Cr140
Open Cluster in Canis Major
About
A young, extended open cluster in Canis Major about 1,226 light-years away and some 20 million years old. Lacaille logged it in 1751 as a nebulous cluster, and a 1980 study noted it may be only a grouping of stars born together. The same cloud may have formed NGC 2516 as well as NGC 2547.
Imaging tips
- Sources give its size as 60′ to about 68′, a wide scatter of stars, so a wide lens suits it better than a long focal length.
- A star cluster, so broadband imaging suits it.
- One imager shot it in LRGB on a mono camera from a Bortle 9 backyard, at about 685 mm on a small sensor, which nearly covered the cluster.
- The same imager notes the cluster is visible to the naked eye even from their light-polluted yard, so it tolerates bright skies.
- Best in December and January, but it peaks near 8° altitude from 50°N and near 23° from 35°N, so a southern site helps.
Facts
- Size
- 42′
- Magnitude
- 3.5
- Coordinates
- RA 7h 23.5m, Dec −31° 58′
- Framing, APS-C
- 580–960 mm
- Framing, full frame
- 880–1470 mm
- Best months
- Jan, Dec
- Peak altitude
- 8° from 50°N, 23° from 35°N