M15 – Globular Cluster in Pegasus

Telescope: Meade 10” LX850 ACF @ f/8, Orion Atlas EQ-G

Camera: Canon EOS Ra

Filter: GSO IR Blocking Filter

Guide scope: Orion 50mm, ASI120MM Mini, PHD2

Exposure: 52x60sec, ISO 800, saved as Raw

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32x1sec, Tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, fair transparency

Lensed Sky Quality Meter: 18.6

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: Backyard EOS, Deep Sky Stacker, Nebulosity, Photoshop

M15, a bright, condensed globular cluster in a relatively lonely stretch of sky in Pegasus. It is one of the oldest known globular clusters with an estimated age of 13.2 billion years and the first globular cluster found to have a planetary nebula (Pease 1), one of only four planetary nebula associated with a globular cluster. M15 is also one of the most condensed globular cluster and at some point in the distant past it experienced a core collapse that may have heralded the formation of a black hole in its nucleus. This is supported by the fact the M15 is an x-ray source.

M15 is currently well placed in the southeast as the sky darkens.