Messier 3 (Canes Venatici)
Fig. 1 - Unusually large population of variable stars (stars that fluctuate in brightness over time): The globular cluster Messier 3 in Canes Venatici, photographed with an 8-inch f/5 Newtonian reflector on a ZWO AM5 mount.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| Messier 3 (NGC 5272) | Canes Venatici | 13h42m / +28°23' | 18' | 6.3 mag |
The globular cluster Messier 3 (NGC 5272) in the constellation Canes Venatici. It was discovered in 1764, and was the first Messier object to be discovered by French astronomer Charles Messier (1730-1817) himself. Messier originally mistook the object for a nebula without stars. This mistake was corrected after the stars were resolved by German-British astronomier and composer Frederick William Herschel around 1784. Since then, it has become one of the best-studied globular clusters. Today it is know to contain 500,000 stars. Messier 3 is notable for containing more variable stars than any other known globular cluster. It is 34,000 light-years from Earth (source: Wikipedia).
Exposure time: 6h 18min (126x3min) at gain 100 and -10°C, taken on March 4 / 5, 2025. Processing with Astro Pixel Processor (APP) and Photoshop. Darks, flats, and bias were used.
Equipment: Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 8" f/5 "ONTC" Newtonian telescope riding on a ZWO AM5 Strain Wave Mount, ZWO OAG-L off axis system, ASI 174MM Mini guide camera, ASIAIR Plus.
Fig. 2 - Search chart for Messier 3. Copyright 2025 'The Mag-7 Star Atlas Project', www.siaris.net.