Great Hercules Cluster
Glubular Cluster in Hercules



M13: M13, the Great Hercules Cluster, is probably the most prominent globular cluster visible from the northern hemisphere, overall about magnitude 5.9 and hence visible with binoculars. This was the first deep sky object I found star hopping with my first "real" telescope. Estimates of the number of stars in M13 vary from 100,000 to over a million, in a diameter of about 150 light years across, and is about 20,000 light years from Earth. Globular clusters are among the oldest objects in the galaxy; M13 is over 12 billion years old.


Technical Information:

LRGB: 60:40:40:30 (L-15x4 min; R&G-4x10 min; B-3x10 min). All images were unbinned.

Equipment: Meade 12" RCX400 at f/8.5, an SBIG ST-8XE camera/CFW8 color filter wheel with Astrodon filter set, guided by an SBIG AO-7 adaptive optics device, guiding at about 5 Hz (luminance) and 3 Hz (RGB).

Image Acquisition/Camera Control: CCDSoft V5.

Processing: Re-processed, January 2007 All images calibrated, registered and combined in CCDStack (darks, dawn flats and flat-darks). 100 iterations of deconvolution performed on luminance layer in CCDStack. Color combine in CCDStack. Curves and levels applied to luminance layer in Photoshop CS2. Luminance layer and finish work (slight unsharp mask to luminance layer; slight Gaussian blur to color layer) applied in Photoshop CS2.

Location: All images taken from my yard in Redmond, Washington, USA, elevation 500'.

Date: All images taken on the night of June 24, 2006.

CCD Temperature: -20C

Moon Phase: New moon

Seeing: Good, with 2.4 Arcsecond average FWHM in single calibrated image, deconvolved to 2.1.

Transparency: Average

Image Scale: .793 arcseconds per pixel

Copyright 2006 Mark de Regt

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