M53
M53 - Click here for full resolution
M53 (Messier 53), also known as NGC 5024, is a globular cluster located in the constellation Coma Berenices. Discovered by Johann Elert Bode in 1775 and later independently rediscovered by Charles Messier in 1777, M53 is one of the most distant globular clusters associated with the Milky Way, lying approximately 58,000 light-years from Earth. It is situated about 60,000 light-years from the Galactic Center. M53 contains hundreds of thousands of stars densely packed into a spherical formation, spanning around 220 light-years in diameter. The cluster is notable for its relatively metal-poor stars, indicating it formed early in the history of the universe. It has a magnitude of around 7.7, making it visible with binoculars or small telescopes. M53 is often observed alongside its neighbouring globular cluster, NGC 5053, which lies nearby in the sky.
source: DeepSeek
NGC/IC:
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Tr. Alt (Oria, Spain):
NGC5024
n.a.
Globular cluster
Coma Berenices
13h 12m 55s
+18° 10.1′
58,000 ly
7.7
18 April
55º S
Conditions
M53 is best visible during Winter. During this time, it reaches altitudes over 50°, when observed from the backyard observatory in Groningen, The Netherlands. During the first half of March 2025, there was an unusual stretch of nights with clear skies, so a telescope was operational many nights during this period. Another target photographed during this time was Sh2-230. M53 was photographed from the backyard observatory over 2 nights in mid March 2025.
Equipment
The rig used for this image consisted of a Takahashi TOA-130, in combination with a ZWO ASI6200MM-Pro full-frame camera. M53 is only a small object, so a full-frame camera is a bit overkill. But for reasons of standardisation, the ASI6200MM Pro with the recently added Antlia filters will be used for all backyard deep sky imaging, unless there is a specific reason not to. The 10Micron GM1000HPS mount allowed for unguided imaging. A Linux version of KStars/Ekos was used to automate the imaging process. The system has seen a few upgrades.
Telescope
Mount
Camera
Filters
Guiding
Accessoires
Software
Takahashi TOA-130, FL67 flattener, Pegasus Astro Motor Focus kit v2
10Micron GM1000HPS, EuroEMC S130 pier
ZWO ASI6200MM Pro, cooled to -15 ºC
Antlia 2” unmounted LRGB V-Pro, ZWO EFW 7-position
Unguided
Fitlet3, Pegasus Ultimate Powerbox v2, DeepSkyDad Flatpanel FT1 (30cm), Pegasus Uranus
Linux Mint 21.1, KStars/Ekos 3.7.5, INDI Library 2.1.2, Mountwizzard4 3.2.7, PixInsight 1.9.3
Imaging
M53 is a typical broadband object and default exposure times were used. For this setup, this means 3 minutes for luminance and 5 minutes for each of the Red, Green and Blue filters. The total exposure was just over 14h. All subs taken were of sufficient quality and made it into the final stack.
Resolution (original)
Focal length
Pixel size
Resolution
Field of View
Rotation
Image center
3308 × 2374 px (7.8 MP)
1000 mm @ f/7.7
3.78 µm
0.773 arcsec/px
42' x 30'
94.491°
RA: 13h 12m 55.200s
Dec: +18° 10’ 05.04”
Processing
All images were calibrated using Darks (50), Flats (50) and Flat-Darks (50), registered and integrated using the WeightedBatchPreProcessing (WBPP) in PixInsight. All further processing was done in PixInsight, including the use of scripts and tools developed by RC-Astro, SetiAstro, GraXpert, and others. For a step-by-step description of the processing techniques applied, see process flow below.
The full frame image had a field of view that was way too much for this target. Therefore at the start of the processing a significant crop was applied. Towards the end of the processing a little bit more cropping was applied to get to the final composition. Due to all this cropping, the final image is of somewhat low resolution at 8MP. With hindsight drizzling could have been applied. If done, the stars would look a bit less blocky when pixel peeping.
To maintain colour in the RGB image, ArcSinhStretch was applied. An alternative is GHS stretching in ‘Colour’ mode, but often I don’t like the results of stars stretched with GHS.
Rest of processing followed a very standard pattern.
Processing workflow (click to enlarge)
This image has been published on Astrobin
