M33 LRGBHa

[Mike in Rancho]

About three years ago I first tried to image M33, shortly after (re?) starting AP but more seriously than just trying to duct-tape a point-and-shoot to the eyepiece of an achro scope. Of course I still had the same 90mm Meade achro, but with a stock DSLR and adapter. I had owned ST for about a week, and produced this hideous abomination:

M33 3nite Oct-Nov 2020 800.jpg (133.56 KiB) Viewed 14276 times

I thought I was scarred for life, and so never returned to M33.

Until now. This was supposed to be throwaway data, meant as a test after remounting my secondary mirror and creating an aperture mask for the primary. Still a work in progress and I think I should flock that new mask as, despite being black, I think it may be too reflective. But results were good enough and stars seemed round and un-tilted enough that I even added a second night of data. Total of 6 hours, one of which is Ha.

Processing has not been easy, and I have made quite a few renditions. Perhaps like M31, there's a lot of range here. Also many great individual features. Resolving of giant or variable stars? Eh, maybe. Originally I think I was taking out too much blue manually, which gave a redder result but also induced purple. ST Color module, however, whether full-FOV or star sampled, seemed to be trying to tell me to leave all that blue in. Maybe this is just a very blue target. So in my last edit I mostly left things alone.

I think I had some overcorrected corners, maybe a flats problem, but Wipe with synthetic inverted flats handled it well IMO. The stars also have a bit of side flaring and I believe that is also causing some multi-color issues i.e. blue/red. Coma corrector backspacing may be the problem here.

Finally I've had some trouble with the low-SNR transition from galaxy to background, for the faint outer arms. This last was about the best I could do to not have things get too choppy, adding in some grain in DN. No SS used.

For the galaxy Ha accenting I changed back to Balmer purple but added a little strength along with other parameter tweaks. This seemed to keep the same hue as what was there already in LRGB, but expanded the acreage greatly.

If anyone wants to see what they can get out of it and come up with some tips, the data is here: https://drive.google.com/drive/folders/ ... sp=sharing

The staging area astrobin is here, looks okay native (of the final which was binned 50%) but a bit iffy if the OS/browser is upscaling for high dpi: https://astrob.in/czugkp/0/

M33 6h LRGBHa ST9 6C 1600.jpg (668.44 KiB) Viewed 14276 times

[Startrek]

Mike,
I’m not familiar with M33 as we southerners don’t see it , but I must say you’ve captured and processed a wonderful image for only 6 hours worth of data.
Also I had no idea you’ve only been involved with Astrophotography for only 3 or so years , your knowledge and understanding of the hobby especially with processing is quite impressive.
I’ve been into AP for 6 years now and still getting my feet wet.
For us on the south east coast of Australia it’s been a terrible summer for AP , sunny days , high humidity and endless cloudy nights ( we are up to 52 consecutive cloudy nights and forecast is poor until the New Year )
Never had a start to summer like this one
Rant over
Merry Christmas and happy New Year

Martin

[fmeireso]

Looks pretty good , Mike, especially colorwise i think..allthough , i would stretch if further or it needs some more integration time dunno. Sofar, i never tried M33. I don't feel attracted to it for some reason, maybe because it seems rather dim and it has that strange oval shape. i always found M101 more appealing.
i will frame it, but not anytime soon...

[Mike in Rancho]

Thanks Martin and Freddy, and happy holidays to you as well!

Yes more integration should allow additional and cleaner stretching, though there will always be some low-SNR transition at the edges, right? They'll just be pushed further out.

M101 is indeed cool, at least when it has a supernova in it.

But I can never get over its broken leg. Looks weird.

Martin as I'm sure you know the South has a couple pinwheels of its own. The distances and relative sizes might not compare - M31 and M33 look pretty large - but M83 is a decent analogue to M101, and NGC 300 has a somewhat similar aspect angle to M33. And all could be great in LRGBHa.

[Startrek]

Mike,
I noticed in Astrobin , your imaging under B8 skies, which makes this image and your processing skills top notch
Yes I’ve imaged quite a few galaxies under our southern skies but only with my 2600MC over 3 years.However, since purchasing the 2600MM in late August , the new moon period has been somewhat cloudy so haven’t had much sky time on galaxy imaging with the 2600MM ( just NGC 253 Sculptor or Silver Coin galaxy )
Popular galaxies down under are -
NGC 253
M83 of course
NGC 300
NGC 6744 Pavo
M104 Sombrero
NGC 1365 Great Barred Spiral
NGC 55
And many others……

Our galaxy season is tailing off now so looking forward to the summer arm of the Milky Way swinging up from the south east with the largest nebula Carina and many satellite nebula surrounding it ready to image in January. Also M42 and Horsehead
If we get some clear skies ???

Cheers
Martin

[decay]

Well done, Mike

and produced this hideous abomination

This one looks pretty much like my first AP images, which were mostly done with self built or assembled equipment in an experimental approach. But I learned a lot and I do not regret a single step of this way.

On topic I agree, processing of M33 is not easy – I did this last year and I produced a lot of renditions just like you. To be honest, I still did not settle with one finally. Yeah, there’s a lot of dynamic range and it is possible to pronounce different within existing structures using Contrast and HDR modules (and maybe even using AutoDev). You managed to reveal the core in a subtle way, which is not easy as M33 does not show a dominant core like most other galaxies. You also pronounced the structure of the major arms – at least as far as there is structure M33 seems to be a disrupted victim at all detail sizes. I also like the way you used HDR to stress the dark clouds near the core. Comparing to other renditions I wonder if it is possible to bring out some more detail in the area between the core and the outer regions?

And yes, I think M33 simply is a very blue target IMHO you succeeded well with colour balance. My renditions show too much red, which results in much too orange coloured stars.

Transition from outer galaxy regions to background is always a problem, for me too. I took the some approach – not to use Super Structure, which often causes mottling, but instead add or leave some some noise grain. This seems to be somehow easier to the eye. And I guess this approach is fine for this object as M33 shows fine grainy structures by itself. Whatever these may be

If you like, you may have a look at my M33 and our discussion last year:
viewtopic.php?f=11&t=2732&hilit=m33

Best regards, Dietmar.

[decay]

For us on the south east coast of Australia it’s been a terrible summer for AP , sunny days , high humidity and endless cloudy nights ( we are up to 52 consecutive cloudy nights and forecast is poor until the New Year )
Never had a start to summer like this one
Rant over

Don't be upset, Martin. I don't know if it helps, but I've stopped counting the endless weeks of cloudy, windy and rainy nights Better times will come ... one fine day, I'm sure

[Stefan B]

Hi Mike,

your first take looks pretty much like my first "image" of M 33

I very much enjoyed your recent renditions of M 33. As Dietmar already wrote, M 33 with the faint outer regions is not an easy one but you found a good balance. Of course I had bumped up the saturation via SS and the clusters would have gotten even bluer but naturally that's a matter of taste

Regards
Stefan

[Mike in Rancho]

Thanks Martin, Dietmar, and Stefan.

And extra thanks Dietmar for the link to the prior discussion. I should have thought to run an M33 search on ST forums to see what had been done and discussed previously.

I have done a small bit of hunting for individual objects within M33. Maybe I'll try to annotate some stuff later. I also want to try some crop regions again without binning and see how things look. With just the first night, SVD was giving me a lot of grief with the selections as well as badly ringing stars that refused to be unrung. With the second night and better SNR, and perhaps if I stretch just right, It'll work out better.

I'll for sure try that big Ha region to see what shows up in there. Yeah every blue dot can't possibly all be globs, but what are they? Open clustering of some type perhaps...