M3
Globular Cluster in Canes Venatici
About
A globular cluster in Canes Venatici, about 34,000 light-years away, holding roughly 500,000 stars. It has 274 known variable stars, more than any other globular cluster, and was the first Messier object Messier found himself.
Imaging tips
- At 1,350–2,240 mm on APS-C (2,060–3,440 mm on full frame) the cluster spans a third to half of the frame; it is about 18′ across.
- One hour of 1-minute colour subs, taken under a near-full Moon, still gave a good result with a simple workflow; the Moon added a slight gradient across the frames.
- A fainter galaxy sits near the upper-right corner of that frame; the authors found it hard to see in the raw data.
- Four 10-minute subs per RGB channel were enough for one filtered-mono image at about 1,090 mm.
- Best in April and May; it reaches 68° altitude from 50°N.
Facts
- Size
- 18′
- Magnitude
- 6.2
- Coordinates
- RA 13h 42.2m, Dec +28° 23′
- Framing, APS-C
- 1350–2240 mm
- Framing, full frame
- 2060–3440 mm
- Best months
- Apr, May
- Peak altitude
- 68° from 50°N, 83° from 35°N