The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on
Mount Graham
Mount Graham (called in Nnee biyati' (Western Apache) Dził Nchaa Sí'an - ′Big Seated Mountain′) is a mountain in Graham County, Arizona, United States, approximately northeast of Tucson. The mountain reaches in height. It is the highes ...
, in the
Pinaleno Mountains of southeastern
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
, United States. It is a part of the
Mount Graham International Observatory
Mount Graham International Observatory (MGIO) is a division of Steward Observatory, the research arm for the Department of Astronomy at The University of Arizona, in the United States. It is located in southeastern Arizona's Pinaleño Mountains ...
.
When using both 8.4 m (330 inch) wide mirrors, with centres 14.4 m apart, the LBT has the same light-gathering ability as a 11.8 m (464 inch) wide single circular telescope and the resolution of a 22.8 m (897 inch) wide one.
The LBT mirrors individually are the joint second-
largest optical telescope in continental North America, next to the
Hobby–Eberly Telescope
The Hobby–Eberly Telescope (HET) is a 10-meter (30-foot) aperture telescope located at the McDonald Observatory in Davis Mountains, Texas.
The Hobby–Eberly Telescope is one of the largest optical telescopes in the world. It combines a numb ...
in
West Texas
West Texas is a loosely defined region in the U.S. state of Texas, generally encompassing the arid and semiarid lands west of a line drawn between the cities of Wichita Falls, Abilene, and Del Rio.
No consensus exists on the boundary betwee ...
. It has the largest monolithic, or in an optical telescope.
Strehl ratios The Strehl ratio is a measure of the quality of optical image formation, originally proposed by Karl Strehl, after whom the term is named. Used variously in situations where optical resolution is compromised due to lens aberrations or due to imagi ...
of 60–90% in the
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
H band and 95% in the
infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...
M band have been achieved by the LBT.
Project
The LBT was originally named the "Columbus Project." It is a joint project of these members: the Italian astronomical community represented by the
Istituto Nazionale di Astrofisica
The National Institute for Astrophysics ( it, Istituto Nazionale di Astrofisica, or INAF) is an Italian research institute in astronomy and astrophysics, founded in 1999. INAF funds and operates twenty separate research facilities, which in turn ...
, the
University of Arizona
The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory.
T ...
,
University of Minnesota
The University of Minnesota, formally the University of Minnesota, Twin Cities, (UMN Twin Cities, the U of M, or Minnesota) is a public land-grant research university in the Twin Cities of Minneapolis and Saint Paul, Minnesota, United States. ...
,
University of Notre Dame
The University of Notre Dame du Lac, known simply as Notre Dame ( ) or ND, is a private Catholic university, Catholic research university in Notre Dame, Indiana, outside the city of South Bend, Indiana, South Bend. French priest Edward Sorin fo ...
,
University of Virginia
The University of Virginia (UVA) is a public research university in Charlottesville, Virginia. Founded in 1819 by Thomas Jefferson, the university is ranked among the top academic institutions in the United States, with highly selective ad ...
,
the LBT Beteiligungsgesellschaft in Germany (
Max Planck Institute for Astronomy
The Max-Planck-Institut für Astronomie (Max Planck Institute for Astronomy, MPIA) is a research institute of the Max Planck Society (MPG). It is located in Heidelberg, Baden-Württemberg, Germany near the top of the Königstuhl, adjacent to the ...
in Heidelberg,
Landessternwarte in Heidelberg,
Leibniz Institute for Astrophysics Potsdam
Leibniz Institute for Astrophysics Potsdam (AIP) is a German research institute. It is the successor of the Berlin Observatory founded in 1700 and of the Astrophysical Observatory Potsdam (AOP) founded in 1874. The latter was the world's first o ...
(AIP),
Max Planck Institute for Extraterrestrial Physics in
Munich
Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the third-largest city in Germany, after Berlin and Ha ...
and
Max Planck Institute for Radio Astronomy
The Max Planck Institute for Radio Astronomy (MPIfRA) (German: ''Max-Planck-Institut für Radioastronomie'') is located in Bonn, Germany. It is one of 80 institutes in the Max Planck Society (German: Max-Planck-Gesellschaft).
History
By com ...
in
Bonn
The federal city of Bonn ( lat, Bonna) is a city on the banks of the Rhine in the German state of North Rhine-Westphalia, with a population of over 300,000. About south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ru ...
);
Ohio State University
The Ohio State University, commonly called Ohio State or OSU, is a public land-grant research university in Columbus, Ohio. A member of the University System of Ohio, it has been ranked by major institutional rankings among the best publ ...
; and the Research Corporation for Science Advancement based in Tucson, AZ. The cost was around 100 million Euro.
The telescope design has two 8.4 m (330 inch) mirrors mounted on a common base, hence the name "
binocular."
LBT takes advantage of
active
Active may refer to:
Music
* ''Active'' (album), a 1992 album by Casiopea
* Active Records, a record label
Ships
* ''Active'' (ship), several commercial ships by that name
* HMS ''Active'', the name of various ships of the British Royal ...
and
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 ...
, provided by
Arcetri Observatory
The Arcetri Observatory ( it, Osservatorio Astrofisico di Arcetri) is an astrophysical observatory located in the hilly area of Arcetri on the outskirts of Florence, Italy. It is located close to Villa Il Gioiello, the residence of Galileo Galile ...
. The collecting area is two 8.4 meter aperture mirrors, which works out to about 111 m
2 combined. This area is equivalent to an circular aperture, which would be greater than any other single telescope, but it is not comparable in many respects since the light is collected at a lower diffraction limit and is not combined in the same way. Also, an
interferometric
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 op ...
mode will be available, with a maximum baseline of for aperture synthesis imaging observations and a baseline of for nulling interferometry. This feature is along one axis with the LBTI instrument at wavelengths of 2.9–13 micrometres, which is the near infrared.
The telescope was designed by a group of Italian firms, and assembled by
Ansaldo in its
Milan
Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
ese plant.
Mountain controversy
The choice of location sparked considerable local controversy, both from the
San Carlos Apache Tribe
The San Carlos Apache Indian Reservation ( Western Apache: Tsékʼáádn), in southeastern Arizona, United States, was established in 1872 as a reservation for the Chiricahua Apache tribe as well as surrounding Yavapai and Apache bands removed f ...
, who view the mountain as sacred, and from environmentalists who contended that the observatory would cause the demise of an endangered subspecies of the American red squirrel, the
Mount Graham red squirrel
The Mount Graham red squirrel (''Tamiasciurus fremonti grahamensis'') is an endangered subspecies of the southwestern red squirrel (''Tamiasciurus fremonti'') native to the Pinaleño Mountains of Arizona. It is smaller than most other subspecies ...
. Environmentalists and members of the tribe filed some forty lawsuits – eight of which ended up before a federal appeals court – but the project ultimately prevailed after an act of the
United States Congress
The United States Congress is the legislature of the federal government of the United States. It is bicameral, composed of a lower body, the House of Representatives, and an upper body, the Senate. It meets in the U.S. Capitol in Washing ...
.
The telescope and mountain observatory survived two major forest fires in thirteen years, the more recent in the summer of 2017. Likewise the squirrels continue to survive. Some experts now believe their numbers fluctuate dependent upon nut harvest without regard to the observatory.
First light
The telescope was dedicated in October 2004 and saw
first light with a single primary mirror on October 12, 2005 which viewed
NGC 891
NGC 891 (also known as Caldwell 23, the Silver Sliver Galaxy, and the Outer Limits Galaxy) is an edge-on unbarred spiral galaxy about 30 million light-years away in the constellation Andromeda. It was discovered by William Herschel on October ...
. The second primary mirror was installed in January 2006 and became fully operational in January 2008.
The first light with the second primary mirror was on September 18, 2006, and for the first and second together it was on January 11–12, 2008.
The first binocular light images show three false-color renditions of the spiral galaxy
NGC 2770. The galaxy is 88 million light years from our Milky Way, a relatively close neighbor. The galaxy has a flat disk of stars and glowing gas tipped slightly toward our
line of sight
The line of sight, also known as visual axis or sightline (also sight line), is an imaginary line between a viewer/observer/ spectator's eye(s) and a subject of interest, or their relative direction. The subject may be any definable object taken ...
.
The first image taken combined ultraviolet and green light, and emphasizes the clumpy regions of newly formed hot stars in the spiral arms. The second image combined two deep red colors to highlight the smoother distribution of older, cooler stars. The third image was a composite of ultraviolet, green and deep red light and shows the detailed structure of hot, moderate and cool stars in the galaxy. The cameras and images were produced by the Large Binocular Camera team, led by Emanuele Giallongo at the Rome Astrophysical Observatory.
In binocular
aperture synthesis
Aperture synthesis or synthesis imaging is a type of interferometry that mixes signals from a collection of telescopes to produce images having the same angular resolution as an instrument the size of the entire collection. At each separation and ...
mode LBT has a light-collecting area of 111 m
2, equivalent to a single primary mirror in diameter, and will combine light to produce the image sharpness equivalent to a single telescope. However, this requires a beam combiner that was tested in 2008, but has not been a part of regular operations. It can take images with one side at 8.4 m aperture, or take two images of the same object using different instruments on each side of the telescope.
Adaptive optics
In the summer of 2010, the "First Light Adaptive Optics" (FLAO) – an
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 ...
system with a deformable
secondary mirror
A secondary mirror (or secondary) is the second deflecting or focusing mirror element in a reflecting telescope. Light gathered by the primary mirror is directed towards a focal point typically past the location of the secondary. Secondary mirro ...
rather than correcting atmospheric distortion further downstream in the optics – was inaugurated.
[ Using one 8.4 m side, it surpassed Hubble sharpness (at certain light wavelengths), achieving a ]Strehl ratio The Strehl ratio is a measure of the quality of optical image formation, originally proposed by Karl Strehl, after whom the term is named. Used variously in situations where optical resolution is compromised due to lens aberrations or due to imag ...
of 60–80% rather than the 20–30% of older adaptive optic systems, or the 1% typically achieved without adaptive optics for telescopes of this size. Adaptive optics at a telescope's secondary (M2) was previously tested at MMT Observatory
The MMT Observatory (MMTO) is an astronomical observatory on the site of Fred Lawrence Whipple Observatory (IAU observatory code 696). The Whipple observatory complex is located on Mount Hopkins, Arizona, US (55 km south of Tucson) in the S ...
by the Arcetri Observatory and University of Arizona team.
In the media
The telescope has made appearances on an episode of the Discovery Channel TV show ''Really Big Things
''Really Big Things'' is a series about massive man-made marvels like big machines, giant telescopes, skyscrapers and other massive structures. It airs on the Discovery Channel, HD Theater and Science Channel
Science Channel (often simply br ...
'', National Geographic Channel ''Big, Bigger, Biggest'', and the BBC #REDIRECT BBC #REDIRECT BBC
Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...
...
''. The
.
. In 2007 the LBT detected a 26th magnitude afterglow from the gamma ray burst
spacecraft, an uncrewed asteroid sample return spacecraft, in space while it was en route.
* LBC – optical and near ultraviolet wide field prime focus cameras. One is optimized for the blue part of the optical spectrum and one for the red. (Both cameras operational)
* PEPSI – A high resolution and very high-resolution optical spectrograph and imaging polarimeter at the combined focus. (In development)
* MODS – two optical multi object and longslit spectrographs plus imagers. Capable of running in a single mirror or binocular mode. (MODS1 operational – MODS2 in integration on the mountain)
* LUCI – two multi-object and longslit infrared spectrographs plus imagers, one for each side (associated with one of the 8m mirrors) of the telescope. The imager has 2 cameras and can observe in both seeing-limited and diffraction-limited (with adaptive optics) modes. End of commissioning and hand over to the LBTO was in 2018.
* LINC/Nirvana – wide-field interferometric imaging with adaptive optics at the combined focus (in commissioning).
* LBTI/LMIRCAM – 2.9 to 5.2 micron
imaging and medium resolution grism spectroscopy at the combined focus.
* LBTI/NOMIC – N band nulling imager for the study of protoplanetary and debris disks at the combined focus. (In commissioning phase – first stabilization of the fringes in Dec 2013)
* FLAO – first light adaptive optics to correct atmospheric distortion
*
– multiple laser guide star unit capable of supporting ground layer or multi conjugate adaptive optics. End of commissioning and handover to LBTO was in 2018.
LUCI (originally LUCIFER: Large Binocular Telescope Near-infrared Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research) is the near-infrared instrument for the LBT.
The name of the instrument was changed to LUCI in 2012. LUCI operates in the 0.9–2.5 µm spectral range using a 2048 x 2048 element Hawaii-2RG detector array from Teledyne and provides imaging and spectroscopic capabilities in seeing- and diffraction-limited modes. In its focal plane area, long-slit and multi-slit masks can be installed for single-object and multi-object spectroscopy. A fixed collimator produces an image of the entrance aperture in which either a mirror (for imaging) or a grating can be positioned. Three camera optics with numerical apertures of 1.8, 3.75 and 30 provide image scales of 0.25, 0.12, and 0.015 arcsec/detector element for wide field, seeing-limited and diffraction-limited observations. LUCI is operated at cryogenic temperatures, and is therefore enclosed in a
of 1.6 m diameter and 1.6 m height, and cooled down to about −200 °C by two closed-cycle coolers.