That is a nice image John. Interesting to have a diffuse nebula in
the "middle" of an open cluster -- are these related objects or just
optical coincidences? In your image I see no evidence of the
periphery of the cluster, so presumably it is actually a bit larger
than my star chart states (nebula 12 x 12 mins, cluster 20 mins).
Perhaps there is some more nebulosity that was too faint to be
recorded in your excellent image. Of course not visible from here.

Serena

--- In ccdimaging2@yahoogroups.com, "John A. Blackwell" <johnb@r...>
wrote:
>
> Hello,
>
> A nice clear evening last night. There were no cataclysmics to
> monitor, so it was pretty-picture-taking-time ;-)
>
> Here is one of the Cocoon Nebula. It was taken through a Takahashi
> CN-212 in Newtonian mode with an ST-7MXE NABG (I LOVE that 89%
> efficiency!) and CFW-8 filters. Times were shorter than I would
> like, but the image is better than my previous attempts at this
> object. LRGB: 30:10:10:16 minutes. An RGB and a luminance image were
> made in MaxImDL using flats, darks and bias frames. The RGB and
> luminance were then imported into Adobe Photoshop to perform a
> luminance layer combine.
>
> http://www.regulusastro.com/regulus/photos/text/ic5146_lrgb.html
>
> ~johnb