Andromeda never gets old

October 8, 2021 - Reading time: ~1 minute

Here it is in hydrogen-alpha, just the one narrowband slice of the spectrum. Andromeda Galaxy, Messier 31, is probably the first target for northern hemisphere astrophotographers--well, it's either M31 or M42 Orion Nebula. Both are intensely bright deep sky objects you can see without a telescope, given reasonably clear and dark skies. I have captured M31 more times than I can count. The galaxy stands out in the night sky when it swings around every year, making it an easy target. Galaxies are also great full spectrum targets for color cameras, DSLRs and mirrorless cameras, but that doesn't mean you can't pull some awesome data out of Andromeda in narrowband or infrared. I captured M31 in near-infrared (longpass 850nm) a couple years ago, and last night I captured our galactic neighbor in very narrow hydrogen-alpha (3nm Ha), and this stacked set of 42 sub-exposures highlights massive HII regions, mostly emission nebulae, along the outer spiral arms, with dense bands of dust and debris ringing the galactic core. This will make a great red channel in an RGB image, or I may go with HaRGB.