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Click the image for a 60%
size wide field view. (2400 x 1600 - 1.45 MB)
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Instrument |
12.5" RCOS @
~ f/9 (2880 mm fl) at 0.64 arcsec/pixel. Shown at 1.06 and
2.64 arcsec/pixel. |
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Mount |
Paramount ME |
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Camera |
SBIG STL-11000 w/
FW8 filter wheel & AstroDon Gen-2 RGB filters. |
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Acquisition Data |
8/7/2017 to
8/17/2017 Chino Valley, AZ. with CCD Commander & CCDSoft. AOL
guided |
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Exposure |
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RGB |
360 min (12 x
10 min. each) Bin 1x1 |
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Software & Processing Notes
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CCDSoft, CCDStack,
PixInsight, Photoshop CS6.
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eXcalibrator
v6.2 for (g:r),(b:r)
color balancing, using 1185 stars from the Pan-STARRS database.
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CCDBand-Aid to repair
KAI-11000M vertical bars.
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CCDStack to
calibrate all sub exposures.
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PixInsight
processing includes
CosmeticCorrection,
data rejection, mean combine all the sub-exposures, create the RGB
image,
gradient removal and non-linear stretching with HistogramTransformation.
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PhotoShop for additional background neutralization and background smoothing.
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Noiseware 5, a PhotoShop plug-in.
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Comment
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The cluster is shown
rotated 130° clockwise.
John Herschel
discovered NGC 6811 in 1829. The cluster is in the constellation of
Cygnus, at a distance of 3000 to 3900 light-years. The presence of
white hot stars suggests an intermediate age of approximately 700
million years. This is relatively young as compared to the Sun's
middle age of about 4.5 billion years.
In 2013, astronomers found two exoplanets in the cluster. The group
measured the age of NGC 6811 to be one billion years, slightly older
than previous estimates. |
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