How to Stack Astrophotography Images Programmatically with Python

The Hacker News front page recently featured a fascinating story about an astrophotographer whose deep-sky images ended up in the movie Project Hail Mary . It got me thinking about the technical side of astrophotography — specifically, the image stacking problem that every astrophotographer (and increasingly, every developer working with scientific imaging) eventually runs into. Here's the frustrating scenario: you've captured 200 frames of the Orion Nebula, each one noisy and underwhelming on its own. You need to combine them into a single clean image. And if you just naively average the pixel values, you get garbage. Let me walk you through why, and how to fix it. Why Naive Averaging Fails The core issue is that astronomical images have extremely low signal-to-noise ratios. Each individual frame contains the faint signal you want (nebula, galaxy, whatever) buried under read noise, thermal noise, and light pollution gradients. A simple mean average of all frames will reduce random noi