Object of the Week - NGC 2237-9, 2246 + NGC 2244, Rosette Nebula + Cluster, in MONOCERUS
R.A.: 06h32m02.0s Dec.: +04°59'10" (2000)
Apparent Size: 70.0'x 60.0'
Magnitude: 5.50

I found it hard to believe that the Rosette Nebula had never before been featured as the Object of the Week, so I jumped at the chance to highlight this wonderful assembly of objects. The Rosette Nebula itself, about 5000 light years distant, is made up of NGCs 2237 and 2246 (discovered by Swift), NGC 2238 (discovered by Marth), and NGC 2237 (discovered by John Herschel)… and the beautiful open star cluster in the center, NGC 2244, was discovered by John Flamsteed, in 1690. The NGC 2237 designation in modern times is usually used to describe the entire nebula, just to keep things simple.

At over one degree in diameter, the Rosette Nebula covers about 5 times the area of our moon, so visibly this is a huge object. Not surprisingly, it can’t be seen in its entirety by most large light-buckets, but it is sure fun to “fly around” observing smaller elements, especially when employing a filter of some kind, and in my experience all of the various deep sky filters work pretty well to bring out subtle and not so subtle details. Smaller telescopes can see the whole nebula in the same field of view, but a fairly dark sky is required and smaller telescopes might be restricted to using a wider passband filter, like the UHC/LPR types.

The Rosette Nebula is a perfect example of a stellar nursery, much like the Eta Carina, Orion, Lagoon, Eagle, and Swan Nebulae, and there are hundreds of others, and they come in all shapes and sizes. We can even see these emission nebulae in other galaxies, and the best known of those might be NGC 604, which is within M 33, a local group galaxy just down the road about 2.7 million light-years away. NGC 604 is one of the biggest HII areas known. The Great Orion Nebula, M 42, is about 1500 light-years away and NGC 604 is about 1500 light-years across, which makes it about 100 times larger than M 42! Think about that for a while and try to wrap your head around it. These stellar nurseries all work pretty much the same way, a large interstellar cloud of gas collapses, stars begin to form in a central cluster, the radiation from the cluster clears a “hole” in the center and lights up the rest of the cloud… and we get to enjoy ourselves for hours on end checking out the whorls of clouds and the dark lanes and the Bok Globules to our heart’s content. I find it to be an amazing adventure when the conditions are favorable and the sky is dark.

Obviously, the Rosette Nebula is very popular with our brothers over on the dark side, the astrophotographers. I know this because the Rosette has been featured on the APOD 27 times since its inception about 24 years ago, averaging more than once a year. Here is a list…

https://apod.nasa.gov/cgi-bin/apod/a...tquery=rosette

If I were an astrophotographer I would make the Rosette Nebula a top priority, too, it makes for an amazing photograph…

https://apod.nasa.gov/apod/image/070...te_gendler.jpg

I had to post a link instead of a photo because this DeepSkyForum interface is not working properly right now... Dragan will take a look at it at his earliest convenience

As always, give it a go and let us know.