Triangulum Galaxy

The third-largest galaxy in the Local Group after Andromeda and the Milky Way, about 2.73 million light-years away in the constellation Triangulum. M33 is a face-on spiral with loose, open arms packed with enormous HII regions — the largest, NGC 604, is one of the biggest star-forming regions known, dwarfing the Orion Nebula. Narrowband imaging brings out the pink hydrogen clouds scattered across the arms beautifully.

This is my longest integration at 10 hours and the image I’m most proud of. The extra time really pays off on a target this faint — pulling out the delicate spiral structure and the individual star-forming knots across the arms.