Print Page - IC5146, the Cocoon Nebula taken at Rother

Title: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: The Thing on Sep 18, 2012, 20:59:52

HEQ5 Pro (recently re-greased), EQMOD, CdC, LX90 8" UHTC Baader Alan Gee II Telecompressor, Canon 350Da, NO Astronomik CLS-CCD clip filter, Lakeside ASCOM Focuser, Meade 8x50 FinderGuidescope & QHY5, PHD Guiding, APT Astro Photography Tool.

Processed in IRIS. 20 flats, 8 darks, 10 offset/bias frames. 32 x 300s (2h40m) at iso800. Stacked with sigma 1.5 with 1 iterations. Colour and dynamic stretching, no wavelet sharpening this time and binning twicex2.

Full size
(http://www.ancientlight.amateur-astronomy.org//images/IC5146_Cocoon_Nebula_Rother_Valley_sm.jpg) (http://www.ancientlight.amateur-astronomy.org//images/IC5146_Cocoon_Nebula_Rother_Valley.jpg)

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: MarkS on Sep 18, 2012, 22:06:49

I like that! You're just beginning to see the dust. If you can deal with the background gradient I think the dust would come out even better. Then increase the blue a bit.

What do you mean when you say "binning twicex2" ?

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: MarkS on Sep 18, 2012, 22:24:32

Hope you don't mind but I took a liberty of having a go myself 'cos I just couldn't resist:

(http://www.markshelley.co.uk/webdisk/dunc_cocoon_small.jpg)

I think you've got a superb result there! 8)

Larger version:
http://www.markshelley.co.uk/webdisk/dunc_cocoon.jpg

I removed the gradient as follows in IRIS:
1) Type the command "pointon"
2) Click 10 points on the background near each corner of the image - 40 points in total. This often works better if you blur the image first (but I didn't in this particular case)
3) Type "poly 1" which creates linear background gradient when followed by the "synthe" command
4) Save this background gradient: "save my_back_gradient"
5) Load the image again, subtract the background gradient image: "sub my_back_gradient 0"
6) Type the command "pointoff" to stop the annoying crosses appearing each time you click the mouse
7) Adjust blackness of background and enhance colour balance.

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: Jim on Sep 18, 2012, 23:15:50

Remember you doing this one Duncan. Amazing detail you've captured.

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: Carole on Sep 19, 2012, 00:08:15

There's some really good data there and you've captured some good star colour as well.

Carole

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: JonH on Sep 19, 2012, 00:27:24

This is some really good stuff!
Think I need to learn how to use Iris!

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: The Thing on Sep 19, 2012, 07:38:47

Thanks for the iris help Mark. I had only tried ~~Sunday~~ subsky (blooming smellpeckers!) and various polynomials.
Thanks for you kind comments everyone.

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: JohnP on Sep 19, 2012, 12:18:28

Well that's a mighty fine Cocoon. Really nice & like your tweak Mark - John

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: Fay on Sep 19, 2012, 16:56:45

Well done Duncan, very nice Cocoon & great stars!!!!

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: The Thing on Sep 19, 2012, 17:52:04

Hi all and thanks.

I have followed Mark's instructions for gradient removal in IRIS and uploaded the images to the web, replacing the previous versions. Thanks again Mark, you learn something new every day!

Title: Re: IC5146, the Cocoon Nebula taken at Rother_Valley 15 Sept 2012
Post by: RobertM on Sep 19, 2012, 18:58:29

That looks really excellent Duncan and lovely star colours too.

Robert

Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: The Thing on Sep 18, 2012, 20:59:52