Wednesday, November 30, 2016

M2 and M15

Two autumn globular clusters.

Before this month ends and with it the fall in the northern hemisphere, I would like to share two of my favorite globular clusters of the Autumn sky: M2 in Aquarius and M15 in Pegasus, both very close neighbors only about 12° from each other.

The first time I saw M2 was from Bogota with my 15x70 binoculars. It was close to the zenith, so I had to lay down on the cold, cement terrace. Despite the uncomfortable position, it wasn’t hard to find. It was there, about 4 Arc degrees from the 2nd magnitude star Sadalsuud (β Aqu). In binoculars, under a Bortle 9 sky, M2 was just a dim spot with some halo around. I sketched and processed this sketch, a long time ago, so it probably doesn’t reflect the sky background at the time of the observation. In fact, that is the most difficult thing to replicate as I work only with dark pencils at the time of sketching and add colors according my notes.

At the end of this Fall I accomplished the sketch of M2 from the view of my telescope, under darker skies (Bortle 5). The view was pleasant, but I must admit that I expected more of this globular, since it is one of the brightest in the entire Messier list. With averted vision, I could resolve some stars in the halo, but most of the appearance to my eyes was like a granulated ball of light.

With an average seeing, I pushed the scope to 166x (the globular in detail outside the main sketch) and I could get a better view of the granulated core plus some more resolved stars outside the core, but I also had to push my observer skills to get the best of it.
In the end, I sketched an idea of what I could see with averted vision.

At that time, I also got this Messier object for the first time in my binoculars, M15. I had seen it before, at the time I sketched M2 and they both looked like twin globes. However, I did not sketch it until the April of 2013, in middle of the spring in the Northern hemisphere.

The only star I could recall was Enif (ε Peg), a 2nd magnitude star in one of the feet of the Pegasus and M15 was only about 4 arc degrees from it, in the opposite edge of the binoculars FOV. M15 was then more affected by light pollution than the first time I saw it and this of course, had an influence in its appearance. I could make out the core without problems, but the halo structure was very washed out from the sky.

So, for those of you haven’t seen these couple of globs: M2 and M15, enjoy these long winter nights and seek them out before they disappear from the sky. 

Clear skies,


Edited by: Jennifer Steinberg (editor in chief).

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