Sculptor Galaxy - first attempt adding Ha

[Jeff]

My first attempt at this galaxy.

120 minutes of RGB captured using an ASI183mc (OSC camera).
Final image includes 65 minutes of Ha captured with an ASI1600mm.

Higher res version here:
https://www.astrobin.com/372913/C/?nc=user (http://https://www.astrobin.com/372913/C/?nc=user)

Just learning the ropes of using Ha for the first time.
Very exiting for me!

Processing tips welcome!

[RickS]

Looks good for a first attempt, Jeff. How did you do the Ha blend?

Here's a PixelMath expression that I often find helpful: "Ha - (R-med(R)) * F". Ha is the Ha master, R is a red master (linear data, i.e. not stretched) and F is a fudge factor multiplier. You can calculate F from the bandwidth of the Ha and R filters but it usually needs a bit of tweaking so I find it easier to just start around 0.1 and adjust up and down until I like the result.

What this does is remove bright broadband sources, like stars, and leaves the Ha features. A simple way to use the result is to denoise and stretch it, apply as a mask to your RGB image and then boost the red and perhaps the blue a little as well (emission from ionised Hydrogen includes blue H beta as well as deep red H alpha.)

Cheers,
Rick.

[Jeff]

Thanks Rick. Had a play with the PixelMath blend method using some of the Deep Sky West data, following the instructions from Harry's videos and Jim's Cribsheet. I agree that it works a treat, and gives plenty of control. Next time! :thumbsup:

I was pretty lazy here, using the RGB in tact from the 183mc and blending in some Ha using the "NBRGBCombination" script under utilities.

Cheers,
Jeff

[Mickoid]

That's a fine first attempt Jeff. You have plenty of good data there to play with and the Ha regions really stand out. I'm very impressed with your blending technique. I hope you don't mind but I downloaded your image to my mobile phone and had a play with it using the phone's photo editor functions just for fun and came up with this. It shows how much detail you have to extract from this nice image.

[Jeff]

Thanks Michael.
Definitely "pops out" better with increased brightness & contrast.
:thumbsup:

[PeterSEllis]

Hi Jeff,
Nice shot, it certainly makes those Ha regions pop out.

Cheers
Peter

[Jeff]

Thanks Peter.