M15 – Globular Cluster in Pegasus

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

Camera: QHY 367c Pro, GSO IR Blocking Filter

Guide scope: Astro-Tech 60mm, ASI120MM Mini, PHD2

Exposure: 28x180sec, gain 2800, offset 50, -10C, saved as Raw16/FITS

Darks: 32x180sec, gain 2800, offset 50, -10C, saved as Raw16/FITS

Flats: 64×0.250sec, tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency, smoke, haze

Lensed Sky Quality Meter: 18.2

Stacking: Mean with a 1-sigma clip.

White Balance: Nebulosity Automatic

Software: SharpCap Pro, 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.

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