M15 – Globular Cluster in Pegasus

Telescope: Meade 10” LX200 SCT (Wide Field) @ f/6.3, Orion Atlas EQ-G
Camera: ZWO ASI071MC, Orion Imaging Skyglow Filter
Sensor Temperature: 0C, Gain: 200, Offset: 50
Guide scope: Astro-Tech 60mm, Meade DSI Pro II, PHD
Exposure: 87x60sec saved as FITS,
Darks: 32x60sec saved as FITS
Flats: 32x30sec, LED tracing tablet covered with 3 layers of muslin
Average Light Pollution: Red zone, fair transparency
Lensed Sky Quality Meter: 18.6 mag/arc-sec^2
Stacking: Mean with a 2-sigma clip.
White Balance: Nebulosity Automatic
Software: Nebulosity, Deep Sky Stacker, 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. 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 also supported by the fact the M15 is an x-ray source.

This is the first time that I have used my wide field 10” f/6.3 is quite a while. Seeing rarely supports this scope, but when it does it is a nice option to have to image small targets like planetary nebula. It also does a very nice job with globular clusters. The fact that the images are well over-sampled gives me some nice processing options including resampling and binning without losing any true resolution.

-John

M15 (9-9-2017)-1j.jpg