By the time March comes around in the Northern Hemisphere, Leo is high in the east and Arcturus is rising around dark—both sure signs that spring is finally coming to the North. The brilliant stars of the “winter” constellations are still high overhead and to the west. For stargazers in places like Australia, the constellation Puppis is straight overhead shortly after dark. Unfortunately, its southern location means that Puppis is down near the southern horizon for those of us in the United States.
Puppis is pretty easy to find to the south and east of Canis Major. Puppis was once part of a much larger constellation called Argo Navis, the Ship. Because of its great size, Argo Navis was split into several constellations many years ago. Puppis represents the stern of the ship, and is the northernmost part of Argo Navis.
Because of its location along the Milky Way, Puppis holds a lot of open star clusters, as well as a few nebulas. The most well-known clusters in Puppis are probably M46 and M47, in the far northern part of the constellation. Although there aren’t any really bright stars in the immediate area of these clusters, they are fairly bright and should be easy to find with a binocular. If your skies are dark, you may be able to see M47 with the unaided eye. Look about 10° north-northwest of the star Asmidiske in Puppis, and about 13° east-northeast of Sirius.
These clusters are similar in size, but they are otherwise very different. M47 is composed of a nice spray of bright stars, while M46 is a much denser cluster of fainter stars. This difference is obvious even with binoculars. A good binocular should resolve some of M47’s stars, but M46 will appear as a hazy spot. A good telescope will not only resolve the stars of M46, but it will also show that one of the “stars” on the cluster’s northern edge is actually a planetary nebula, NGC 2438. At low magnification, the planetary will look like a fuzzy star, but high magnification may reveal an annular (ring) shape. Although it appears to be a member of the cluster, NGC 2438 is actually much closer to us than the cluster is.
M93 is another open cluster just 1.5° northwest of Asmidiske. This triangle-shaped cluster is easily visible with binoculars, but it is fairly small, and a telescope at low to moderate magnification will give the best views.
Next, hop across Asmidiske and go almost 2° south-southeast of the star to find NGC 2467, a small star cluster and emission nebula. This is an interesting field, and it deserves a little careful observation. The cluster itself is not very impressive, but the nebula has some fascinating structure and detail. The most obvious part of the nebula is fairly round, but a closer look with the right equipment will show extensions and dark lane structure in the field of view. As is the case with any other nebula, your view will improve by increasing the size of your telescope and the darkness of your observing site. A UHC or OIII filter will increase the contrast of the nebula and can reveal a lot more detail.
Swing your telescope south one more time to find NGC 2477, a very rich open cluster. NGC 2477 is about 2.5° northwest of Naos, the brightest star in Puppis. Once you’ve found the cluster, experiment with different levels of magnification. Higher magnification may reveal more stars, but lower magnification might give a more pleasing overall view of the cluster.
