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Sept. 26, 2023

Media Advisory: Primary mirror for Giant Magellan Telescope nears completion: Seventh mirror about to be cast at UArizona

  • What: Casting of the seventh mirror for the Giant Magellan Telescope (GMT)
  • When: Saturday, Oct. 7, 12:30 p.m. 
  • Where: Richard F. Caris Mirror Lab, 527 N. National Championship Drive, Tucson
  • RSVP: Fill out this form to RSVP.

TUCSON, Ariz. – Media are invited to witness the onset of production of the seventh and final required primary mirror segment for the Giant Magellan Telescope, or GMT. During the "high fire" event, chunks of glass will melt inside a one-of-a-kind, spinning oven housed beneath the stands of Arizona Stadium.

Measuring 27.5 feet (8.4 meters) in diameterabout two stories tall when standing on edgethe mirror will cool over the next three months before it is ready for the next stage of being prepared for the telescope. The four-year process of fabricating mirror segment 7 will provide the GMT with the minimum number of mirror segments required to complete the telescope's 4,155-square-foot light collecting surface, the world's largest and most challenging optics ever produced. The Giant Magellan Telescope will be the first extremely large telescope to complete its primary mirror array.

At 50 million times more powerful than the human eye, "the telescope will make history through its future discoveries," said Buell Jannuzi, director of Steward Observatory and head of the Department of Astronomy, who serves as principal investigator for the fabrication of the GMT's primary mirror segments. "We are thrilled to be closing in on another milestone toward completion of this groundbreaking observatory."

According to Rebecca Bernstein, the GMT's chief scientist, the combination of light-gathering power, efficiency and image resolution will enable researchers to make new discoveries across all fields of astronomy.

"We will have a unique combination of capabilities for studying planets at high spatial and spectral resolution, both of which are key to determining if a planet has a rocky composition like our Earth," Bernstein said, "whether it contains liquid water, and whether its atmosphere contains the right combination of molecules to indicate the presence of life."

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Media contact:
Cathi Duncan
Steward Observatory


The University of Arizona, a land-grant university with two independently accredited medical schools, is one of the nation's top public universities, according to U.S. News & World Report. Established in 1885, the university is widely recognized as a student-centric university and has been designated as a Hispanic Serving Institution by the U.S. Department of Education. The university ranked in the top 20 in 2021 in research expenditures among all public universities, according to the National Science Foundation, and is a leading Research 1 institution with $824 million in annual research expenditures. The university advances the frontiers of interdisciplinary scholarship and entrepreneurial partnerships as a member of the Association of American Universities, the 71 leading public and private research universities in the U.S. and Canada. It benefits the state with an estimated economic impact of $4.1 billion annually.


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