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Instrument |
12.5" RCOS @
~f/9 (2880 mm fl) 0.64 arcsec / pixel. The Zoomify image scale
is 1.28 to 3.26 arcsec / pixel. |
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Mount |
Paramount ME |
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Camera |
SBIG STL-11000 w/ internal filter wheel, AstroDon Gen I Filters |
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Acquisition Data |
9/9/2010 to 10/26/2010 Chino Valley, AZ... with CCDAutoPilot3
& CCDSoft. AOL guided |
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Exposure |
Ha
540 min (18 x 30 min, bin 1x1)
OIII
540 min (18 x 30 min, bin 1x1)
Lum (no filter)
465 min (16 x 15 min, bin 1x1)
RGB
270 min ( 6 x 15 min each, bin 2x2)
Click
here for the color mapped narrowband version.
Click
here for an Ha filtered b/w image. |
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Software |
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CCDSoft, CCDStack,
Photoshop CS w/ the Fits Liberator plugin.
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eXcalibrator for (b-v), (v-r)
star color calibration, using 12 stars
from the NOMAD1 database.
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PixFix32 (pre-beta) to
repair column defects.
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CCDStack to calibrate,
register, normalize, data reject, combining the sub exposures
and RGB combine
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PhotoShop for
non-linear stretching
and
sharpening.
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Noiseware Pro, a PhotoShop plug-in
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Comment |
North is ~ to the
left. The image is rotated 70 degrees CCW.
The Western Veil, NGC
6960, commonly named The Witch's Broom, is part of the Veil Nebula,
which is also known as the Cygnus Loop. The Veil nebula is located
in the constellation, Cygnus, at a distance of about 1400 light-years. Its
apparent size is more than five times the full Moon.
The Veil Nebula is a supernova remnant of heated and ionized gas.
The source supernova exploded some 10,000 to 20,000 years ago. The
expanding debris cloud gains its colors by sweeping up and exciting
existing nearby gas.
Although this image was taken with narrow band filters it is a
fairly good presentation of what the nebula looks like if red, green
and blue filters were used. This is possible because the band width
of the OIII filter is about half way between green and blue. This
technique works especially well with this nebula because the RGB
colors are mostly red and cyan. I used this method because, with
true RGB, the stars completely overwhelm the nebula. Using
narrowband filters also reveals greater detail.
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