They've got fast fiber to get the data off the mountain and into multiple data processing centers in near real-time including alerts when something interesting happens.

"The nightly pipelines are based on image subtraction, a process that highlights differences between two exposures of the same field, and are designed to rapidly detect interesting transient events in the image stream and send out alerts to the community within 60 seconds of completing the image readout. "

https://www.lsst.org/about/dm