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M31 Andromeda


Midnight_lightning

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EDIT - new HaLRGB Version added further down the post

 

This is the first time I have revisited M31 since swapping my D750 for an SX814 and the results are quite different.

LRGB with around 65 x 5 minute lights, I took 20 of each but lost quite a few, mainly Reds as a haze moved in without me noticing. 

The processing is my usual heavy handed approach but I would like to try and build on this with a couple more nights of exposures and would be interested in any feedback on how best to do this.

So, I am wondering do I just take more 5 min lights, perhaps add some longer exposures (10 mins?) or maybe add some Ha. I haven't tried LHaRGB yet but it would be great to see some areas of nebulosity within the dust lanes.

All suggestions welcome.

Thanks for looking.

M31 APP ST v4 Star Reduction Final 1024.jpg

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6 minutes ago, Midnight_lightning said:

Thanks Peter.

Does anyone know how I could add some Ha in, I'm a bit out of my depth with this?

I use Star Tools and Affinity Photo for post processing, could I some how process the Ha separately in Star Tools and then add it to the image as another layer?

Thanks

Jon

I think Affinity is very similar to PS but you will have to try it and see if it works the same.

There are a couple of ways to do it, my preferred method is to do your normal curve stretches as you would do if you were processing a raw fits file. Once you have a done that it helps to do some sort of star removal whether you do that manually by selecting and using the minimum filter or use something like Stratton. If you don't do a star removal you can get strange colour cast in you stars. You then need to convert from mono to an RGB image then fill in the Green and Blue channel in with black so that your mono data looks red. Copy and paste the red Ha frame onto your RGB as a separate layer and change the layer mode to screen adjust the brightness and opacity till it blends smoothly. 

There are other ways to do it but I find this works well for me :thumbsup:

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Great, thanks Peter I think I can do that.

Star Tools will let me do all the usual development, decon etc and also remove the stars.

I have done some (complete novice) HST with Affinity and I was able to set each layer to RGB so I think this is very similar.

Thanks for the help, much appreciated - will post the outcome if the clouds ever clear :)

Jon

 

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  • 3 weeks later...

I have been working on adding Ha for 3 days now and finally worked out how to do it so thought I would post this.

The colours are not right yet so this is still work in progress but I'm starting to understand the process  better so should be able to improve colours with practice. I also didn't do any star masking yet. I only have 3 hours of Ha so far which I suspect isn't enough so will add more if the clouds ever relent!

Pre-processing done in Astro Pixel Processor.

Development, Deconvolution, Light Pollution Gradient removal etc on the LRGB and Ha stacks all done in Star Tools.

Merging the Ha and LRGB, and further post processing, done in Affinity Photo (I love this software!!) .

M31 Ha LRGB v3 1024.jpg

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That's looking fantastic ?

You specifically asked for suggestions to improve so I would say I'm struggling with the neighbouring galaxy (M32) being yellow in colour instead of the blue/white of M110.

I say that but the first image I saw on the net on Universe Today highlighted it in a very yellow tone - so well done! ?

Also, it's near pointless to critique colour in these objects isn't it - but I like the way the core moves to blue and maintains a glow about it.

David

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Thanks David, it is difficult to decide where to take colours, very subjective, but I take your point on M32 - they should at least be consistent.

I was focused on learning to merge in the Ha so I didn't worry too much about colours but I think it's probably a little over saturated. I might try toning down the yellows for a more natural look. 

BTW, just clicked your Welford link - you have some very nice images :)

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Nice image and colors. Colors are so subjective that I usually tend to have the widest range possible from red to blue. The only thing that disturbs me when watching your shot is the saturated core of M32. ¿is it saturated in the individual frames or is consequence of the processing stretch?

Sergio

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Without inspecting the raw image to read the values in the core of M32 I can't  assure if they are saturated but they seem saturated in the crop you have posted.  To solve this kind of problems is usual, and there are a lot examples of M31 all around, to take different exposures to combine them in a single file using HDR integration.

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This is better than anything I’ve ever managed on M31, so I probably shouldn’t invoke grannies and eggs - but as you asked, I just wondered if you could blend in some shorter or less stretched subs to bring out a bit more detail in the core.  But, great detail and nice sharp stars with cracking colours.  Not much wrong with this effort...

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