Messier 13 The Great Globular Cluster of HerculesAbout 145 light-years in diameter, M13 is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, also known as V1554 Herculis, with an apparent visual magnitude of 11.95. M13 is 22,200–25,000 light-years away from Earth, and the globular cluster is one of over one hundred that orbit the center of the Milky Way.Single stars in this globular cluster were first resolved in 1779.  Compared to the stars in the neighborhood of the Sun, the stars of the M13 population are more than a hundred times more densely packed. They are so close together that they sometimes collide and produce new stars.  The newly formed, young stars, so-called "blue stragglers", are particularly interesting to astronomers.

This was my First Light for my new monochrome setup and my first monochrome image processing effort.  I'm pleased with the results and had significant learnings, plus trying to avoid clouds.  Approximately 40% of my frames had to be discarded due to cloud passage and as a LRGB image set, that impacted total integration time heavily.

In the final image, there are 118 frames for a total of 3.62 hrs integration time, which is works for this target but would not be as good for anything with extensive nebulosity or NB frames.
L= 23 x 120
R = 20 x120
G= 21x120
B=26 x 120
There were also 28x180 NB Ha frames that I decided to not use since they added nothing to the final image that I could determine.

This was a more time consuming effort than my prior experiences with OSC imaging and post processing.  Much of the time  was just working out what the steps need to be in the workflow.  One thing that cost me extra steps in the post processing was the setting to allow PixInsight/WBPP to select a reference frame in each filter set.  That gives the 'best' calibration results, but it also means that the individual masters for each filter are not star aligned with each other.  This becomes painfully evident when a master has a different orientation than others due to a meridian flip.  The 'fix' is a separate star alignment step with to align the master files to each other.  It's a compromise, since WBPP will also use just one reference frame for the entire data set of all the filters.  Depending on the data, that may impact the calibration, but would have the masters all aligned to that reference frame and thus to each other.  All it eliminates is the extra star alignment step for the masters so how much that saves is probably not that much.  YMMV.

I did not get good results with NoiseExterminator in the linear filter masters.  At first glance they looked great, but after removing the temporary stretch and then putting it back, the images looked very mottled with numerous artifacts.  I could have taken some time to attempt to tweak the settings, but found the defaults work just fine on the non-linear (stretched) images.

A LOT of trial and error this time around but I think the final image looks good.  M13 is one of the few globular clusters large enough in my OTA to provide an appealing image, at least IMO.  I did crop the final a bit further to increase the apparent size of M13 in the final jpeg version.  No other post processing in Photoshop/DeNoiseAI was needed, IMO.

I added another revision after reprocessing the data set based on techniques I learned in Adam Block's PixInsight tutorials.  I also incorporated the Ha data using a PixelMath tool shared on VisibleDark's YouTube channel.  Getting the Ha data into the image added a little detail the galaxies visible in the image even though they are very small.  It also increase the integration time to almost 4.5 hours (without the Ha, the integration is 3 hrs).

Let me know what you think.  M13 is, purposefully, not a challenging target for a First Light monochrome attempt, by choice.  When the nebuli start showing up, the game will get a lot more intense!!!