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The W. M. Keck Observatory is an
astronomical observatory An observatory is a location used for observing terrestrial, marine, or celestial events. Astronomy, climatology/meteorology, geophysical, oceanography and volcanology are examples of disciplines for which observatories have been constructed. His ...
with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of
Mauna Kea Mauna Kea ( or ; ; abbreviation for ''Mauna a Wākea''); is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii and second-highest peak of an island on Earth. The peak is ...
in the
U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...
of
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
. Both telescopes have aperture primary mirrors, and when completed in 1993 (Keck 1) and 1996 (Keck 2) were the largest astronomical telescopes in the world. They are currently the 3rd and 4th largest.


Overview

With a concept first proposed in 1977, telescope designers at the
University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
(Terry Mast) and
Lawrence Berkeley Laboratory Lawrence Berkeley National Laboratory (LBNL), commonly referred to as the Berkeley Lab, is a United States national laboratory that is owned by, and conducts scientific research on behalf of, the United States Department of Energy. Located in ...
(
Jerry Nelson Jerry L. Nelson (July 10, 1934 – August 23, 2012) was an American puppeteer, best known for his work with The Muppets. Renowned for his wide range of characters and singing abilities, he performed Muppet characters on ''Sesame Street'', ' ...
) had been developing the technology necessary to build a large, ground-based telescope. With a design in hand, a search for the funding began. In 1985,
Howard B. Keck Howard Brighton Keck (September 20, 1913 – December 14, 1996) was an American businessman. He was also a Thoroughbred horse racing, racehorse owner and breeder, and the owner of an auto racing team that twice won the Indianapolis 500. Early ...
of the
W. M. Keck Foundation The W. M. Keck Foundation is an American charitable foundation supporting scientific, engineering, and medical research in the United States. It was founded in 1954 by William Myron Keck, founder and president of Superior Oil Company (now part ...
gave $70 million to fund the construction of the Keck I telescope, which began in September 1985, with first light occurring on 24 November 1990 using nine of the eventual 36 segments. With construction of the first telescope well advanced, further donations allowed the construction of a second telescope starting in 1991. The Keck I telescope began science observations in May 1993, while first light for Keck II occurred on October 23, 1996. The key advance that allowed the construction of the Keck telescopes was the use of
active optics Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, and mechanical stress. Without active op ...
to operate smaller mirror segments as a single, contiguous mirror. 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. In the Keck telescopes, each primary mirror is made of 36 hexagonal segments that work together as a unit. Each segment is 1.8 meters wide, 7.5 centimeters thick, and weighs half a ton. The mirrors were made from
Zerodur Zerodur (notation of the manufacturer: ZERODUR®), registered trademarkof Schott AG, is a lithium-aluminosilicate glass-ceramic produced by Schott AG since 1968. It has been used for a number of very large telescope mirrors including GTC, Keck ...
glass-ceramic Glass-ceramics are polycrystalline materials produced through controlled crystallization of base glass, producing a fine uniform dispersion of crystals throughout the bulk material. Crystallization is accomplished by subjecting suitable glasses to ...
by the German company
Schott AG Schott AG is a German multinational glass company specializing in the manufacture of glass and glass-ceramics. Headquartered in Mainz, Germany, it is owned by the Carl Zeiss Foundation. The company's founder and namesake, Otto Schott, is credi ...
. On the telescope, each segment is kept stable by a system of
active optics Active optics is a technology used with reflecting telescopes developed in the 1980s, which actively shapes a telescope's mirrors to prevent deformation due to external influences such as wind, temperature, and mechanical stress. Without active op ...
, which uses extremely rigid support structures in combination with three actuators under each segment. 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
nanometer 330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re ...
s. 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. Each Keck telescope sits on an
altazimuth mount An altazimuth mount or alt-azimuth mount is a simple two-axis mount for supporting and rotating an instrument about two perpendicular axes – one vertical and the other horizontal. Rotation about the vertical axis varies the azimuth (compass bea ...
. Most current 8–10 m class telescopes use altazimuth designs due to their reduced structural requirements compared to older equatorial designs. 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. 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. Each of the two telescopes has a primary mirror of 10 meters (32.8 ft or 394 in), slightly smaller than the
Gran Telescopio Canarias The Gran Telescopio Canarias (GranTeCan or GTC) is a reflecting telescope located at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain. It is the world's largest single-aperture optical telescope. Constr ...
. However, all of the light collected by the Keck primary mirrors (75.76 m2) is sent to the secondary mirror and instruments, compared to GTC's primary mirror, which has an effective light-collection area of 73.4 m2, or less than each of the Keck primary mirrors. Because of this fundamental design difference, the Keck telescopes arguably remain the largest steerable, optical/infrared telescopes on Earth. The telescopes are equipped with a suite of
camera A camera is an Optics, optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), ...
s and
spectrometers A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where the ...
that allow observations across much of the visible and near-infrared spectrum.


Management

The Keck Observatory is managed by the California Association for Research in Astronomy, a non-profit
501(c)(3) A 501(c)(3) organization is a United States corporation, trust, unincorporated association or other type of organization exempt from federal income tax under section 501(c)(3) of Title 26 of the United States Code. It is one of the 29 types of 50 ...
organization whose board of directors includes representatives from
Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
and the
University of California The University of California (UC) is a public land-grant research university system in the U.S. state of California. The system is composed of the campuses at Berkeley, Davis, Irvine, Los Angeles, Merced, Riverside, San Diego, San Francisco, ...
. Construction of the telescopes was made possible through private grants of over $140 million from the W.M. Keck Foundation. The National Aeronautics and Space Administration (NASA) joined the partnership in October 1996 when Keck II commenced observations. Telescope time is allocated by the partner institutions. Caltech, the
University of Hawaii System A university () is an institution Institutions are humanly devised structures of rules and norms that shape and constrain individual behavior. All definitions of institutions generally entail that there is a level of persistence and continu ...
, and the University of California accept proposals from their own researchers; NASA accepts proposals from researchers based in the United States.
Jerry Nelson Jerry L. Nelson (July 10, 1934 – August 23, 2012) was an American puppeteer, best known for his work with The Muppets. Renowned for his wide range of characters and singing abilities, he performed Muppet characters on ''Sesame Street'', ' ...
, Keck Telescope project scientist, contributed to later multi-mirror projects until his death in June 2017. He conceived one of the Kecks's innovations: a reflecting surface of multiple thin segments acting as one mirror.


Instruments

; MOSFIRE : MOSFIRE (''Multi-Object Spectrometer for Infra-Red Exploration''), a third-generation instrument, was delivered to Keck Observatory on February 8, 2012; first light was obtained on the Kecks I telescope on April 4, 2012. A multi-object
spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...
wide-field camera for the near-infrared (0.97 to 2.41 μm), its special feature is its cryogenic Configurable Slit Unit (CSU) that is reconfigurable by remote control in under six minutes without any thermal cycling. Bars move in from each side to form up to 46 short slits. When the bars are removed, MOSFIRE becomes a wide-field imager. It was developed by teams from the
University of California, Los Angeles The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California St ...
(
UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California St ...
), the California Institute of Technology (
Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...
) and the
University of California, Santa Cruz The University of California, Santa Cruz (UC Santa Cruz or UCSC) is a public university, public Land-grant university, land-grant research university in Santa Cruz, California. It is one of the ten campuses in the University of California syste ...
, (UCSC). Its co-principal investigators are Ian S. McLean (
UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California St ...
) and
Charles C. Steidel Charles C. Steidel (born October 14, 1962) is an American astronomer, and Lee A. DuBridge Professor of Astronomy at California Institute of Technology. Life He graduated from Princeton University with an AB in Astrophysical Sciences, and from Cal ...
(Caltech), and the project was managed by WMKO Instrument Program Manager Sean Adkins. MOSFIRE was funded in part by the Telescope System Instrumentation Program (TSIP), operated by AURA and funded by the National Science Foundation; and by a private donation to WMKO by Gordon and Betty Moore. ; DEIMOS : The Deep Extragalactic Imaging Multi-Object
Spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...
is capable of gathering spectra from 130 galaxies or more in a single exposure. In "Mega Mask" mode, DEIMOS can take spectra of more than 1,200 objects at once, using a special narrow-band filter. ; HIRES : The largest and most mechanically complex of the Keck Observatory's main instruments, the High Resolution Echelle Spectrometer breaks up incoming light into its component colors to measure the precise intensity of each of thousands of color channels. Its spectral capabilities have resulted in many breakthrough discoveries, such as the detection of planets outside our solar system and direct evidence for a model of the
Big Bang The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature. Various cosmological models of the Big Bang explain the evolution of the observable universe from the ...
theory. The radial velocity precision is up to one meter per second (1.0 m/s). The instrument detection limit at 1 AU is . ; KCWI : The Keck Cosmic Web Imager is an
integral field spectrograph Integral Field Spectrographs (IFS) combine spectrographic and imaging capabilities in the optical or infrared wavelength domains -from 0.32 μm to 24 μm- to get from a single exposure spatially resolved spectra in a bi-dimensional region. Develop ...
operating at wavelengths between 350 and 560 nm. ; LRIS : The Low Resolution Imaging
Spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...
is a faint-light instrument capable of taking spectra and images of the most distant known objects in the universe. The instrument is equipped with a red arm and a blue arm to explore stellar populations of distant galaxies,
active galactic nuclei An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...
,
galactic cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...
s, and
quasar A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a m ...
s. ; LWS: The Long Wavelength Spectrometer for the Keck I telescope is and imaging, grating spectrometer working in the wavelength range of 3-25 microns. Like NIRC, the LWS was a forward-CASS instrument, and was used for studying cometary, planetary, and extragalactic objects. The LWS is now retired from science observations. ; NIRC : The Near Infrared Camera for the Keck I telescope is so sensitive it could detect the equivalent of a single candle flame on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
. This sensitivity makes it ideal for ultra-deep studies of galactic formation and evolution, the search for proto-galaxies and images of quasar environments. It has provided ground-breaking studies of the Galactic center, and is also used to study
protoplanetary disk A protoplanetary disk is a rotating circumstellar disc of dense gas and dust surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may also be considered an accretion disk for the star itself, be ...
s, and high-mass star-forming regions. NIRC was retired from science observations in 2010. ; NIRC-2 : The second generation Near Infrared Camera works with the Keck Adaptive Optics system to produce the highest-resolution ground-based images and spectroscopy in the 1–5 micrometers (µm) range. Typical programs include mapping surface features on
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
bodies, searching for planets around other stars, and analyzing the morphology of remote galaxies. ; NIRES : The Near-Infrared Echellette Spectrometer is a spectrograph that provides simultaneous coverage of wavelengths from 0.94 to 2.45
micron The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
s. ; NIRSPEC : The Near Infrared Spectrometer studies very high redshift
radio galaxies A radio galaxy is a galaxy with giant regions of radio emission extending well beyond its visible structure. These energetic radio lobes are powered by jets from its active galactic nucleus. They have luminosities up to 1039  W at radio wav ...
, the motions and types of stars located near the
Galactic Center The Galactic Center or Galactic Centre is the rotational center, the barycenter, of the Milky Way galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, a compact rad ...
, the nature of
brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
s, the nuclear regions of dusty starburst galaxies, active galactic nuclei, interstellar chemistry, stellar physics, and Solar System science. ;
OSIRIS Osiris (, from Egyptian ''wsjr'', cop, ⲟⲩⲥⲓⲣⲉ , ; Phoenician: 𐤀𐤎𐤓, romanized: ʾsr) is the god of fertility, agriculture, the afterlife, the dead, resurrection, life, and vegetation in ancient Egyptian religion. He was ...
: The OH-Suppressing Infrared Imaging Spectrograph is a near-infrared spectrograph for use with the Keck I adaptive optics system. OSIRIS takes spectra in a small field of view to provide a series of images at different wavelengths. The instrument allows astronomers to ignore wavelengths where the
Earth's atmosphere The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
shines brightly due to emission from OH (
hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
) molecules, thus allowing the detection of objects 10 times fainter than previously available. Originally installed on Keck II, in January, 2012 OSIRIS was moved to the Keck 1 telescope. ; Keck Interferometer : The Interferometer allowed the light from both Keck telescopes to be combined into an baseline, near infrared,
optical interferometer Interferometry is a technique which uses the ''interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opti ...
. This long baseline gave the interferometer an effective
angular resolution Angular resolution describes the ability of any image-forming device such as an optical or radio telescope, a microscope, a camera, or an eye, to distinguish small details of an object, thereby making it a major determinant of image resolution. ...
of 5 milliarcseconds (mas) at 2.2 µm, and 24 mas at 10 µm. Several back-end instruments allowed the interferometer to operate in a variety of modes, operating in H, K, and L-band near infrared, as well as
nulling interferometry A nuller is an optical tool used to block a strong source so that fainter signals near that source can be observed. An example of a nuller is being employed on the Keck Interferometer. This causes the light from a star to destructively interfere, ...
. As of mid-2012 the Keck Interferometer has been discontinued for lack of funding. Both Keck Observatory telescopes are equipped with
laser guide star A laser guide star is an artificial star image created for use in astronomical adaptive optics systems, which are employed in large telescopes in order to correct atmospheric distortion of light (called '' astronomical seeing''). Adaptive op ...
adaptive optics Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of incoming wavefront distortions by deforming a mirror in order to compensate for the distortion. It is used in astronomical tele ...
, which compensates for the blurring due to
atmospheric turbulence An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...
. The first AO system operational on a large telescope, the equipment has been constantly upgraded to expand the capability.


See also

*
Extremely large telescope The Extremely Large Telescope (ELT) is an astronomical observatory currently under construction. When completed, it is planned to be the world's largest optical/near-infrared extremely large telescope. Part of the European Southern Observator ...
*
Gemini Observatory The Gemini Observatory is an astronomical observatory consisting of two 8.1-metre (26.6 ft) telescopes, Gemini North and Gemini South, which are located at two separate sites in Hawaii and Chile, respectively. The twin Gemini telescopes prov ...
*
List of astronomical interferometers at visible and infrared wavelengths Here is a list of currently existing astronomical optical interferometers (i.e. operating from visible to mid-infrared wavelengths), and some parameters describing their performance. Current performance of ground-based interferometers Columns ...
*
List of largest optical reflecting telescopes A ''list'' is any set of items in a row. List or lists may also refer to: People * List (surname) Organizations * List College, an undergraduate division of the Jewish Theological Seminary of America * SC Germania List, German rugby union ...
*
List of largest optical telescopes historically Telescopes have grown in size since they first appeared around 1608. The following tables list the increase in size over the years. Different technologies can and have been used to build telescopes, which are used to magnify distant views especia ...
*
Mauna Kea Observatories The Mauna Kea Observatories (MKO) are a group of independent astronomical research facilities and large telescope observatories that are located at the summit of Mauna Kea on the Big Island of Hawaiʻi, United States. The facilities are located ...
* Navigator Program *
Subaru Telescope is the telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the wo ...
*
Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m across, ...


References


External links


W. M. Keck Observatory
(official site)
Mauna Kea Observatories
(official site)
Keck Observatory Archive (KOA)




by Michael J. West. . {{DEFAULTSORT:Keck Observatory, W. M. University of California University of California, Santa Cruz California Institute of Technology buildings and structures Astronomy institutes and departments Interferometric telescopes Astronomical observatories in Hawaii Buildings and structures in Hawaii County, Hawaii Buildings and structures completed in 1993 Buildings and structures completed in 1996 1990 establishments in Hawaii