M13 - Globular Star Cluster in Hercules


Copyright 2005 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:    June 4, 2005     Griffin/Hunter Observatory    Bethune, SC
Instrument:    Canon 300D Digital SLR (modified) through f6.3 10" Meade LX-200 
Focal Ratio:   Approx. f4 using Lumicon GEG Focal Reducer
Guiding:    Auto through Orion ED-80 w/ SBIG ST-237
Conditions:    Visually clear 
Weather:    73 deg. F 
Exposure: 27 minutes total @ ISO 800 (27 x 1 min exposures average combined with no dark or flat frame calibrations)
Filters:    Baader UV/IR Block
Processing:    Focused and captured with DSLRFocus.  RAW to TIFF conversion, frame alignment and stacking, Digital Development, Adaptive Richardson_Lucy deconvolution, scaling and JPEG conversion with ImagesPlus.  Noise reduction with NeatImage.