ESO

European Southern Observatory

Reaching New Heights in ESO and Astronomy

Astronomy is the oldest of the natural operating the world’s powerful sciences. The majestic Milky Way, and productive ground-based observing stretching across the sky on a clear facilities. For this purpose, ESO is built dark night, has been an awe-inspiring on very constructive partnerships with sight for generations of people from the scientific community and industry, all historical eras and cultures past and and in some cases with other parties present. around the world.

Today, astronomy stands out as one of Observing proposals to use ESO’s the most dynamic sciences, using ­ outnumber the amount of advanced technologies and sophisti- available nights by a factor of between cated techniques to study objects at the three and five, or even more. This edge of the observable Universe, to demand is part of the reason why ESO detect planets around other stars and to is the most productive ground-based explore many other celestial bodies in observatory in the world, with almost unprecedented detail. We can begin to three peer-reviewed papers based on answer some of humanity’s most funda- ESO data being published every day mental questions, such as: Where did on average. These scientific papers we come from? Is there life elsewhere in report some of the most remarkable the Universe? How do stars and planets discoveries in astronomy, and ESO is form? How do galaxies evolve? What is committed to continue enabling them the Universe made of? by pursuing the most ambitious obser- vational astronomy project in history, The European Southern Observatory the construction of the Extremely Large (ESO) is the world’s foremost inter­ . governmental astronomical organisa- tion. It carries out an ambitious pro- Xavier Barcons gramme of designing, constructing and ESO Director General

ESO’s ,­ home to the Very Large ­Telescope.

2 ESO/B. Tafreshi (twanight.org) ESO/S. Guisard (www.eso.org/~sguisard) Sagittarius (the Archer) to Scorpius spanning from the constellation of sky of region the shows image The Reaching out to the stars at Paranal. at stars the to out Reaching (the Scorpion). 3 ESO/J. Girard Highlights from ESO’s History

5 October 1962 6 November 1963 30 November 1966 Founding members Chile is chosen as the site First light for the ESO Belgium, France, for the ESO observ­atory 1-metre telescope at ­Germany, the Netherlands and the Convenio (also La Silla, the first tele- and Sweden­ sign the known as the ­Acuerdo), scope to be used by ESO Convention. the agreement between ESO in Chile. Chile and ESO, is signed.

23 March 1989 25 May 1998 17 March 2001 First light for the First light for the VLT’s First light for the New Technology first Unit Telescope (UT1), ­Telescope. Antu. Interferometer.

8 June 2011 30 September 2011 5 October 2012 First images from the ALMA starts Early ESO celebrates its VLT Survey Telescope. ­Science observations 50th Anniversary. and the first image is published. Infrared image of the Carina Nebula from the HAWK-I camera on the VLT.

4 takes place. TelescopeLarge (ELT) Extremely the for mony Groundbreaking cere 19 2014 June Observatory. Silla La the at scope tele ESO’sat 3.6-metre Planet Searcher (HARPS) Accuracy Radial velocity First light for the High 2003 11 February 3.6-metre telescope. ESO the for light First 1976 7 November - - Garching, Germany. in Headquarters ESO the of Inauguration 19815 May Michelle Bachelet Jeria. Chile, of President the by ELTthe attended is First Stone ceremony for 2017 May 26 (APEX). ­PathfinderExperiment Atacamamillimetre sub the for light First 14 2005 July

­ ­telescope. 2.2-metreMPG/ESO the for light First 1983 June 22 discoveries await... ­discoveries new States, Member ESO’s in the to flow data nomical astro of terabytes As The future work. starts infrared survey ­ VISTA, the pioneering 11 December 2009 telescope,

- 5 ESO/T. Preibisch The ESO Sites

Northern Chile, which includes the ­Atacama Desert, has exceptionally clear and dark skies that, for 300 nights a year, offer stunning views of the southern­ skies, including the important central­ region of the Milky Way and the two Magellanic Clouds.

Chajnantor Plateau At 5000 metres above sea level, the Chajnantor plateau is one of the highest astronomical sites in the world. It is home to the Atacama Large Millimeter/submillimeter­ Array (ALMA) — a partnership of ESO, North America and East Asia in ­cooperation with the Republic of Chile — and the Atacama Pathfinder Experiment (APEX), a 12-metre telescope operating at millimetre and submillimetre wavelengths.

Cerro Paranal At 2600 metres above sea level, 130 kilometres south of Antofagasta and 12 kilometres inland from the Pacific coast of northern Chile, Paranal is one of the driest areas on Earth. It is home to the Very Large ­Telescope — an array of four Unit Telescopes and four movable 1.8-metre Auxiliary ­Telescopes, which form part of the VLT Interferometer — and two powerful ­survey telescopes: the VST and VISTA.

Cerro Armazones The 39-metre Extremely Large Telescope is under construction here, just 23 kilometres from the ­Paranal Observatory, and will be integrated into the Paranal operational system.

Vitacura, Santiago de Chile, Chile ESO’s office in Santiago is an active centre for the education of new generations of researchers, and promotes exchanges between European and Chilean scientists through collaborations.

The Gum 15 region imaged with the MPG/ESO 2.2-metre telescope.

6 Headquarters, Garching, Germany ESO’s Headquarters are located in Garching bei München in Bavaria, Germany. This is the scien- tific, technical and administrative centre of ESO. La Silla The site is home to a technical building, where ESO’s most advanced instruments are developed, ESO’s first observatory was built at 2400 metres built, assembled, tested and upgraded. It is also above sea level and 600 kilometres north of home to one of the largest computer archives ­Santiago in Chile. It is equipped with several opti- of astronomical data in the world and to the ESO cal telescopes with mirror diameters of up to Supernova Planetarium & Visitor Centre. 3.6 metres. The ESO 3.6-metre telescope is now home to the world’s foremost hunter, HARPS (the High Accuracy Radial velocity Planet Searcher).

7 ESO Science HighlightsESO Science 8 this result. for awarded was Physics in Prize 2011The Nobel accelerating. is Universe the of expansion the that showed Paranal, and La Silla at ESO’s telescopes from data included which supernovae of tions Two independent research teams, using observa 2 | supermassive . —a galaxy our of heart the at lurking ­monster the of surroundings the of ever view detailed most the obtain to study long-term acontinuous in used were telescopes ESO’s flagship of Several 1 | supermassive black hole Way’s Milky the orbiting Stars The accelerating Universe

- possible abode for life outside the . Solar the outside life for abode ­possible closest the be also may it —and us to exoplanet closest the is and Earth the than massive more alittle is world rocky This surface. its on exist to liquid for suitable atemperature has 11 and days every star parent red cool its orbits b, Proxima designated world, long-sought The 3 | Proxima Centauri zone around the nearest star, Planet found in the habitable

55 times the mean Earth- distance. Earth-Sun mean the times 55 of adistance —at dwarf —abrown reactions nuclear ignite to failed that astar orbits planet five-Jupiter-mass The System. Solar our outside planet of a image ever first the VLT obtained The 5 |

ALMA (ESO/NAOJ/NRAO) First image of an exoplanet an of image First protoplanetary disc. a in gas and dust up gather planets forming how show They lengths. ever made at sub sharpest the were HL Tauri of images forming system. planetary The revealed remarkable details of a meter/ (ALMA) Milli- Large 2014, Atacama In the 4 | reveals ­ Revolutionary ALMA image ­millimetre wave planetary genesis planetary

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ESO/M. Kornmesser ESO/N. Bartmann/spaceengine.org SDSS neutron stars. merging two of collision violent the from originate likely most gamma-ray burst,short showing that this family of objects ­ the time first the for observed La Silla at stars, solving a long-time puzzle. In addition, a telescope massive of explosion ultimate the with linked are bursts ray gamma- long that proof definitive provided telescopes ESO | 10 supernovae and merging neutron stars Gamma-ray bursts — the connections with as an independent estimate of the age of the galaxy. the of age the of estimate independent an as used and forming, still Way was Milky the when born astar in detected was Uranium Universe. the in mation for star of period earliest the in born was star the old, years billion 13.2 At galaxy. our in known star oldest the of age the measured VLT, the astronomers Using 6 | ESO/L. Calçada Oldest star known in the Milky Way Milky the in known star Oldest visible light from a from light visible

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hazes. or clouds thick by dominated or steam of form the in water mostly either is atmosphere throughpassed the planet’s atmosphere. The starlight the of some and star parent its transited it VLT. as the 1214b GJ studied was using time first the for analysed was exoplanet The atmosphere around a super-Earth 7 | their surfaces. on water liquid support could that worlds of number largest the and found yet planets sized Earth- of number largest the both has system This life. to host play could system star the habitable zone, increasing the that possibility the in lie planets the of TRAPPIST-1. Three as known star dwarf ultracool the orbiting away seven planets Earth-sized just 40 light-years of asystem found ESO’s VLT, astronomers Using ground and space telescopes, including 9 | epoch. aremote such in temperature cosmic the of measurement cise pre most the obtain to astronomers allowed This 25 years. for elusive remained had that afeat ago, years 11 billion almost was it as seen agalaxy in molecules monoxide VLT detected the time, first the For 8 | atmospheres ­spectra of and their Direct measurements of the planetary system Record-breaking independently measured Cosmic temperature located at the . La Silla the at located MPG/ESO 2.2-metre telescope the on (WFI) Imager Field Wide the with taken image Deep-field

- 9 The Very Large Telescope

The Very Large Telescope array is the The 8.2-metre Unit Telescopes are optical flagship facility for European housed in compact, thermally-­controlled astronomy at the beginning of the third buildings, which rotate synchronously millennium. It is the world’s most with the telescopes. This significantly advanced optical and infrared observa- minimises local effects on the observing tory, consisting of four Unit Telescopes conditions, such as air turbulence in the with main mirrors 8.2 metres in dia­ telescope tube, which might result from meter. They can be used individually or variations in temperature and wind flow. together, like the four movable 1.8- metre Auxiliary Telescopes, to form an The first of the Unit Telescopes interferometer. These telescopes are began routine scientific operations on so powerful that they can obtain images 1 April 1999 and since then the VLT of celestial objects that are four billion has made an immense impact on obser- times fainter than can be seen with the vational astronomy. It is the most pro- unaided eye. ductive individual ground-based facility in the world, and VLT results lead to, The VLT instrumentation programme is on average, the publication of more than the most ambitious ever conceived one and a half peer-reviewed scientific for a single observatory. It includes papers every day. cameras and spectrographs that cover a broad spectral region, spanning ultra­ ESO’s Paranal Observatory also hosts violet (0.3 µm) to mid-infrared (20 µm) the NGTS (Next-Generation Transit wavelengths. ­Survey) and SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) national telescopes.

Name VLT

Site Cerro Paranal

Altitude 2635 metres

Wavelengths Ultraviolet/optical/infrared

Components/techniques Interferometry with 4 telescopes (maximum baseline 130 metres); 3 of which have adaptive optics

Optical design Ritchey-Chrétien reflector

Primary mirror diameter 8.2 metres

Mount Alt-Azimuth

First light May 1998–September 2000

UT4 (Yepun)

VST VISTA

UT3 (Melipal)

UT2 (Kueyen)

UT1 (Antu)

VLTI

This spectacular image of the Orion ­Nebula star-formation region was obtained from multiple exposures using the HAWK-I infrared camera on ESO’s Very Large Telescope in Chile. This is the deepest view ever of this region and reveals more very faint planetary-mass objects than expected.

10 ESO/H. Drass et al.

ESO/G. Hüdepohl (atacamaphoto.com) Y. Beletsky (LCO)/ESO the centre of the Milky Way. Milky the of centre the on trained (LGS) Star Guide Laser spectacular shot captures the VLT’s this (VLT), Telescope Large Very ­ Unit fourth the of dome the inside Taken from Atacama Desert in northern Chile. northern in Desert ­Atacama amazing aerial image from the this in light in platform Paranal the bathing Ocean, Pacific the of ­horizon the below dips Sun setting The Telescope of ESO’s of Telescope

11 12 Gerhard Hüdepohl/atacamaphoto.com ESO is a leader in the development of development the in aleader ESO is atmosphere. Earth’s upper into the up 90 kilometres beam laser apowerful by shining stars reference artificial create astronomers ble, availa always not are stars suitable Since them. for correct can mirror adaptive the that so atmosphere by the caused distortions the to measure needed is study under object to the sky the in close very located star A reference space. from taken those as sharp as almost obtained images the making Earth’s of the atmosphere, turbulence by the caused distortion the for time real in correct can by computers trolled Sophisticated deformable mirrors con atmosphere. of the effect the for to compensate optics adaptive called amethod ESO at use mers astrono But to twinkle. stars causes and ­distorts images obtained from the ground Earth’s atmosphere the in Turbulence pointing at the Carina Nebula. system star guide 4laser Paranal VLT ELTfuture and science. for vital be will that view, of result a field corrected awider obtaining way for the paves stars guide of multiple use The ELT,the development. active under are of challenges the to meet tailored tems, sys advanced more Even finders. planet as such instruments optics adaptive and also includes advanced extreme nology employs multiple laser guide stars VLT. the on tech installed This been has optics of adaptive generation next The Way p. (see 8). Milky of the centre the at hole black the ­ of the study detailed p. the (see as 8), well as exoplanet of an observations direct first the include These results. scientific remarkable many obtained have facilities optics adaptive ­European institutes and industries. ESO’s ­technologies and collaborates with star guide laser and optics adaptive Adaptive Optics Adaptive environment around around environment

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- - - - ESO/G. Hüdepohl Deformable mirror Secondary mirrorSecondary Primary mirror Primary Computer Light rays Atmospheric turbulence Turbulence measure Telescope 4 of the VLT. the 4of ­Telescope ­ star guide 4laser The optics works. Illustration showing how adaptive Astronomical camera system on Unit Unit on system 13 The VLT Interferometer

The telescopes of the VLT can be com- Although light from the four 8.2-metre bined to form the Very Large Telescope Unit Telescopes can be combined in Interferometer (VLTI), allowing astrono- the VLTI, most of the time these large mers to see details up to 16 times finer telescopes are used individually for than with the individual telescopes other purposes, and so are only availa- alone. With the VLTI, it is possible to ble for interferometric observations for see details on the surfaces of stars and a limited number of nights every year. even to study the environment close to a black hole at the centre of another In order to exploit the power of the VLTI galaxy. every night, four smaller Auxiliary Tele- scopes (ATs) are available. The ATs are Light beams from the telescopes are mounted on tracks and can be moved combined in the VLTI using a complex between precisely-defined observing system of mirrors in underground positions. From these positions, light ­tunnels, where the light path lengths beams are reflected from the AT mirrors must be kept equal to within one and combined in the VLTI. ­thousandth of a millimetre over more than 100 metres. With this 130-metre The ATs are very unusual telescopes large “virtual telescope”, the VLTI can — self-sufficient in their ultra-compact perform measurements equivalent to protective domes, they carry their own picking out the head of a screw on the electronics, ventilation, hydraulics International Space Station, 400 kilo­ and cooling systems, and include their metres above us in orbit, from the own transporters which lift the tele- ground. scopes and move them from one posi- tion to another.

Name Auxiliary Telescopes

Site Cerro Paranal

Altitude 2635 metres

Wavelengths Optical/infrared

Components/techniques Interferometry with 4 smaller telescopes (maximum baseline 200 metres)

Optical design Ritchey-Chrétien with coudé optical train

Primary mirror diameter 1.82 metres

Mount Alt-Azimuth

First light January 2004–December 2006

Panoramic view of the Very Large Telescope ­Interferometer tunnel.

14 P. Horálek/ESO for observations. Auxiliary Telescopes open and ready the of one with Paranal at Sunset 15 16 Chile. in Observatory Paranal ESO’s VISTA at with taken was Earth, from light-years 1350 about 42), lying (Messier Nebula Orion the of view wide-field This to come. to by forharvested decades astronomers be will that objects of catalogues and ­ are telescopes two The deeply. and quickly areas large to image designed are VST VISTA the but and time, one any at sky the of part aminute study only can telescopes largest The to find. hard —are quasars remote Way most to the Milky the in stars dwarf brown dim from — objects astronomical interesting Many Observatory. Paranal the of potential discovery scientific the increase hugely they and world the in telescopes survey imaging dedicated powerful most the are They Observatory. ESO’sat Paranal sited are (VST) VLT Telescope Survey the and (VISTA) Astronomy for scope Tele Survey Infrared and Visible The First light First Mount diameter mirror Primary Optical design 1,058 Wavelengths Altitude Site Name light First Mount diameter mirror Primary Optical design Component Wavelengths Altitude Site Name creating vast archives of both images images both of archives vast creating Survey TelescopesSurvey 2518 metres Paranal to Cerro Close VISTA 8 June 20118 June Alt-Azimuth fork 2.61 metres correctors with reflector Ritchey-Chrétien Modified view of 1° × 1° field OmegaCAM; camera 268-megapixel Ultraviolet/optical/near-infrared 2635 metres Paranal Cerro VST 2009 11 December Alt-Azimuth fork 4.10 metres in camera lenses corrector with reflector Ritchey-Chrétien Modified view of × 1.65° 1.65° field VIRCAM; camera 67-megapixel Near-Infrared

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visible- the VISTA surveying is and plements com It Moon. full the of area the times four than more view of afield with camera CCD 268-megapixel a monster telescope equipped with OmegaCAM, 2.6-metre astate-of-the-art is VST The nomical near-infrared camera. astro any of coverage widest the has It 67 of megapixels. total acombined with light to infrared sensitive 16 detectors containing camera VISTAof a3-tonne is heart At the world. the in vey telescope sur near-infrared powerful most the is VISTA and a4.1-metre has mirror main ih sky. ­light

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ESO/J. Emerson/VISTA at sunset. The VISTA telescope ­ above. Way shining Milky Inside the VST dome with the enclosure

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ESO/B. Tafreshi (twanight.org) ESO/B. Tafreshi (twanight.org) 18 ESO/L. Calçada from the NASA/ESA Hubble Space Space Hubble NASA/ESA the from those than 15 sharper times images adaptive optics technology will provide ­single optical telescopes today. Its largest the than light 15 more times about gather will and combined scopes existing large optical tele research currently all than ELTThe bigger be will sky. the eye on world’s biggest the it making metres, square 1000 almost of area a collecting with mirror main have a39-metre (ELT) will Telescope ESO’s Large Extremely revolutionary Universe. ter that and dark energy dominate the mat dark the of distribution and nature the and holes, black supermassive Universe, the in objects first the stars, detailed studies of planets around other astrophysical knowledge, allowing advance vastly will They astronomy. of the highest priorities in ground-based large telescopes are oneExtremely Survey Telescope First light Mount mirror diameterPrimary Optical design Technique Wavelengths Altitude Site Name Large Synoptic Large (planned 2020) (planned 8.4 metres El Peñón, El Chile Size comparison of of mirrors the giant primary optical telescopes under construction. Observatory, Chile (planned 2021+)(planned Giant Magellan Las Campanas 24.5 metres 24.5 Telescope ELT 2024 Alt-Azimuth 39 metres Five-mirror design stars guide to 8laser up and ­mirror Built-in adaptive optics using 2.6-metre deformable Optical/near-infrared metres 3046 Armazones Cerro -

ELT - (planned 2022+)(planned Thirty Meter Thirty , Telescope 30 metres 30 the ELT. the with made discoveries the from arise new and unforeseeable questions to energy. are also expecting Astronomers dark and matter dark of nature the probing and galaxies, and stars first the by studying to cosmology tions contribu fundamental making as well as stellar populations in nearby galaxies, and stars old by studying archaeology stellar perform also will It astronomy. observational modern of Grails Holy the of —one exist could life where stars, in the zones habitable around other aim to study Earth-like planets orbiting will It time. our of challenges scientific biggest the tackle will 2024, it in and light first to see ELTThe expected is thick. 5 centimetres each about 1.4 metres across but only of­composed 798 hexagonal segments, is mirror primary the and design mirror ELT The five- anovel ­Telescope. has Hawaii Cerro Armazones, Extremely Large Extremely (planned 2024)(planned Telescope 39 metres 39 Chile

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- ESO/M. Tarenghi Cerro Armazones Armazones Basecamp Armazones Extremely Large Extremely Telescope VISTA 23 kilometres Giant Magellan Very Large Telescope Large Very Telescope Cerro Paranal Thirty Meter Thirty Telescope Paranal Basecamp Road Large Synoptic Survey Telescope Armazones in northern Chile. inArmazones northern Telescope in operation on Cerro Large Extremely the of view night a shows rendering artist’s This them. between road the and sites Armazones Cerro and ESO’s Paranal shows Chile northern of region the of map This Lower: construction. under currently are that telescopeground-based facilities major other of those with Telescope the dome of the Large Extremely compares Upper: This graphic

19 20 Way above. Milky the of regions central the and antennas ALMA the of several shows view This submillimetre parts of the spectrum. the of parts submillimetre and millimetre the in brightly shine but light, visible in obscured and dark often are regions Such Universe. the andearliest in most distant galaxies interstellar space and from some of the in clouds cold vast from comes and waves in the spectrum, electromagnetic radio and light infrared between lies Space Telescope. The light it observes Hubble NASA/ESA the of that as sharp as times to ten up is vision —its tion and resolu sensitivity unprecedented and submillimetre wavelengths with the at Universe millimetre probes ALMA 12-metre and twelve 7-metre antennas. four of array compact additional an and telescope, asingle as together act which antennas, 12-metre fifty of array main the antennas: precision high- 66 of composed is ALMA Universe. the in objects coldest the of some from thatradio studies observatory light astate-of-the-art is ALMA ­existence. inthe project astronomical largest Millimeter/submillimeter (ALMA), Array operate the Atacama Large ­partners global its and ESO Andes, Chilean the in Plateau Chajnantor the on High First light First Mount diameter Antenna Optical design Technique Wavelengths Altitude Site Name

30 September 2011 September 30 Alt-Azimuth 12 ×12 ×7metres 54 metres; Cassegrain with 150-metre toInterferometry 16-kilometre baselines Submillimetre metres 4576–5044 Chajnantor ALMA

ALMA

- ation with the Academia Sinica (AS) Sinica Academia the with ation cooper in by NINS and Taiwanof (NSC) Council Science National the and (NRC) Canada of Council Research National the with cooperation in by NSF States, Member its of behalf on by ESO funded is ALMA Chile. of Republic the with cooperation in Japan of (NINS) Sciences Natural of Institutes National the and (NSF) Foundation Science National U.S. the ESO, of apartnership is ALMA tions are unsurpassed for observing. atmospheres and on the Earth condi driest the of one has site The Chile. northern in plateau Chajnantor the on level sea above metres 5000 built was ALMA atmosphere, Earth’s the in vapour by water absorbed heavily is radiation millimetreBecause and submillimetre about our cosmic origins. address some of the questions deepest to astronomers allowing itself, life systems, and planetary stars, galaxies of blocks building the studies ALMA Space Science Institute (KASI). Institute Science Space and Astronomy Korea the Taiwanin and

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ESO/B. Tafreshi (twanight.org) ALMA (ESO/NAOJ/NRAO)/M. Kaufman & the NASA/ESA ALMA (ESO/NAOJ/NRAO), J. Bally/H. Drass et al. taken on an ocular structure. ocular an on taken have that galaxies interacting of pair a sight: cosmic rare avery shows HubbleNASA/ESA Space Telescope, the and (ALMA) Array submillimeter from the Atacama Millimeter/ Large data of acomposite image, This stellar life cycle, star birth. the of end other the at explosions Nebula complex provide insights into Orion the of observations ALMA new But stars. of deaths spectacular associated with supernovae, the Stellar explosions are most often

21 APEX

A complementary facility for millimetre the wild early lives of today’s most and submillimetre astronomy is also ­massive galaxies, studied matter torn located on the Chajnantor Plateau: the apart by a supermassive black hole, Atacama Pathfinder Experiment (APEX). and detected molecules of hydrogen This 12-metre telescope is based on an peroxide in interstellar space for the first ALMA prototype antenna and operates time. APEX is also used study the con- at the ALMA site. APEX was operational ditions inside molecular clouds, such as for many years before ALMA and is those in the Orion Nebula or the Pillars ­taking on an important survey role now of ­Creation in the Eagle Nebula, advanc- that ALMA is complete. ing our understanding of the cradles­ of gas and dust where new stars are born. Like ALMA, APEX is designed to work at submillimetre wavelengths, which are APEX is a collaboration between the key to revealing some of the coldest, Max-Planck-Institut für Radioastronomie, dustiest and most distant objects in the the Onsala Space ­Observatory and Universe. Over the years, it has probed ESO. The telescope is operated by ESO.

Name APEX

Site Chajnantor

Altitude 5050 metres

Wavelengths Submillimetre

Optical design Cassegrain

Primary antenna diameter 12 metres

Mount Alt-Azimuth

First light 14 July 2005

The Atacama Pathfinder Experiment (APEX) telescope looks skyward during­ a bright, moonlit night on Chajnantor, one of the highest and driest observatory sites in the world.

22 ESO/Digitized Sky Survey 2 ESO/WFI (Optical); MPIfR/ESO/APEX/A. Weiss et al. (Submillimetre); NASA/CXC/CfA/R. Kraft et al. (X-ray) galaxy’s central black hole. and jets emanating from the active lobes the revealing A, ­Centaurus Colour composite image of ribbon in the sky. the in ­ribbon afiery be to seems what reveals Orion of constellation the in clouds cosmic of image new dramatic This

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ESO/B. Tafreshi (twanight.org) 24 ESO/B. Tafreshi (twanight.org) spectrograph with unrivalled precision. a HARPS, hunter: exoplanet foremost world’s to the home is It hemisphere. telescopes in the4-metre-class southern of line front the at remains it upgrades, in operation since 1977. Following major been has telescope 3.6-metre ESO The telescopes. large world’s current the of VLT to the most and applied now and ESO at developed atechnology optics), computer-controlled main mirror (active have to a world the in telescope first the was It design. and engineering telescope in ground new broke (NTT) ­Telescope The 3.58-metre New Technology observatories in the world. productive scientifically most the of one as position its to maintain La Silla telescopes, enabling 4-metre-class best the of two operates still ESO Here, ESO stronghold since the 1960s. an been has Observatory Silla La The La Silla La

near-Earth objects. near-Earth natural and artificial surveys — ESA with collaboration in —aproject ­Telescope Test-Bed the and wave detections, for optical counterparts to gravitational exoplanets. In addition, BlackGEM looks for hunt telescopes CAmeRA) All-Sky Multi-site (The MASCARA and pheres) Atmos their and Transits in (Exoplanets PlanetesImals Small Telescope), ExTrA Planets andTRAPPIST (TRAnsiting are gamma-ray The chasers. burst Action Telescope for Transient Objects) —Rapid Transitoires Objets les pour Rapide àAction TAROTand (Télescope scopes. The Rapid Eye Mount (REM) tele 1.54-metre Danish the and metre 2.2- MPG/ESO the telescope, Euler Leonhard 1.2-metre Swiss the as such States for targeted national projects Member ESO the of by many used also is Silla La of infrastructure The at the La Silla Observatory. Silla La the at telescope 2.2-metre MPG/ESO the on with the Wide Field Imager camera obtained images 6611), on NGC based or (Messier 16, Nebula Eagle the of compositeThree-colour mosaic image - -

The ESO 3.6-metre telescope dome is silhouetted against the sky in a nighttime view of the La Silla Observatory.

25 26 CTAO participating in theparticipating CTA project. currently are institutes 210 research over and countries 32 continents, five from engineers and 1350 scientists wide community. Over to a facility open an as CTA serves institutes. science Chilean for reserved be will array southern the on time observing the %of 10 addition, In States. ­Member available to scientists in the ESO made be —would Palma La —on array northern the and southern the both on time observing the %of 10 return, in and array southern the operate would VLT. the of ESO south-east kilometres ten around site, southern larger the at scopes worldwide, with 99 telescopes 118 CTA to have around is The plan tele ing advanced ESO infrastructure. exist by the supported be would which telescope, the of array southern the host will Observatory ESO’sthat Paranal gamma-ray astronomy. It is foreseen energy high very for built being vatory a obser next-generation ground-based (CTA) is Array Telescope Cherenkov The

CTA

- - - in the high-energy Universe. Universe. high-energy the in events violent and extreme most the of helping to astronomers study some source, cosmic to its back traced to be radiation will allow each gamma-ray phere. Pinpointing the of source this with the atmos interact gamma-rays when produced is that radiation Cherenkov blue eerie characteristic the of flashes short-lived capture will CTA’s mirrors and high-speed cameras gamma-rays from reaching the surface, prevents the Earth’s atmosphere black holes and supernovae. Although supermassive as such Universe, the in objects powerful most and hottest the of by some emitted are Gamma-rays instruments. existing than sensitive more 10 times accuracyunprecedented and will be with gamma-rays detect will It world. in gamma-rayenergy the observatory the and largest most sensitive high- be —will coverage sky wide and area collecting CTA large its —with

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Artist’s rendering of southern site of the Cherenkov Telescope Array.

27 28 to Argentina. 23 Route on driving when lake beautiful this by pass visitors ALMA, of south kilometres 80 about Located Argentina. to border the to close Altiplano, Andean the in high situated is Miñiques Laguna Chile Joint Committee and the ALMA ALMA the and Committee Joint Chile of ESO–Government by the managed funds the through Chile in astronomy of ESO contributes to the development ESO. for partners valuable very engineers and scientists Chilean made has advancement This States. ESO’s in Member technologies ciated advances in astronomy and its asso the with step in developed has prowess engineering and technological tific, scien Chilean collaboration this During industry. and tutes ­government, universities, insti science including levels, many at Chile with collaboration fruitful very and a close in engaged is ESO Europe. and Chile between link cultural important an of forging the and story success national inter 50-year than amore of beginning the was This signed. was ESO and Chile of Government the between ment agree initial 1963 the 6November On ESO &Chile ­

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- - - technology. and science of progress the and States, Member ESO the Chile, of benefit the —for future the into pathway exciting importantly, this association opens an long-lasting, but also flexible. Most and solid only not to be proved has ESO The cooperation between Chile and regions. those in skies, dark the including heritage, local the of awareness an and natural conservation programmes promotes also ESO located. are sites observatory the where Antofagasta, and Coquimbo of regions the in grammes regional and local cooperation pro several out carries ESO addition, In telescopes. ESO on time observing of to apercentage access preferential has also community astronomical Chilean astrotechnology, and education. The science, in activities of range a wide financing Committee, Joint CONICYT

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A. Duro/ESO From Idea to Published Paper: The Data Flow

The operation of ESO telescopes forms and the survey telescopes VISTA and a seamless process that starts when the VST. It also contains observations astronomers submit a proposal for an obtained with the La Silla telescopes observing project that addresses specific­ and with the APEX submillimetre radio scientific objectives. Proposals are peer- ­telescope on Chajnantor. Observations reviewed by experts from the community stored in the archive typically become and the approved projects are translated publicly available one year after they were into a detailed description of the observa- obtained, allowing them to be used by tions to be made. other researchers.

The observations are then performed The traditional way of observing is to allow at ESO’s telescopes, and the data astronomers to travel to the telescope ­collected are immediately made available to carry out the observations themselves, to the corresponding research teams via assisted by expert locally-based person- the ESO archive. The scientific observa- nel. Known as visitor mode, this allows tions and their associated calibration data astronomers to adapt their observing are also used by ESO scientists to monitor strategies to the atmospheric conditions the quality of the data and the behaviour and the results as they are obtained. of the instruments in detail, to ensure But the necessary observing conditions that their performance is always within ­cannot be guaranteed on any given night. speci­fication. This entire process relies on the continuous transfer of huge ESO has also developed an alternative amounts of data between the observato- scheme, called service observing. ries in Chile and ESO’s Headquarters in Each predefined observation specifies Garching, Germany. the acceptable conditions which should be obtained in order to fulfil its scientific All the scientific and calibration data goals. Based on these specifications, ­gathered are stored in the ESO Science observations are flexibly scheduled at Archive Facility. This contains a complete the telescope and carried out. The many record of all observations obtained since advantages of flexible scheduling have the start of operations on Paranal by the made service observing the mode of Very Large Telescope, its interferometer choice for about 60–70 % of VLT users.

The data centre at ESO’s Head­ quarters in Garching bei München, Germany, which archives and dis­ tributes data from ESO’s telescopes.

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- 31 www.eso.org Phone: +49 89 320 06-0 | Fax: +49 89 320 23 62 | E-mail: |E-mail: 62 23 320 89 +49 |Fax: 06-0 320 89 +49 Phone: Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany ESO Headquarters 09.2017 —English 09.2017 [email protected]

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