[Sticky] Combining R, G, B with Ha & OIII data using an Optolong L-eNhance filter

@michaelacg and galaxieshas less of OIII details. 

You can select RGB HAO3 in combine RGB.

This will make sure the stars got there natural color, also the galaxies.

Now you can play with the HA as red color and OIII as blue green. 

With the HA you also can add green or blue to make the HA a little orange.

But I do my best when I got time to make a video tutorial.

Posted by: @stastro

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@michaelacg Yes, your Ha Extract must include stars to be merged into the HaRGB image, stars need to be present for sure.

Looking at the screenshots, it looks like the OIII Extract has similar detail to the Ha Extract from the RGB Split, so as a test, use the OIII Extract and merge that into the RGB using the HaRGB profile and see what the resulting image is

After the O3 extract from Ha-OIII worked, (but the Ha extract is not working) ...
... I tried the O3 extract without stars.

Perfectly working ... stars (at least here) seem not be needed.

@stastro
Of course, for registration stars are needed. 
--> So, what I did: Ha-OIII extract OIII, registered with the 3 R, G, B channels. Stored. Then removed stars. Same for Ha.

I will now re-generate the Ha-OIII extract Ha ... maybe something went wrong and the Ha FITS is somehow defect.

@stefanastro

I cannot find "RGB HAO3".

I find RGBHOO ... and assigned
R to Red
G to Green
B to Blue
Ha to Hydrogen Alpha  --> correct?  (I am confused, some assign Ha to Red ... what is correct, or what is the difference?)
O3 to Oxygen III
O3 to Oxygen III --> correct? I interpreted the "OO" that I need to add O3 twice.
(I used the version with stars)

Result is ...

My summary so far:
- Ha extract from Ha-OIII gives in all examples weird colours
- O3 extract from Ha-OIII is working 
- Using as Ha the R-channel vom RGB integration of the Ha-OIII filter is working
- with or without stars does not make a difference.

I find it confusing, what to assign as "filter" in the add channel dialog.

• Of course: R channel -> Red, G -> Green and B -> Blue is clear.
• But Ha channel to Red or to Hydrogen Alpha? When what?

Hi all.

I regenerated the "Ha-OIII extract Ha", lpr, register with the R G B channels.  ... and now HaRGB1 is working. 
I did not regenerate the "Ha-OIII extract OIII".

--> Most, most probably ... I made a mistake when generating the first "Ha-OIII extract Ha".
--> But maybe you want to check, what's messed up with this first file. Let me know.

So I messed up this thread with wrong file, missing knowledge. (I still have no idea how to do LRGHO, so adding both channels to RGB).
Sorry.

@michaelacg nice, OIII is not so usefull in galaxies. Most people's use HaRGB. So you don't need OIII.

Hi Simon @stastro

With fresh mind I have redone all steps, and can confirm that I mixed yesterday Ha-extract from Ha-OIII with OIII-extract.
With correct channels I managed to do Combine RGB successful for RGB 1, RGB 2, RGB 3 and HaRGB 1, HaRGB 2. 
I did not manage to get a meaningful result whenever I use the OIII channel from "Ha-OIII extract OIII", I tried a few of the pre-settings.

Here are my observations, plus a small wish list to change in your software:

• Ha-OIII extract Ha (resp. OIII)
  --> Please add "Ha2" or "OIII" to the filename, on saving. --> This will help, not to mix the files.
  --> Please put into the FITS header as a filter name "Ha" / "OIII" instead "custom" --> Helps to allocate in Combine RGB
  .
• Before using Combine RGB it is necessary to register/normalise the channels.
  --> Here I found that Combine RGB is sensitive on which reference is chosen.
  I have a reproducible example that
  - HaRGB 1 is working, if I have as reference the Ha channel
  - HaRGB 1 is complete weird colours, if reference is one of the R,G,B channels.
  .
• It is confusing, which channel has to be allocated to which filter.
  Maybe, because in the tutorials some say Ha -> red filter, some say Ha --> Hydrogen alpha.
  --> I tried both, both is okay, the difference is the multiplier, which I can adjust.
  --> It is not okay, to leave "custom" as filter. Therefore it would be helpful, to not have "custom" in the FITS header.
  .
• A very nasty pitfall is that you need to click "new formula", when you change the dropdown pre-set.
  --> Please, please, please ... either make a biiiiig hint, or better reset the formula, after dropdown selection is changed.

My 6 channels are

1. monochrome R, G, B from an OSC integration of 3 nights, with 1.5/1.5 drizzle, lpc/cbg, csc, SC
   --> R, G, B
2. Ha, OIII from "Ha-OIII extract xx" from an OSC integration of 3 hours with Altair 6nm Ha OIII filter, 1.5/1.5 drizzle, lpc/cbg, SC
   --> Ha, OIII
3. Ha-red, the red channel from splitting the No. 2 into R, G, B
   --> HaRed
4. I registered, normalised all 6 channels in one run
   --> ref-R, the R channel from 1) as reference after Analyse Stars
   --> ref-Ha, the Ha channel from 2) as reference

I tested the following:

• RGB 1, RGB 2, RGB 3 --> all good, both ref-R and ref-Ha
• HaRGB 1, HaRGB 2
  --> good for ref-Ha using Ha as red or as Ha. Weird colours, if I leave Ha on "custom".
  --> somehow okay (but quite off, the red) for ref-Ha using HaRed.
  --> not working for ref-R. Background is completely red.
• I played a bit with other presets ... but gave up
  - Whatever I try, the OIII channel is not giving meaningful colours.
  - And it is not clear to me, whether the cause might be the dependency on the reference for reg, norm.

  @stefanastro ... I still do not find a RGBHO.

It would be great if you can include my suggestions for naming, FITS header and the hint that "new formula" is mandatory.
And check the dependency on which reference is chosen ... it very well might be that I still do something wrong.

Best regards.

Michael 

@michaelacg Hi its a long time ago, but i had holiday. But i am back, what i see in your image you forgot to check the button on the right top, neutralize BG. That have to be ON, because the OSC got twice more green pixels than red and blue.

That is why you see that green background in the combine RGB.

Thank you Stefan. 

I learnt this … but missed to post it here.