Globular Clusters are essentially islands of hundreds of thousands of stars that were formed at a similar time about 13 billion years ago---about the same that our galaxy formed.. These clusters orbit at the periphery of our galaxy, with almost 150 of them scattered around the Milky Way galaxy.  M15 contains about 150,000 stars with a diameter of about 175 light-years.  M15 has a very dense core of stars and is possibly harboring a black hole at its center.  M15 is about 35,000 light-years from Earth. With a collective apparent magnitude of 5.80 and a size of roughly 23 arc-minutes, this globular cluster is easily visible with a small telescope.

IMAGE DETAILS:

• Date & Location:  October 30, 2011 - Bernville, PA

• Weather:  Calm wind, fresh snow cover, start temp 33F - end temp 27F

• Sky Conditions:  Average transparency. 

• SQM-L: Average Start 19.78 (setting moon0 / Stop 20:12 (light fog)

• 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:  None - PEM active

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

• Exposure:  13 x 5min ISO1600 / 10 x 5 min ISO800 / 9 x 5min ISO400 (total 2 hr - 40 min)

• Calibration Frames:  None (sub freezing)

• Processing:  Images Plus 3.82, PS CS4, Noise Ninja, GradientXTerminator, NIK 

• Comments:  Light pollution was a bit enhanced due to fresh 6" snow cover and a shallow light fog.