12/14/2023 0 Comments Anand vishy hawaii telescope![]() Two proposed designs for the next generation 30 and 40 m telescopes use the same basic technology pioneered at Keck Observatory: a hexagonal mirror array coupled with an altazimuth mounting.Įach of the two telescopes has a primary mirror of 10 meters (32.8 ft or 394 in), slightly smaller than the Gran Telescopio Canarias. Altazimuth mounting provides the greatest strength and stiffness with the least amount of steel, which, for Keck Observatory, totals about 270 tons per telescope, bringing each telescope's total weight to more than 300 tons. ![]() Most current 8–10 m class telescopes use altazimuth designs due to their reduced structural requirements compared to older equatorial designs. As the telescope moves, this twice-per-second adjustment counters the effects of gravity and other environmental and structural effects that can affect mirror shape.Įach Keck telescope sits on an altazimuth mount. During observation, the computer-controlled system of sensors and actuators dynamically adjusts each segment's position relative to its neighbors, keeping a surface shape accuracy of four nanometers. On the telescope, each segment is kept stable by a system of active optics, which uses extremely rigid support structures in combination with three actuators under each segment. The mirrors were made from Zerodur glass-ceramic by the German company Schott AG. Each segment is 1.8 meters wide, 7.5 centimeters thick, and weighs half a ton. In the Keck telescopes, each primary mirror is made of 36 hexagonal segments that work together as a unit. A mirror of similar size cast of a single piece of glass could not be made rigid enough to hold its shape precisely it would sag microscopically under its own weight as it was turned to different positions, causing aberrations in the optical path. The key advance that allowed the construction of the Keck telescopes was the use of active optics to operate smaller mirror segments as a single, contiguous mirror. The Keck II telescope showing the segmented primary mirror The Keck I telescope began science observations in May 1993, while first light for Keck II occurred on October 23, 1996. With construction of the first telescope well advanced, further donations allowed the construction of a second telescope starting in 1991. Keck Foundation gave $70 million to fund the construction of the Keck I telescope, which began in September 1985, with first light occurring on November 24, 1990, using nine of the eventual 36 segments. With a design in hand, a search for the funding began. With a concept first proposed in 1977, telescope designers at the University of California, Berkeley (Terry Mast) and Lawrence Berkeley Laboratory ( Jerry Nelson) had been developing the technology necessary to build a large, ground-based telescope. They are currently the 3rd and 4th largest. Both telescopes have 10 m (33 ft) aperture primary mirrors, and when completed in 1993 (Keck 1) and 1996 (Keck 2) were the largest optical reflecting telescopes in the world. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S.
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