Deep Sky – December 2008 by Dave Owen

M37 / NGC2099

M37 / NGC2099

The constellation of Auriga culminates, reaches its highest point in our sky, at about midnight in mid December.
However, even at about 21:00, in mid December, it is about 60 degrees above the horizon and conditions should be excellent for finding the 3 bright star clusters included in Charles Messier’s 18th century list of comet like objects;

  • M36 (RA 05:36, Dec +34:08 epoch 2000)
  • M37 (RA 05:52, Dec +32:33)
  • M38, (RA. 05:29, Dec +35:50).

People often ask me if their alignment in the sky follows a simple east/west pattern, i.e., do you go west to east, or east to west as you go from M36 to M37 to M38? Unfortunately, as ever, life is not that simple.
Going from west to east the sequence is M38, M36 then M37. Why? Well, only one of these objects, M37, was discovered by Messier, in 1764. The other two were discovered by Le Gentil, (his full name is a lot longer than this!), in 1749.
Perhaps Messier was trying to emphasise that there is something different about M37. Is there? I think so. M36 and M38 were discovered first. This is almost certainly because they are easier to see in very small telescopes. They are only about 2.25 degrees apart and although M38 is bigger, they both consist of fairly bright stars that are easily resolved in very small telescopes.

M37 is almost 4 degrees from the middle cluster of this trio, M36. It is also much more comet like, in small telescopes, than the other two. There are very few bright starsin M37 but it is very rich in faint stars. In the 16 inch Robertson Reflector, at Pex Hill, it never fails to provide a stunning view, even at low power. The other two clusters are best appreciated with smaller telescopes or binoculars.