The Globular Star Cluster M13 in the Constellation Hercules
The Great Hercules Cluster (M13) captured using an Astro-Tech AT72ED telescope (2.8"/72mm aperture, 430mm prime focal length, f/6) and a Sony NEX-5N digital camera (ISO 3200, a stack of ninety-one images each exposed for 30 seconds, producing a total exposure integration time of 45.5 minutes). Tracking for each of the 30 second exposures was performed by a Celestron CGEM mount (no manual or auto guiding, standard sidereal rate after one star polar align).
The image notes also identify the small spiral galaxy NGC 6207 that appears about halfway toward the upper right corner of this photo (best seen in the Flickr light box). There is also a very faint trace of the 15th magnitude galaxy IC 4617 which is located about midway between M13 and NGC 6207 (left as an exercise for the viewer to find this small smudge which appears just below the 14th magnitude star GSC 2588-2034).
Image registration, integration, and adjustments done with PixInsight v01.07.06.0793 with final tweaks in Photoshop CS5.
This image is best viewed against a dark background (press the "L" key to enter the Flickr light box).
This photo was taken just after midnight on the morning of June 18, 2012 from a moderately dark-sky location and can be compared to an earlier version that I captured from my light-polluted home town (M13 from a pretty bad observing site).
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