The Gran Telescopio Canarias (GranTeCan or GTC) is a

reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...

located at the

Roque de los Muchachos Observatory Roque de los Muchachos Observatory ( es, Observatorio del Roque de los Muchachos, ORM) is an astronomical observatory located in the municipality of Garafía on the island of La Palma in the Canary Islands, Spain. The observatory site is operated ...

on the island of

La Palma La Palma (, ), also known as ''La isla bonita'' () and officially San Miguel de La Palma, is the most north-westerly island of the Canary Islands, Spain. La Palma has an area of making it the fifth largest of the eight main Canary Islands. The ...

, in the Canaries, Spain. It is the world's largest single-aperture optical telescope. Construction of the telescope took seven years and cost €130 million. Its installation was hampered by weather conditions and the logistical difficulties of transporting equipment to such a remote location. First light was achieved in 2007 and scientific observations began in 2009. The GTC Project is a partnership formed by several institutions from

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

, the

University of Florida The University of Florida (Florida or UF) is a public land-grant research university in Gainesville, Florida. It is a senior member of the State University System of Florida, traces its origins to 1853, and has operated continuously on its ...

, the

National Autonomous University of Mexico The National Autonomous University of Mexico ( es, Universidad Nacional Autónoma de México, UNAM) is a public research university in Mexico. It is consistently ranked as one of the best universities in Latin America, where it's also the bigges ...

, and the

Instituto de Astrofísica de Canarias The Instituto de Astrofísica de Canarias (IAC) is an astrophysical research institute located in the Canary Islands, Spain. It was founded in 1975 at the University of La Laguna. It operates two astronomical observatories in the Canary Islands: ...

(IAC). Planning for the construction of the telescope, which started in 1987, involved more than 1,000 people from 100 companies. The division of telescope time reflects the structure of its financing: 90% Spain, 5% Mexico and 5% the University of Florida.

History

First light

The GTC began its preliminary observations on 13 July 2007, using 12 segments of its

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 or parabolic shaped disks of polished reflective metal ...

, made of

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 cre ...

. Later, the number of segments was increased to a total of 36

hexagon In geometry, a hexagon (from Ancient Greek, Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple polygon, simple (non-self-intersecting) hexagon is 720°. Regular hexa ...

al segments fully controlled by an

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 ...

control system, working together as a reflective unit. Its first instrument was the

Optical System for Imaging and low Resolution Integrated Spectroscopy The Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) is an optical spectrometer at the Gran Telescopio Canarias (GTC) in Spain. It was the first instrument in operation at the GTC. OSIRIS's key scientific project is ...

(OSIRIS). Scientific observations began in May 2009.

Inauguration ceremony

The Gran Telescopio Canarias formally opened its shutters on July 24, 2009, inaugurated by King

Juan Carlos I of Spain Juan Carlos I (;, * ca, Joan Carles I, * gl, Xoán Carlos I, Juan Carlos Alfonso Víctor María de Borbón y Borbón-Dos Sicilias, born 5 January 1938) is a member of the Spanish royal family who reigned as King of Spain from 22 Nov ...

. More than 500 astronomers, government officials and journalists from Europe and the Americas attended the ceremony.

MEGARA

MEGARA (Multi-Espectrografo en GTC de Alta Resolucion para Astronomia) is an optical integral-field and 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 ...

covering the visible light and near infrared wavelength range between 0.365 and 1 µm with a

spectral resolution The spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum. It is usually denoted by \Delta\lambda, and is closely related to the resolvi ...

in the range R=6000-20000. The MEGARA IFU (also called the Large Compact Bundle, or LCB) offers a contiguous

field of view The field of view (FoV) is the extent of the observable world that is 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 electromagnetic radiation. Humans a ...

of 12.5 arcsec x 11.3 arcsec, while the multiobject spectroscopy mode allows 92 objects to be observed simultaneously in a

of 3.5 arcmin x 3.5 arcmin by means of an equal number of robotic positioners. Both the LCB and MOS modes make use of 100 µm-core optical fibers (1267 in total) that are attached to a set of microlens arrays (with 623 spaxels in the case of the LCB and 92x7 in the case of the MOS) with each microlens covering an hexagonal region of 0.62 arcsec in diameter.

CanariCam

The University of Florida's CanariCam is a mid-

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 ...

imager with

spectroscopic Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

, coronagraphic, and

polarimetric Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves. Typically polarimetry is done on electromagnetic waves that have traveled through or ...

capabilities. Since 2012, it had been operating in queue mode at one of the

Nasmyth focus The Nasmyth telescope, also called Nasmyth–Cassegrain or Cassegrain–Nasmyth, is a reflecting telescope developed by the Scottish inventor James Nasmyth. It is a modified form of a Cassegrain telescope, with light reflected sideways to an ey ...

stations, until it was temporarily decommissioned in April 2016. Following an upgrade project, started in mid-2018, it has been installed and recommissioned (December 2019) on a different folded-Cassegrain focus providing superior performance with the instrument. CanariCam is designed as a

diffraction-limited The resolution of an optical imaging system a microscope, telescope, or camera can be limited by factors such as imperfections in the lenses or misalignment. However, there is a principal limit to the resolution of any optical system, due to t ...

imager An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of cur ...

. It is optimized as an imager, and although it will offer a range of other observing modes, these will not compromise the imaging capability. CanariCam works in the thermal

between approximately 7.5 and 25 μm. At the short-wavelength end, the cut-off is determined by the atmosphere—specifically

atmospheric seeing In astronomy, seeing is the degradation of the image of an astronomical object due to turbulence in the atmosphere of Earth that may become visible as blurring, twinkling or variable distortion. The origin of this effect are rapidly changing var ...

. At the long wavelength end, the cut-off is determined by the detector; this loses sensitivity beyond around 24 μm, although the cut-off for individual detectors varies significantly. CanariCam is a very compact design. It is expected that the total weight of the

cryostat A cryostat (from ''cryo'' meaning cold and ''stat'' meaning stable) is a device used to maintain low cryogenic temperatures of samples or devices mounted within the cryostat. Low temperatures may be maintained within a cryostat by using various ...

and its on-telescope electronics will be under 400 kg. Most previous mid-infrared instruments have used

liquid helium Liquid helium is a physical state of helium at very low temperatures at standard atmospheric pressures. Liquid helium may show superfluidity. At standard pressure, the chemical element helium exists in a liquid form only at the extremely low temp ...

as a cryogen; one of the requirements of CanariCam was that it should require no expensive and difficult to handle cryogens. CanariCam uses a two-stage closed cycle

cryocooler A refrigerator designed to reach cryogenic temperatures (below ) is often called a cryocooler. The term is most often used for smaller systems, typically table-top size, with input powers less than about 20 kW. Some can have input powers as l ...

system to cool the cold optics and cryostat interior down to approximately , and the detector itself to around , the temperature at which the detector works most efficiently. CanariCam has been decommissioned .

OSIRIS

The IAC's OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy), is an imager and

covering wavelengths from 0.365 to 1.05 µm. It has a field of view (FOV) of 7 × 7 arcmin for direct imaging, and 8 arcmin × 5.2 arcmin for low resolution spectroscopy. For spectroscopy, it offers tunable filters.

References

External links

Gran Telescopio Canarias

GTC News

Instituto de Astrofísica de Canarias (IAC)

*
Consejo Nacional de Ciencia y Tecnología de México
*
Instituto de Astronomía de la Universidad Nacional Autónoma de México
* CBC article�

Images

Gran Telescopo Canarias inauguration press dossier
(in English) * {{National Autonomous University of Mexico Astronomical observatories in La Palma Optical telescopes National Autonomous University of Mexico University of Florida