M13 - Hercules Globular Cluster (2019)

This is my latest version of M13.  Like all globular clusters, M13 or the Hercules Globular Cluster (NGC 6205), does not reside in the galactic plane but rather outside surrounding the central bulge. The cluster contains several hundred thousand stars, a  diameter of 145 light-years and is 22,000 light years away. The cluster, like most clusters, contains very old stars on the order of 12 to 13 billion years old, however, this cluster is of particular interest because it produces young blue stragglers - large blue giant stars formed as result of colliding old stars.

I find globular clusters particularly difficult to process for some reason.  Possibly because the data is never as good as it could be because I am always imaging these under less than ideal circumstances like when the moon is out - this image is no exception.  Also, the green layer was fine this time around as opposed to having those magenta splotches plaguing my last image.  I was prepared to stack everything in DSS, however, PI worked fine this time (astro-gremlins?). 

I did manage to get more color than my previous images which was very happy with.  I rotated the image 90 degrees and cropped it in such a way to maximize the small ~12th magnitude spiral galaxy on the lower left of the image.  Despite being 46 million light-years away there is a small amount of structure. 

M13 - The Hercules Globular Cluster
Location: Home Monroe, CT
Date: 6-11-19, 6-14-19
Camera: ZWO ASI1600MM-Pro
Telescope: Astro-Tech AT115EDT 115mm Refractor Telescope
Barlow: None
Focal Length: 805mm
f/7
Focal Reducer: Astro-Tech 0.8x Focal Reducer/Field Flattener for Refractor Telescopes
Mount: Orion Sirius
Filter Wheel: ZWO EFW 8x 1.25"
Filter: ZWO R, G, B
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: R 60 x 60s, G 49 x 60s, B 57 x 60s
Gain: 139
Offset 21
Temp: 8 C
Post Processing: PixInsight, Photoshop, Lightroom
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