Rapid Eye Mount telescope, Robotic telescope at La Silla Observatory, Chile

The Rapid Eye Mount telescope is a robotic Ritchey-Chrétien telescope with a 0.60 m primary mirror at ESO's La Silla Observatory, at 2,400 m on the edge of the Atacama Desert. Two cameras, the REMIR infrared imager and the ROS2 visible imager, share a 10×10 arcminute field through a dichroic placed before the focus.

The Rapid Eye Mount was built in 2003 by the Italian National Institute for Astrophysics and installed at ESO's La Silla Observatory that June, with operations run for INAF since 2002. It was designed to slew at 10°/s so it could point at gamma-ray burst alerts from satellites such as Swift within about 30 seconds. A wide-field camera, TORTORA, was added in 2006 and removed in 2014.

The telescope serves the international astronomical community by monitoring gamma-ray bursts detected through the NASA Swift satellite communication network.

REM runs without on-site operators: its nightly schedule is planned in advance but is overridden the moment a gamma-ray burst alert arrives, typically slewing to the new target within 30 seconds. The site lies at 2,400 m on the edge of the Atacama Desert, and observing time is offered to the worldwide community under an open sky policy rather than to casual visitors.

REM observed the electromagnetic counterpart of the gravitational-wave event GW170817 in 2017, which stayed visible for about 100 seconds. The same telescope also helped catch the afterglows of GRB 080319B, GRB 060418 and GRB 06067A within seconds of their discovery.