Rubin Observatory sends millions of alerts per night. Nine ML brokers sort them.
On February 25, 2026, the Vera C. Rubin Observatory in Chile sent its first batch of real-time alerts — 800,000 of them in a single night. Each one flagged something that changed in the sky: a new point of light, a brightening star, a moving dot that might be an asteroid. The Legacy Survey of Space and Time (LSST) had officially started talking. That was the gentle version. At full survey depth, Rubin will generate up to 10 million difference-image alerts every night. No research group, no observatory control room, no grad student with a caffeine problem can review that by hand. The only reason the alerts are useful at all is a network of nine community software platforms — called alert brokers — that run machine-learning classifiers on every packet before the Sun comes up. ...