Open Cluster NGC 2251
History
This open cluster was discovered by German-British astronomer William Herschel on 26 December 1783 using his 18.7-inch speculum reflector of 20 feet focal length. He logged the cluster as VIII 3 and noted: «An extended cluster of large scattered stars.» [464]
John Herschel listed the cluster as h 395 and observed it on 8 January 1828 (sweep 118) and noted: «A large tract full of stars; very rich; place from working list. Viewed» [466]
Physical Properties
| Designation | NGC 2251 |
| Type | OCL (III2p) |
| Right Ascension (J2000.0) | 06h 34m 38.4s |
| Declination (J2000.0) | +08° 21' 59" |
| Diameter | 10 arcmin |
| Visual magnitude | 7.3 mag |
| Metric Distance | 1.329 kpc |
| Dreyer Description | Cl, vL, E, Ri, lC |
| Identification, Remarks | WH VIII 3; h 395; GC 1429; OCL 499 |
Finder Chart
The open cluster NGC 2251 can be found in the constellation Monoceros. On 30 December it in opposition with the Sun and is therefore highest in the sky at local midnight.
