M36 (open cluster in Auriga)
is the first of three bright open clusters in the southern part of Auriga
included in Messier's catalog. M36 is between 3,700 and 4,100 light years
distant and has an apparent angular diameter of 19 arcminutes, or about 2/3 the
diameter of the full moon. At about 25 million years, M36 is a very young open
cluster. It has about 60 members, the brightest of which are about magnitude 9.
If M36 were located at one tenth its actual distance, it would appear quite
similar to the Pleiades.
360: M36 with the Telrad
It takes about 30 seconds to get M36 into your scope’s field of view. Just draw an imaginary line between the two stars 37 Theta Auriga and Alnath, which are two of the five stars that form the pentagram of Auriga. Place your Telrad as shown, with the bulk of its field within the pentagram and the 4-degree circle centered on and just barely overlapping the line between 37 Theta Auriga and Alnath.
M36 should appear in your low-power eyepiece, although you can verify its location with your optical finder and center it if necessary. Like most open clusters, M36 is a low- to medium-power object. Its extent is a circle of about 12 arcminutes, or about 40% the diameter of the full moon. That means an eyepiece with a true field of view of 30 to 45 arcminutes or ½ to ¾ degree allows you to view the details of the cluster in context with its surroundings.