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M11 open cluster in Scutum

 

Also known as the Wild Duck Cluster.

M11 in Scutum

Canon EOS5DMkII 254mm Newtonian @ 2380mm 14 x 20s f/9.4 ISO6400 2010:8:17 23:04:36-23:10:23 UT
From Rookhope 54.8N 2.1W 330m asl. Rural, almost no light pollution (3 Bortles)

This is my first deep sky photo from the darker observing site. The focus is not very good. I think that is because I had not allowed the telescope enough time to acclimatise to outside temperatures. However, the advantage of less-than-sharply-focussed stars is that we can see their colours more clearly. It is fairly obvious here that we have two groups of stars: orange ones and blue ones. That is even more obvious of we push up the colour saturation by using GRIP:

Saturated version of M11 in Scutum

Canon EOS5DMkII 254mm Newtonian @ 2380mm 14 x 20s f/9.4 ISO6400 2010:8:17 23:04:36-23:10:23 UT

This image prompted me to add a new facility in GRIP, to graph the colours of detected objects:

Graph of star colours in M11

This was plotted from the original (unsaturated) image. Stars in a cluster like this are likely to have all been formed in the same cloud of interstellar gas and therefore have similar composition and therefore similar colour. The group of crosses near the bottom of the plot is therefore likely to represent the stars that are in the cluster. Other stars simply happen to lie in a similar direction but are nearer to us or further away.

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