(telescope array to follow up gravitational wave detections)
BlackGEM is an array of opticaltelescopes at La Silla Observatory (LSO) in Chile,
to follow up GW detections by Virgo and LIGO.
It began operation in 2023 with three telescopes of 65-cm diameter,
each with a 2-square-degreefield of view, the aim being to search
a significant portion of the sky quickly.
They carry out surveys while awaiting alerts of
GW detections.
Future plans are to expand to 15 such telescopes.
BG4 is a term used for a planned interim-configuration of four
of the telescopes.