The Giant Magellan Telescope’s 6th Mirror has Just Been Cast. One More to Go Posted on The Giant Magellan Telescope’s 6th Mirror has Just Been Cast. One More to Go By 2029, the Giant Magellan Telescope (GMT) in northern Chile will begin collecting its first light from the cosmos. As part of a new class of next-generation instruments known as “extremely large telescopes” (ELTs), the GMT will combine the power of sophisticated primary mirrors, flexible secondary mirrors, adaptive optics (AOs), and spectrometers to see further and with greater detail than any optical telescopes that cam...