M13 – Globular Cluster in Hercules

Telescope: Meade 12” LX850 ACF @ f/8, Orion Atlas EQ-G

Camera: ZWO ASI071 MC Pro, -10C, Gain 200

Filter: Orion Imaging Skyglow Filter

Guide scope: Astro-Tech 60mm, ASI290MM Mini, PHD2

Exposure: 67x120sec, saved as FITS

Darks: 32x120s, saved as FITS

Flats: 32×0.2sec, Tee shirt flats taken at dusk

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

Lensed Sky Quality Meter: 18.4 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

Software: Nebulosity, Deep Sky Stacker, Photoshop

This is M13, the Great Cluster in Hercules. Also in the picture is the galaxy NGC 6207 (Mv 11.6) in the upper left corner, and about halfway between NGC 6207 and M13 is the tiny galaxy IC 4617 (Mv 15.2) . If you look carefully at M13 you can see a dust lane to the lower left of the cluster. This is a very unusual feature for globular clusters and it is not clear if this is actually associated with M13 or simply lies in the line of sight with the cluster.

M13 currently rises in the northeast late in the evening and is high overhead at dawn.