Messier 13 - The Great Globular Cluster in Hercules
Updated: Jun 7, 2023
Featured in The Astrophotographer's Guidebook.
Featured on Sciences et Avenir's Instagram account
Messier 13 is one of the best globular clusters to observe and photograph from the northern hemisphere. It is bright, large, and stays high in the sky for a long period of time.
Photographing this cluster is easy and does not require a lot of exposure time. For the best results, keep your exposure times short to avoid blowing up the bright stars, and always check that your guiding is perfect.
M13 has been targeted on November 16, 1974, to send a message to potential extraterrestrial civilizations. It will take 25,000 years to get there, and the same amount of time for an eventual response.
We have imaged Messier 13 several times over the years, and we'll show you our main attempts below!
Attempt #3 - Messier 13 with a Small Refractor and DSLR Camera
June 2, 2020
We decided to go back to our DSLR roots for a night when recording the content for the Galactic Course.
The first section of Season 1 is all about imaging a deep sky object with a small beginner refractor telescope and a DSLR camera.
We only spend about one hour and some on it this time, and you can see that it already looks pretty nice! This was taken from a Bortle 4 zone. Make sure to become a lifetime member of the Galactic Course to learn exactly how to capture this target, and many more!
GEAR USED:
Camera: Canon 7D Mk II
Telescope: Meade 70mm APO f/5
Mount: Motorized Equatorial Mount
Guiding: ZWO ASI290MM Mini
Processing: Pixinsight
ACQUISITION DETAILS:
Total Exposure Time: 1.8 hours
Exposure Time per frame: 30 seconds
225 lights - 15 Darks - 15 Bias
ISO: 800
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Attempt #2 - M13 with an 8" Reflector and OSC-Cooled Camera
May 25, 2020
Four years after the first attempt, I decided to head back to the desert and revisit this object with our current gear. We used a full-frame cooled one-shot color camera, the same telescope we had the last time, and the Software Bisque Paramount MyT mount.
I spent a total of 1 hour and 45 minutes on the target. I initially wanted to image it for 3 hours, but the laptop died quicker than I anticipated and I had to unplug the camera from the battery in order to charge the computer instead... Then I switched to a different target.
I am very pleased with the result but had a terrible time trying to take care of the large background halo produced by the bright cluster core. I believe I would not have had this problem if I had an IR cut filter. I did my best during processing but, as you can see below, the background is not really even throughout the image.
GEAR USED:
Camera: QHYCCD 128C
Telescope: 8" Newtonian
Guiding: Autoguider - 50mm Guide Scope
Processing: Pixinsight
ACQUISITION DETAILS:
Total Exposure Time: 1 hour and 45 minutes
Exposure Time per frame: 30 seconds
70 lights - 15 Darks
Gain: 3200
Attempt #1 - M13 with an 8" Reflector and Stock DSLR Camera
May 31, 2016
Here was our very first attempt at imaging this bright globular cluster. This was taken with poor guiding conditions and, to be honest, our processing skills were pretty terrible. Look at how dark the background is!
GEAR USED:
Camera: Canon 7D Mk II
Telescope: 8" Newtonian
Mount: Motorized Equatorial Mount
Guiding: Autoguider - 50mm Guide Scope
Processing: Pixinsight
ACQUISITION DETAILS:
Total Exposure Time: 2 hours
Exposure Time per frame: 3 minutes
40 lights - 15 Darks - 15 Bias
ISO: 400
How to Locate the Great Globular Cluster
The Great Globular Cluster in Hercules can be seen with telescopes, binoculars, and the naked eye! The latter must be seen from a dark zone with no light pollution. Through a telescope, the cluster really looks impressive and many stars can be resolved.
You will find the cluster in the constellation of Hercules and have no issue spotting it! Once you find it, take a moment to think about how Charles Messier found the same cluster many years ago through his own telescope. With his instrument, M13 looked like a nebula!
This is his entry for his famous catalog after having discovered the cluster:
“In the night of June 1 to 2, 1764, I have discovered a nebula in the girdle of Hercules, of which I am sure it doesn’t contain any star; having examined it with a Newtonian telescope of four feet and a half, which magnified 60 times, it is round, beautiful & brilliant, the center brighter than the borders”.
Cool Facts
Charles Messier thought it was a nebula
The cluster is half a million solar masses
About 11.65 billion years old
How to Process M13
Processing M13 is not very difficult, but as always with clusters, you will need to be careful to not ruin the stars.
A good thing to do once you are done is to revisit the crispness of the object in a different editing software (we use Lightroom). This usually has a great impact on the final image!
If you centered M13 properly, you might get a galaxy in your frame. This is NGC 6207!
Try to also bring it up during processing using masks, but do not sacrifice any quality in your star cluster for it!
Final Thoughts
Messier 13 is the most famous star cluster for amateur astrophotographers in the northern hemisphere. It is huge, has a lot more stars than most other visible globulars, and is not too difficult to photograph!
Have you captured the Hercules Cluster? Attach your image in the comments and let us know your acquisition details!
Clear Skies,
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Here's my first and only attempt (so far) at M13.
Date: 2021-06-17
Location: Garner State Park, TX (Bortle class 2)
Mount: IOptron SkyGuider Pro
Camera: Nikon D5300 astromod
Scope: William Optics Zenithstar 61II + Field Flattener FLAT61A
Focal/Aperture: 360 mm @ f/5.9
Lights: 6x180s (total exposure: 18 min)
Calibration frames: 20xdarks, 60xflats, 60xbiases
ISO 800
Stacked in DDS and Processed in GIMP, Siril, DeNoise AI
I enjoy seeing the progression of your images, from the beginning until the present. It is instructive to see the strengths and limitations of each camera/scope combo. This is my effort shot with:
8" f/4 TS Optics Newtonian Astrograph w/ coma corrector
Sony A6000 DSLR (aps-c)
16 frames @ 80" each, ISO 800
Sky quality was SQM 21.7
Ironically I just imaged M13 last night and saw your post about the time I finished processing my version. I always enjoy the detailed information you provide about the targets.
This was imaged from the remote observatory at Utah Desert Remote Observatories using the PlaneWave CDK12.5 and an ASI6200MM Pro camera. Moonlight made it a less than ideal night and created a lot of background gradient that I had to remove in PixInsight and Photoshop. This is 13 red, 7 green and 12 blue frames at 300s each.