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ampleamp

NGC4038 - The Antennae, Arp244

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ampleamp    439

I can't remember if Peter or I came up with this galaxy back in April when it was imaged from ICA in Spain using Peter's APM 152/1200 and QSI6120. 

After scrubbing some truly terrible subs, this is Lx79, Rx29, Gx17 and Bx17; all 5 minutes. What is immediately apparent to me is that I should have taken longer subs to catch more of the actual antennae, but that will have to wait until next year now. 

This is still work in progress for me but i think this is as far as i can go with my level of knowledge so i am very interested if anyone has any techniques to being out the antennae without destroying other structures, which is where i have got to.

Thanks for looking 

NGC4038_LRGB.jpg

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wimvb    1,918

Looks great. What software do you use for processing? If PixInsight, then have a look at Gerald Wechselberger's video tutorials

http://www.werbeagentur.org/oldwexi/PixInsight/PixInsight.html

The one on enhancing weak nebulae without pushing the stars, may help. It's a technique also described by Rogelio Bernal Andreo in "Lessons from the Masters".

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ollypenrice    17,056

That's very good and just needs more data. In Ps I'd use two stretches in Layers, the lower one for the galaxies and their tidal tails and the top one for the starfield. Provided you have both at exactly the same background value you can simply use the eraser to let the faint tidal tails through. 

Olly

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gorann    1,386

Using curves and layers in PS as Olly suggested, this is as far as I could go with your image. There are definitively antennae there and a bit more dust to be found around the galaxies. With the original 16 bit image you could probably do better.

I also think your image would be improved by shrinking the stars so that more emphasis is put on the galaxies (In the second image I used the RC Astro star shrink filter for PS).

ampleamp NGC4038_LRGB GN.jpg

NGC4038_LRGB star shrink.jpg

Edited by gorann

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gorann    1,386

PS.

If you use the "equalize" function in PS, which is doing some kind of extreme stretch, you get a really ugly image but it is very informative since it reveals if there is any signal to bring out, and in your case there is a lot of signal from the antennae, and probably also a gradient but it is apparently minor since it is not apparent in your image.

ampleamp NGC4038_LRGB equalize.jpg

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wimvb    1,918

It is only a minor gradient, but I would clean it up nonetheless. It will allow a harder stretch to reveal the antennae. The hard stretch that @gorann used, when done on a luminance copy, can act as a mask for further stretching. After star removal.

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