Messier 83 - The Southern Pinwheel Galaxy in LRGB

It's been a while since I posted an image due to both life/family events and abysmally consistent cloudy skies.

Due to this, I chose to process this Telescope LIve dataset from the CHI-1 OTA, in Chile.  It is a Planewave CDK-24 with a QHY large frame sensor Astro camera (monochrome).  In the Telescope Live suite of available OTAs, this OTA provides consistently great datasets.  It's only drawback is the long focal length which makes it unsuitable for objects that cover a larger expanse of the night sky.

Adam Block has published a new YouTube video and a tutorial on his website covering the processing of LRGB dataset with a newly developed script.  His example happens to be this dataset.

I had every intention of trying out his script, but decided not to.  Not because his script won't work, but because I didn't want to save the L frame as an RGB image - which is required for the script to work.  When it came time to merge the L frame and the RGB image, I used my 'normaI' PixInsight LRGB channel combination tool.  I also chose to utilize the lightness and saturation sliders that Adam mentions as not having much effect.  I had never used them before and felt I should know how they impacted the channel merge.  I found they had quite a bit of effect and it only took a couple of iterations before I had both tweaked to where I wanted them.  FYI, I do use the L Frame as a mask prior to the channel combination to protect the background.

The biggest advantage I see to the new script that Adam helped develop is that it has a preview image (the LRGB channel combination tool does not have a preview).  This does allow you to quickly tweak the image before committing the changes without the necessity of iterating images until you get the result you want.

I think I may have slightly overcooked the application of the HDR tool, something that can do a lot of good on images with a wide dynamic range.  However, getting aggressive with it can create artifacts in some areas of an image.
I used the PixInsight Gradient correction tool but I have not yet linked it to the MARS data.  The examples I've seen indicate that is the MARS data that provides a big boost in capability to this tool.

I did "prove" that BXT has much more impact on the channel combined image than it does on the single channel images if applied separately before the channel combination.  This aligns with what Russ told me about the tool, that the AI is looking at the full spectrum of data as it makes its adjustments so works better with an RGB or HSO/etc. image than the R frame, G frame, etc. done separately.  I utilized my usual suite of tools in the final processing - GC, RGB Channel combination, BXT, SPCC, SXT, Bill Blankenship's STF scripts, Color masks, HDR, NXT, Dark Enhance Script, Curve tools, etc.

This Telescope Live dataset encompasses data acquistion in April 2023 and 2024.

Update:
I have posted version B after going back and working to mitigate the artifacts that I found (to my surprise) that were being introduced by a combination/inteeaction between BlurXterminator and StarXterminator.  Working the stars a little too hard with BXT setup some unfortunate results when StarXterminator is applied, at least in the body of M83.. I modified the BXT setting somewhat (actually went back to straight defaults) which reduced the artifacts created by SXT by  not working star "corrections" quite as hard.  I understand that Russ Croman is working on an AI update to address some similar issues that have cropped up, but to my knowledge he has not yet indicated a timeline for the update.

Update 2:
I have posted a new updated version C and D.  I went back and utilized a couple of "new" tools, at least new to me in one case.  For merging the Lum Mask image and the RGB image (both Starless), I used the new ImageBlend script tool that Adam Block has been highlighting in his most recent videos.  With the preview pane and the ability to adjust parameters on the Lum file and the RGB image, it gives an ease/flexibility in tweaking how the two come together before you commit to creating or modifying the blended image.  I can't say that the final blended image is "better" than what I achieve with the PixInsight LRGB Channel combination tool, but if you like to play with a lot of adjustable parameters, this is the tool for you.

Taking one step back to the RGB image, there is a "new" (new to me) color mask tool/script available from a link in the PixInsight forum.  It is a color masking tool using the setup of colormask_mod script as a take off point.  It is not exactly the same, but it has one very useful attribute - it allows you to preview what the mask is going to look like in a manner somewhat similar to the range mask tool.  This allows you to tweak your color mask to a better fit before committing to creating the mask.  I found this very useful as I used this to go back and reprocess the RGB starless image.  I *may* have overdone the blue region saturation a bit, but it does look good the eye - IMO.  I also pulled back the Stars image brightness a tiny bit to allow M83 to stand out a bit more.  What I did post both a cropped and uncropped version the image while I left the original posted version up as well. 

I like both images, but I'm somewhat inclined to prefer the original version with its softer palette and less stark dark structures.  YMMV

About M83, The Southern Pinwheel Galaxy:
Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy approximately 15 million light-years away in the constellation borders of Hydra and Centaurus. Nicolas-Louis de Lacaille discovered M83 on 17 February 1752 at the Cape of Good Hope.  Charles Messier added it to his catalogue of nebulous objects (now known as the Messier Catalogue) in March 1781.

It is one of the closest and brightest barred spiral galaxies in the sky and is visible with binoculars. It has an isophotal diameter at about 36.24 kiloparsecs (118,000 light-years). Its nickname of the Southern[a] Pinwheel derives from its resemblance to the Pinwheel Galaxy (M101).

Characteristics
M83 is a massive, grand design spiral galaxy.  Its morphological classification in the De Vaucouleurs system is SAB(s)c, where the 'SAB' denotes a weak-barred spiral, '(s)' indicates a pure spiral structure with no ring, and 'c' means the spiral arms are loosely wound.  The peculiar dwarf galaxy NGC 5253 lies near M83, and the two likely interacted within the last billion years resulting in starburst activity in their central regions.

The star formation rate in M83 is higher along the leading edge of the spiral arms, as predicted by density wave theory.  NASA's Galaxy Evolution Explorer project on 16 April 2008 reported finding large numbers of new stars in the outer reaches of the galaxy—20 kpc from the center. It had hitherto been thought that these areas lacked the materials necessary for star formation.

Supernovae
Six supernovae have been observed in M83: SN 1923A (mag. 14), SN 1945B (mag. 14.2), SN 1950B (mag. 14.5), SN 1957D (mag. 15), SN 1968L (mag. 11.9), and SN 1983N (type Ia, mag. 11.9).

Environment
M83 is at the center of one of two subgroups within the Centaurus A/M83 Group, a nearby galaxy group. Centaurus A is at the center of the other subgroup. These are sometimes identified as one group, and sometimes as two. However, the galaxies around Centaurus A and the galaxies around M83 are physically close to each other, and both subgroups appear not to be moving relative to each other.