This is my 3rd visit to the Sombrero Galaxy with the Planewave CDK24. It was not visible at my location when I started with the 8" Celestron.
My first visit in April 2018 was my first completed image from the CDK24. It won an IOTD and thus got lots of exposure over the years...
https://www.astrobin.com/341900/?nc=&nce=I then reprocessed this data in 2019 using PI PCC...
https://www.astrobin.com/384024/?nc=&nce=I then visited again in May 2020 to focus on the huge halo and very long tail...
https://www.astrobin.com/smi4rk/C/?nc=&nce=I then used this very deep data to "uncover". This wasn't ideal because I used 30m L subs which largely overexposed the core...
https://www.astrobin.com/7wsd78/B/?nc=&nce=https://www.astrobin.com/b2rr1o/B/?nc=&nce=For May 2023 I decided to go for a "reimagined" look after seeing two references...
1. Kevin Morefield's excellent capture using a CDK17 in sub 1" Chile skies...
https://www.astrobin.com/ss7plo/B/2. New Hubble processing published March 2019...
https://science.nasa.gov/m104-sombrero-galaxyI say "reimagined" for three reasons...
1. I wanted to capture what the Sombrero might looks like when approaching from a few million light years. The color would likely be "natural" with a smooth halo with no abrupt edge.
2. The May skies in Julian, CA are very dark (21.5+) and steady between weather changes.
3. This is my first use of the relatively new AI sharpening and denoise tools by Russel Croman. Thank you Kevin Morefield for your AI processing tips!
I hope you enjoy this new version! I'm always welcome to feedback to help with the next one. (-;
CAPTURE
1. 300s x 24 L, 900s x 8 for each R, G, B (8 hours total).
2. L FWHM between 1.74" and 2.03". This stacked to 1.96". I had 60 x 300s L subs up to 2.5", but the 24 best gave the sharpest results with this very bright object. It's extremely rare to see 1" skies at this 4,200' location.
3. RGB between 2.07" and 3.27".
4. 21.5+ SQM skies.
5. Used PI WBPP for L with cosmetic correction, 20 bias, 30 dark, and 20 flats/20 flat darks (light panel) for each LRGB.
6. Used Maxim DL calibration followed by PI registration and integration for RGB. Although this yields minor cosmetic defects, the process is MUCH faster and the cosmetic defects are easy to correct in Photoshop with Spot Healing.
LUMINANCE PROCESSING (new AI tools GREATLY simply deconvolution, denoise and sharpening with better results)
1. BlurXTerminator with automatic PSF, Sharpen Nonstellar = 0.48 (thank you Kevin!) and Correct First option. This reduced FWHM from 1.96" to 1.51".
2. PI Rotate 180°.
3. PI default stretch.
4. Photoshop Levels.
5. Two passes of Photoshop Shadows/Highlights. This is very similar to PI HDR but with much better control to avoid distorting the large halo. PI HDR tends to "contain" the halo. This is especially seen in the NASA processing.
6. NoiseXTerminator with Denoise = 0.9 and Detail = 0.3.
7. Mild sharpening on all non-stellar objects only using PI MLT with 0.1 Bias on Detail Layer 2.
RGB PROCESSING
1. PI ABE.
2. PI BN.
3. PI Rotate 180°.
4. PI CC using core and background.
5. PI Masked Stretch.
6. NoiseXTerminator.
7. Photoshop color stretching, HVLG, white calibration, Shadows/Highlights and tiny color balance tweaks using multiple 32x32 samples on core and background.
8. Cosmetic correction and desaturation on brighter stars.
LRGB COMBINATION
1. Soft light layering in PS.
2. Levels.
3. Curves.
4. Mild StarShrink on stars (not galaxies).
5. Very mild color saturation and highlight tinting (towards red) based on NASA reference. (-:
6. Cropping to highlight Sombrero and small surrounding galaxies (similar to Kevin's cropping).
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