Smooth Mirror for Giant Telescope

摘要

Twenty tons of glass-that's what went into casting the first of seven mirrors that comprise the light-collecting area of the 25-meter Giant Magellan Telescope (GMT). The 8.4-meter-diameter, single-piece mirror was finished last week. The GMT will peer at the heavens from a remote Chilean moun-taintop when it is ready for operations by the end of this decade. The mirror was cast using a technique pioneered by University of Arizona astronomer Roger Angel.