Some summer open clusters

[Ed astro]

Hi all, 

over the last few weeks I have been working on some sketches of open clusters with my 150 mm reflector. This started with the aim to observe NGC 6633 and IC 4756, which were selected as “objects of the month” on the Dutch astronomy forum (Astroforum). 

I observed NGC 6633 on July 14. It is a fairly rich cluster looking like a slightly curved stream of stars about 30’ long. I wonder if the shape is due to some gravitational interaction/ disruption of the cluster. It took me over an hour to draw this object, there were so many stars! After sketching NGC6633, which took over an hour, I was getting too tired to continue so sketching IC4756 had to wait for another time.

The skies finally cleared once again one week later, last saturday night. The moon was almost full and transparency was not great. Despite suboptimal observing conditions I still decided to observe IC 4756 and was not disappointed,  I could still see a fair number of stars in this cluster. It is composed of a few dozen rather faint stars (> mag 9) scattered in an area about 30’ across. 

That same night I also observed M29. Despite spending a lot of time observing star clusters and nebulae in Cygnus (in fact it is my favorite constellation) I had never really done a proper sketch of this Messier object. M29 appeared as a rather compact group of 6- 7 brighter stars arranged in a rectangular shape with some fainter stars scattered around. 

 

[lunator]

Ed

Very nice sketches, you have caught the feel of the star clusters well.

Cheers

Ian

[SwiMatt]

Beautiful sketches @Ed astro! Very realistic too. 

I love the way you seem to draw a little bit of halo around the single stars. How do you achieve that effect?

[Ed astro]

I use a white water colour pencil, applying lighter pressure as I am moving the tip away from the star. Then I use a smudger, or if I am lazy my finger, to soften the halo. It is a bit of extra work but it gives the bright stars a nice “glow” effect. 

[SwiMatt]

21 hours ago, Ed astro said:

I use a white water colour pencil, applying lighter pressure as I am moving the tip away from the star. Then I use a smudger, or if I am lazy my finger, to soften the halo. It is a bit of extra work but it gives the bright stars a nice “glow” effect. 

It does indeed! Very nice!