Richard F. Caris Mirror Lab
The GMT’s mirrors are being produced by the Richard F. Caris Mirror Lab of the Steward Observatory of the University of Arizona. The GMT’s 24.5 meter primary mirror will be comprised of seven separate 8.4 meter diameter segments. Each of the primary mirror segments weighs approximately 17 tons and takes a year to cast and cool. After casting, the fabrication of each segment requires more than three years of surface generation and meticulous polishing. Learn more about the mirror production process in our FAQs.
GMT Segment 5
Segment 5 was cast on November 4, 2017. The mirror was cleaned out and moved into the integration hall in 2019, awaiting its turn on the grinding machines.
GMT Segment 4
As of July 2019, Segment 4 has completed rear surface polishing and load spreaders are being attached.
GMT Segment 3
As of July 2019, Segment 3 is undergoing fine grinding of its front surface.
GMT Segment 2
Segment 2 was moved into temporary storage next to Segment 1 on July 18, 2019. The mirror is named for George P. and Cynthia Woods Mitchell.
GMT Segment 1
Segment 1 was moved from the Richard F. Caris Mirror Lab into temporary storage near Tucson Airport in September 2017. The mirror is named for George P. and Cynthia Woods Mitchell.
Mirror Test Cell and Simulator