Updated: Jun 7
Messier 46 and Messier 47 are two young open clusters in the constellation Puppis. The twist? A small but bright planetary nebula can be seen "hiding" within M46!
We drove to a Bortle 4 zone to image this pair of clusters and did our best while processing it to reveal the nebula as best as possible. How did it turn out? find out below!
Object Designation: M46 & M47
Also known as: N/A
Object Type: Open Clusters
Distance: 5,545 & 1,624 light-years away
Magnitude: 6.1 & 4.2
Discovered in: 1771
What makes Messier 46 unique is that is overlays a bright planetary nebula, NGC 2438. Although the object will look very small and lack any interesting features, it really is a fantastic nebula to image with large telescopes, as seen on the left.
In our image, we tried to make sure that the two main colors, red and blue, popped out nicely, without blowing up the bright core. Check it out below!
Messier 46 and Messier 47 each contain about the same amount of stars: 500. They're both medium size open clusters and share similar characteristics. The main differences here are their distance and age. M46 lies farther than M47 (5,500 vs 1,600 light-years away), and is also much older (251 vs 78 million years old).
Photographing M46 and M47 was simple. The framing was important to capture both clusters nicely but was easily achieved by angling the camera in a way that each object is on opposite corners.
M46, M47, and NGC 2438 with an OSC camera and a refractor telescope.
Use the arrows to zoom in on each cluster!
Telescope: Stellarvue SVX130
Mount: Astro-Physics Mach1
Guiding: ZWO ASI 290MM Mini
Accessories: Moonlite Nitecrawler focuser
Total Exposure Time: 3 hours
Exposure Time per frame: 5 minutes
How to Locate M46 and M47?
Messier 46 and Messier 47 are both located extremely close to each other and will easily fit in the same field of view if using binoculars or any telescope with a focal length of up to 800mm.
The open clusters lie in the constellation Puppis, which does not rise high in the northern hemisphere. Luckily, M46 and M47 are at the northern extremity of the constellation, so they stay visible for a fair amount of time despite the constellation being so quick to disappear on the horizon.
The easiest way to find the clusters is to first locate Canis Major, easily visible due to it being home to the brightest star in the sky, Sirius. Grab your binoculars or use a small telescope to scan the area going from Sirius to the constellation Hydra. M46 and M47 should be visible midway to Hydra.
How to Process M46 and M47
Processing open clusters is, most of the time, simple. It is also the case for M46 and M47. The only tricky challenge here is to of course deal with the small planetary nebula within M46. NGC 2438 is tiny but bright. Make sure to keep an eye on it throughout your processing workflow so that you don't blow it up or mess up the colors.
The image below shows what our unprocessed image looked like, right after stacking all the raw files. As you can see, the nebula is pretty obvious!
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Messier 46 and Messier 47 are two beautiful open clusters! The small planetary nebula visible in M46 is a nice addition to any image, and a great challenge as well!
Have you captured M46 and/or M47? Attach your image in the comments and let us know your acquisition details!