Messier 53 (Coma Berenices)
The globular clusters Messier 53 (NGC 5024) and NGC 5053 in the constellation Coma Berenices
Fig. 1 - Possible interaction in the past: The ancient pair of globular clusters Messier 53 (top left) and NGC 5053 (bottom right) in Coma Berenices, photographed with an 8-inch f/4 Newtonian reflector on a ZWO AM5 mount.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| Messier 53 (NGC 5024) | Coma Berenices | 13h13m / +18°10' | 13' | 7.6 mag |
| NGC 5053 | Coma Berenices | 13h16m / +17°42' | 10' | 9.0 mag |
Messier 53 (NGC 5024) is a metal-poor globular cluster in the constellation Coma Berenices. It appears as a compact, well-defined system containing several hundred thousand stars, with estimates typically around 500,000 members. The cluster spans roughly 200 light-years in diameter, although most of its light is concentrated in a much smaller core region. For a long time, Messier 53 was considered one of the most metal-poor globular clusters in the Milky Way, indicating that it is composed of very old stars formed early in the Galaxy’s history.
A large fraction of the red giant branch stars in Messier 53 belong to the so-called first stellar generation, meaning they formed from primordial gas rather than from material enriched by earlier stellar evolution. This conclusion is based on their chemical composition, as spectroscopic studies show little evidence of the characteristic abundance patterns—such as enhanced sodium and depleted oxygen—typically associated with later stellar generations. This is somewhat unusual, as many globular clusters are dominated by second-generation stars. In Messier 53, however, the second-generation population is more centrally concentrated, suggesting internal dynamical evolution over time. Located in the outer halo of the Milky Way, Messier 53 lies about 58,000 light-years from Earth and roughly 60,000 light-years from the Galactic Center. It was discovered by Johann Elert Bode in 1775 and later included in Charles Messier’s catalog in 1777.
About 1° to the southeast lies NGC 5053, a much more diffuse and irregular cluster that contrasts strongly with the compact appearance of M53. With a diameter of roughly 150–200 light-years, it is of comparable size but far lower stellar density. NGC 5053 contains only about 3,000–4,000 known stars down to approximately 21st magnitude, giving it a sparse and almost ghostly appearance. Its loose structure makes classification difficult: it is often described as a very low-density globular cluster, bordering on the characteristics of a rich open cluster. Like M53, it is also extremely metal-poor, pointing to a similarly ancient origin. NGC 5053 was discovered by William Herschel in 1784.
Deep observations reveal that both clusters exhibit tidal features such as extensions, clumps, and ripple-like structures, likely caused by gravitational interactions with the Milky Way. Particularly intriguing is the presence of a very faint tidal bridge and a diffuse stellar envelope that appear to connect Messier 53 and NGC 5053. These features suggest that the two clusters may have interacted dynamically in the past or could even share a common origin, possibly as remnants of a disrupted dwarf galaxy that was accreted by the Milky Way (source: Wikipedia).
Technical Details:
Exposure time: 5h (100x3min)
Gain: 0
Date: March 12/13, 2026
Processing: Astro Pixel Processor (APP) and Photoshop
Calibration: Darks, flats, and bias
Equipment:
Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 8" f/4 "ONTC" Newtonian telescope, ZWO AM5 Strain Wave Mount, ZWO OAG-L off-axis system, ASI 174MM Mini guide camera, ASIAIR Plus
Fig. 2 - Finder chart for Messier 53 and NGC 5053. Copyright 2026 'The Mag-7 Star Atlas Project', www.siaris.net.