M33 has been on the list since I first purchased my portable rig as it is one of those targets that photographs well specifically because of how it’s angled toward us. Most spiral galaxies we see at some tilt, foreshortened into an ellipse. Triangulum is close to face-on, which means almost all of its structure is actually visible: the loose, slightly ragged spiral arms, the scattered pink knots of active star formation, and if you get enough signal, NGC 604, a single star-forming region out near the edge of one arm that’s roughly 40 times the size of the Orion Nebula.
This one took 14 hours and 30 minutes total, with 13 hours and 16 minutes of RGB data (on a OSC camera), plus an additional 1 hour and 14 minutes of Ha data layered in to pull out the ionized hydrogen, where the regions like NGC 604 that would otherwise wash out against the galaxy’s broader light.
At a Bortle 4 location, a target like this needs real integration time to pull away from the sky background. M33’s surface brightness is lower than you’d expect for something this large in the sky, which is part of why it has a reputation as a harder narrow-field target than its size suggests.
Leave a Reply