The Cocoon Nebula - A Very Short Glance

[The-MathMog]

This is an image created from data I took almost a month ago. I didn't really intend to do anything with the data, as I was just testing the mount and different exposure lengths contra ISO settings.
But a very long period of clouds, (I've literally not been out with the scope for a month) made me go back through some old files to see if there was anything I could fiddle with to fill the time.
I found these and merged them together. 3 subs with a total integration time of 16 minutes (what an astounding amount of data!). One sub of 120 secs with ISO 6400. One sub of 360 secs ISO 1600 and one with 480 secs ISO 1600. No darks, bias or flats either. Just pure, raw, noisy data!

But I am honestly pleased with what I could make of it, as I first off didn't even expect to get anything out of doing those images, and not knowing how easy pulling our details on this object was either.

The Cocoon Nebula (IC 5146)
3 Subs (2 Min, 6 Min, 8 Min)
Iso 6400 and 1600
16 Minute Integration Time 
Skywatcher 150pds
Celestron Advanced VX Mount
Nikon d5200
Explore Scientific Coma Corrector
Baader Neodymium Filter
Stacked and Processed in Photoshop CS2

[Tim]

Well, you've got star colours, reflection and emission nebulosity, and even a good trace of the dark nebula associated with the Cocoon. Sixteen  inutes well spent I reckon

[The-MathMog]

7 hours ago, Tim said:

Well, you've got star colours, reflection and emission nebulosity, and even a good trace of the dark nebula associated with the Cocoon. Sixteen  inutes well spent I reckon

Definitely spend much time of processing too, as doing pretty much any stretching would leave a horrible mess. As long as you don't zoom in too much the horrendous noise-floor is hidden enough.
And then knowing that I won't be able to add to it for probably several more weeks.. Lovely..
Cropped the image a bit too, as there are some weird star shapes. Can't quite figure out if it is still a small amount of coma, or some other optical aberration caused by tilt, mirror pinch or something else entirely. 

[Tim]

Weird star shapes? How do they look?

Coma will show itself evenly over the image and worst in the corners, assuming your collimation is good, but if the secondary mirror should be even slightly out, especially if it is rotated a touch, then star shapes plus a bit of coma will give you all kinds of odd shapes across the image. A good way to check if your cameras focal plane is properly square to the optical axis is to measure any vignetting you get in the corners. This should be evenly distributed.

Pop a piccy up if you like and we'll see what we think is the root of the problem.

 

[The-MathMog]

Well feel free to have a look at it Here is the how the four corners of one of the raws look. Lower right corner looks like more regular coma, while the other ones look a bit different, while upper left doesn't have much at all.
It could be a lot worse, but it is still annoying to have to crop the image to get it out of the frame
 

[Rodd]

Short but sweet.  The dark nebulosity is visible--very visible.  Yes the stars look a bit off at 6:1 or whatever you zoomed to, but at 1:1 they look just fine.  Keep going!

Rodd