Original post - 5-10-2021:
Took this M13 image in my front yard with bortle 6 sky and every house light in the neighborhood blaring. I read and applied a lot of the steps from Inside Pixinsight by Warren A. Keller. I highly recommend it. That combined with my previous couple months of studying and techniques were a satisfying run at this one. M13 sits 22 to 25 million light years from Earth.

NOTE: The propeller is located in the lower right of the core with a Y shape and slight tilt to the left.

Update - 12-27-2022:
After over a year of learning and lots of new processes and software that has come available.  These subs are pretty poor by my current standards, but thought I would apply some new experience to this target.  I ended up dropping out some poor subs and all the L subs.  The detail is lacking when zoomed in as a result, but I am more pleased with this version regardless.  I also had poor flats at the time due to just learning how to do those.  I updated the acquisition and process details for the new version.  Amazing what the results are with a little more experience and the new tools.  Clusters are not a fan of many folks, but hope you enjoy.  CS. -- T.

Latest process - 12-27-2022 (Pixinsight): 

Target Workflow:

Blink
- Review all subs and remove visually bad frames

WBPP
- w/ Interactive mode for Local Normalization
- Cosmetic Correction Applied
- Pedestal added to avoid clipping in later processes
- Drizzle Enabled
- Best Images reviewed and used to Generate Local Normalization Ref for each channel

Subframe Selector
- Sort by PSF Signal Weight and Star Count to weed out subs that are far from median values
- Note best reference image for each filter for use in Image Integration

Image Integration
- Use Normalization and Drizzle files

Drizzle Integration
- Use Normalization Files

Dynamic Crop

DBE 
- all channels separately

Linear Fit
- use Statistics to find the lowest channel Median value for reference sub

LRGB Combination
- Uncheck L channel and load R, G, B
- No Chrominance Noise Reduction

BlurXTerminator
- This target uses defaults
- PSF Image script and note average of FWHMx and FWHMy = 4.15
- Uncheck Auto PSF and set to 4.15

Image Solver Script
- Search and set target from database for best result

Spectrophotometric Color Calibration
- Set Background Preview
- Use Preview for Background Neutralization

Bill Blanshan SCNR
- Drag to image without modification

NoiseXTerminator
- Defaults

Generalized Hyperbolic Stretch - RGB image
- Multiple iterations to zero in and finalize with Linear at end

Extract Luminance
- for use in later steps
- save as L

Curves Transformation
- Apply L as mask to RGB
- Adjust contrast and colors to taste

Exponential Transformation
- Apply L as mask to protect background
- Utilized defaults with Order = 0.6

Histogram Transformation
- Darken background

Curves Transformation
- Final tweaks