Build a site that lists every satellite pass over any location

The poster, a self-described satellite enthusiast, brought the idea and the direction and had Claude Code write most of Watched. A visitor types a place and the site lists the imaging, radar, weather and crewed satellites that passed over it in the last seven days, with real photos where an archive has them (Sentinel-2, Landsat, NASA). Claude Code wrote the pass search on SGP4 orbit propagation, a GPU shader that moves around 17,000 tracked objects on a 3D globe each frame, the code that pulls images from the archives and matches each one to its pass, and most of the interface. The poster clicked around to find bugs and had Claude Code fix them. It also made the promo video.

The site is live, free and needs no signup, and the code is public on GitHub. The poster had Claude Code write a brute-force checker for the pass search, which found no missed passes across 22 edge cases. The top comment said that, in limited testing, the site worked as described. Other commenters asked for satellite detail pages and the ability to follow one object.

The poster says the most useful habit was asking Claude Code to prove its work with tests and brute-force comparisons rather than trusting the output, especially for the orbit math. No cost or build time was given. One commenter raised the surveillance angle of a tool like this.