6/19/2010 to 6/21/2010 Chino Valley, AZ... with CCDAutoPilot3
& CCDSoft. AOL guided
Exposure
Lum (no filter)
95 min (19 x 5 min, bin 1x1)
RGB
105 min (7 x 5 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 21 stars
from the NOMAD1 database. The lower image is corrected to
compensate for galactic extinction.
PixFix32 (pre-beta) to
repair hot/cold pixels and column defects.
CCDStack to calibrate,
register, normalize, data reject, combine the sub exposures and LRGB
color.
North is to the top.
The M10 globular cluster, NGC 6218, is in the constellation
Ophiuchus and was discovered by Charles Messier on May 29, 1764. The
cluster is 14,000 light-years from Earth and has a spatial diameter
of about 83 light-years. The cluster's apparent diameter is about
two-thirds the size of the Moon.
Because M10 is positioned close to the galactic plane, we view it
through a lot of dust and various nebulae. This causes the light to
become reddish, just as the Sun is red at sunset. This effect is
called Galactic Extinction. The top image was calibrated with
foreground stars and shows the cluster with the effects of galactic
extinction.
The bottom image was color corrected for galactic extinction and
shows the cluster with its intrinsic color. The following color
magnitude correction factors were obtained from the NASA/IPAC
Extragalactic Database (NED).
