C73
Globular Cluster in Columba
About
NGC 1851, a globular cluster in Columba about 39,500 light-years away. It is one of the most tightly packed clusters known. Its wide, sparse outer halo suggests it could be the stripped core of a dwarf galaxy, a bit like Omega Centauri.
Imaging tips
- Roughly 11–13′ across, so it needs a long focal length: 1860–3110 mm on APS-C spans a third to half of the frame without leaving it mostly empty.
- A globular cluster is a broadband subject. One published LRGB frame used 80 minutes of luminance and an hour for each colour on a 37 cm f/9 scope.
- Surface brightness is 21.5 mag/arcsec². The dense core is the hard part, so resolving it depends on fine pixel scale.
- Best in November and December. It never rises from 50°N.
Facts
- Size
- 13′
- Magnitude
- 7.3
- Coordinates
- RA 5h 14.1m, Dec −40° 3′
- Framing, APS-C
- 1860–3110 mm
- Framing, full frame
- 2860–4760 mm
- Best months
- Nov, Dec
- Peak altitude
- never rises from 50°N, 15° from 35°N