Sketch: Three Winter Open Clusters

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 I have found three winter open clusters in Auriga and Gemini to show sketches of.



Clockwise from upper left: M37 with 10" dob, M36 with 10" dob, M36 and M37 with 2" refractor, M35 with 10" dob.

A little over a week ago I observed two open clusters in Auriga with my 50mm f/10 Galileoscope using a Synta 25mm Plossl (20x). They weren't much, but they were interesting enough that I resolved to go find them with a larger telescope later.

2020-December-08 08:10 PM EST.

M36 - Galileoscope - 20x (25mm Plossl)

The overall shape of the cluster is round, and seems especially so w/ averted vision. Direct vision reveals a u-shape group of stars; individual stars which come and go.

M37 - Galileoscope - 20x

Just below M36 is M37, an OPEN cluster which is a round fuzzy patch with suspected grannularity. [I didn't mention it explicitly, but it struck me as looking a lot like small globular clusters do in larger telescopes]

Later, a few days ago, I observed the two again, as well as a nearby star cluster in Gemini.

2020-December-14 10:10 PM EST

M36 - 250P - 25mm Plossl (48x)

(Sketch zoomed in/cropped slightly, around 15%, by mistake. [object is drawn too large relative to field circle, instead it appears roughly the same size as M37])

M36 is an easy to find and fairly bright star cluster with several dozen stars fairly well spread out. More compact than depicted.

[tiny field circle] Cartoon of actual FOV.

M37 - 250P - 25mm (48x)

M37 is nothing like M36 despite being near in the sky and having about the same size and magnitude. It is spherical, very round, and made of hundreds of dim stars. My reaction at first was a matter-of-factly "woah." It's very glittery, and in the finderscope looks like a globular cluster. Fascinating comparison w/ M36.

M35 - 250P - 25mm (48x)

Much of the glitteriness of M37, but with fewer, brighter stars. There's a sort of distinct hole in the middle. The whole field is densely packed with stars, hard to tell where cluster ends and background begins.

When looking up pictures of M35 I realized there's a component of the object that I completely missed! I wasn't even sure if I had correctly identified the object, but after staring at charts and other sketches it's all it could be. There is another compact open cluster NGC 2158 just outside of this field of view that I completely missed. Sketches by other astronomers show it as a fuzzy nebulous patch, again like a globular cluster. I have to revisit M35 asap. And there are indeed several more open cluster Messiers that I must catch!

 

P.S.: I do hate that feeling when I have forgotten to talk about so many things that I feel as though I can't post to my blog without covering it in chronological order. Just know that this isn't the only thing I've done over the past few weeks. I will probably cover my observations of the early stages of the conjunction when I do a writeup about the day of the great conjunction itself--but i have already observed Jupiter & Saturn at the same time in the eyepiece of the DT6. I've also found several new DSOs. I've got into star testing telescopes and have preliminary results on the comparison between the 10" and 6" dobs, but need to do more testing to be sure of the results.




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