M103 -- Open Cluster
From the author of   Welcome to the Universe in 3D
Click here for Hertzsprung-Russell diagram
18:10 EST Jan 08, 2021.
Starlight Express Trius SX694 on 10" RC at f/9.
L = 5 min, R = G = B = 5 min
(unguided 20-second exposures).