PROMPT Telescopes, Optical telescope array at Cerro Tololo Inter-American Observatory, Chile

The PROMPT Telescopes are six 0.41-m Ritchey-Chrétien reflectors built by RC Optical Systems at Cerro Tololo Inter-American Observatory in Chile. Each sits under its own Astro Haven clamshell dome on a Paramount ME mount that slews at 9° per second. Five carry Apogee Alta U47+ cameras with E2V CCDs; the sixth is fitted with an LN2-cooled Rockwell Scientific Micro-Cam for near-infrared imaging.

The system was installed in the early 2000s to automatically catch sudden events in the night sky. It built upon decades of research operations at the mountain site, which has hosted astronomical work since 1965.

Researchers from around the world work together through these telescopes to observe sudden cosmic events like stellar explosions. This global partnership has transformed how astronomers study rapid changes in the night sky.

Visitors can view the telescopes from outside, but this is primarily a research facility with restricted access to the instruments. The high altitude means thin air and cold nights, so anyone planning to visit should bring warm clothing and allow time to adjust.

The five telescopes are electronically linked to observe the same sky target simultaneously at different wavelengths of light. This synchronized approach allows them to detect rapid changes like gamma-ray bursts within seconds rather than miss them entirely.