Roaming the Deep Sky #2
M35
By Don Clouse
M35 is a large, bright, beautiful open cluster. On a good night at a dark site, it is visible to the naked eye as a dim hazy patch. M35 is located only about two degrees north of the plane of the galaxy. At a galactic latitude of approximately 187 degrees, it is nearly opposite the galactic center in our skies. At around 2,400 light years distance, M35 seems to fall within a patchy boundary area where the Local and Perseus Spiral Arms seem to merge. It is located in western Gemini at the top of the west most foot (see the chart which shows stars to 8th magnitude). M35 is listed with a diameter of 28’, magnitude of 5.1, and 200 stars.
I used my Celestron 8" SCT with a 35mm eyepiece (with a 49 degree apparent filed) to observe M35. This combination yields a 50.6’ true field with a magnification of 58 power. From a dark site I estimated at least 150 stars, including a nice curving chain located just off the cluster’s center. M35 has a rough oval shape oriented north-south. Comparing its size in the eyepiece versus the known field size allowed me to estimate a size of 30’x25’ for the cluster. M35 exhibits a wide range of stellar brightness. The stars are fairly evenly distributed across the cluster with very little centralization. However, the northern two-thirds of the cluster is somewhat more concentrated.
M35 is a very suitable target for a small telescope, arguably even more attractive than in a moderate sized scope. Using by 80mm f/5 Celestron refractor from an urban site with a limiting magnitude of 4.5 (faintest stars visible to the naked eye) at best, I was able to count 30 stars. Averted vision caused numerous additional tiny pinpoints to pop into view. At 27x in a 2.5 degree field of view, the cluster was only one-fifth the width of the field. This makes its nature as a distant cluster of stars much easier to appreciate. It is a very lovely panorama indeed.
If viewing from a dark site, be sure to visit NGC2158 while in the vicinity. This open cluster is located about 20’ southwest of M35 and is visible in the same field. Its listed magnitude of 8.6 and size of 5’ should make it a fairly easy target for a moderate sized scope. In January 1998, I saw these two contrasting clusters, one nearer and the other six times further away, together in the same field for the first time. I saw them through the 16" Meade LX200 at the Kitt Peak National Observatories’ visitor’s center. Quite a beautiful sight indeed! Look for Gemini and M35 in the western skies early in the evening during March. Clear skies.
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