Capturing M20: The Trifid Nebula in Broadband Deep-Sky Imaging

View fullsize

M20: The Trifid Nebula in Sagittarius

Sweating Through August Nights for Deep Space Colors

August in Texas brings triple-digit heat by day, but once the sun drops, the clear skies call me out to the backyard with my telescope. Right now, Messier 20—the iconic Trifid Nebula—is positioned beautifully overhead in the northern hemisphere’s late summer sky. Located roughly 5,200 light-years away in the constellation Sagittarius, this deep-sky jewel is a rare combination of an emission nebula, a reflection nebula, an open star cluster, and dark lanes of cosmic dust. The name "Trifid" comes from its three-lobed structure, divided by prominent dark dust lanes that cut right through the glowing pink heart of the star-forming region.

The Backyard Session and Processing Workflow

I set up my Vaonis Vespera Pro last night after sunset with the intention of capturing two targets; the Trifid nebula and the Iris nebula. The Trifid nebula was first, tracking it for about three hours. After discarding frames affected by drift, air turbulence, or atmospheric haze and all the things that cause distortions, I landed on almost two solid hours of clean broadband sub-exposures. Broad integration is essential here to capture both the subtle blue glow of light reflecting off interstellar dust and the rich magenta emission driven by energetic young stars. In the upper-left corner of the frame, you can also spot the open star cluster Messier 21 (M21), a group of roughly 570 young stars sharing the same galactic neighborhood about 4,250 light-years away.

For processing, after spending months wrestling with complex workflows in Siril, I decided to run this dataset through a new free processing software called AstroWizard. In about ten minutes, I was able to stretch and balance the data with remarkable detail. The dark dust lanes crisp up sharply against the glowing core, while the delicate blue haze on the northern edge pops clean without blowing out the surrounding starfield. It is impressive how far automated processing algorithms have come for smart telescope imaging and having smart people build new tools for us.

With this heatwave showing no signs of slowing down, these clear summer nights are too good to waste. The Vespera Pro will be out there in the yard again tonight collecting photons as I go after the next deep-sky target.

---

Explore More of My Adventures