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|
|
Instrument |
12.5" RCOS @ ~f/9
(2880 mm fl) 0.64 arcsec / pixel. The Zoomify image scale is
0.85 to 2.69 arcsec / pixel. |
|
Mount |
Paramount ME |
|
Camera |
SBIG STL-11000 w/
FW8 filter wheel, AstroDon Filters |
|
Acquisition Data |
6/12/2009 to 6/22/2009
Chino Valley, AZ |
|
Exposure |
|
Lum |
120 min (11 x 10 min,
bin 1x1) |
|
RGB |
360 min (12 x 10 min
each, bin 1x1) |
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Software |
-
CCDSoft, CCDStack,
Photoshop CS6, PixInsight and Noel Carboni's actions.
-
No SDSS stars were
available for color balancing, so a standard image-train
color
calibration was used, as determined by
eXcalibrator and then adjusted for altitude extinction.
-
CCDBand-Aid
to repair STL-11000M vertical bars.
-
CCDStack to calibrate,
register, normalize, data reject, combine the sub exposures and
selective luminance Maximum Entropy deconvolution.
-
PixInsight for
RGB creation, gradient removal and
initial non-linear stretching.
-
PhotoShop for the LRGB
combine & final touch-up.
-
Noiseware 5, a PhotoShop plug-in.
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Comment |
North is to the top.
The M12 globular
cluster, NGC 6218, is in the constellation Ophiuchus and was
discovered by Charles Messier on May 30, 1764. The cluster is 16,000
light-years from Earth and has a spatial diameter of about 75
light-years. It is loosely packed and was once thought to be a
tightly concentrated open cluster. M12 has thirteen variable stars.
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