Editing European Southern Observatory (section)

=== La Silla ===
{{Main|La Silla Observatory}}
[[File:Observatorio la silla1.JPG|thumb|upright=1.2|La Silla cluster of telescopes]]
La Silla, located in the southern [[Atacama Desert]] {{convert|600|km}} north of [[Santiago de Chile]] at an altitude of {{convert|2400|m}}, is the home of ESO's original observation site. Like other observatories in the area, La Silla is far from sources of [[light pollution]] and has one of the darkest night skies on Earth.<ref>{{cite web |url=http://www.chile.travel/en/what-to-do/astronomy/touristic-observatories.html |title=Observatories in Chile |access-date=2011-10-05 |url-status=dead |archive-url=https://web.archive.org/web/20110923095254/http://chile.travel/en/what-to-do/astronomy/touristic-observatories.html |archive-date=2011-09-23 }}</ref> 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 the [[High Accuracy Radial Velocity Planet Searcher|HARPS-spectrograph]] detection of the planets orbiting within the [[Gliese 581 planetary system]], which contains the first known rocky planet in a habitable zone outside the solar system.<ref>{{cite news|date=25 April 2007|url=http://www.eso.org/public/news/eso0722/|publisher=ESO|title=Astronomers Find First Earth-like Planet in Habitable Zone|access-date=2011-04-28|archive-date=2020-06-12|archive-url=https://web.archive.org/web/20200612200927/https://www.eso.org/public/news/eso0722/|url-status=live}}</ref><ref>{{cite web|url=http://obswww.unige.ch/%7Eudry/udry_preprint.pdf | title = The HARPS search for southern extra-solar planets | access-date = 2011-10-04}}</ref> Several telescopes at La Silla played a role in linking [[gamma-ray burst]]s, the most energetic explosions in the universe since the [[Big Bang]], with the explosions of massive stars. The ESO La Silla Observatory also played a role in the study of supernova [[SN 1987A]].<ref>{{cite news |date=24 February 2007 |title=SN 1987A's Twentieth Anniversary |url=http://www.eso.org/public/news/eso0708/ |publisher=ESO |access-date=2011-05-04 |archive-date=2020-06-12 |archive-url=https://web.archive.org/web/20200612060522/https://www.eso.org/public/news/eso0708/ |url-status=live }}</ref>

==== ESO 3.6-metre telescope ====
{{Main|ESO 3.6 m Telescope}}
[[File:3.6-m Telescope at La Silla.jpg|thumb|upright=0.6|The [[ESO 3.6 m Telescope]]]]
The ESO 3.6-metre telescope began operations in 1977. It has been upgraded, including the installation of a new [[secondary mirror]].<ref>{{cite web |url=http://www.eso.org/sci/facilities/lasilla/telescopes/3p6/ |title=The ESO 3.6m Telescope |access-date=2011-05-05 |archive-date=2012-10-19 |archive-url=https://web.archive.org/web/20121019071518/http://www.eso.org/sci/facilities/lasilla/telescopes/3p6/ |url-status=live }}</ref> The conventionally designed [[Telescope#Telescope mountings|horseshoe-mount]] telescope was primarily used for [[infrared]] [[spectroscopy]]; it now hosts the HARPS spectrograph, used in search of [[extra-solar planets]] and for [[asteroseismology]]. The telescope was designed for very high long-term [[radial velocity]] accuracy (on the order of 1&nbsp;m/s).<ref>{{cite web |url=http://www.eso.org/sci/facilities/lasilla/instruments/harps/overview.html |title=HARPS: The Planet Hunter |access-date=2011-05-05 |archive-date=2020-05-30 |archive-url=https://web.archive.org/web/20200530003012/https://www.eso.org/sci/facilities/lasilla/instruments/harps/overview.html |url-status=live }}</ref>

==== New Technology Telescope ====
{{Main|New Technology Telescope}}
[[File:The NTT Enclosure.jpg|thumb|upright=0.6|The [[New Technology Telescope]]]]
The New Technology Telescope (NTT) is an [[Altazimuth mount|altazimuth]], 3.58-metre [[Ritchey–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 as [[active optics]]) is now applied to all major telescopes, including the VLT and the future ELT.<ref>{{cite journal | url = http://www.eso.org/sci/publications/messenger/archive/no.142-dec10/messenger-no142-41-41.pdf | title = Raymond Wilson honoured with two prestigious prizes | journal = The Messenger | volume = 142 | pages = 41 | access-date = 2011-10-05 | bibcode = 2010Msngr.142...41W | last1 = Walsh | first1 = J. | year = 2010 | archive-date = 2019-12-08 | archive-url = https://web.archive.org/web/20191208003846/http://www.eso.org/sci/publications/messenger/archive/no.142-dec10/messenger-no142-41-41.pdf | url-status = live }}</ref>

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.<ref>{{cite web |url=http://www.eso.org/public/teles-instr/lasilla/ntt.html |title=ESO NTT |access-date=2011-05-05 |archive-date=2013-08-07 |archive-url=https://web.archive.org/web/20130807080311/http://www.eso.org/public/teles-instr/lasilla/ntt.html |url-status=live }}</ref>

==== MPG/ESO 2.2-metre telescope ====
{{Main|MPG/ESO telescope}}

The 2.2-metre telescope has been in operation at La Silla since early 1984, and is on indefinite loan to ESO from the [[Max Planck Society]] ({{Lang|de|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 a [[Field of view#Astronomy|field of view]] as large as the full moon,<ref>{{cite web |url=http://www.eso.org/lasilla/instruments/wfi/index.html |title=WFI—Wide Field Imager |access-date=2011-04-29 |archive-url=https://web.archive.org/web/20110902075709/http://www.eso.org/lasilla/instruments/wfi/index.html |archive-date=2011-09-02 |url-status=dead }}</ref> which has taken many images of celestial objects. Other instruments used are [[GROND]] (Gamma-Ray Burst Optical Near-Infrared Detector), which seeks the afterglow of gamma-ray bursts—the most powerful explosions in the universe,<ref>{{cite news |date=6 July 2007 |url=http://www.eso.org/public/news/eso0730/ |title=GROND Takes Off |publisher=ESO |access-date=2011-04-29 |archive-date=2020-05-23 |archive-url=https://web.archive.org/web/20200523172814/https://www.eso.org/public/news/eso0730/ |url-status=live }}</ref> and the high-resolution spectrograph FEROS (Fiber-fed Extended Range Optical Spectrograph), used to make detailed studies of stars.

==== Other telescopes ====

{{multiple image
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 |image1=LaSillaByNight2.jpg
 |image2=REMTelescopeDaylight.jpg
 |caption1=The [[Euler Telescope]] and the ESO 3.6-m Telescope (background) have discovered many [[exoplanet]]s.
 |caption2=The [[Rapid Eye Mount telescope]]
}}

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.<ref name="National and Project Telescopes">{{cite web |url=http://www.eso.org/sci/facilities/lasilla/telescopes/national.html |title=National and Project Telescopes |access-date=2011-04-29 |archive-date=2020-05-31 |archive-url=https://web.archive.org/web/20200531155900/https://www.eso.org/sci/facilities/lasilla/telescopes/national.html |url-status=live }}</ref>
* The [[Euler Telescope]] is a 1.2-metre telescope built and operated by the [[Geneva Observatory]] in Switzerland. It is used to conduct high-precision radial velocity measurements primarily used in the search for large extrasolar planets in the southern celestial hemisphere. Its first discovery was a planet orbiting [[Gliese 86]].<ref>{{cite news|date=24 November 1998|url=http://www.eso.org/public/news/eso9855/|title=Extrasolar Planet in Double Star System Discovered from La Silla|publisher=ESO|access-date=2011-04-29|archive-date=2020-05-21|archive-url=https://web.archive.org/web/20200521205711/https://www.eso.org/public/news/eso9855/|url-status=live}}</ref> Other observing programmes focus on [[variable star]]s, [[asteroseismology]], gamma-ray bursts, monitoring [[Active galactic nucleus|active galactic nuclei]] (AGN) and [[gravitational lens]]es.<ref>{{cite web|url=http://obswww.unige.ch/exoplanets/coralie.html|title=Southern Sky extrasolar Planet search Programme|access-date=2011-10-05|archive-date=2011-09-27|archive-url=https://web.archive.org/web/20110927021703/http://obswww.unige.ch/exoplanets/coralie.html|url-status=dead}}</ref>
* The 1.54-metre ''Danish National Telescope'' was built by [[Sir Howard Grubb, Parsons and Co|Grubb-Parsons]] and has been in use at La Silla since 1979. The telescope has an [[Off-axis optical system|off-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.<ref>{{cite book |chapter-url = http://www.eso.org/sci/facilities/lasilla/telescopes/d1p5/ |chapter = The Danish Telescope at La Silla |title = The La Silla Observatory – from the Inauguration to the Future. Held 25–29 March |pages = 1 |access-date = 2011-04-29 |bibcode = 2019lsof.confE...1A |last1 = Andersen |first1 = Michael I. |journal = The la Silla Observatory - from the Inauguration to the Future |year = 2019 |doi = 10.5281/zenodo.3245240 |s2cid = 210314337 |archive-date = 2012-10-17 |archive-url = https://web.archive.org/web/20121017182659/http://www.eso.org/sci/facilities/lasilla/telescopes/d1p5/ |url-status = live }}</ref>

[[File:The Great Dane.jpg|thumb|Dome of the Danish 1.54-metre telescope that has been in operation at [[La Silla Observatory]] since 1979<ref>{{cite journal|title=The Great Dane|journal=Nature|volume=338|issue=6210|pages=27–28|url=http://www.eso.org/public/images/potw1512a/|access-date=18 June 2015|bibcode=1989Natur.338...27C|last1=Casimir|first1=H. B. G.|year=1989|doi=10.1038/338027b0|s2cid=4364680|doi-access=free|archive-date=26 June 2015|archive-url=https://web.archive.org/web/20150626183011/http://www.eso.org/public/images/potw1512a/|url-status=live}}</ref>]]
* The [[Rapid Eye Mount telescope]] is a small rapid-reaction automatic telescope with a primary {{convert|60|cm|in|adj=on}} mirror. The telescope, in an [[altazimuth mount]], began operation in October 2002. The primary purpose of the telescope is to follow the afterglow of the GRBs detected by the [[Swift Gamma-Ray Burst Mission]] satellite.<ref name="National and Project Telescopes"/><ref>{{cite web |url=http://www.rem.inaf.it/ |title=Rapid Eye Mount |access-date=2011-04-29 |archive-date=2020-05-20 |archive-url=https://web.archive.org/web/20200520114506/http://www.rem.inaf.it/ |url-status=live }}</ref>
* The Belgian [[TRAPPIST]] is a joint venture between the [[University of Liège]] and Geneva Observatory. The 0.60-metre telescope is specialised in [[comets]], exoplanets, and was one of the few telescopes that observed a [[stellar occultation]] of the dwarf planet [[Eris (dwarf planet)|Eris]], revealing that it may be smaller than [[Pluto]].<ref name=beatty>Newscientist.com, [https://www.newscientist.com/article/dn19697-former-tenth-planet-may-be-smaller-than-pluto.html Kelly Beatty – Former 'tenth planet' may be smaller than Pluto] {{Webarchive|url=https://web.archive.org/web/20120223213839/http://www.newscientist.com/article/dn19697-former-tenth-planet-may-be-smaller-than-pluto.html |date=2012-02-23 }}, November 2010</ref>
* The ''Quick-action telescope for transient objects'', [[TAROT-South robotic observatory|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 a [[Minute of arc#Astronomy|sub-arc second]] position to the astronomical community. Data from the TAROT telescope is also useful in studying the evolution of GRBs, the physics of a [[Meteoroid#Fireball|fireball]] and its surrounding material.<ref>{{cite web |url=http://tarot.obs-hp.fr/tarot/ |title=TAROT website |access-date=2011-05-04 |url-status=dead |archive-url=https://web.archive.org/web/20110830125651/http://tarot.obs-hp.fr/tarot/ |archive-date=2011-08-30 }}</ref> It is operated from the [[Haute-Provence Observatory]] in France.