Andromeda, using AltStars SVD

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Mike in Rancho
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Andromeda, using AltStars SVD

Post by Mike in Rancho »

Warning, this is a work in progress. :D

3 hours and 39 minutes total LRGB, more or less in 3:1:1:1 filter ratio. I had to toss some bad subs. And in fact I need to go find which one has that satellite trail that didn't reject out, and cull that sub also.

Taken over two nights this month. And in between I added some coma corrector backfocus spacing and worked on my tilt. Which just means I tried to be extra careful keeping the whole camera contraption seated to the visual back when tightening the compression ring. Anyway, I threw them all together anyway in ASTAP.

Processing is not a piece of cake, really. There are many options here -- which I tend to call imager's choice, not artistic license which I would deem to be something else entirely. The Wipe is always critical, especially for diagonal M31's taking up most of the space. AutoDev can vary greatly with ROI and IFD. And of course perhaps the biggest of all - color balance and saturation. Though color balance could head off into the art zone, if not based on a reference or something logical anyway.

This is a bit more muted rendition of others I have made with this data so far. I can just barely squeeze most of M31 into my field of view, and I am kind of thinking that it needs more space. M31 perhaps looks better with more star field around it, rather than just some giant angled galaxy right in your face. :lol: But, I have what I have.

This was also my first time trying out AltStars in SVD, coming off the discussion in another thread. Interesting, really. I need more practice at choosing samples, and modifying the mask if need be, but I think the stars came out rather good - even all my funny shaped ones from the tilt and spacing errors. I need to try more iterations as well as compare with the regular apod mask as far as the non-star fine detail goes, but so far so good for a first try.

I did have to go into Mask and add a couple brighter stars that didn't end up starfished and were left bare. Not to use as a sample (no clue how I might manually draw a starfish), but for deringing purposes.

This was a Crop edges; Bin to 35%; no-mask Wipe; AutoDev with ROI including near the core but not the dead-center core; Contrast with reduced shadow range and very reduced locality; HDR with reduced taming and highlight detail but increased shadow boost and smoothen, context 50, medium quality; SVD AltStars 16 samples, 12x iterations; Color as set by star sampling except 0.01 extra blue bias decrease, green cap, highlight repair, and saturation adjustments; Sharpen 200%, 95%/5% dark-light; and Denoise grain 6.0 pixels and defaults. No Shrink or SS.

M31 2-nite 3h 39m LRGB ST8 3A 1100-96.jpg
M31 2-nite 3h 39m LRGB ST8 3A 1100-96.jpg (487.78 KiB) Viewed 524 times
fmeireso
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Re: Andromeda, using AltStars SVD

Post by fmeireso »

That is a really nice Andromeda Mike...
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admin
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Re: Andromeda, using AltStars SVD

Post by admin »

Text book visual spectrum Andromeda. Rather excellent!

Color-wise, a good M31-and-friends shows a slight blueing of M110's core (a peculiar collection of young blue stars - see description on Wikipedia for example), which shows up here correctly.

As is usual with a good visual M31, there are hints of purplish H-II regions just on the edge of coming through (but never quite strong enough to overcome the rest of the wavelengths in the visual spectrum). These areas are prime candidates for Ha accentuation.

Very nice.
Ivo Jager
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jhart
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Re: Andromeda, using AltStars SVD

Post by jhart »

Hi Ivo,

I am still unclear on the AltStars preset in SVD and how it contributes to that module. Am I correct that it does not matter how large or misshapen the APOD mask is because only the star profile that is within SVD's sampled box will be used? That is, only the star profile within both the mask AND the SVD box are used in SVD? If that is correct, what does AltStars add over the regular Auto Star mask?

Thanks,
Jeff
Mike in Rancho
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Re: Andromeda, using AltStars SVD

Post by Mike in Rancho »

admin wrote: Mon Sep 26, 2022 12:40 am Text book visual spectrum Andromeda. Rather excellent!

Color-wise, a good M31-and-friends shows a slight blueing of M110's core (a peculiar collection of young blue stars - see description on Wikipedia for example), which shows up here correctly.

As is usual with a good visual M31, there are hints of purplish H-II regions just on the edge of coming through (but never quite strong enough to overcome the rest of the wavelengths in the visual spectrum). These areas are prime candidates for Ha accentuation.

Very nice.
Thanks Ivo. Yes along with the extent of blue in M110, I was also keeping an eye on a couple stars there on the middle left - one towards the top and the other near M31's edge. Their B-V values were warning me that I had too much blue when I was fiddling with the first night's data.

I was also wondering whether those little magenta hints might be the H areas that might show up if I got a bit of time on that filter too. Just a tiny bit of accent I think would reveal it just right, without stealing the show and overwhelming M31.
Stefan B
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Re: Andromeda, using AltStars SVD

Post by Stefan B »

Really great looking M 31, Mike :bow-yellow: Just awesome what you can do in not even four hours with a mono cam (and a rather bright object like M 31)! By the way, your field of view appears very nice to me, it's not too tight. Wider fields with more surrounding stars are of course also fine but yours is just right in terms of capturing the whole thing and keeping it close at the same time. In my eyes it's better than many of the images with APS-C and 700-800 mm focal length (like my first tries) which just doesn't fit. If you want to go close you should do it like Marko recently with his stunning result :)

Regards
Stefan
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Re: Andromeda, using AltStars SVD

Post by admin »

jhart wrote: Mon Sep 26, 2022 1:36 am Hi Ivo,
Hi Jeff,
jhart wrote: Mon Sep 26, 2022 1:36 am Am I correct that it does not matter how large or misshapen the APOD mask is because only the star profile that is within SVD's sampled box will be used? That is, only the star profile within both the mask AND the SVD box are used in SVD?
Correct!
If that is correct, what does AltStars add over the regular Auto Star mask?
The approach better detects stellar profiles tapering off. In other words, more of the stellar profiles are available in the mask, which in turn should yield marginally more accurate results and slightly less ringing.

The approach is a precursor to a new approach to sampled decon I'm working on, and I may be putting out a request for guinea pigs soon to test this new approach to sampled decon.
Ivo Jager
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dx_ron
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Re: Andromeda, using AltStars SVD

Post by dx_ron »

Mike in Rancho wrote: Sun Sep 25, 2022 8:59 pm This was also my first time trying out AltStars in SVD, coming off the discussion in another thread. Interesting, really. I need more practice at choosing samples, and modifying the mask if need be, but I think the stars came out rather good - even all my funny shaped ones from the tilt and spacing errors. I need to try more iterations as well as compare with the regular apod mask as far as the non-star fine detail goes, but so far so good for a first try.

I did have to go into Mask and add a couple brighter stars that didn't end up starfished and were left bare. Not to use as a sample (no clue how I might manually draw a starfish), but for deringing purposes.
Sweet!

I finally went back to re-process my own M31, as I'm running out of month. I keep generating a black hole in the center of both M31 and M110 during svd. I had figured out how to avoid that - 3 weeks ago. I should take notes...

My small stars seem much brighter than yours, for some reason. Might have to hit it with one of the sticks.
Mike in Rancho
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Re: Andromeda, using AltStars SVD

Post by Mike in Rancho »

dx_ron wrote: Tue Sep 27, 2022 11:47 pm Sweet!

I finally went back to re-process my own M31, as I'm running out of month. I keep generating a black hole in the center of both M31 and M110 during svd. I had figured out how to avoid that - 3 weeks ago. I should take notes...

My small stars seem much brighter than yours, for some reason. Might have to hit it with one of the sticks.
Hmm. :think: I was sort of actually thinking mine might be a little too high wattage, and perhaps too white as well. But, I kind of had to use highlight repair. Maybe I'll let DSS register the stacks instead of ASTAP, and see if that would let me dial back the H.R.

I assume it's the new reprocess that has brighter small stars? If I toggle the image above with yours from the image gallery early in the month, it seems the other way around.

Lots of ways it could happen I suppose. Possibly acquisition but more likely processing. The AutoDev ROI and IFD can make a big difference in star appearance. As could just about any other module, up to of course SVD. Plus I believe your M31 feeds in some Ha accent. Did you keep that completely out of adding anything to star cores?

Oh I had the little black holes too of course, except my M110 was clean and I got it in M31 and M32. Those artifacts were repaired in Layer at the end with a mask on the offending pixels, and then just a tiny bit of add function to brighten but try not to go full white, and then again on M31 with a slight kernel blur on a slightly larger mask. I suppose I could also have done an undo buffer layer with mask on those right after SVD. I mean, just overbright galaxy cores anyway. :confusion-shrug:
hixx
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Re: Andromeda, using AltStars SVD

Post by hixx »

Hi Mike,
congrats to the nice image!
I tried to capture M31 this year as well, but due to cloudy weather in Central Europe I had no luck so far.
My field of view is similar to Your image and I get Your point. In fact, the very outer (weak) spiral arms actually do not fit at all.
Maybe one can work around that by mosaicing 2 images shifted a few arcmin. One centered just 30" to the left and below M31, one 30" above and right, both on the diagonal. Key is to find a stacking software capable of mosaic stacking. The resulting picture would have an aspect ratio leaning towards 4:3 rather than 3:2. This would give M31 a nice "space" framing and enough leeway to fully spread its border arms.

And as Ivo mentioned, You might want to create an HA or douband stack to bring out the Ha regions with NBA, or use a duoband stack as LUM from the get go....

Clear skies,
Jochen
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