Geometry Main reflector: paraboloid D=10 m F/D=0.35. Subreflector: hyperboloid d=0.69 m Fe/D=13.8. Focus: Nasmyth or bent Cassegrain foci (2-outside each elevation bearing).

Reflector Spaceframe support: carbon fiber reinforced plastic (CFRP) tubes with invar steel joints (3040 kg weight). Panels: CFRP skin with aluminum honeycomb sandwich core (110 Kg weight). Subreflector support: CFRP tube quadrupod (110 kg weight). Surface accuracy is measured by holography observations. The most recent results are summarized in 2000. The surface has an average rms of 15 microns over the entire surface. Previous holography runs are: 1998, 1997, and 1995.

Secondary Single mirror - CFRP aluminum honeycomb sandwich. Chopping mechanism - at 80% duty cycle: 10 Hz with 4 arcminute throw. 25 Hz with 25 arcsecond throw. 16 mirror positions possible for raster scanning.

Mount: Altitude/Azimuth - steel with thermal insulation. Absolute pointing accuracy: 1 arcsecond rms. Tracking precision: 0.2 arcsecond rms. Azimuth range: +/-270 degrees. Elevation range: -2 degrees to 91 degrees. Slew speed: 60 degrees/min. 41500 kg weight.