Messier 3 - 1 Hour on a Bright Globular Cluster
Updated: Jun 8, 2023
Messier 3 is one of the brightest, largest, and most impressive globular clusters in the sky. It contains more than 500,000 stars, lies at a distance of 32,615 light-years away, and is estimated to be about 11.4 billion years old.
We imaged this object from a Bortle 4 zone on a night when the moon was almost full. We only spent one hour on this object, mostly because we only decided to image it while waiting for our primary target to rise.
Object Designation: M3
Also known as: N/A
Constellation: Canes Venatici
Object Type: Globular Cluster
Distance: 32,615 light-years away
Magnitude: 6.2
Discovered in: 1764
The image on the left shows Messier 3 taken by the Hubble Space Telescope.
As you can see, the globular cluster appears very dense, with a compact core. Most stars seem to be white and yellow, with just a few small blue ones scattered around. It does not seem to contain any bright red or orange stars as is sometimes the case in other globular clusters.
M3 lies far above the galactic plane of the Milky Way, isolated from other deep-sky objects.
Messier 3 was the very first object discovered by Charles Messier himself, in 1764.
Then, Messier was convinced that M3 was in fact a nebula without any stars. It isn't until 20 years later, in 1784, that William Herschel observed the object and stated that many individual stars could be resolved. M3 was then known to be a globular cluster and not a nebula.
Today, Messier 3 is one of the most studied globular clusters in the sky. Scientists discovered more than 274 variable stars within M3, the highest number ever found in any globular cluster.
Below you can see our image of M3. It doesn't look fantastic mostly because it was taken on a full moon night with only one hour of total exposure. Besides that, the cluster does look crisp and colorful, and you can even spot a galaxy close to it if you have a keen eye! Can you find it?
M3 with an OSC camera and a refractor telescope.
GEAR USED:
Camera: QHY600C
Telescope: Stellarvue SVX130
Mount: Astro-Physics Mach1
Guiding: ZWO ASI 290MM Mini
Accessories: Moonlite Nitecrawler focuser
Processing: Pixinsight
ACQUISITION DETAILS:
Total Exposure Time: 1 hour
Exposure Time per frame: 1 minute
Filters: N/A
Gain: 26
How to Locate M3
Messier 3 can be found in the constellation Canes Venatici. This is a popular area of the sky due to several other famous deep-sky objects being located there, including:
Messier 51 (The Whirlpool Galaxy)
Messier 63 (The Sunflower Galaxy)
Messier 94 (The Cat's Eye Galaxy)
M3 is not close to these beautiful galaxies though, as it lies near the extreme south edge of the constellation. The best way to find it is to locate the line that separates Canes Venatici from Coma Berenices. Messier 3 can be spotted just around that area. Another great method to use is to look for the bright star Arcturus (the bright star in the lower-left corner of the map above) and start to drift towards Cor Caroli. M3 will be located almost exactly halfway to Cor Caroli.
It is difficult to see M3 with the naked eye, but not impossible under dark skies. A telescope of any size or even binoculars will have no problem showing the cluster.
Processing Messier 3
Just like most globular clusters, M3 was very easy to process and there is nothing really tricky about it! Processing this object can be done quickly, we ran through our usual processing workflow and skipped a lot of steps yet got a great result.
The only thing to look out for is the galaxy that is visible near the upper right in our image, as it is not easily visible in the raw frames as you can see below. It also is not super obvious when processing the image.
Below is what a single shot of 60 seconds looks like before stacking and processing. It doesn't look bad, although there seems to be a slight gradient of light in the image due to the moon being up.
Process your photos exactly as we do with our processing workflow. Get more information HERE.
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Final Thoughts
Messier 3 is a very easy target for beginner astrophotographers. It is large, bright, and impressive! It is also easy to process and you don't need to spend a lot of time imaging this target in order to have great results.
Have you captured M3? Attach your image in the comments and let us know your acquisition details!
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Target: M3 Date: 2022-06-25 Location: San Antonio, TX (Bortle class 7) Mount: IOptron SkyGuider Pro Camera: Nikon D5300 astromod OTA: William Optics Zenithstar 61II + Field Flattener FLAT61A Focal/Aperture: 360 mm @ f/5.9 Guide scope: William Optics Uniguide 32mm Guide camera: ZWO ASI120MM mini + ASIair Pro Lights: 63x600s (total exposure: 1h03) @ ISO 800 Calibration frames: 40xdarks, 60xflats, 80xbiases Stacked in DSS and Processed in PixInisght and GIMP.