Keck telescopes

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**W. M. Keck Observatory**
Physical characteristics
The summit of Mauna Kea is considered one of the most important astronomical viewing sites in the world. The twin Keck telescopes are two of the largest optical/near-infrared instruments.
Organization	California Association for Research in Astronomy
Location	Mauna Kea, Hawai'i, USA
Wavelength regime	Optical, near infrared
Completion date	Keck I 1993, Keck II 1996
Webpage	http://www.keckobservatory.org/
Telescope style	Reflector
Diameter	10m each
Effective Angular Resolution	85m
Focal length	17.5 m (f/1.75)
Mounting	Alt/az
Dome	Spherical

The W. M. Keck Observatory is home to two of the largest optical/near-infrared telescopes in the world, at the 4,145 meter (13,600 ft) summit of Mauna Kea in Hawai'i. At the heart of each 10-meter (400-inch) Keck telescope is a revolutionary primary mirror composed of 36 hexagonal segments that work together as a single piece of reflective glass.

Each Keck telescope sits on an altitude-azimuth design. Extensive computer analysis determined the greatest strength and stiffness for the least amount of steel--about 270 tons per telescope. On the telescope, each segment's figure is kept stable by a system of extremely rigid support structures and adjustable warping harnesses. During observing, a computer-controlled system of sensors and actuators adjusts the position of each segment, relative to its neighbors, to an accuracy of four nanometers. This twice-per-second adjustment effectively counters varying distortions due to the tug of gravity.

Both Keck telescopes are equipped with adaptive optics, which compensates for the blurring due to atmospheric turbulence. In addition, the Keck I and Keck II telescopes can work together as the Keck Interferometer; the 85 m separation gives them the effective angular resolution in one direction of an 85 m mirror, comparable with the resolution of other astronomical interferometer arrays such as the VLTI (200 m separation) but with no interferometric imaging capability.

The W. M. Keck Observatory is managed by the California Association for Research in Astronomy, a non-profit 501 (c)(3) organization whose board of directors includes representatives from Caltech and the University of California. In 1996, the National Aeronautics and Space Administration (NASA) joined as a partner in the Observatory. The telescopes sit on land leased from the University of Hawai'i System based in Honolulu, Hawai'i. Construction of the telescopes were made possible through private grants totaling more than $140 million provided by the W. M. Keck Foundation. Headquarters for the W. M. Keck Observatory are located in Kamuela, Hawaii. Telescope time is allocated by the partner institutions. Caltech, the University of Hawai'i System, and the University of California accept proposals from their own researchers. NASA accepts proposals from researchers based in the U.S., while NOAO accept proposals from researchers around the world [1].

In 2001, the two Keck telescopes were linked together using interferometry to increase the resolution of images observed. With the two telescopes combined they have a resolution equivalent to that of a telescope with a mirror 85 m in diameter. [Jacaranda Physics 2 HSC course, Michael Andriessen, Peter Pentland, Richard Gaut, Bruce McKay, Jill Tacon, 2003, published by John Wiley & Sons Australia. Ltd]