Nightscapes & Deep Sky Colors

Astrophotography Brian A. Morganti

M13 - Globular Cluster

The Great Globular Cluster



M13 is one of the largest and most impressive globular star clusters visible from the northern hemisphere. The cluster is about 25,000 light years from Earth, and contains several hundred thousand stars. M13 covers about 20 arc minutes in the sky, which makes it about 2/3 the size of a full moon.  This corresponds to a real size of about 145 light-years and it contains hundreds of thousands of stars.  At magnitude 5.8, M13 is visible to the keen unaided eye from a dark-sky observing site. 

Galaxy NGC 6207 can be seen at the lower left.  M13 was discovered in 1714 by Edmond Halley and catalogued by Charles Messier in 1764.

North is to the left in the above image.


  • Date & Location:  July 16, 2015 - StarEffects Observatory - Bernville, PA

  • Weather:  Calm winds, average temp of 62F

  • Sky Conditions:  Clear with Average Transparency. 

  • SQM-L:  Average 20.46

  • Optics:  TeleVue NP101is Refractor with 1.5x extender 810mm @ f8.1

  • Filter:  Astronomic  EOS clip-in CLS-CCD (Light Pollution Suppression)

  • Mount:  AstroPhysics AP900GTO

  • Guiding:  SSAG - 5 seconds exposures - Good Graph.

  • Camera:  Canon T1i (500D) Hap Griffin Modified - Baader UV/IR

  • Exposure:  20 x 5min ISO800  (total 100 min)

  • Calibration Frames:  Darks, Bias 60F - 10 Field Flats w/Alnitak Flat Man

  • Processing:    Images Plus 5.75a, PS CS6, NIK filter tools 

  • Comments:  Average sky conditions prevailed for imaging, with some deterioration in transparency occurring after midnight due to increasing dew points. 



Astrophotography  -  Nightscapes & Deep Sky Colors