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Lost in a sea of stars: Cocoon Nebula (first 383 LRGB)

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Despite the small number of subs used for this project, its been an epic battle just trying to get them! I had to weed out and reshoot a lot of cloud damaged subs (most of the R channel), as well as get a good blue and green channel. This is the first LRGB project for the Atik 383L+ (and my first fot a while it seems!), so I was keen to see how it would get on.

Fortunately, last night was one of those night where the forecast was completely wrong (in a good way!), really clear it was - almost ink black with the MW overhead like a long misty smudge in the sky. Many, many stars - all the way down to the horizon too, so I knew it was important to grab as much data as poss becuase nights like that dont come around that often (ie: moonless and perfect seeing). So, at the end of the session I'd bagged 30min worth of data per channel, per pane. It would be nice to have an hour per channel, but there is no point at the moment as I'd prefer to boost the Lum first - just to take the noise out of that dust, which is starting to pop out a bit now Ive picked up some of the stars behind it.

DSS needed to have the star detection threshold increased for this one because it was taking ages to calibrate images, I dont think its ever seen so many stars! But the colour turned out as is normal for this object, quite a few red stars - some blue in there, but I think that could be improved with a few more subs. Though star colour really isnt my strong point when it comes to processing :p

IC5148: Cocoon Nebula (Widefield)

12x450 L, 6x300 RGB x2 panes

80ED (0.85x), Atik 314L+, NEQ6

Setpoint: -20

Calib: Bias, flats, BPM

Thanks for looking! :)



Fullsize image here:


Edited by Uranium235
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It looks to me like the nebula has created a wake as if the stars are flowing past it - rather like the effect on the surface of a stream. This isn't the case, of course, but it does look a bit like that. Nice capture and the detail is stunning.

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Cheers Mark! Yep the weather has indeed taken a turn for the worse. By the time it improves the Moon will probably be back again, so im glad I took the decistion to collect the green channel rather than start the next project.

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Nicely done Rob,

you may consider adding Ha, very interesting in this area.


Cheers Mark, Ive been giving the Ha some thought. Though it may take some longer exposures because the background Ha is pretty weak from what I remember. I'd also like to fix the blue, there should be more of it.

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Excellent, by Gad. No doubt about it. Great dust, great outlying regions of the main nebula. (Great nebula too!)

You might try using a special curve for the starfield where you lift the bottom of the curve as you have done here in order to get the faint stuff, but flatten it early to bring down the field stars. In a layer you could then decide what you wanted out of the the two layers.

But this is a splendid image with lots to say.


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Thanks Olly, yet another nugget of wisdom! I've had already used one of those curves you mentioned (thats lifted at the bottom), but I used it as an additional step right after the main curves and levels - and on the whole image (still much to learn!).

I really should pop down to France one day and see for myself just how to properly process these areas of dark dust. :)

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Stunning widefield Rob, and great processing on limited data. Gotta stay up all night when the weather gods smile on us. Hope you can get the extra on the blue and lum channels and perhaps some Ha as suggested if conditions permit.

Look forward to seeing on a decent screen tomorrow!

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Thanks Sara :)

It looks as though tonight might be last chance saloon for any LRGB work, so I might dump a few more subs into the pot for this one. Also, last night I had a go a reprocessing the colour layer using average stacking - which seems to have turned out a better result than SD mask did. I have yet to combine it with the Lum, but I might hold off on that part in case tonight turns out to be productive.

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