|Great Hercules Cluster M13
The colossus of globular clusters, the Great Hercules Cluster can be seen with the unaided eye from a dark sky site. It packs about a
half million stars in a region only 150 light years across, orbiting our galaxy like a giant satellite 20,000 light years away. The brightest stars
in this image are red giants, thousands of times brighter than our sun. At its core, the glare of brilliant suns would obscure the remainder of
the universe. Of course, planets are unlikely in the center of a globular cluster, as frequent gravitational interactions with other stars would
strip away plantets.
The image above represents my latest effort to image this object from the Hidden Lake Observatory. I used an ST10XME camera, with an
AP 0.67x reducer, through a 12" Meade LX200R telescope. I combined exposures of 45 minutes luminance with 12 minutes of red and
green, and 18 minutes of blue. The image below, obtained 3 years earlier, combined 60 minutes of luminance exposures with red, green,
and blue exposures of 27, 21, and 25 minutes. A Celestron C8 telescope was used with an ST10XME camera, yielding almost the same
scale as the more recent image.