|
Instrument |
12.5" RCOS @
~f/9 (2880 mm fl) 0.64 arcsec / pixel. The Zoomify image scale
is 1.28 to 3.42 arcsec / pixel. |
Mount |
Paramount ME |
Camera |
SBIG STL-11000 w/ internal filter wheel, AstroDon Gen I Filters |
Acquisition Data |
10/9/2010 to 10/29/2010 Chino Valley, AZ... with CCDAutoPilot3
& CCDSoft. AOL guided |
Exposure |
Lum (no filter) 180
min (12 x 15 min, bin 1x1)
RGB
360 min ( 8 x 15 min each, bin 2x2) |
Software |
-
CCDSoft, CCDStack,
Photoshop CS w/ the Fits Liberator plugin, Noel Carboni's actions
and Russell Croman's GradientXTerminator.
-
eXcalibrator for (b-v), (v-r) color calibration, using 18 stars
from the NOMAD1 database.
-
PixFix32 (pre-beta) to
repair column defects.
-
CCDStack to calibrate,
register, normalize, data reject, combine the sub exposures and LRGB
color.
-
PhotoShop for
non-linear stretching,
LLRGB combine.
|
Comment |
NGC 7788 and 7790 are
two small open clusters in the constellation Cassiopeia, at
distances of about 8,000 and 10,000 light-years respectively. NGC
7790 is at the top center and NGC 7788 is to the lower right. The
beautiful bright copper colored star, to the left center, at
magnitude 6.63 is SAO 20954.
NGC 7790 is astronomically important because it contains three
Cepheid variable stars. These three Cepheids are useful for
determining a zero point distance for this special type of star.
Cepheid variables are used to determine galactic distances.
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