* Effective diameter
(diameter of light affecting area)
*: 8.2 m (27 ft.)
* Thickness: 20 cm (7.9 inches)
* Weight: 22.8 metric tons (25.1 tons)
* Material: ULE (ultra-low thermal expansion glass)
* Mean Surface error: 14 nanometer (1/5,000,000 inch)
* Focal length: 15 m (49'2")
* Mounting: altitude-azimuth
(Alt-Az)
* Basic Optics: Ritchey-Chretien System
* Height: 22.2 m (72 ft.)
* Maximum width: 27.2 m (89 ft.)
* Weight: 555 metric tons (612 tons)
* Foci: Four

-Primary
focus : F2.0 (with corrector lens)

-Cassegrain
focus : F12.2

-Nasmyth focus (optical) : F12.6

-Nasmyth focus (infrared) : F13.6
* Maximum slewing speed: 0.5 deg/sec
* Tracking accuracy without guiding: 0.1"
* Blind pointing accuracy: less than 1.0"
* Best angular resolution achieved: 0.2"

(without
adaptive optics @ 2.15 μm)