M31 - part of

[decay]

Hi all,

so here comes my take on M31. I decided to post it here in the gallery and not under troubleshooting, because - despite to a lot of problems I had during capturing and processing - I'm quite happy with it.

m31-1.jpg (449 KiB) Viewed 2308 times

- 200/1000 GSO Newton / SkyWatcher EQ-5
- Baader MPCC
- UV/IR cut filter
- EOS 2000Da, APT
- 50/200 Guide Scope, ASI 120 MC, PHD2

- 31 x 45s (~ 23 mins) + 44 x 60s (~ 44 mins) @ ISO 800
- flats, darks, bias
- ASTAP

So this is one of the images where M31 'jumps into your face', as Mike wrote , but as well, this 'is what if have'. I had severe problems with guiding - at first I thought, that the subs would be completely unusable. But I manually sorted out the worst and stacked the remaining ones - the best 90% with ASTAP. The prolonged stars are pretty ugly, but I posted this high resolution version because there's a lot of fine detail visible in this image - at least I believe that I like the fine dark clouds that HDR revealed which are visible towards the inner parts of M31. And I'm happy that there's just yet NGC 206 visible in the lower left corner (of course, not that perfect like in Marko's image). My scope shows visible vignetting towards the corner, which is quite fine mitigated with the flats, but of course signal is getting weaker anyway and this is visible in the corners.

At first I thought, that SVDecon invented 'stars' in the cores of M31 and M32, but a closer look shows that this problem is visible right at the beginning after AutoDev.

2022-10-02 17_03_39-Window.jpg (5.38 KiB) Viewed 2308 times

This looks pretty much like the problem with the stars and their rings that we discussed in Sven's thread, doesn't it?! I will try to stack again with DSS instead of ASTAP ... Any thoughts would be much appreciated.

Best regards, Dietmar.

[Mike in Rancho]

Nice, Dietmar.

Yes NGC 206 can make for a really nice crop. Alas, my stars are just too wonky down there to pull it off. Maybe I'll try to collect some data with 206 in the center of field, where things look better.

I ordered a set of tools from Catseye, so once I get those I should - depending on my skill and scope - be able to get the collimation right. After I am confident of that, I can go to work on the CC backspacing and tilt problems. Sigh.

I kind of doubt ASTAP vs DSS is the problem with any M31 core - maybe more the ROI chosen in AutoDev? But, there might be a star buried in there too. Uncertain. Sometimes if I zoom Stellarium way in it seems so, though I haven't been able to match it up with any of my data.

[decay]

But, there might be a star buried in there too.

Thank you, Mike - you're right ! Instead of suspecting a problem, I should have taken a closer look at other images. But many images show a blown out core region of M31, so that's not so easy ...
I found an image of the core region ... hm ... yes ... but it's on the site of this software which must not be named ... you now which

https://pixinsight.com/gallery/M31-CAHA/

So it was taken with a 3.5 m Zeiss scope? Pfhhh ... our scopes are almost as good, aren't they?

2022-10-05 13_42_12-Window.jpg (50.65 KiB) Viewed 2259 times

So my fault - ST did a great job revealing this features in my data .

P.S.: Good luck and let us know how you go on tuning your scope.
P.P.S.: BTW this was my first image without using a ROI (AutoDev) and without using SuperStructure (and no Shrink as well). Thanks for describing your ST workflow.

[Mike in Rancho]

Thanks Dietmar! Just waiting on a shipping notice. Not yet. I really want to get that template and see how far off GSO set my primary donut. If it is off. And then see if it can handle a precise collimation using real tools.

PI can be named. It is the stated reason for ST's birth, after all. And for what it is it's probably fine, if used "correctly." Though IMHO I tend to think it's oft used in heavily-artsy mode lately, perhaps even unawares by the users.

Check out this fine M31 info: https://www.nasa.gov/feature/goddard/20 ... eda-galaxy

The core shot is the third one down, which can be clicked a couple times for biggerness, and the caption contains some details.

So that center super bright "star" may not be so much of a star, but actually the gathering of many stars near to the central BH. Note also their description of the scattered blue stars about. I noticed that in your crop. Maybe they match up?

At first I was thinking it could be a bit of remnant ringing, that perhaps could be ameliorated with a no-iteration Shrink but click the deringing up slightly.

I don't think my data will necessarily look so good on a deep crop. For sure it didn't over by NGC 206 where I have just way too much tilt or whatever. But perhaps in the center it'll work, and I'll see if I can unleash the full power of HDR in there.

[Mike in Rancho]

I found an image of the core region ... hm ... yes ... but it's on the site of this software which must not be named ... you now which

https://pixinsight.com/gallery/M31-CAHA/

So it was taken with a 3.5 m Zeiss scope? Pfhhh ... our scopes are almost as good, aren't they?

Okay, here's my mostly lame attempt to replicate that 3.5m Zeiss + PI core with my mostly lame data.

I didn't match the rotation and crop exactly -- I just spun it 90° and called that close enough, and also went a little larger because I thought there was some more cool stuff I didn't want to crop out. The result was all of 700 x 800 or so, and I just left it there without binning and processed that. So no extra SNR, just my tiny bit of integration as-is.

I'm really bumping up against my resolution limits, perhaps tracking/guiding flaws, poor seeing maybe, and for sure the fact that I haven't got my collimation and tilt and coma corrector issues worked out. But aside from all that, I like that some of the general structure still seems to match up well into the core.

I'm not getting some star color I'd like on these little guys in here, just hints of it.

Not quite sure what's going on with the blue in that image either...my stuff comes up yellowy-beige as most of them do. Maybe it's explained in the text.

So, from my 0.15m GSO Orion --

M31 Deep Core Crop ST8 1A.jpg (458.21 KiB) Viewed 2229 times

[decay]

Check out this fine M31 info

Thanks, Mike. I agree, that's not a star visible in the centre of M31. For me, it's interesting to see, that we now have two kinds of renditions: Yours and that great NASA image show a bright centre, but obviously not a stellar profile. With the image on the PI site and my rendition it looks pretty much like a star. Probably due to different stretching and further processing. With my ST workflow, it evolves with every module more and more into a 'star' . At the beginning it looks very much like in your rendition, as you can see in the AutoDev screenshot in my first post. Interesting, but probably nothing which needs to be clarified further on? So I can live with having a star in the centre of my M31

here's my mostly lame attempt to replicate that 3.5m Zeiss + PI core

Well done . Nice to see, what additionally shows up with an extra deep crop processing. Maybe I will try that with my data, too. And yes, at this resolution is visible what you are talking about. I'm no expert, but I would assume collimation and tilt as well . I guess, the colouring our images show is quite OK. The PI article explains some kind of special processing, so maybe that's the reason for the different colouring in that case.

Best regards, Dietmar.