M66 Goup (Leo Triplet)

[Mike in Rancho]

The unusual, and still going, cold and rainy SoCal winter allowed me to only get 3 hours on the March target. March is ending soon and more rain is incoming, so this is it. No tidal tails for me.

And on my clear night I killed most of my pre-meridian time checking tilt and trying out a new backspacing by pulling 0.6mm out. First light as well for having the EFW bolted to the camera instead of threaded. All that aside, I ended up with 1.5h L and 30m each of RGB, and I took flats for each side of the flip just in case of some mirror shift. All tossed into WBPP and I hit go.

First run through, with 536, 50% bin, came out fair. Then 547 landed and I tried out a crop version at 71%, which I was reasonably happy with. Tonight I gave a try to the same thing at the full FOV, also only 71% bin. SVD add-sample speed was a nice improvement, though I think I've run into more trouble with OSC files than the discrete LRGB, so still have to try that. Still, that made things much easier. Deringing improvement also helped I think, although perhaps improved stars from the backspacing adjustments made that go smoother also. I still did use Shrink afte Color for a little no-iteration dering boost, but all very doable. Yay!

In the wider version I used a stronger Wipe and I think I got a better OptiDev, and I also reduced the strength of SS to gamma 85 in order to keep some more of the tiny little pinpoint stars showing. I probably should have bumped up the denoise to take account of that, but forgot.

Lots of good stuff picked up in the background here, even at my mere 3 hours. Once I decide I have my final final versions, it'll be cool to put the less resampled files up on astrobin. Then by the 31st I'll have to decide whether to enter the crop or the full FOV.

M66 Group 3h LRGB CROP ST9-547 2B.jpg (468.95 KiB) Viewed 3417 times

M66 Group 3h LRGB ST9-547 2B.jpg (442.54 KiB) Viewed 3417 times

The full FOV is nice because along with the extra medium galaxy in the lower corner, there's a lot of great star colors here. I think the channel balance of the full field is closer to correct also, as I believe that one brighter star closest to the Triplet should be more towards the white than blue.

[decay]

Nice, Mike

It never rains in Southern California - but obviously this is not the case right now. Probably nothing to play jokes about, people lost their homes and some even their lives, as I heard in the news some weeks ago The same here, bad weather since weeks (but no heavy storm or likewise!).

Glad to hear, that you got at least a few clear hours. And if you take a closer look, you can see a very faint shimmer of the tidal tail of NGC 3628. And you captured a pretty nice bunch of detail in M66!

I never noticed problems with flats due to mirror shift, but I lately had the impression that this maybe could cause focus problems?! Hm. Not sure. BTW: How did you solve your problems with the mirror holdings causing triangular shaped stars? Obviously you succeeded well?

I tried processing with more resolution (bin 71% and not 50% like I do most times) like you did, but I had no luck. Maybe the quality of my data set was not good enough.

I think colour balance is fine. I compared this with an old image I took some years ago (in fact one of my first images at all) and at first I thought the same like you: This one bigger star is a bit too blue. But now I think this is maybe because you dialled in a lot of colour saturation. This is most obvious in M66, a very strong colour contrast between the blue and the yellow areas. Well - I guess this star can live with being blue and in return you have got a worth seeing M66

Best regards, Dietmar.

[fmeireso]

Hi Mike,

Personaly i like the first picture better. Very nice coloring, i think it is very well done.
The second one is nice but i find the left big blue stars a bit disturbing, it is just a thought.

I skip this object this season. I tried it last year, but winded up with crazy dustspots on the sensor and the image was just garbage...i just don't feel the urge to try again ..I think at F=910 the objects still remain a bit small..anyhow..

Weather over here is not great either and the days are becoming longer and longer...this means longer work during the night...ah well

[Mike in Rancho]

Thanks Freddy. You don't like blue? I love blue stars, and it's great when you can see all different colors together, especially brighter ones with nice sharp diffraction spikes.

Disturbing huh?

Saturations were left pretty much default, 200% global, Full bright, and a mild bump of the dark sat to about 4 or 4.5.

The reds and blues, with the lower one and the middle Triplet one being a bit whiter, all seem to match up with Stellarium.


Thanks Dietmar. And yes I did see the tidal tails, mostly in Wipe during the hyperstretch, but they are just barely above the noise floor, if even, and so not really worth trying to reveal. But a little bit of glimmer can poke through.

Yeah following Martin's lead, the 71% for APS-C size images seems a good compromise to get a wee bit more SNR and provide room for SVD to work. There's still the whole auto-apod-mask, starfishie detection, and blue box sizing thing to get worked out. But I seem to be getting decent results if I can get enough stars across the field, even if they aren't all nice green-cored or a good size match to the blue boxes. I'm not quite sure what the auto-detection and outline sizing is based on. I'd have to open things up side by side or take some screenshots. Full resolution without binning can sometimes still pose a problem, where there's a ton of tiny shapes but no visible stars inside them.

I'm not sure on the triangular stars. As usual, I failed to follow the scientific method and changed lots of things at once. Well, not at once, since I went 30+ days without clear skies and just did stuff over the month.

I removed the mirror, cleaned it, and reinstalled with a bit more play for the clips, making sure I could slide a thin piece of paper under them. I also learned (but unsure if due to the now slightly looser clips?) that my collimation can shift with OTA movement, at least if I collimate on the mount with the scope horizontal. Which is the way I've always done it.

Looking through the autocollimator, I could see it move as I moved the scope's orientation. But, if I recollimate with the scope angled up somewhat, the spots in the autocollimator will stay perfect no matter how I move the scope, except for the fully horizontal position. Well, I never image anything with the scope horizontal anyway.

I also changed my EFW to Camera connection from a threaded adapter to bolted-on, and tried out a couple different new backspacings for the coma corrector. That could perhaps still use a little dialing in.

So - all of the above, none of the above, or just dumb luck and maybe the temperatures were different.

I made a new cropped version of the Triplet this morning that I think is a tiny bit better. Though it probably doesn't look any different to anyone else. I'll re-work the wide FOV version too later tonight, maybe see if I can add more saturation to the blue giants.

EDIT x2: I keep changing the image. Indecision about background.

M66 Group 3h LRGB CROP ST9-547 3E.jpg (480.39 KiB) Viewed 3365 times

[Stefan B]

Hi Mike,

great image! Color balance appears fine for me, stars look awesome and as Dietmar already noted, a great M66!

I prefer the crop version(s). It's suprising how much you can crop/zoom and still retain a decent image which doesn't fall apart...doesn't work for me somehow. I always have the impression with my crops that they look blurry. Anyway, well done!

Regards
Stefan

[decay]

It's suprising how much you can crop/zoom and still retain a decent image which doesn't fall apart...doesn't work for me somehow.

I tried processing with more resolution (bin 71% and not 50% like I do most times) like you did, but I had no luck.

following Martin's lead, the 71% for APS-C size images seems a good compromise to get a wee bit more SNR and provide room for SVD to work.

Hmm, my first thought was, that Mike uses a mono cam and Stefan and I use OSC cameras with bayer matrix and this might result in less resolution. But Martin also uses an OSC cam ... so why does 71% work so well for Martin but not for Stefan and me? I'm not sure, if Martin uses 71% only with his large (10 " ?) or with his smaller scope (6 " ?) too?

Best regards, Dietmar.

[Mike in Rancho]

Well, I'm not sure mine doesn't start to fall apart with enough zoom. To me it sure seems to. Especially something like this with only 3 hours.

With that in mind, I do tend to sledgehammer things with Wipe - not necessarily too bad with only widefield scattered galaxy going on - and ROI stretch just what is reasonable. And I keep things fairly dark and compressed in the shadows, suppressing that junk and giving up on much in the way of tidal tails. Just doesn't seem to me that this data can cleanly support revealing that.

Bayer interpolation shouldn't be too bad I would think, though depends on the program and algorithm chosen.

I sometimes try to watch what is going on with the browser I am using also, especially now with a 4K monitor. Browsers can upscale to match whatever OS settings you have to account for high DPI. I think mine right now is 150%. So, particularly for using astrobin, I have a second instance of Firefox set up that is tweaked to be at 100% scale. Good for images, but text and everything else is of course tiny.

I did finalize this image for the end of the month and put a "full scale" jpg up on astrobin, meaning the 71% bin as the only resampling.

https://astrob.in/pu2pu6/0/

I do like the new session information dialogue for entering subs and exposures and equipment. Though they still seem to have StarTools split into two separate programs.

EDIT: M66 is just a really incredible looking galaxy. I doubt I can manage much out of 3 hours only, but may try processing just that object at full scale and see how good/bad that comes out.