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

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

Processing tips welcome!

[RickS (Rick)]

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!

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 (Michael)]

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]

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.

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

[PeterSEllis (Peter)]

Originally Posted by 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

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

Processing tips welcome!

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

Cheers
Peter

[Jeff]

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

Thanks Peter.