Star ClusterCharles LilloJune 17, 2026M13, globular clusterComment

M13

Star ClusterCharles LilloJune 17, 2026M13, globular clusterComment

M13 globular cluster cropped — M13 Globular Cluster Cropped

Well, I finally got the weather gods to cooperate this week, and I managed to capture one of my favorite deep-sky targets: M13, the Great Globular Cluster in Hercules. This absolute masterpiece has been on my "gotta get a better image" list for a while, and I'm stoked with how this turned out.

The Setup

I was using my 150mm refractor (f/3.8 with a reducer—love that focal length for wide-field work) mounted on my AM5 Mount. he camera was my ZWO 2600 Mono.

The Data

Here's what I collected:

50 x 120-second exposures for Luminance (L)
50 x 120-second exposures for each of Red (R), Green (G), and Blue (B)

That's 50 subs per channel, meaning I spent roughly 6.5-7 hours gathering photons. You can see the difference when you gather that kind of integration time to a globby.

ocessing Notes

Processed in PixInsight. I won't bore you with every slider I moved, but the typical workflow was:

Calibration (darks, flats, bias)
Alignment and stacking
Deconvolution and some careful stretching
Color mapping for the RGB
Luminance blending with the RGB data
Some selective sharpening in the core region
Final color balance and curve adjustments

From my backyard in Mars Hill, with light pollution that's... let's call it "moderate to mild" the detail in this globular cluster came through beautifully. You can really see the individual stars resolved across the core, and the outer halo shows that characteristic density gradient that makes M13 so photogenic.

Why M13?

Visually It's one of the best globular clusters visible from the Northern Hemisphere, a tight ball of roughly 100,000 stars in space about 22,000 light-years away.

he Takeaway

If you're thinking about diving into astrophotography—especially planetary or globular cluster work—start with something like this. M13 is forgiving, it's bright enough to gather data quickly, and it never disappoints.

Clear skies, everyone.

Equipment Summary: