TheEuropean Organisation for Astronomical Research in the Southern Hemisphere,[2] commonly referred to as theEuropean Southern Observatory (ESO), is anintergovernmental research organisation made up of 16 member states for ground-basedastronomy. Created in 1962, ESO has provided astronomers with state-of-the-art research facilities and access to the southern sky. The organisation employs over 750 staff members and receives annual member state contributions of approximately €162 million.[3] Its observatories are located in northernChile.
ESO has built and operated some of the largest and most technologically advancedtelescopes. These include the 3.6 mNew Technology Telescope, an early pioneer in the use ofactive optics, and theVery Large Telescope (VLT), which consists of four individual 8.2 m telescopes and four smaller auxiliary telescopes which can all work together or separately. TheAtacama Large Millimeter Array observes theuniverse in themillimetre and submillimetre wavelength ranges, and is the world's largest ground-based astronomy project to date. It was completed in March 2013 in an international collaboration by Europe (represented by ESO), North America, East Asia and Chile.[4][5]
Currently under construction is theExtremely Large Telescope. It will use a 39.3-metre-diametersegmented mirror, and become theworld's largest optical reflecting telescope when operational towards the end of this decade. Its light-gathering power will allow detailed studies of planets around other stars, the first objects in the universe,supermassive black holes, and the nature and distribution of thedark matter anddark energy which dominate the universe.
ESO's observing facilities have made astronomical discoveries and produced severalastronomical catalogues.[6] Its findings include the discovery of the most distantgamma-ray burst and evidence for ablack hole at the centre of theMilky Way.[7][8] In 2004, the VLT allowed astronomers to obtain the first picture of anextrasolar planet (2M1207b) orbiting abrown dwarf 173 light-years away.[9] The High Accuracy Radial Velocity Planet Searcher (HARPS) instrument installed on the older ESO 3.6 m telescope led to the discovery of extrasolar planets, includingGliese 581c—one of the smallest planets seen outside theSolar System.[10]
The same site in 2014, a year after a new extension was built (in the foreground)
The idea that European astronomers should establish a common large observatory was broached byWalter Baade andJan Oort at theLeiden Observatory in the Netherlands in spring 1953.[11] It was pursued by Oort, who gathered a group of astronomers in Leiden to consider it on 21 June that year. Immediately thereafter, the subject was further discussed at the Groningen conference in the Netherlands. On 26 January 1954, an ESO declaration was signed by astronomers from six European countries expressing the wish that a joint European observatory be established in the southern hemisphere.[12]
At the time, allreflector telescopes with anaperture of 2 metres or more were located in the northern hemisphere. The decision to build the observatory in the southern hemisphere resulted from the necessity of observing the southern sky; some research subjects (such as the central parts of theMilky Way and theMagellanic Clouds) were accessible only from the southern hemisphere.[13]
It was initially planned to set up telescopes in South Africa where several European observatories were located (Boyden Observatory), but tests from 1955 to 1962 demonstrated that a site in theAndes was preferable: WhenJürgen Stock enthusiastically reported his observations fromChile,Otto Heckmann decided to leave the South African project on hold. ESO—at that time about to sign the contracts with South Africa—decided to establish their observatory in Chile.[15] The ESO Convention was signed 5 October 1962 by Belgium, Germany, France, the Netherlands and Sweden. Otto Heckmann was nominated as the organisation's first director general on 1 November 1962. On 15 November 1963 Chile was chosen as the site for ESO's observatory.[16]
Directors general of ESO (from left to right): Lodewijk Woltjer, Harry van der Laan, Catherine Cesarsky, Tim de Zeeuw and Xavier Barcons
A preliminary proposal for a convention of astronomy organisations in these five countries was drafted in 1954. Although some amendments were made in the initial document, the convention proceeded slowly until 1960 when it was discussed during that year's committee meeting. The new draft was examined in detail, and a council member ofCERN (the European Organization for Nuclear Research) highlighted the need for a convention between governments (in addition to organisations).[17]The convention and government involvement became pressing due to rapidly rising costs of site-testing expeditions. The final 1962 version was largely adopted from the CERN convention, due to similarities between the organisations and the dual membership of some members.[18]
In 1966, the first ESO telescope at the La Silla site in Chile began operating.[12] Because CERN (like ESO) had sophisticated instrumentation, the astronomy organisation frequently turned to the nuclear-research body for advice and a collaborative agreement between ESO and CERN was signed in 1970. Several months later, ESO's telescope division moved into a CERN building inGeneva and ESO's Sky Atlas Laboratory was established on CERN property.[19] ESO's European departments moved into the new ESO headquarters inGarching (nearMunich), Germany, in 1980.
Although ESO is headquartered in Germany, its telescopes and observatories are in northernChile, where the organisation operates advancedground-based astronomical facilities:
These are among the best locations for astronomical observations in the southern hemisphere.[21] An ESO project is theExtremely Large Telescope (ELT), a 40-metre-class telescope based on a five-mirror design and the formerly plannedOverwhelmingly Large Telescope. The ELT will be the largest visible and near-infrared telescope in the world. ESO began its design in early 2006, and aimed to begin construction in 2012.[22] Construction work at the ELT site started in June 2014.[23] As decided by the ESO council on 26 April 2010, a fourth site (Cerro Armazones) is to be home to ELT.[24][25][26]
Each year about 2,000 requests are made for the use of ESO telescopes, for four to six times more nights than are available. Observations made with these instruments appear in a number of peer-reviewed publications annually; in 2017, more than 1,000 reviewed papers based on ESO data were published.[27]
ESO telescopes generate large amounts of data at a high rate, which are stored in a permanent archive facility at ESO headquarters. The archive contains more than 1.5 million images (or spectra) with a total volume of about 65 terabytes (65,000,000,000,000 bytes) of data.
A ALMA is a partnership among Europe, the United States, Canada, East Asia and the Republic of Chile. · Additional ESO research facilities are located in Santiago, Chile and include a library, computing resources and programmes for visiting scientists.[29] · ESO also maintains close ties with other observatories and universities throughout the country.[30][31] · Source:ESO – Telescopes and Instrumentation[32]
La Silla, located in the southernAtacama Desert 600 kilometres (370 mi) north ofSantiago de Chile at an altitude of 2,400 metres (7,900 ft), is the home of ESO's original observation site. Like other observatories in the area, La Silla is far from sources oflight pollution and has one of the darkest night skies on Earth.[33] In La Silla, ESO operates three telescopes: a 3.6-metre telescope, the New Technology Telescope (NTT) and the 2.2-metre Max-Planck-ESO Telescope.
The observatory hosts visitor instruments, attached to a telescope for the duration of an observational run and then removed. La Silla also hosts national telescopes, such as the 1.2-metre Swiss and the 1.5-metre Danish telescopes.
About 300 reviewed publications annually are attributable to the work of the observatory. Discoveries made with La Silla telescopes include theHARPS-spectrograph detection of the planets orbiting within theGliese 581 planetary system, which contains the first known rocky planet in a habitable zone outside the solar system.[34][35] Several telescopes at La Silla played a role in linkinggamma-ray bursts, the most energetic explosions in the universe since theBig Bang, with the explosions of massive stars. The ESO La Silla Observatory also played a role in the study of supernovaSN 1987A.[36]
The New Technology Telescope (NTT) is analtazimuth, 3.58-metreRitchey–Chrétien telescope, inaugurated in 1989 and the first in the world with a computer-controlled main mirror. The flexible mirror's shape is adjusted during observation to preserve optimal image quality. The secondary mirror position is also adjustable in three directions. This technology (developed by ESO and known asactive optics) is now applied to all major telescopes, including the VLT and the future ELT.[39]
The design of the octagonal enclosure housing the NTT is innovative. The telescope dome is relatively small and ventilated by a system of flaps directing airflow smoothly across the mirror, reducing turbulence and resulting in sharper images.[40]
The 2.2-metre telescope has been in operation at La Silla since early 1984, and is on indefinite loan to ESO from theMax Planck Society (Max-Planck-Gesellschaft zur Förderung der Wissenschaften, or MPG, in German). Telescope time is shared between MPG and ESO observing programmes, while operation and maintenance of the telescope are ESO's responsibility.
Its instrumentation includes a 67-million-pixel wide-field imager (WFI) with afield of view as large as the full moon,[41] which has taken many images of celestial objects. Other instruments used areGROND (Gamma-Ray Burst Optical Near-Infrared Detector), which seeks the afterglow of gamma-ray bursts—the most powerful explosions in the universe,[42] and the high-resolution spectrograph FEROS (Fiber-fed Extended Range Optical Spectrograph), used to make detailed studies of stars.
La Silla also hosts several national and project telescopes not operated by ESO. Among them are the Swiss Euler Telescope, the Danish National Telescope and the REM, TRAPPIST and TAROT telescopes.[43]
The 1.54-metreDanish National Telescope was built byGrubb-Parsons and has been in use at La Silla since 1979. The telescope has anoff-axis mount, and the optics are a Ritchey-Chrétien design. Because of the telescope's mount and limited space inside the dome, it has significant pointing restrictions.[46]
Dome of the Danish 1.54-metre telescope that has been in operation atLa Silla Observatory since 1979[47]
TheRapid Eye Mount telescope is a small rapid-reaction automatic telescope with a primary 60-centimetre (24 in) mirror. The telescope, in analtazimuth mount, began operation in October 2002. The primary purpose of the telescope is to follow the afterglow of the GRBs detected by theSwift Gamma-Ray Burst Mission satellite.[43][48]
The BelgianTRAPPIST is a joint venture between theUniversity of Liège and Geneva Observatory. The 0.60-metre telescope is specialised incomets, exoplanets, and was one of the few telescopes that observed astellar occultation of the dwarf planetEris, revealing that it may be smaller thanPluto.[49]
TheQuick-action telescope for transient objects,TAROT, is a very fast-moving optical robotic telescope able to observe a gamma-ray burst from its beginning. Satellites detecting GRBs send signals to TAROT, which can provide asub-arc second position to the astronomical community. Data from the TAROT telescope is also useful in studying the evolution of GRBs, the physics of afireball and its surrounding material.[50] It is operated from theHaute-Provence Observatory in France.
The Paranal Observatory is located atopCerro Paranal in the Atacama Desert in northern Chile. Cerro Paranal is a 2,635-metre-high (8,645 ft) mountain about 120 kilometres (75 mi) south ofAntofagasta and 12 kilometres (7.5 mi) from the Pacific coast.[51]
The observatory has seven major telescopes operating in visible and infrared light: the four 8.2-metre (27 ft) telescopes of the Very Large Telescope, the 2.6-metre (8 ft 6 in) VLT Survey Telescope (VST) and the 4.1-metre (13 ft) Visible and Infrared Survey Telescope for Astronomy. In addition, there are four 1.8-metre (5 ft 11 in) auxiliary telescopes forming an array used forinterferometric observations.[52] In March 2008, Paranal was the location for several scenes of the 22nd James Bond film,Quantum of Solace.[53][54]
A 360-degree panoramic view of the southern night sky from Paranal, with telescopes in foreground
Very Large Telescope (VLT). Complex of four large telescopes and several smaller ones.
VLT Laser Guide Star. The orange laser beam from the telescope is used foradaptive optics.
The main facility at Paranal is the VLT, which consists of four nearly identical 8.2-metre (27 ft) unit telescopes (UTs), each hosting two or three instruments. These large telescopes can also work together in groups of two or three as a giantinterferometer. The ESO Very Large Telescope Interferometer (VLTI) allows astronomers to see details up to 25 times finer than those seen with the individual telescopes. The light beams are combined in the VLTI with a complex system of mirrors in tunnels, where the light paths must diverge less than 1/1000 mm over 100 metres. The VLTI can achieve anangular resolution of milliarcseconds, equivalent to the ability to see the headlights of a car on the Moon.[55]
The first of the UTs had itsfirst light in May 1998, and was offered to the astronomical community on 1 April 1999.[56] The other telescopes followed suit in 1999 and 2000, making the VLT fully operational. Four 1.8-metre auxiliary telescopes (ATs), installed between 2004 and 2007, have been added to the VLTI for accessibility when the UTs are used for other projects.[57]
Data from the VLT have led to the publication of an average of more than one peer-reviewed scientific paper per day; in 2017, over 600 reviewed scientific papers were published based on VLT data.[27] The VLT's scientific discoveries include imaging an extrasolar planet,[58] tracking individual stars moving around thesupermassive black hole at the centre of the Milky Way[59] and observing the afterglow of the furthest known gamma-ray burst.[60]
At the Paranal inauguration in March 1999, names of celestial objects in theMapuche language were chosen to replace the technical designations of the four VLT Unit Telescopes (UT1–UT4). An essay contest was prior arranged for schoolchildren in the region concerning the meaning of these names which attracted many entries dealing with the cultural heritage of ESO's host country. A 17-year-old adolescent fromChuquicamata, nearCalama, submitted the winning essay and was awarded an amateur telescope during the inauguration.[61] The four unit telescopes, UT1, UT2, UT3 and UT4, are since known asAntu (sun),Kueyen (moon),Melipal (Southern Cross), andYepun (Evening Star),[62] with the latter having been originally mistranslated as "Sirius", instead of "Venus".[63]
VST seen in the back between VLT's dome-shaped auxiliary telescopes
Visible and Infrared Survey Telescope for Astronomy (VISTA) is housed on the peak adjacent to the one hosting the VLT, sharing observational conditions. VISTA's main mirror is 4.1 metres (13 ft) across, a highly curved mirror for its size and quality. Its deviations from a perfect surface are less than a few thousandths the thickness of a human hair, and its construction and polishing presented a challenge.[64]
VISTA was conceived and developed by a consortium of 18 universities in the United Kingdom led byQueen Mary, University of London, and it became an in-kind contribution to ESO as part of the UK's ratification agreement. The telescope's design and construction were managed by the Science and Technology Facilities Council'sUK Astronomy Technology Centre (STFC, UK ATC). Provisional acceptance of VISTA was formally granted by ESO at the December 2009 ceremony at ESO headquarters in Garching, which was attended by representatives of Queen Mary, University of London and STFC. Since then the telescope has been operated by ESO,[65] capturing quality images since it began operation.[66][67]
TheVLT Survey Telescope (VST) is a state-of-the-art, 2.6-metre (8 ft 6 in) telescope equipped with OmegaCAM, a 268-megapixel CCD camera with a field of view four times the area of the full moon. It complements VISTA by surveying the sky in visible light. The VST (which became operational in 2011) is the result of a joint venture between ESO and theAstronomical Observatory of Capodimonte (Naples), a research centre at the Italian National Institute for AstrophysicsINAF.[68][69]
The scientific goals of both surveys range from the nature of dark energy to assessingnear-Earth objects. Teams of European astronomers will conduct the surveys; some will cover most of the southern sky, while others will focus on smaller areas. VISTA and the VST are expected to produce large amounts of data; a single picture taken by VISTA has 67 megapixels, and images from OmegaCam (on the VST) will have 268 megapixels. The two survey telescopes collect more data every night than all the other instruments on the VLT combined. The VST and VISTA produce more than 100 terabytes of data per year.[70]
POLARBEAR (on the Huan Tran Telescope; not operated by ESO)
ALMA is a telescope designed for millimetre and submillimetre astronomy. This type of astronomy is a relatively unexplored frontier, revealing a universe which cannot be seen in more-familiar visible or infrared light and ideal for studying the "cold universe"; light at these wavelengths shines from vast cold clouds in interstellar space at temperatures only a few tens of degrees aboveabsolute zero. Astronomers use this light to study the chemical and physical conditions in thesemolecular clouds, the dense regions of gas and cosmic dust where new stars are being born. Seen in visible light, these regions of the universe are often dark and obscure due to dust; however, they shine brightly in the millimetre and submillimetre portions of theelectromagnetic spectrum. This wavelength range is also ideal for studying some of the earliest (and most distant) galaxies in the universe, whose light has beenredshifted into longer wavelengths from the expansion of the universe.[72][73]
ESO hosts the Atacama Pathfinder Experiment, APEX, and operates it on behalf of theMax Planck Institute for Radio Astronomy (MPIfR). APEX is a 12-metre (39 ft) diameter telescope, operating at millimetre and submillimetre wavelengths—between infrared light and radio waves.
ALMA is an astronomical interferometer initially composed of 66 high-precision antennas and operating at wavelengths of 0.3 to 3.6 mm. Its main array will have 50 12-metre (39 ft) antennas acting as a singleinterferometer. An additional compact array of four 12-metre and twelve 7-metre (23 ft) antennas, known as the Morita array is also available.[74] The antennas can be arranged across the desert plateau over distances from 150 metres to 16 kilometres (9.9 mi), which will give ALMA a variable "zoom". The array will be able to probe the universe at millimetre and submillimeter wavelengths with unprecedented sensitivity and resolution, with vision up to ten times sharper than theHubble Space Telescope. These images will complement those made with theVLT Interferometer.[75] ALMA is a collaboration between East Asia (Japan andTaiwan), Europe (ESO), North America (US and Canada) and Chile.
The scientific goals of ALMA include studying the origin and formation of stars, galaxies, and planets with observations of molecular gas and dust, studying distant galaxies towards the edge of the observable universe and studyingrelic radiation from theBig Bang.[76] A call for ALMA science proposals was issued on 31 March 2011,[77] and early observations began on 3 October.[78][79]
Outreach activities are carried out by the ESO education and Public Outreach Department (ePOD).[81]
ePOD also manages theESO Supernova Planetarium & Visitor Centre, an astronomy centre located at the site of the ESO Headquarters in Garching bei München, which was inaugurated 26 April 2018.[82]
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^Satoru Iguchi; Morita, Koh-Ichiro; Sugimoto, Masahiro; Vila Vilaró, Baltasar; Saito, Masao; Hasegawa, Tetsuo; Kawabe, Ryohei; Tatematsu, Ken'Ichi; Seiichi, Seiichi; et al. (2009)."The Atacama Compact Array (ACA)".Publications of the Astronomical Society of Japan.61 (1):1–12.Bibcode:2009PASJ...61....1I.doi:10.1093/pasj/61.1.1.Archived from the original on 23 June 2017. Retrieved29 April 2011.
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Various conventions, treaties, agreements, memorandums, charters or declarations establishing and governing intergovernmental organisations or inter-agency bodies dealing with space affairs
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