M 47 (NGC 2422 = NGC 2478) & NGC 2423 -- Open Clusters in Puppis
What Messier object has two NGC numbers?
The answer is Open Cluster M47 on Puppis. A mistake in the location data resulted in the
object being “discovered” twice and thus assigned two New General Catalog numbers
(NGC 2422 and NGC 2478). M47’s one-hundred and seventy-seven plus stars contain both
bright and dim members. Most clusters do, but it is extreme in M47. The brighter stars in M47
stand out nicely, which is helpful in finding the cluster in a section of the sky devoid of bright
stars. Only 1 ½ degrees east of M47, is M46 another large Open Cluster (but much dimmer).
In addition, about a half of a degree north of M47 is NGC 2423 another Open Cluster that is
one of the Herschel 400 objects. This nice threesome is just a bit too large for me to enjoy in a
single field-of-view through my 155mm refractor. Not a problem, since M46 makes a nice
drawing on its own.
object being “discovered” twice and thus assigned two New General Catalog numbers
(NGC 2422 and NGC 2478). M47’s one-hundred and seventy-seven plus stars contain both
bright and dim members. Most clusters do, but it is extreme in M47. The brighter stars in M47
stand out nicely, which is helpful in finding the cluster in a section of the sky devoid of bright
stars. Only 1 ½ degrees east of M47, is M46 another large Open Cluster (but much dimmer).
In addition, about a half of a degree north of M47 is NGC 2423 another Open Cluster that is
one of the Herschel 400 objects. This nice threesome is just a bit too large for me to enjoy in a
single field-of-view through my 155mm refractor. Not a problem, since M46 makes a nice
drawing on its own.