M46 (NGC 2437) & NGC 2438 -- Open Cluster with Planetary Nebula in Puppis
M46 & the Calabash Nebula
M46 is only 1 ½ degrees away from much brighter M47. The two are very different. M47
(shown in another drawing) contains several bright stars that helps locate the twin Open
Clusters using binoculars. M46 appears about the same size as M47 but lacks bright stars.
M46 is still easy to spot with binoculars. Through the 155mm telescope the two star-clusters
could not be more different looking. M47 is an irregular spattering of bright stars while M46
is a nearly circular collection of about equally dimmer stars. M47 wins in looks when viewed
through binoculars but M46 comes out on top when viewed with a telescope. The addition
of the Calabash Nebula in the northern section of M46 is an added telescopic treat. This
Planetary Nebula is currently believed to be a member of the M46 star cluster (but the
debate continues). Even from my suburban house, the Calabash Nebula (NGC 2438) is
subtle but not difficult to find, however, if you add an OIII filter it really jumps out in the star
field. The Calabash Nebula is one of the Herschel 400 objects.