Open Cluster M46 & M47

M46 (NGC 2437) is an open cluster in the constellation of Puppis. It was discovered by Charles Messier in 1771. Dreyer described it as "very bright, very rich, very large". M46 is about 5,500 light-years away with an estimated age on the order of several 100 million years. The planetary nebula NGC 2438 appears to lie within the cluster near its edge (the faint blue stain at the top center of the image), but it is most likely unrelated since it does not share the cluster's radial velocity.The case is yet another example of a superposed pair, joining the famed case of NGC 2818. M46 is about a degree east of M47 in the sky, so the two fit well in a binocular or wide-angle telescope field. Open Cluster M47 (NGC 2422) is an open cluster in the constellation Puppis. It was discovered by Giovanni Batista Hodierna before 1654 and independently discovered by Charles Messier on February 19, 1771. There is actually no cluster in the position indicated by Messier, which he expressed in terms of its right ascension and declination with respect to the star 2 Puppis. However, if the signs of Messier's coordinate differences are changed, the position matches that of NGC 2422. M47 is at a distance of about 1,600 light-years from Earth with an estimated age of about 78 million years. There are about 50 stars in this cluster, the brightest one being of magnitude +5.7.