M10 – Globular Cluster in Ophiuchus

Telescope: ES Comet Hunter MN6 at f/4.8, Orion Atlas EQ-G

Camera: Baader modified Nikon 610

Filter: High Point 2” IR Blocking Filter

Guide scope: Williams Optics 50mm, ASI290MM mini, PHD

Exposure: 19x60sec, ISO 200, saved as RAW

Darks: Internal (Long Exposure Noise Reduction On)

Flats: 32×1/4sec, tee shirt flats taken at dusk

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

Lensed Sky Quality Meter: 18.1 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

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

M10 is one of several bright, beautiful globular clusters in Ophiuchus. Although superficially globulars appear similar, they each have their own distinct character. The globulars that populate the summer sky are a great opportunity to visit several in one night to see for yourself how different they are.

M10 rises in the east late in the evening and is high in the south in the early morning. (Photo credit; John Graham, 3/20/2021)