C49, Rosette Nebula
Imaging: ST120 achro, Canon 1000D 400 & 800 ISO, L-Enhance filter
Subs: 63x180 400ISO, 134x180 800ISO (9.6h total), bias, darks, and flats
(Additional notes below)
The Rosette Nebula is an H II region (i.e. region with lot of ionized hydrogen) in a molecular cloud in the Milky Way. The cluster and nebula are about 5000 ly from Earth and are about 130 ly across. The radiation from the young stars excites the atoms in the nebula, causing them to emit light radiation (this is why it is called an "emission nebula").
I took these pictures over 6 nights from mid February to early March 2021. I used a special type of filter that blocks all light except around the 3 bandwidths of light that this nebula produces. It is a rather expensive 2" piece of glass but it works wonders on emission nebula! I was actually quite lucky to capture this because with my backyard tree profile, the Rosette Nebula is only visible for about 1.5h each night for about 3 weeks. And with all of the snow and rain and cloudiness, most of those nights were unusable.