Combining Ha with LGRB

[woldsstargazer]

Is there a way to combine Ha with LRGB in Astroart? eg Ha + L or Ha + R. Or is this best done in another software program?
Thanks.

[Dunmunro]

Is there a way to combine Ha with LRGB in Astroart? eg Ha + L or Ha + R. Or is this best done in another software program?
Thanks.

You can experiment with combining Ha with LRGB using the Color drop down menu and/or the Arithmetic menu in the free Astroart 9 demo:

https://www.msb-astroart.com/down_en.htm

[woldsstargazer]

Thanks.

[fabdev]

Hi, here is an example, taken from:
https://www.arciereceleste.it/tutorial- ... axy-ha-eng

1) Subtract from the HAlpha a fraction of the continuous spectrum of the Red image:

e.g. select the HAlpha, click "Merge" from Arithmetic menu, select the Red, copy the Background value of Red (1748 in the example, to subtract it), and find the coefficient which subtracts correctly the (non-saturated) stars, in this case 0.138, using the real time preview. Let's call this image "HaMod".

2) Subtract from HaMod its background value, so that it becomes zero, let's call this "HaMod_ZeroBkg", (menu Arithmetic/Add offset -1280).

3) Create a special RGB with the command Trichromy, where R = HaMod_ZeroBkg, G = 0 and B = 0 (or a small fraction of HaMod_ZeroBkg, it's 0.15 in the example below), let's call this image: TrichromyMod.

4) Now open the real RGB image you created in the past, and use the Merge window again to add the H-Alpha signal (the image TrichromyMod we just created).

Again, use the realtime preview to find a proper coefficient, in the example it's 2.15. Higher values will add more H_Alpha signal to the final image.

[Apricoup]

Hi, I'm a beginner and somehow lost with this advice. Could you please elaborate?

My situation:
- I work with QHY 268 color camera on a Celestron C8, using AA9.
- Made a set of LRGB lights (some 10h in total) plus a set of Ha- lights (some 4h in total) of Messier 106
- I pre-processed both with darks, flat darks and flats.
- Applied DDP and White balance. Looks ok so far.
Now I want to add the Ha into the LRGB

Questions:
- is this the right workflow?, I mean first preprocessing + applying filters and then add Ha?
- How did you find the 0.138 in the example?
I'm also lost with the example description herunder. How/where did you find/calculate the numbers?
2) Subtract from HaMod its background value, so that it becomes zero, let's call this "HaMod_ZeroBkg", (menu Arithmetic/Add offset -1280).
3) Create a special RGB with the command Trichromy, where R = HaMod_ZeroBkg, G = 0 and B = 0 (or a small fraction of HaMod_ZeroBkg, it's 0.15 in the example below), let's call this image: TrichromyMod.

Thank you for your advice and sorry for asking 'low level questions'

[fabdev]

- is this the right workflow?, I mean first preprocessing + applying filters and then add Ha?
- How did you find the 0.138 in the example?

1) Yes, HA is inserted after preprocessing and filtering (gradient removal only).
2) The 0.138 was found visually: Enable the "lock" preview, then using the mouse wheel change the field of the "multiplication field" until most stars disappear. This takes a few seconds. The number could anything from 0.05 to 2.00, just look at the stars.