ROTSE (for Robotic Optical Transient Search Experiment) is an array of four optical telescopes located around the world, operated by computer following up on reported Gamma-Ray Bursts. While not responding to alerts for GRBs, it Surveys for other Transients.
The original ROTSE (ROTSE-I) was deployed in 1998. A upgrade plan (ROTSE-II) was canceled, and a redesigned upgrade (ROTSE-III) to the current configuration was carried out in 2004. It is designed to respond to alerts of GRBs from other sources, and to start imaging within seconds of receiving the alert.