Third mirror casting event for the Giant Magellan Telescop

Phys.org August 2013 | On Saturday, August 24, 2013, the third mirror for the Giant Magellan Telescope (GMT) will be cast inside a rotating furnace at the University of Arizona's Steward Observatory Mirror Lab, the only facility in the world where mirrors of this size are being made. The Mirror Lab will host a rare media opportunity to witness this milestone in the creation of the optics for the GMT. Each of the seven mirrors weighs roughly 20 tons, yet the surface has to be smooth to within a twentieth of a wavelength of light. The GMT mirrors are considered to be the greatest astronomical optics challenge ever undertaken. Here's a short video discussing the mirror making process.  more>