DeepSkyStacker (free and Open Source) In case you have PixInsight: from bulrichl: beginner guide to PixInsight Jon Rista(a software engineer and architect by day, photographer and astrophotographer in my spare time): Effective noise reduction Madratter trappedphotons David Ault Harryastroshed lightvortexastronomy DuncanKitchin minDN calc on github 20xRN rule etc big shoutout cloudynights diminishing returns sub exposure tables from Shiraz