Two detections per night: implementing LSST's audacious asteroid-finding paradigm

While most asteroid surveys aim to image each survey field four times per night, the Vera Rubin Observatory's Legacy Survey of Space and Time (LSST) cadence of two repeat visits per night cannot confidently identify new asteroids in a single night's data. Instead, an asteroid must be linked across several nights before it can be discovered. This multi-night discovery paradigm requires new algorithms and methods, as well as many times more compute power. Four images per night is an established standard for good reason, and surveys that use it will continue to make important contributions in the LSST era. But in spite of serious challenges, the LSST's aggressive new strategy has been successfully implemented. We describe these challenges and accomplishments, the intrinsic limitations of multi-night linking, and science highlights from early asteroid discoveries.