H-NGC2251
Open Cluster in Monoceros
About
A large, scattered open cluster in Monoceros, listed about 4,300 light-years away. William Herschel found it on 26 December 1783 describing a stretched-out group of big, spread-out stars. It is in the Herschel 400.
Imaging tips
- About 10′ across. At 2420–4040 mm on APS-C (3710–6190 mm full frame) it takes a third to half of the frame.
- At 20.9 mag/arcsec² it is not especially faint, so broadband data suits an open cluster.
- It is opposite the Sun around 29 December and peaks near 48° from 50°N.
Facts
- Size
- 10′
- Magnitude
- 7.3
- Coordinates
- RA 6h 34.7m, Dec +8° 20′
- Framing, APS-C
- 2420–4040 mm
- Framing, full frame
- 3710–6190 mm
- Best months
- Jan, Dec
- Peak altitude
- 48° from 50°N, 63° from 35°N