NGC 2403 LRGBHa

[Mike in Rancho]

Picked up a total of 5 hours on this the other night, under pretty decent seeing and guiding. Which allowed me to throw my prior night's 2.5 hours, under terrible seeing and wind, into the recycle bin!

2h of L, 40m each of R, G, and B, and 1h of Ha, in two sessions, each with 30 flats per session, plus darks and bias, stacked in WBPP.

Yes, another broadband image for me. Taken in two sessions, 2.5h each side of the meridian, so that I could use separate flats for each to be better direction matched in case of mirror shift. But while my LP is "better" to the north than the south, where my M78 was, a 5+ hour arc of tracking the sky still leads to some complicated gradients. Sigh.

But ST has that handled, and being a widefield galaxy shot I could go either way between strong basic Wipe aggression or Uncal1 with throttled back vignetting strength.

There are a ton of little fuzzy galaxies across this field, including I suppose NGC 2403 itself -- not the largest target here at my focal length. And that makes it sort of hard to blend in tiny Ha knots, but I tried anyway, since this galaxy is sort of known for that.

The amount of blue surprised me. Even after star sampling I took more blue bias out, just to tame the galaxy some but not affect blue stars being blue, but the arms remained strongly blue.

This is still the full FOV, 35% bin. I'll see if I can pull anything more out of this with a crop version and less bin.

NGC2403 5h LRGBHa ST9 3B.jpg (465.75 KiB) Viewed 3180 times

[firebrand18]

Nice image Mike, and great color balance! What size scope did you use? I'm looking for a new target to image but my 81mm /382mm FL APO may be too small for this galaxy.

When you Bin, do you use the 35% preset in the module? What camera do you use at what resolution? With my QHY 168C OSC (Image sizes 4952 x 3288), if I bin less than 71%, I start getting blocky stars and detail so I never go below that; probably scope/camera/sky conditions (Bortle 8) leads to under-sampling for me.

CS
Nick

[Mike in Rancho]

Hi Nick, and thanks. Work in progress for sure. I actually pulled a little more blue out (and a tiny bit of green) to post it on CN as my interim image, just to try to match what I see for B-V values on Stellarium in this area. I know that's not really proper on a non-linear image, but I didn't feel like running through the whole thing again just yet. I wonder what's up here? Maybe the field isn't representative of average white, or maybe my blue filter is haloing a little, making me think a star is more blue than it has really been set to.

Regardless, ST is getting me very close, whether I star sample or just go into Color with a full mask.

This is the Orion 6" f/4. With the Sharpstar .95x coma corrector I'm at 585mm. For me, pretty short! Unless I pull out a camera lens. The camera is a 2600MM, so APS-C with 3.76u pixels, and giving me an imaging scale of 1.33". The files are 6248x4176. You are right though, and a bin 35% is right on the line of being too far. 25% and I'll get blocky little stars. But, 35% usually has me processing at about 2200x1500, which is more than my FHD monitor can show (I've ordered a 4K though!).

I'm Bortle 8 here too straight up. Likely 9 if I get near the LP domes. Maaaybe if I could find my darkest patch of sky, and it was like 3 a.m., I could measure Bortle 7.99999.

I do have a 900mm f/9 refractor, but after getting the Newt - beyond loving star spikes - it's hard to go away from acquisition at f/3.8. Pretty useful to suck in the photons quickly in this light pollution, and then up the SNR in ST with binning.

[firebrand18]

Thanks for the details Mike. Yep, imaging from Bortle 8/9 is not easy but half the fun turning out nice images despite the heavy LP.

Your recent Andromeda was superb as well.

I really like what ST 1.9 is putting out too; big improvements in final image processing quality.

Cheers,
Nick

[Mike in Rancho]

A new version. Cropped and rotated, and then only binned to about 62%. Processed in 1.9.536, and the extra resolution did seem helpful. I was able to increase iterations in SVD, get intra-iteration and deringing right, and even used a good bit of spatial error correction. Gee, you can find all sorts of little star shape flaws when you haven't binned to 35%.

The lack of the really big SNR increase on the bin meant that this could probably stand to be, oh, doubled in integration. But that's not going to happen here. Maybe not too bad overall for chasing a galaxy at only 585mm focal length. A lot of the details and even the Ha accenting seem a reasonable match to the stock image on Stellarium.

Upgrading to a 4K monitor really changes sizes and perspectives on things. I have no idea how this is going to look to anyone, let alone via my own browser. And as late as I am to the higher dpi monitor game, it's a disappointing nightmare how difficult Windows makes sizing text, icons, menus, and taskbars appropriately - if one doesn't want to just globally scale up everything. Which would ruin the whole point of getting a 4K monitor. Silly.

EDIT: Changing uploaded file. Web browsers, at least the ones I am trying, don't seem to be showing images at a UHD dpi, closer to QHD it seems. Sigh.

NGC2403 5h 62pct crop ST9 1Bii 1280.jpg (536.18 KiB) Viewed 3026 times

[fmeireso]

Nice shooting Mike. I like the first one, nice starcolor...

[Mike in Rancho]

Nice shooting Mike. I like the first one, nice starcolor...

Thanks Freddy. The shooting was...fair. I've realized I have some sort of tilt/backspace issue that I need to get to the bottom of, though on my latest edit, SVD with extra iterations and spatial error helped out quite a bit.

I like the star field in the wide version too, more variety, though I have the saturation kind of high. The closer crop is needed for better galaxy detail though I think, unless I process a full scale/zoomable image?

I finished a new edit this morning that I like, but I don't really like the browser image scale-up I'm seeing when using the new 4K monitor, so not sure what to do yet.

[Startrek]

Mike,
That’s an excellent result on a mag 9 Galaxy with relatively short focal length and only 6” aperture
Love the Star field too, great Color’s
I never used to adjust Binning prior to 1.8 but now I’m always experimenting with Binning as it directly affects resolution , SNR and the performance of SV Decon
Well done !!

Martin
Down Under

[Mike in Rancho]

Thanks Martin,

Here's a link to my most recent effort on it. If it works! I made a trial astrobin account, and don't really know my way around it yet.

As before I maintained a 100% crop for ST processing. SVD was decently strong, 13 samples, 20 iterations, intra+centroid, deringing (536) 40%, and spatial error of 3.5 due to some tilt or backspacing issues that I saw less of when working binned earlier.

I hope the colors are okay! I'm not quite sure on things at the moment with this new monitor, which I haven't run calibration on yet.

One neat thing about maintaining the higher resolution, even if the SNR boost is lost, is the ability to dig in and see some better details. Supposedly it seems, anyway. There are some cool faint fuzzies around here - one upper left that has a great swirl, and two interacting little galaxies over by the right edge.

Also in the main target itself is a star cluster that was famous for blowing up (a star in there, anyway) about 20 years ago!

https://esahubble.org/images/opo0423b/

I can just make out a small blue dot that I believe is that very extra-galactic (to us) star cluster.

EDIT: Do astrobin thumbnail links not work here? I used the same code that seems to work on CN.

Maybe this? https://astrob.in/wv97zk/0/

[Mike in Rancho]

Oh one extra thing I wanted to add - I'm still getting my feet wet with this astrobin trial, but in the details/software section I noticed that ST is split into two slightly different options. One starts out with "Startools..." and the other "Silicon Fields Startools..."

Beyond being uncertain which to pick (I did the latter as it is more in line with most of the options there), that is also splitting up ST's total of users and images, when they really should be combined.

Maybe something that somebody with some pull can fix up with a note to their admins, or admin since it seems mostly a one-man shop.