M31 - The Andromeda Galaxy (2021 Edition)

[eshy76]

(An update - this image has been published in the November edition of Astronomy Now magazine...a first for me and incredibly humbling...and a motivation to keep making the most of every clear night! It's taken me almost 4 years to get to this level, but so worth it!)

Hi everyone - me again....

Another year, another M31! I got a pretty decent result last year in pretty bad sky conditions - this year, I was back in my Bortle 7 garden (Bortle 8 last year) and the moon was almost non-existent this time around...so in theory superior conditions.

Something new I tried for this image was to drop the gain values for my broadband filters from their usual values and increase sub length to 60 seconds instead of the usual 30 seconds...the idea was to increase dynamic range and also lower the number of subs on my hard drive!

Intriguingly, I now have collected decent data on M31 over the last three years...it might be worth combining them all for a definitive image...hmm...

...thanks for looking!

Shot on September 6th and 7th using WO Z73/Rainbow Astro RST-135 mount/Astrodon L,Ha, R, G, B filters. Captured in Voyager, pre-processed in APP and post in PI. 10 hours integration time.

Full details here

Edited October 22, 2021 by eshy76
New information

[bottletopburly]

Excellent image though the reds for me are probably too red and I’d definitely combine all your other data .

[eshy76]

2 hours ago, bottletopburly said:

Excellent image though the reds for me are probably too red and I’d definitely combine all your other data .

Thank you for the feedback! Yes there is a bit of red clip going on - I brought the Ha in at 50% of the overall red channel very early on in the processing. I might have lost a bit of control that way - in the past I've brought the Ha at a later stage.

[ONIKKINEN]

7 minutes ago, eshy76 said:

Thank you for the feedback! Yes there is a bit of red clip going on - I brought the Ha in at 50% of the overall red channel very early on in the processing. I might have lost a bit of control that way - in the past I've brought the Ha at a later stage.

In my opinion don't worry about this.

There is literally no way to stay objective with a multi band capture, like yours. For what its worth i believe your colours are very believable and "right" even considering the added reds. This is one of the best Andromedas i have seen in a while, real colours across the entire galaxy. It is very easy to compare a shot you have taken to others taken from amateurs and compare the blues to them. Problem is 99% of Andromedas have unreal blues in them, leading you to believe that M31 should have vibrant blues in the halo. Most people ignore photometry and just choose that the edge must be vibrantly blue, which is not really "true".

This is not true of course and you have IMO captured a very real Andromeda. M31 should be moderately blue, and only around the edges. Your shot is great, if not ideal!

[eshy76]

4 hours ago, ONIKKINEN said:

In my opinion don't worry about this.

There is literally no way to stay objective with a multi band capture, like yours. For what its worth i believe your colours are very believable and "right" even considering the added reds. This is one of the best Andromedas i have seen in a while, real colours across the entire galaxy. It is very easy to compare a shot you have taken to others taken from amateurs and compare the blues to them. Problem is 99% of Andromedas have unreal blues in them, leading you to believe that M31 should have vibrant blues in the halo. Most people ignore photometry and just choose that the edge must be vibrantly blue, which is not really "true".

This is not true of course and you have IMO captured a very real Andromeda. M31 should be moderately blue, and only around the edges. Your shot is great, if not ideal!

Thank you! I try not to push my data too hard when I process, going for as "natural" a look as possible (I don't always succeed). To be fair to the other poster, almost as soon as I brought the Ha-enhanced red into the RGB combination in I could see those regions were a little deeper than my previous efforts, so I had to go easy on overall saturation.

And I've seen the blues elsewhere...I'd have to selectively saturate the blues a lot to get close to that...but I don't think I would avoid artefacts doing things that way.

I really like the image as you say - a good 10 hours of data in basically new moon conditions. I'm definitely going to give the overall 3 year data combination a go - I would have an integration of 30 hours or so!

[vlaiv]

4 hours ago, ONIKKINEN said:

There is literally no way to stay objective with a multi band capture, like yours

There is literally way to get it accurate / objective with LRGB+Ha - although no one is using it

12 hours ago, eshy76 said:

Another year, another M31!

Very nice image. I think that colors are very good and I don't mind red at all - In fact, I'd say it's nice rendition of Ha blended with the rest.

I do think that background could be nicer. It has some color gradients in it (hard to deal with probably due to passing high altitude clouds or whatever) and it is "too smooth" at some places - maybe a bit too much of denoising?

[ollypenrice]

I agree with Vlaiv and like the overall colour balance with the blues set lower than is usual. I think the background is, indeed, a bit 'busy' and the red field stars are shouting a bit but that could easily be tamed in any program with layers. 

I really do like this one. It somehow has an 'old and far away' look which is great.

Olly

[gorann]

Really nice but I am also a bit distracted by the very red and rather big stars. I would try to only add Ha to the galaxy to highlight its Ha regions rather than the whole image and see what it looks like.

[Chris]

Lovely Ha regions in the arms, and It's a very rich rendition with a nice glow to the stars, nice one!

[Andy R]

Lovely rendition I captured M31 Llast week too with Ha LRGB filters alas I can’t make the Ha pop out like yours as it’s only an hours worth of Ha I guess. Very similar colour in the stars thou. 

[eshy76]

3 hours ago, vlaiv said:

There is literally way to get it accurate / objective with LRGB+Ha - although no one is using it

Very nice image. I think that colors are very good and I don't mind red at all - In fact, I'd say it's nice rendition of Ha blended with the rest.

I do think that background could be nicer. It has some color gradients in it (hard to deal with probably due to passing high altitude clouds or whatever) and it is "too smooth" at some places - maybe a bit too much of denoising?

Thank you for the kind words - I did my usual 2 passes of DBE on each filter stack and one on the RGB combination...I'm not surprised that there maybe gradients still there given my location...thinking back I used "subtraction" instead of "division" for one or two of them where the gradients were more circular in appearance (vignetting maybe)...perhaps not the right approach.

On the denoising - a TGV and MMT on the linear Lum, another set on the linear RHaGB and an ACDNR and another MMT on the non-linear LRHaGB combination...maybe an MMT too many, even though the last one was less intense.

Thank you for the kind words and feedback - I really want to keep improving, so I appreciate it from everyone!

 

[eshy76]

2 hours ago, ollypenrice said:

I agree with Vlaiv and like the overall colour balance with the blues set lower than is usual. I think the background is, indeed, a bit 'busy' and the red field stars are shouting a bit but that could easily be tamed in any program with layers. 

I really do like this one. It somehow has an 'old and far away' look which is great.

Olly

Thank you Olly for the kind words!

On the background, my star mask (I used DSO Mask in Pixinsight) did not quite fully cover the haloes of some of the larger stars - for eg the big red one above the galaxy...so when I tweaked saturation at the end, some of them reddened, despite being masked...maybe I need to blur or apply convolution or something similar to the star mask slightly to avoid this!

[eshy76]

1 hour ago, gorann said:

Really nice but I am also a bit distracted by the very red and rather big stars. I would try to only add Ha to the galaxy to highlight its Ha regions rather than the whole image and see what it looks like.

Hi there thank you for this - i applied Ha to the red channel while masking the stars to avoid this scenario. I think my faulty star mask may be more to blame as I mentioned in another reply to Olly. I noticed as I carefully tweaked the saturation level (the last step!) that some stars reddened despite being masked...thank you for the feedback!

[eshy76]

1 hour ago, Chris said:

Lovely Ha regions in the arms, and It's a very rich rendition with a nice glow to the stars, nice one!

Thank you very much!

[eshy76]

1 hour ago, Andy R said:

Lovely rendition I captured M31 Llast week too with Ha LRGB filters alas I can’t make the Ha pop out like yours as it’s only an hours worth of Ha I guess. Very similar colour in the stars thou. 

Hi - thanks! My approach was to use Pixelmath in PI on the red channel after cropping and applying DBE. I masked the stars first and then weighted the Ha 50% in the red channel. So Red channel = 0.5xHa + 0.5xR (normal red stack).

It was definitely a deeper red than my last attempt a year ago using the same approach, so maybe the amount of Ha capture also made a difference.

I hope this helps!

 

[whatablanker]

All a bit technical for me but it's a fantastic image. Everyone's got an opinion and I appreciate that but credit where credit's due well done

[callisto]

19 minutes ago, whatablanker said:

All a bit technical for me but it's a fantastic image. Everyone's got an opinion

Totally agree...an image can look different to many people, Too much red too much blue, bloated stars/non bloated stars, too busy/no busyness at all 😉

I enjoy every image posted on here, thats what Astronomy is all about, regardless of the quality 

[eshy76]

1 hour ago, whatablanker said:

All a bit technical for me but it's a fantastic image. Everyone's got an opinion and I appreciate that but credit where credit's due well done

Thank you very much!

[Magnum]

Excellent

[eshy76]

I've put an edit in the first post - this image is my first image to ever be published in a magazine...this M31 is one for the wall...thanks for looking as always!

[Sunshine]

A beautiful image!

[eshy76]

1 hour ago, Sunshine said:

A beautiful image!

Thank you!