Saturday, January 28, 2017

M11 Wild Duck Cluster

City sky vs Suburban sky 

The southern constellation Scutum has probably one of the most precious open clusters in the whole sky: wild duck cluster, a massive collection of stars located less than 2 degrees east from β Stc.

Under urban skies the duck becomes a domesticated creature and loses its wildness. The heavy light pollution washes out the hundreds of dim stars in it and all that one can see is a fuzzy cloud around a couple of dim stars.

In 2013, I saw it and sketched for the first time. At the time of the sketch, the full moon was close to setting while Scutum was high in the sky, at about 50° over the horizon. At that time, I had only the two eyepieces provided with my scope: a 20mm erecting eyepiece and a 10mm, that I believe was Kellner model. Most beginners try to fight light pollution with more magnification and that was my case. I poped in the 10mm expecting to see more, but all that I saw was couple of 7th-8th magnitude stars and a nebulous like fuzz cloud in the middle of a reduced field of view that contained less than 20 stars.

I always thought the best view of M11 I could have was with low magnification because of that view I had had from my Bortle 9 skies. With the telescope or the binoculars I could not see much of it, but a mere fuzz and dim cloud. Still, it was one of the best views from my severe light polluted sky.

Of course, the wild duck had more to offer; now from my actual Bortle 5 skies, I can begin to enjoy it more. Now I have 20mm more in aperture and better eyepieces, but the main factor that makes possible better views is definitely a darker sky. During the last summer I had a couple of times to enjoy the amazing view of it, but it was not until last October that I decided to sketch it. The cluster’s view was richer in stars, more dense and definitely more wild.

Sketching M11 is a hard task too, in part because it has a vast number of stars only resolved with averted vision. With 100x I can estimate more than 60 stars that can be resolved with averted vision and the structure still shows some some of nebulosity inside and between the branches of stars.

The cluster has even more to give with darker skies and bigger aperture, but the view from my semiurban skies is a good start. Definitely a good target for the next months in the very early morning.

Happy new Chinese year!


Edited by: Jennifer Steinberg (editor in chief)

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