. Finally, the image was recombined
with the RGB data using a Hue layer to correct for any LRGB color
distortion. Thus the color in this image rings true to the RGB