The Keck telescope has a Ritchey-Chretien optical design. Its mount is Altazimuth. It has a height of 80.71 feet, a total weight of glass of 14.4 tons and a total moving weight of 270 tons.
The design of the primary mirror is an actively controlled, segmented hexagon. The equivalent diameter of the mirror is 32.81 feet and its figure is a concave hyperboloid. It has 36 different segments, with each segment diameter measuring 5.906 feet, each segment thickness measuring 2.953 inches and each segment weighing 881.8 pounds. The gap between each segment is 0.1181 inches. The segments are made of Zerodur low-expansion glass-ceramic. The light collection area of the primary mirror is 807.3 feet and its focal ratio is f/1.75.
The secondary mirror has a convex hyperboloid figure and a circular shape. Its height and width dimensions are 101 feet by 121.4 feet. It has a moving weight of 635 tons. Its total air replacement is 5 minutes. It has a visible band of 11.81 microinches by 39.37 microinches and adaptive optics of 39.37 microinches by 196.9 microinches.
Two universities jointly operate the Keck telescope, the California Institute of Technology and the University of California. It is located atop volcano Mauna Kea in Hawaii.