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M13 - Globular Cluster in
Hercules
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Copyright 2010 Hap Griffin M13 is the best known of a class of objects called globular star clusters.
They are generally groups of several hundred thousand stars in a distinctly
spherical shape that occupy a halo region around the central bulge of spiral
galaxies, such as our own Milky Way galaxy. They also are some of the
oldest objects in the universe based on studies of the concentrations of
elements within the constituent stars. In the cores of such clusters, the
stars are more than 500 times closer together than in normal space. M13 lies at
a distance of 25,100 light years. It is visible by the naked eye from dark
sky locations as a very faint smudge along one edge of the "keystone"
of stars in the central part of the constellation Hercules. In 1974, M13
was selected to be the target of the first radio message to possible
extraterrestrial civilizations intentionally beamed into space from the large
radio telescope in Arecibo, Puerto Rico.
Date/Location:
February 13, 2010 Griffin/Hunter
Observatory Bethune, SC
Camera: QSI 583wsg
Filters: Astrodon E Series Generation 2 LRGB
CCD Temperature: -20 C
Instrument: Planewave CDK 12.5"
Focal Ratio: f/8
Mount: AP-1200
Guiding: Auto via the QSI camera's built in Off-Axis Guider
mirror and a Starlight Express Lodestar Guider
Conditions: Clear and cold
Weather: 21F, still
Exposure: 24 minutes total (8 x 1 minutes each in RGB binned 1x1)
Capture: CCDAutopilot 4 w/ Maxim DL Camera Control, focused automatically w/
FocusMax
Processing: Frame calibrations, alignment and stacking with ImagesPlus v3.80.
Finishing in Photoshop CS4.