HOME

TheInfoList



OR:

The Hobby–Eberly Telescope (HET) is a
telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...
located at the
McDonald Observatory McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional faci ...
in
Davis Mountains The Davis Mountains, originally known as Limpia Mountains, are a range of mountains in West Texas, United States, located near Fort Davis, Texas, Fort Davis, after which they are named. The fort was named for then-United States Secretary of War ...
,
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
. The Hobby–Eberly Telescope is one of the largest optical telescopes in the world. It combines a number of features that differentiate it from most telescope designs, resulting in lowered construction costs: * The telescope's main mirror is fixed at a 55° angle and can only rotate around its base. A target is tracked by moving the instruments at the focus of the telescope; this provides access to about 70–81% of the sky at its location and allows a single target to be tracked for up to two hours. * The
primary mirror A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope. Description The primary mirror of a reflecting telescope is a spherical, parabolic, or hyperbolic shaped disks of polished ...
is constructed from 91 hexagonal segments, which is less expensive than manufacturing a single large primary. The telescope is named for former Texas Lieutenant-Governor Bill Hobby and for Robert E. Eberly, a Penn State benefactor. Three instruments are available to analyze the light from the targets. All three instruments are
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 ...
s. The instruments work at high, medium and low spectral resolution. The low-resolution spectrograph is housed at the prime focus, while the medium and high-resolution spectrographs reside in the basement and the light is fed into them via a fiber-optic cable. Since achieving first light in 1996, the telescope has been used for a wide variety of studies ranging from the
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 "Sola ...
to stars in our galaxy and studies of other
galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...
. The telescope has been used successfully to find
planet A planet is a large, Hydrostatic equilibrium, rounded Astronomical object, astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets b ...
s orbiting around other stars by measuring radial velocities as precisely as 1 m/s. Using the low-resolution spectrograph, the telescope has been used to identify
Type Ia supernova A Type Ia supernova (read: "type one-A") is a type of supernova that occurs in binary systems (two stars orbiting one another) in which one of the stars is a white dwarf. The other star can be anything from a giant star to an even smaller white ...
e to measure the acceleration of the universe. The telescope has also been used to measure the rotation of individual galaxies. The telescope was upgraded for use in the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX), which will provide the first observations to allow narrowing of the list of possible explanations for
dark energy In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe. It also slows the rate of structure format ...
. Along with the new Visible Integral-Field Replicable Unit Spectrograph (VIRUS) to enable observations for the HETDEX project with 192 spectrographs. The Hobby–Eberly Telescope is operated by The University of Texas McDonald Observatory for a consortium of institutions which includes The
University of Texas at Austin The University of Texas at Austin (UT Austin, UT, or Texas) is a public university, public research university in Austin, Texas, United States. Founded in 1883, it is the flagship institution of the University of Texas System. With 53,082 stud ...
,
Pennsylvania State University The Pennsylvania State University (Penn State or PSU) is a Public university, public Commonwealth System of Higher Education, state-related Land-grant university, land-grant research university with campuses and facilities throughout Pennsyl ...
,
Ludwig Maximilian University of Munich The Ludwig Maximilian University of Munich (simply University of Munich, LMU or LMU Munich; ) is a public university, public research university in Munich, Bavaria, Germany. Originally established as the University of Ingolstadt in 1472 by Duke ...
, and
Georg August University of Göttingen Georg may refer to: * ''Georg'' (film), 1997 *Georg (musical), Estonian musical * Georg (given name) * Georg (surname) * , a Kriegsmarine coastal tanker * Spiders Georg "Spiders Georg" is an Internet meme that began circulating on the mic ...
. The physical main reflector mirror is larger than 10 meters; it is actually about 11 m by 9.8 m. Upon first light, the usable optical aperture at any given time was 9.2 m. After a multi-year upgrade completed on July 29, 2015, the usable optical aperture was increased to 10m. The mirror itself is composed of 91 hexagonal segments, a
segmented mirror A segmented mirror is an array of smaller mirrors designed to act as segments of a single large curved mirror. The segments can be either spherical or asymmetric (if they are part of a larger parabolic reflector). They are used as objectives ...
design like the
Keck telescopes The W. M. 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. state of Hawaii. Both telescopes have aperture primary mirrors, and, when ...
. Updates to the telescope have increased its
field of view The field of view (FOV) is the angle, angular extent of the observable world that is visual perception, seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to elec ...
from 4 arcminutes to 22 arcminutes (a full moon is 30 arcminutes for comparison). The telescope mirrors are aligned within a fraction of a wavelength of visible light by actuators under each segment. The tower next to the telescope, called the Center of Curvature Alignment Sensor Tower (CCAS), is used to calibrate the mirror segments. One of the advantages of this telescope design is that it was over 5 times more cost efficient for its aperture size than a more traditional design. As reported in ''Nature'' of 28 November 2012, astronomers have used the Hobby–Eberly Telescope to measure the mass of an extraordinarily large black hole (with mass approximates 17 billion Suns), possibly the largest black hole found so far. It has been found in the compact, lenticular galaxy NGC 1277, which lies 220 million light-years away in the constellation
Perseus In Greek mythology, Perseus (, ; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of the Perseid dynasty. He was, alongside Cadmus and Bellerophon, the greatest Greek hero and slayer of ...
. The black hole has approximately 59 percent of the mass of the bulge of this
spiral galaxy Spiral galaxies form a galaxy morphological classification, class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''
(14 percent of the total
stellar mass Stellar mass is a phrase that is used by astronomers to describe the mass of a star. It is usually enumerated in terms of the Sun's mass as a proportion of a solar mass (). Hence, the bright star Sirius has around . A star's mass will vary over ...
of the galaxy). The Habitable Zone Planet Finder is a spectrograph for the Hobby–Eberly Telescope capable of detecting earth like planets. The design of the Hobby–Eberly was used as the basis for the Southern African Large Telescope.


See also

*
List of largest optical reflecting telescopes This list of the largest optical reflecting telescopes with Objective (optics), objective diameters of or greater is sorted by aperture, which is a measure of the light-gathering power and resolution of a reflecting telescope. The mirrors themse ...
* Southern African Large Telescope * List of the largest optical telescopes in the contiguous United States * List of largest optical telescopes in the 20th century


References


External links

*
HET General Information Page
{{DEFAULTSORT:Hobby-Eberly Telescope Reflecting telescopes University of Texas at Austin