Christmas Tree Cluster
By Shawn Grant
In February the skies can get very clear, so clear it seems like you can get lost in the vast voids of space. The Milky Way stretches from Canis Major in the south to Cassiopeia to the north. The Milky Way is not as bright or as big as in the summer skies but non-the less spectacular. There are many open clusters, bright nebula and dark nebula to explore. We are going to explore northwestern Monoceros around the Christmas Tree Cluster and its associated nebula. This area holds many surprises. You will discover open clusters that look like diamond dust, vast nebulas and dark nebulas.
Let’s start the hop. Locate the constellation Gemini the twins. In the southwest portion you should see a 3.3 magnitude star named Alzirr also known as Xi Gemini. It is a yellow star that is 12 times more luminous then our own sun. It is at a distance of 57 light years. In the telescope or binoculars you will see that it is the brightest star in a trio of 2 other stars 30 Gemini and 32 Gemini. 30 Gemini is a very nice double star. The first component is magnitude 4.49 and its second component is magnitude 11.1 and has a position angle of 184 at a separation of 27 seconds.
3 degrees to the southwest of Alzirr lies NGC 2264 the Christmas Tree cluster. It is very bright, large and sparse. Upon first glance you will immediately see the christmas tree shape. The point of the tree faces to the south. The cluster is involved in a large nebula complex called sh2-273. The nebula covers 2 degrees by 2 degrees of the sky. You will need a dark sky and a nebula filter to spot the nebula. The brightest portion is near the christmas tree cluster.
About 25 minutes west of NGC 2264 is a dark nebula called the cone nebula. It looks like it is wedging itself into the nebula sh2-273. The key to seeing this dark nebula is to enhance sh2-273 with a nebula filter and look for a cone shape of nothing but black. Many people say you can’t see the cone nebula but fact you can see it. I have seen it myself and several other people have visually seen it. This whole complex is a photographer’s favorite target and is very easy to photograph. Let’s go deeper and explore the surrounding area.
NGC 2259 is a little over a degree to the north of NGC 2264. It is a very nice open cluster. It is somewhat small with a size of 4.5 minutes. It is also dim at a magnitude 10.8. Don’t let those figures fool you. It is very rich and compressed. The stars are faint giving the cluster an over all appearance of diamond dust. Here are a few challenges.
25 minutes west of NGC 2259 is LDN 1502 a dark nebula. I have not seen this nebula myself but I am going to try the next time I am out. If you have seen it let me know I would be interested in your observations.
About a degree to the west of LDN 1502 is another nebula NGC 2247. It is a reflection nebula two minutes in size. It is a faint circular glow surrounding 8th magnitude star. In the same field of view to the west is NGC 2245. It is a nebula 2 minutes by 2 minutes in size. It is comet shaped fanning to the southwest. There is a 11th magnitude star embedded in the nebulously. A half a degree to the west of NGC 2245 is the open cluster CR 95. It is 19 minutes in size and loose. It is not well detached and very sparse. I am not sure why this was considered a cluster.
Lets work our way a degree and a half to the southeast to a very nice cluster TR 5. It is 7 minutes in size and very rich. It is composed of 150 faint stars. In a dark sky it will look like stardust. It is a very pretty and nice cluster. NGC 2261, Hubble’s Variable Nebula is on of my favorite objects in the sky. It is located little less then a degree to the south of TR 5. It is 2 minutes by 1 minute in size. It is shaped like a comet. Something interesting about this nebula is there is a variable star embedded in it. When the star is at its maximum the nebula appears a little brighter and bigger. When the star is at minimum the nebula dims and get smaller. A nebula filter greatly enhances this object. This region is packed full of great wonders. Expand the star hop, explore the sky and see what is really there instead of bright object here bright object there.
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