The Walraven Photometer

<!DOCTYPE html> <html lang="en"> <head prefix="og: http://ogp.me/ns# fb: http://ogp.me/ns/fb#"> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <base target="_top" /> <meta name="robots" content="index,follow" /> <meta name="author" content="information@eso.org" /> <meta name="description" content="ESO, European Organisation for Astronomical Research in the Southern Hemisphere" /> <meta name="keywords" content="ESO, eso.org, Astronomy, Astrophysics, Astronomie, Suedsternwarte, telescopes, detectors, comets, planets, stars, galaxies, nebulae, universe, NTT, VLT, VLTI, ALMA, ELT, La Silla, Paranal, Garching, Chile" /> <meta name="statvooVerification" content="f546f5bccd3fb7f8c5d8e97c6beab814" /> <link rel="alternate" href="https://www.eso.org/public/teles-instr/lasilla/09metre/walraven/" hreflang="x-default" /><link rel="alternate" href="https://www.eso.org/public/australia/teles-instr/lasilla/09metre/walraven/" hreflang="en-au" /><link rel="alternate" href="https://www.eso.org/public/unitedkingdom/teles-instr/lasilla/09metre/walraven/" hreflang="en-gb" /><link rel="alternate" href="https://www.eso.org/public/ireland/teles-instr/lasilla/09metre/walraven/" hreflang="en-ie" /><link rel="alternate" href="https://www.eso.org/public/czechrepublic/teles-instr/lasilla/09metre/walraven/" hreflang="cs" /><link rel="alternate" href="https://www.eso.org/public/denmark/teles-instr/lasilla/09metre/walraven/" hreflang="da" /><link rel="alternate" href="https://www.eso.org/public/netherlands/teles-instr/lasilla/09metre/walraven/" hreflang="nl" /><link rel="alternate" href="https://www.eso.org/public/belgium-nl/teles-instr/lasilla/09metre/walraven/" hreflang="nl-be" /><link rel="alternate" href="https://www.eso.org/public/finland/teles-instr/lasilla/09metre/walraven/" hreflang="fi" /><link rel="alternate" href="https://www.eso.org/public/france/teles-instr/lasilla/09metre/walraven/" hreflang="fr" /><link rel="alternate" href="https://www.eso.org/public/belgium-fr/teles-instr/lasilla/09metre/walraven/" hreflang="fr-be" /><link rel="alternate" href="https://www.eso.org/public/switzerland-fr/teles-instr/lasilla/09metre/walraven/" hreflang="fr-ch" /><link rel="alternate" href="https://www.eso.org/public/germany/teles-instr/lasilla/09metre/walraven/" hreflang="de" /><link rel="alternate" href="https://www.eso.org/public/austria/teles-instr/lasilla/09metre/walraven/" hreflang="de-at" /><link rel="alternate" href="https://www.eso.org/public/belgium-de/teles-instr/lasilla/09metre/walraven/" hreflang="de-be" /><link rel="alternate" href="https://www.eso.org/public/switzerland-de/teles-instr/lasilla/09metre/walraven/" hreflang="de-ch" /><link rel="alternate" href="https://www.eso.org/public/italy/teles-instr/lasilla/09metre/walraven/" hreflang="it" /><link rel="alternate" href="https://www.eso.org/public/switzerland-it/teles-instr/lasilla/09metre/walraven/" hreflang="it-ch" /><link rel="alternate" href="https://www.eso.org/public/poland/teles-instr/lasilla/09metre/walraven/" hreflang="pl" /><link rel="alternate" href="https://www.eso.org/public/portugal/teles-instr/lasilla/09metre/walraven/" hreflang="pt" /><link rel="alternate" href="https://www.eso.org/public/spain/teles-instr/lasilla/09metre/walraven/" hreflang="es" /><link rel="alternate" href="https://www.eso.org/public/chile/teles-instr/lasilla/09metre/walraven/" hreflang="es-cl" /><link rel="alternate" href="https://www.eso.org/public/sweden/teles-instr/lasilla/09metre/walraven/" hreflang="sv" /> <link rel="shortcut icon" href="https://www.eso.org/public/archives/favicon.ico" /> <title>The Walraven Photometer | ESO</title>  <style type="text/css"> @import url("https://fast.fonts.net/t/1.css?apiType=css&projectid=03892b9b-79f6-4f01-9746-af912ebf5e47"); </style> <link href="/public/archives/djp/css/main.9116bda0b9f3.css" rel="stylesheet" type="text/css" /> <link href="https://feeds.feedburner.com/EsoTopNews" rel="alternate" type="application/rss+xml" title="ESO Top News" /> <link href="https://feeds.feedburner.com/EsoAnnouncements" rel="alternate" type="application/rss+xml" title="ESO Announcements" /> <link href="https://feeds.feedburner.com/ESOcast" rel="alternate" type="application/rss+xml" title="ESOCast" /> <link href="https://recruitment.eso.org/jobs.rss" rel="alternate" type="application/rss+xml" title="Jobs@ESO" /> <link href="https://www.eso.org/public/blog/feed/" rel="alternate" type="application/rss+xml" title="ESOblog" />  <meta name="twitter:card" content="summary" /> <meta name="twitter:site" content="@ESO" /> <meta name="twitter:creator" content="@ESO" />  <script type="text/javascript"> var _paq = window._paq || []; /* tracker methods like "setCustomDimension" should be called before "trackPageView" */ _paq.push(['trackPageView']); _paq.push(['enableLinkTracking']); (function() { var u="/mtmo/"; _paq.push(['setTrackerUrl', u+'matomo.php']); _paq.push(['setSiteId', '1']); var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'matomo.js'; s.parentNode.insertBefore(g,s); })(); </script>  <meta property="og:title" content="The Walraven Photometer" /> </head> <body> <input type='hidden' name='csrfmiddlewaretoken' value='HRMqvXzfYHv8Odj84p2XPp5S0Lo7hv5nqCJzP8gneJnEcofKUT9OozeaBJ68mSHc' /> <div id="privacy-notice" style="display: none"> <p> By continuing to use this website, you are giving consent to our use of cookies.<br> For more information on how ESO uses data and how you can disable cookies, please view <a href="/public/about-eso/privacy/"> our privacy policy</a>. </p> <button type="button" class="btn btn-primary" onclick="accept_privacy_notice()"> Accept </button> <script> // Display the privacy cookie if the cookie is not set if (!has_privacy_cookie()) { document.getElementById('privacy-notice').style.display = 'block' } function has_privacy_cookie() { return document.cookie.split(';').filter(function(item) { return item.indexOf('privacy_notice_accepted=True') >= 0 }).length > 0 } function accept_privacy_notice() { let data = { LANGUAGE_CODE: 'en' } let csrftoken = getCookie('csrftoken'); let headers = new Headers(); headers.append('Content-Type', 'application/json; charset=utf-8'); headers.append('X-CSRFToken', csrftoken); fetch('/public/accept-privacy-notice/', { method: 'post', headers: headers, credentials: 'include', body: JSON.stringify(data) }).then( document.getElementById('privacy-notice').style.display = 'none' ) } function getCookie(name) { var cookieValue = null; if (document.cookie && document.cookie !== '') { var cookies = document.cookie.split(';'); for (var i = 0; i < cookies.length; i++) { var cookie = jQuery.trim(cookies[i]); // Does this cookie string begin with the name we want? if (cookie.substring(0, name.length + 1) == (name + '=')) { cookieValue = decodeURIComponent(cookie.substring(name.length + 1)); break; } } } return cookieValue; } </script> </div> <nav class="navbar-general-wrapper" role="navigation"> <div class="navbar-general"> <div class="minilogo"> <a href="/public/"> <div class="sprites-esologo-23-30" title="European Organisation for Astronomical Research in the Southern Hemisphere"></div> </a> </div> <div id="select-language"> <div class="flags"> <div title="Austria" class="sprites-flag_at"></div> <div title="Belgium" class="sprites-flag_be"></div> <div title="Czechia" class="sprites-flag_cz"></div> <div title="Denmark" class="sprites-flag_da"></div> <div title="Finland" class="sprites-flag_fi"></div> <div title="France" class="sprites-flag_fr"></div> <div title="Germany" class="sprites-flag_de"></div> <div title="Ireland" class="sprites-flag_ie"></div> <div title="Italy" class="sprites-flag_it"></div> <div title="Netherlands" class="sprites-flag_nl"></div> <div title="Poland" class="sprites-flag_pl"></div> <div title="Portugal" class="sprites-flag_pt"></div> <div title="Spain" class="sprites-flag_es"></div> <div title="Sweden" class="sprites-flag_sv"></div> <div title="Switzerland" class="sprites-flag_ch"></div> <div title="UK" class="sprites-flag_gb"></div> <div style="margin-left: 8px" title="Chile" class="sprites-flag_cl"></div> </div> <div class="languages"> <div class="language-button"> <span class="language-text">Select Language (en)</span> <div class="language-flag"><div title="en" class="flag sprites-flag_gb"> </div><span> (en)</span></div> <span class="caret"></span> </div> <ul class="languages-dropdown" role="menu"> <li class="language selected"><a role="menuitem" href="/public/teles-instr/lasilla/09metre/walraven/?lang"><div title="International English" class="flag sprites-flag_en"> </div>International English</a></li> <li class="language"><a role="menuitem" href="/public/denmark/teles-instr/lasilla/09metre/walraven/?lang"><div title="Dansk" class="flag sprites-flag_da"> </div>Dansk</a></li> <li class="language"><a role="menuitem" href="/public/germany/teles-instr/lasilla/09metre/walraven/?lang"><div title="Deutsch" class="flag sprites-flag_de"> </div>Deutsch</a></li> <li class="language"><a role="menuitem" href="/public/belgium-de/teles-instr/lasilla/09metre/walraven/?lang"><div title="Deutsch (Belgien)" class="flag sprites-flag_be"> </div>Deutsch (Belgien)</a></li> <li class="language"><a role="menuitem" href="/public/switzerland-de/teles-instr/lasilla/09metre/walraven/?lang"><div title="Deutsch (Schweiz)" class="flag sprites-flag_ch"> </div>Deutsch (Schweiz)</a></li> <li class="language"><a role="menuitem" href="/public/austria/teles-instr/lasilla/09metre/walraven/?lang"><div title="Deutsch (Österreich)" class="flag sprites-flag_at"> </div>Deutsch (Österreich)</a></li> <li class="language"><a role="menuitem" href="/public/australia/teles-instr/lasilla/09metre/walraven/?lang"><div title="English (Australia)" class="flag sprites-flag_au"> </div>English (Australia)</a></li> <li class="language"><a role="menuitem" href="/public/ireland/teles-instr/lasilla/09metre/walraven/?lang"><div title="English (Ireland)" class="flag sprites-flag_ie"> </div>English (Ireland)</a></li> <li class="language"><a role="menuitem" href="/public/unitedkingdom/teles-instr/lasilla/09metre/walraven/?lang"><div title="English (UK)" class="flag sprites-flag_gb"> </div>English (UK)</a></li> <li class="language"><a role="menuitem" href="/public/spain/teles-instr/lasilla/09metre/walraven/?lang"><div title="Español" class="flag sprites-flag_es"> </div>Español</a></li> <li class="language"><a role="menuitem" href="/public/chile/teles-instr/lasilla/09metre/walraven/?lang"><div title="Español (Chile)" class="flag sprites-flag_cl"> </div>Español (Chile)</a></li> <li class="language"><a role="menuitem" href="/public/france/teles-instr/lasilla/09metre/walraven/?lang"><div title="Français" class="flag sprites-flag_fr"> </div>Français</a></li> <li class="language"><a role="menuitem" href="/public/belgium-fr/teles-instr/lasilla/09metre/walraven/?lang"><div title="Français (Belgique)" class="flag sprites-flag_be"> </div>Français (Belgique)</a></li> <li class="language"><a role="menuitem" href="/public/switzerland-fr/teles-instr/lasilla/09metre/walraven/?lang"><div title="Français (Suisse)" class="flag sprites-flag_ch"> </div>Français (Suisse)</a></li> <li class="language"><a role="menuitem" href="/public/italy/teles-instr/lasilla/09metre/walraven/?lang"><div title="Italiano" class="flag sprites-flag_it"> </div>Italiano</a></li> <li class="language"><a role="menuitem" href="/public/switzerland-it/teles-instr/lasilla/09metre/walraven/?lang"><div title="Italiano (Svizzera)" class="flag sprites-flag_ch"> </div>Italiano (Svizzera)</a></li> <li class="language"><a role="menuitem" href="/public/netherlands/teles-instr/lasilla/09metre/walraven/?lang"><div title="Nederlands" class="flag sprites-flag_nl"> </div>Nederlands</a></li> <li class="language"><a role="menuitem" href="/public/belgium-nl/teles-instr/lasilla/09metre/walraven/?lang"><div title="Nederlands (België)" class="flag sprites-flag_be"> </div>Nederlands (België)</a></li> <li class="language"><a role="menuitem" href="/public/poland/teles-instr/lasilla/09metre/walraven/?lang"><div title="Polski" class="flag sprites-flag_pl"> </div>Polski</a></li> <li class="language"><a role="menuitem" href="/public/portugal/teles-instr/lasilla/09metre/walraven/?lang"><div title="Português" class="flag sprites-flag_pt"> </div>Português</a></li> <li class="language"><a role="menuitem" href="/public/finland/teles-instr/lasilla/09metre/walraven/?lang"><div title="Suomi" class="flag sprites-flag_fi"> </div>Suomi</a></li> <li class="language"><a role="menuitem" href="/public/sweden/teles-instr/lasilla/09metre/walraven/?lang"><div title="Svenska" class="flag sprites-flag_sv"> </div>Svenska</a></li> <li class="language"><a role="menuitem" href="/public/czechrepublic/teles-instr/lasilla/09metre/walraven/?lang"><div title="Česky" class="flag sprites-flag_cs"> </div>Česky</a></li> </ul> </div> </div> <div class="sections"> <a href="https://www.eso.org/sci.html">Science</a> <a href="/UserPortal/">User Portal</a> </div> <div class="searchbox"> <button type="button" class="btn btn-default" id="searchbox-button"> <span class="fa fa-search"></span> </button> <div id="searchbox-dropdown"> <form action="/public/search/" method="get" class="form-inline" role="search"> <div class="form-group"> <div class="input-group"> <input type="text" value="" placeholder="Search..." name="q" class="form-control"> <span class="input-group-btn"> <button class="btn btn-default" type="submit"><span class="fa fa-search"></span></button> </span> </div>   </div> </form> </div> </div> <div class="links"> <a href="/public/outreach/newsletters/esonews/">Subscribe</a> <a href="/public/about-eso/travel/">Contact</a> <a href="/public/sitemap/">Site Map</a> </div> </div> </nav> <nav class="main-menu-wrapper" role="navigation"> <div class="main-menu"> <div class="mobile-menu clearfix"> <button class="menu-trigger"><span class="fa fa-navicon"></span> Open Menu</button> </div> <ul class="level0 mainmenu-aim"> <li><a href="/public/about-eso/">About<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-2" class="submenu-aim"> <li class=""><a href="/public/about-eso/esoglance/"> ESO, the European Southern Observatory </a></li><li class=""><a href="/public/about-eso/organisation/"> Organisation </a></li><li class=""><a href="/public/about-eso/mission-vision-values-strategy/"> Mission-Vision-Values-Strategy </a></li><li class="submenu"><a href="/public/about-eso/dg-office/"> Director General <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-6" class="submenu-aim sublevel"><li class="submenu"><a href="/public/about-eso/dg-office/previous-dg/"> List of Directors General <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-7" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/dg-office/xbarcons/"> Prof. Xavier Barcons </a></li><li class=""><a href="/public/about-eso/dg-office/tdezeeuw/"> Prof. T. de Zeeuw </a></li><li class=""><a href="/public/about-eso/dg-office/ccesarsk/"> Dr. C. Cesarsky </a></li><li class=""><a href="/public/about-eso/dg-office/rgiacconi/"> Prof. R. Giacconi </a></li><li class=""><a href="/public/about-eso/dg-office/hvanderlaan/"> Prof. H. van der Laan </a></li><li class=""><a href="/public/about-eso/dg-office/lwoltjer/"> Prof. L. Woltjer </a></li><li class=""><a href="/public/about-eso/dg-office/ablaauw/"> Prof. A. Blaauw </a></li><li class=""><a href="/public/about-eso/dg-office/otto-heckmann/"> Prof. O. Heckmann </a></li></ul></li></ul></li><li class=""><a href="/public/about-eso/committees.html"> ESO's Governing Bodies </a></li><li class="submenu"><a href="/public/about-eso/memberstates/"> Member States and Partners <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-17" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/memberstates/austrianinvolvement/"> Austria </a></li><li class=""><a href="/public/about-eso/memberstates/belgianinvolvement/"> Belgium </a></li><li class=""><a href="/public/about-eso/memberstates/czechinvolvement/"> Czechia </a></li><li class=""><a href="/public/about-eso/memberstates/danishinvolvement/"> Denmark </a></li><li class=""><a href="/public/about-eso/memberstates/finnishinvolvement/"> Finland </a></li><li class=""><a href="/public/about-eso/memberstates/frenchinvolvement/"> France </a></li><li class=""><a href="/public/about-eso/memberstates/germaninvolvement/"> Germany </a></li><li class=""><a href="/public/about-eso/memberstates/irishinvolvement/"> Ireland </a></li><li class=""><a href="/public/about-eso/memberstates/italianinvolvement/"> Italy </a></li><li class=""><a href="/public/about-eso/memberstates/dutchinvolvement/"> Netherlands </a></li><li class=""><a href="/public/about-eso/memberstates/polishinvolvement/"> Poland </a></li><li class=""><a href="/public/about-eso/memberstates/portugueseinvolvement/"> Portugal </a></li><li class=""><a href="/public/about-eso/memberstates/spanishinvolvement/"> Spain </a></li><li class=""><a href="/public/about-eso/memberstates/swedishinvolvement/"> Sweden </a></li><li class=""><a href="/public/about-eso/memberstates/swissinvolvement/"> Switzerland </a></li><li class=""><a href="/public/about-eso/memberstates/britishinvolvement/"> United Kingdom </a></li><li class=""><a href="/public/about-eso/strategicpartners/australianinvolvement/"> Australia (Partner) </a></li></ul></li><li class="submenu"><a href="/public/about-eso/eso-and-chile/"> ESO & Chile <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-35" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/eso-and-chile/representation-office-chile/"> ESO Representation Office in Chile </a></li></ul></li><li class="submenu"><a href="/public/about-eso/travel/"> Travel and Contacts <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-37" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/travel/garching/"> Travel to ESO Headquarters </a></li><li class=""><a href="/public/about-eso/travel/vitacura/"> Travel to Vitacura Office </a></li><li class=""><a href="/public/about-eso/travel/guesthouse/"> Travel to Guesthouse </a></li><li class=""><a href="/public/about-eso/travel/lasilla/"> Travel to La Silla </a></li><li class=""><a href="/public/about-eso/travel/laserena/"> Travel to La Serena </a></li><li class=""><a href="/public/about-eso/travel/paranal/"> Travel to Paranal </a></li><li class=""><a href="/public/about-eso/travel/antofagasta/"> Travel to Antofagasta </a></li><li class=""><a href="/public/about-eso/travel/chajnantor/"> Travel to Chajnantor </a></li><li class=""><a href="/public/about-eso/travel/elt/"> Travel to ELT Armazones </a></li></ul></li><li class="submenu"><a href="/public/about-eso/visitors/"> Visits to ESO Sites <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-47" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/visitors/paranal/"> Weekend visits to Paranal </a></li><li class=""><a href="/public/about-eso/visitors/lasilla/"> Weekend Visits to La Silla </a></li><li class=""><a href="/public/outreach/pressmedia/mediavisits/"> Media Visits </a></li><li class=""><a href="/public/about-eso/visitors/virtual-tours/"> Virtual Visits </a></li><li class=""><a href="/public/about-eso/visitors/artists-at-eso/"> Artistic Visits </a></li></ul></li><li class=""><a href="/public/about-eso/societal-benefits/"> ESO and Society </a></li><li class=""><a href="/public/about-eso/architecture/"> Architecture at ESO </a></li><li class=""><a href="/public/about-eso/collaborations/"> Collaborations with ESO </a></li><li class=""><a href="/public/about-eso/acronyms/"> ESO Acronyms </a></li><li class=""><a href="/public/about-eso/timeline/"> Timeline </a></li><li class="submenu"><a class="no-link children" href="#"> Sustainability <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-58" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/sustainability/green/"> Environmental sustainability at ESO </a></li><li class=""><a href="/public/about-eso/sustainability/eso-un-sdgs/"> ESO and the UN's Sustainable Development Goals </a></li><li class=""><a href="/public/about-eso/sustainability/dei-at-eso/"> Diversity, Equity and Inclusion </a></li></ul></li><li class="submenu"><a href="/public/about-eso/faq/"> Frequently Asked Questions <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-62" class="submenu-aim sublevel"><li class=""><a href="/public/about-eso/faq/faq-eso/"> ESO </a></li><li class=""><a href="/public/about-eso/faq/faq-vlt-paranal/"> VLT/Paranal </a></li><li class=""><a href="/public/about-eso/faq/faq-apex-alma/"> APEX/ALMA </a></li><li class=""><a href="https://elt.eso.org/about/faq/"> ELT </a></li><li class=""><a href="/public/about-eso/faq/privileges_and_immunities/"> Privileges and Immunities </a></li><li class=""><a href="/public/about-eso/faq/faq-eso-australia/"> ESO & Australia </a></li></ul></li><li class=""><a href="/public/about-eso/dark-skies-preservation/"> Dark skies preservation </a></li><li class=""><a href="/public/about-eso/privacy/"> Terms and Conditions </a></li> </ul> </div> </div> </li> <li><a href="/public/images/">Images<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-71" class="submenu-aim"> <li class=""><a href="/public/images/search/"> Advanced Search </a></li><li class="submenu"><a class="no-link children" href="#"> Categories <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-73" class="submenu-aim sublevel"><li class=""><a href="/public/images/archive/category/360pano/ "> 360 Panorama </a></li><li class=""><a href="/public/images/archive/category/alma/"> ALMA </a></li><li class=""><a href="/public/images/archive/category/apex/"> APEX </a></li><li class=""><a href="/public/images/archive/category/chile/"> Chile </a></li><li class=""><a href="/public/images/archive/category/cosmology/"> Cosmology </a></li><li class=""><a href="/public/images/archive/category/elt/"> ELT </a></li><li class=""><a href="/public/images/archive/category/eso-supernova/"> ESO Supernova </a></li><li class=""><a href="/public/images/archive/category/exoplanets/"> Exoplanets </a></li><li class=""><a href="/public/images/archive/category/fulldome/"> Fulldome </a></li><li class=""><a href="/public/images/archive/category/galaxies/"> Galaxies </a></li><li class=""><a href="/public/images/archive/category/galaxyclusters/"> Galaxy Clusters </a></li><li class=""><a href="/public/images/archive/category/illustrations/"> Illustrations </a></li><li class=""><a href="/public/images/archive/category/lasilla/"> La Silla </a></li><li class=""><a href="/public/images/archive/category/nebulae/"> Nebulae </a></li><li class=""><a href="/public/images/archive/category/paranal/"> Paranal </a></li><li class=""><a href="/public/images/archive/category/peopleandevents/"> People and Events </a></li><li class=""><a href="/public/images/archive/category/premises/"> Premises </a></li><li class=""><a href="/public/images/archive/category/blackholes/"> Quasars and Black Holes </a></li><li class=""><a href="/public/images/archive/category/solarsystem/"> Solar System </a></li><li class=""><a href="/public/images/archive/category/starclusters/"> Star Clusters </a></li><li class=""><a href="/public/images/archive/category/stars/"> Stars </a></li><li class=""><a href="/public/images/archive/category/surveytelescopes/"> Survey Telescopes </a></li></ul></li><li class=""><a href="/public/images/comparisons/"> Image Comparisons </a></li><li class=""><a href="/public/images/imageformats/"> Image Formats </a></li><li class="submenu"><a href="/public/images/potw/"> Picture of the Week <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-98" class="submenu-aim sublevel"><li class=""><a href="/public/images/potw/archive/year/2024/"> 2024 </a></li><li class=""><a href="/public/images/potw/archive/year/2023/"> 2023 </a></li><li class=""><a href="/public/images/potw/archive/year/2022/"> 2022 </a></li><li class=""><a href="/public/images/potw/archive/year/2021/"> 2021 </a></li><li class=""><a href="/public/images/potw/archive/year/2020/"> 2020 </a></li><li class=""><a href="/public/images/potw/archive/year/2019/"> 2019 </a></li><li class=""><a href="/public/images/potw/archive/year/2018/"> 2018 </a></li><li class=""><a href="/public/images/potw/archive/year/2017/"> 2017 </a></li><li class=""><a href="/public/images/potw/archive/year/2016/"> 2016 </a></li><li class=""><a href="/public/images/potw/archive/year/2015/"> 2015 </a></li><li class=""><a href="/public/images/potw/archive/year/2014/"> 2014 </a></li><li class=""><a href="/public/images/potw/archive/year/2013/"> 2013 </a></li><li class=""><a href="/public/images/potw/archive/year/2012/"> 2012 </a></li><li class=""><a href="/public/images/potw/archive/year/2011/"> 2011 </a></li><li class=""><a href="/public/images/potw/archive/year/2010/"> 2010 </a></li><li class=""><a href="/public/images/potw/archive/year/2009/"> 2009 </a></li><li class=""><a href="/public/images/potw/archive/year/2008/"> 2008 </a></li><li class=""><a href="/public/images/potw/archive/year/2007/"> 2007 </a></li></ul></li><li class="submenu"><a href="/public/images/archive/top100/"> Top 100 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-117" class="submenu-aim sublevel"><li class=""><a href="https://cdn.eso.org/images/top100-large.zip"> Large JPG Zip File (3.5 GB) </a></li><li class=""><a href="https://cdn.eso.org/images/top100-original.zip"> Original TIF Zip File (50 GB) </a></li></ul></li><li class=""><a href="/public/copyright/"> Usage of ESO Images and Videos </a></li><li class=""><a href="/public/images/archive/wallpapers/"> Wallpapers </a></li><li class=""><a href="/public/images/archive/zoomable/"> Zoomable </a></li> </ul> </div> </div> </li> <li><a href="/public/videos/">Videos<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-123" class="submenu-aim"> <li class=""><a href="/public/videos/search/"> Advanced Search </a></li><li class="submenu"><a class="no-link children" href="#"> Categories <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-125" class="submenu-aim sublevel"><li class=""><a href="/public/videos/archive/category/abouteso/"> About ESO </a></li><li class=""><a href="/public/videos/archive/category/alma/"> ALMA </a></li><li class=""><a href="/public/videos/archive/category/apex/"> APEX </a></li><li class=""><a href="/public/videos/archive/category/chasingstarlight/"> Chasing Starlight </a></li><li class=""><a href="/public/videos/archive/category/compilations/"> Compilations </a></li><li class=""><a href="/public/videos/archive/category/cosmology/"> Cosmology </a></li><li class=""><a href="/public/videos/archive/category/elt/"> ELT </a></li><li class=""><a href="/public/videos/archive/category/esocast/"> ESOcast </a></li><li class=""><a href="/public/videos/archive/category/events/"> Events </a></li><li class=""><a href="/public/videos/archive/category/exoplanets/"> Exoplanets </a></li><li class=""><a href="/public/videos/archive/category/featuremovies/"> Feature Movies </a></li><li class=""><a href="/public/videos/archive/category/fulldome/"> Fulldome </a></li><li class=""><a href="/public/videos/archive/category/galaxies/"> Galaxies </a></li><li class=""><a href="/public/videos/archive/category/galaxyclusters/"> Galaxy Clusters </a></li><li class=""><a href="/public/videos/archive/category/lasilla/"> La Silla </a></li><li class=""><a href="/public/videos/archive/category/nebulae/"> Nebulae </a></li><li class=""><a href="/public/videos/archive/category/paranal/"> Paranal </a></li><li class=""><a href="/public/videos/archive/category/premises/"> Premises </a></li><li class=""><a href="/public/videos/archive/category/blackholes/"> Quasars and Black Holes </a></li><li class=""><a href="/public/videos/archive/category/solarsystem/"> Solar System </a></li><li class=""><a href="/public/videos/archive/category/starclusters/"> Star Clusters </a></li><li class=""><a href="/public/videos/archive/category/stars/"> Stars </a></li><li class=""><a href="/public/videos/archive/category/vnr/"> Video News Releases </a></li></ul></li><li class=""><a href="/public/copyright/"> Usage of ESO Videos and Images </a></li><li class=""><a href="/public/videoformats/"> Video Formats </a></li> </ul> </div> </div> </li> <li><a href="/public/news/">News<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-151" class="submenu-aim"> <li class="submenu"><a href="/public/news/"> Press Releases <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-152" class="submenu-aim sublevel"><li class="submenu"><a class="no-link children" href="#"> 2021-2030 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-153" class="submenu-aim sublevel"><li class=""><a href="/public/news/archive/year/2024/"> 2024 </a></li><li class=""><a href="/public/news/archive/year/2023/"> 2023 </a></li><li class=""><a href="/public/news/archive/year/2022/"> 2022 </a></li><li class=""><a href="/public/news/archive/year/2021/"> 2021 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 2011–2020 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-158" class="submenu-aim sublevel"><li class=""><a href="/public/news/archive/year/2020/"> 2020 </a></li><li class=""><a href="/public/news/archive/year/2019/"> 2019 </a></li><li class=""><a href="/public/news/archive/year/2018/"> 2018 </a></li><li class=""><a href="/public/news/archive/year/2017/"> 2017 </a></li><li class=""><a href="/public/news/archive/year/2016/"> 2016 </a></li><li class=""><a href="/public/news/archive/year/2015/"> 2015 </a></li><li class=""><a href="/public/news/archive/year/2014/"> 2014 </a></li><li class=""><a href="/public/news/archive/year/2013/"> 2013 </a></li><li class=""><a href="/public/news/archive/year/2012/"> 2012 </a></li><li class=""><a href="/public/news/archive/year/2011/"> 2011 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 2001–2010 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-169" class="submenu-aim sublevel"><li class=""><a href="/public/news/archive/year/2010/"> 2010 </a></li><li class=""><a href="/public/news/archive/year/2009/"> 2009 </a></li><li class=""><a href="/public/news/archive/year/2008/"> 2008 </a></li><li class=""><a href="/public/news/archive/year/2007/"> 2007 </a></li><li class=""><a href="/public/news/archive/year/2006/"> 2006 </a></li><li class=""><a href="/public/news/archive/year/2005/"> 2005 </a></li><li class=""><a href="/public/news/archive/year/2004/"> 2004 </a></li><li class=""><a href="/public/news/archive/year/2003/"> 2003 </a></li><li class=""><a href="/public/news/archive/year/2002/"> 2002 </a></li><li class=""><a href="/public/news/archive/year/2001/"> 2001 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 1991–2000 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-180" class="submenu-aim sublevel"><li class=""><a href="/public/news/archive/year/2000/"> 2000 </a></li><li class=""><a href="/public/news/archive/year/1999/"> 1999 </a></li><li class=""><a href="/public/news/archive/year/1998/"> 1998 </a></li><li class=""><a href="/public/news/archive/year/1997/"> 1997 </a></li><li class=""><a href="/public/news/archive/year/1996/"> 1996 </a></li><li class=""><a href="/public/news/archive/year/1995/"> 1995 </a></li><li class=""><a href="/public/news/archive/year/1994/"> 1994 </a></li><li class=""><a href="/public/news/archive/year/1993/"> 1993 </a></li><li class=""><a href="/public/news/archive/year/1992/"> 1992 </a></li><li class=""><a href="/public/news/archive/year/1991/"> 1991 </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> 1985–1990 <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-191" class="submenu-aim sublevel"><li class=""><a href="/public/news/archive/year/1990/"> 1990 </a></li><li class=""><a href="/public/news/archive/year/1989/"> 1989 </a></li><li class=""><a href="/public/news/archive/year/1988/"> 1988 </a></li><li class=""><a href="/public/news/archive/year/1987/"> 1987 </a></li><li class=""><a href="/public/news/archive/year/1986/"> 1986 </a></li><li class=""><a href="/public/news/archive/year/1985/"> 1985 </a></li></ul></li></ul></li><li class="submenu"><a href="/public/announcements/"> Announcements <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-198" class="submenu-aim sublevel"><li class=""><a href="/public/announcements/archive/year/2024/"> 2024 </a></li><li class=""><a href="/public/announcements/archive/year/2023/"> 2023 </a></li><li class=""><a href="/public/announcements/archive/year/2022/"> 2022 </a></li><li class=""><a href="/public/announcements/archive/year/2021/"> 2021 </a></li><li class=""><a href="/public/announcements/archive/year/2020/"> 2020 </a></li><li class=""><a href="/public/announcements/archive/year/2019/"> 2019 </a></li><li class=""><a href="/public/announcements/archive/year/2018/"> 2018 </a></li><li class=""><a href="/public/announcements/archive/year/2017/"> 2017 </a></li><li class=""><a href="/public/announcements/archive/year/2016/"> 2016 </a></li><li class=""><a href="/public/announcements/archive/year/2015/"> 2015 </a></li><li class=""><a href="/public/announcements/archive/year/2014/"> 2014 </a></li><li class=""><a href="/public/announcements/archive/year/2013/"> 2013 </a></li><li class=""><a href="/public/announcements/archive/year/2012/"> 2012 </a></li><li class=""><a href="/public/announcements/archive/year/2011/"> 2011 </a></li><li class=""><a href="/public/announcements/archive/year/2010/"> 2010 </a></li><li class=""><a href="/public/announcements/archive/year/2009/"> 2009 </a></li></ul></li><li class=""><a href="https://www.eso.org/public/blog/"> ESOblog </a></li><li class=""><a href="/public/announcements/webupdates/"> New on eso.org </a></li><li class="submenu"><a href="/public/outreach/pressmedia/"> Press Room <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-217" class="submenu-aim sublevel"><li class=""><a href="/public/outreach/broadcast/"> Broadcast Services </a></li><li class=""><a href="/public/outreach/pressmedia/mediavisits/"> Media Visits </a></li><li class=""><a href="/public/copyright/"> Copyright Notice </a></li></ul></li><li class="submenu"><a href="/public/newsletters/"> ESO Newsletters <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-221" class="submenu-aim sublevel"><li class=""><a href="/public/newsletters/esonews/"> ESO News </a></li><li class=""><a href="/sci/publications/newsletter/"> ESO Science Newsletter </a></li><li class=""><a href="/public/outreach/newsletters/#2"> ESO Media Newsletter </a></li></ul></li><li class=""><a href="/public/news/pitch-your-research/"> Pitch your Research </a></li> </ul> </div> </div> </li> <li><a href="/public/shop/">ESOshop<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-226" class="submenu-aim"> <li class="submenu"><a href="/public/shop/category/"> Shop Products <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-227" class="submenu-aim sublevel"><li class=""><a href="/public/shop/category/annualreport/"> Annual Reports </a></li><li class=""><a href="/public/shop/category/apparel/"> Apparel </a></li><li class=""><a href="/public/shop/category/book/"> Books </a></li><li class=""><a href="/public/shop/category/brochure/"> Brochures </a></li><li class=""><a href="/public/shop/category/calendar/"> Calendars </a></li><li class=""><a href="/public/shop/category/capjournal/"> CAPjournals </a></li><li class=""><a href="/public/shop/category/conferenceitem/"> Conferences </a></li><li class=""><a href="/public/shop/category/donation/"> Donations </a></li><li class=""><a href="/public/shop/category/media/"> DVDs/Bluray/CDs </a></li><li class=""><a href="/public/shop/category/educationalmaterial/"> Educational Material </a></li><li class=""><a href="/public/shop/category/supernovaactivity/"> ESO Supernova Activities </a></li><li class=""><a href="/public/shop/category/flyer/"> Flyers </a></li><li class=""><a href="/public/shop/category/handout/"> Handouts </a></li><li class=""><a href="/public/shop/category/map/"> Maps </a></li><li class=""><a href="/public/shop/category/merchandise/"> Merchandise </a></li><li class=""><a href="/public/shop/category/messenger/"> Messengers </a></li><li class=""><a href="/public/shop/category/mountedimage/"> Mounted Images </a></li><li class=""><a href="/public/shop/category/postcard/"> Postcards </a></li><li class=""><a href="/public/shop/category/printedposter/"> Posters </a></li><li class=""><a href="/public/shop/category/technicaldocument/"> Reports </a></li><li class=""><a href="/public/shop/category/sticker/"> Stickers </a></li></ul></li><li class=""><a href="/public/shop/cart/"> View shopping cart </a></li><li class=""><a href="/public/shop/checkout/"> Checkout </a></li><li class="submenu"><a href="/public/shopinfo/"> Information <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-251" class="submenu-aim sublevel"><li class=""><a href="/public/shopinfo/bulk_orders/"> Bulk Orders </a></li><li class=""><a href="/public/shopinfo/"> Purchasing Steps </a></li><li class=""><a href="/public/shopinfo/payment/"> Payment </a></li><li class=""><a href="/public/shopinfo/shipping/"> Shipping </a></li><li class=""><a href="/public/shopinfo/shopstaff/"> Staff Shopping </a></li><li class=""><a href="/public/shopinfo/terms/"> Terms & Conditions </a></li></ul></li><li class=""><a href="/public/shop/freeorder/"> Free Orders for Educators and Media </a></li> </ul> </div> </div> </li> <li class="current"><a href="/public/teles-instr/">Telescopes & Instruments<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1 current"> <ul id="submenu-aim-259" class="submenu-aim selected current"> <li class="submenu"><a href="/public/teles-instr/paranal-observatory/"> Paranal Observatory <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-260" class="submenu-aim sublevel"><li class="submenu"><a href="/public/teles-instr/paranal-observatory/vlt/"> Very Large Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-261" class="submenu-aim sublevel"><li class="submenu"><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/"> VLT Instruments <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-262" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/4lgsf/"> 4LGSF </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/cubes/"> CUBES </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/crires/"> CRIRES </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/crires+/"> CRIRES+ </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/espresso/"> ESPRESSO </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/eris/"> ERIS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/flames/"> FLAMES </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/fors/"> FORS1 and FORS2 </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/hawk-i/"> HAWK-I </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/isaac/"> ISAAC </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/kmos/"> KMOS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/mad/"> MAD </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/mavis/"> MAVIS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/moons/"> MOONS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/muse/"> MUSE </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/naco/"> NACO </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/sinfoni/"> SINFONI </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/sphere/"> SPHERE </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/uves/"> UVES </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/vimos/"> VIMOS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/vtl-test-cameras/"> VLT Test Cameras </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/visir/"> VISIR </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/x-shooter/"> X-shooter </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/paranal-observatory/vlt/vlt-names/"> VLT Unit Telescopes Names <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-286" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-names/antu/"> Antu </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-names/kueyen/"> Kueyen </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-names/melipal/"> Melipal </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-names/yepun/"> Yepun </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/paranal-observatory/vlt/vlti/"> VLT Interferometer <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-291" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/gravity+/"> GRAVITY+ </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/gravity/"> GRAVITY </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/matisse/"> MATISSE </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/naomi/"> NAOMI </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/pionier/"> PIONIER </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/amber/"> AMBER </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/midi/"> MIDI </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/vlt-instr/vinci/"> VINCI </a></li></ul></li><li class=""><a href="/public/teles-instr/paranal-observatory/vlt/auxiliarytelescopes/"> Auxiliary Telescopes </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/paranal-observatory/surveytelescopes/"> Survey Telescopes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-301" class="submenu-aim sublevel"><li class="submenu"><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vista/"> VISTA <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-302" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vista/mirror/"> The VISTA mirror </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vista/camera/"> VIRCAM </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vista/4most/"> 4MOST </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vista/surveys/"> The VISTA surveys </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vista/consortium/"> The VISTA consortium </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vst/"> VST <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-308" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vst/mirror/"> The VST mirrors </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vst/camera/"> OmegaCAM </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/surveytelescopes/vst/surveys/"> The VST surveys </a></li></ul></li></ul></li><li class=""><a href="/public/teles-instr/paranal-observatory/speculoos/"> SPECULOOS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/ngts/"> NGTS </a></li><li class=""><a href="/public/teles-instr/paranal-observatory/ctao/"> Cherenkov Telescope Array Observatory </a></li></ul></li><li class="submenu current"><a href="/public/teles-instr/lasilla/"> La Silla Observatory <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-315" class="submenu-aim sublevel selected current"><li class="submenu"><a href="/public/teles-instr/lasilla/swedish/"> Swedish–ESO Submillimetre Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-316" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/swedish/simba/"> SIMBA </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/ntt/"> New Technology Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-318" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/ntt/efosc2/"> EFOSC2 </a></li><li class=""><a href="/public/teles-instr/lasilla/ntt/emmi/"> EMMI </a></li><li class=""><a href="/public/teles-instr/lasilla/ntt/irspec/"> IRSPEC </a></li><li class=""><a href="/public/teles-instr/lasilla/ntt/sofi/"> SOFI </a></li><li class=""><a href="/public/teles-instr/lasilla/ntt/soxs/"> SOXS </a></li><li class=""><a href="/public/teles-instr/lasilla/ntt/susi2/"> SUSI and SUSI2 </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/36/"> ESO 3.6-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-325" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/36/adonis/"> ADONIS </a></li><li class=""><a href="/public/teles-instr/lasilla/36/caspec/"> CASPEC </a></li><li class=""><a href="/public/teles-instr/lasilla/36/irspec/"> IRSPEC </a></li><li class=""><a href="/public/teles-instr/lasilla/36/harps/"> HARPS </a></li><li class=""><a href="/public/teles-instr/lasilla/36/mefos/"> MEFOS </a></li><li class=""><a href="/public/teles-instr/lasilla/36/nirps/"> NIRPS </a></li><li class=""><a href="/public/teles-instr/lasilla/36/optopus/"> OPTOPUS </a></li><li class=""><a href="/public/teles-instr/lasilla/36/timmi2/"> TIMMI/2 </a></li><li class=""><a href="/public/teles-instr/lasilla/36/36-infrared-photometer-spectrophotometer/"> Infrared Photometer/Spectrophotometer </a></li><li class=""><a href="/public/teles-instr/lasilla/36/36-standard-photometer/"> Standard Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/36/infrared-specklegraph/"> Infrared Specklegraph </a></li><li class=""><a href="/public/teles-instr/lasilla/36/infrared-speckle-interferometer/"> Infrared Speckle Interferometer </a></li><li class=""><a href="/public/teles-instr/lasilla/36/efosc/"> EFOSC </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/mpg22/"> MPG/ESO 2.2-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-339" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/mpg22/feros/"> FEROS </a></li><li class=""><a href="/public/teles-instr/lasilla/mpg22/grond/"> GROND </a></li><li class=""><a href="/public/teles-instr/lasilla/mpg22/irac2/"> IRAC & IRAC2 </a></li><li class=""><a href="/public/teles-instr/lasilla/mpg22/pisco/"> PISCO </a></li><li class=""><a href="/public/teles-instr/lasilla/mpg22/wfi/"> WFI </a></li><li class=""><a href="/public/teles-instr/lasilla/mpg22/infrared-photometer-spectrophotometer/"> Infrared Photometer/Spectrophotometer </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/swiss/"> Swiss 1.2-metre Leonhard Euler Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-346" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/swiss/coralie/"> CORALIE </a></li></ul></li><li class=""><a href="/public/teles-instr/lasilla/rem/"> Rapid Eye Mount telescope </a></li><li class=""><a href="/public/teles-instr/lasilla/trappist/"> TRAnsiting Planets and PlanetesImals Small Telescope–South </a></li><li class="submenu"><a href="/public/teles-instr/lasilla/danish154/"> Danish 1.54-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-350" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/danish154/coravel/"> CORAVEL </a></li><li class=""><a href="/public/teles-instr/lasilla/danish154/dfosc/"> DFOSC </a></li><li class=""><a href="/public/teles-instr/lasilla/danish154/ccd/"> CCD camera </a></li><li class=""><a href="/public/teles-instr/lasilla/danish154/hb-photometer/"> Hβ Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/danish154/two-channel-photometer/"> Two-Channel Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/danish154/four-channel-photometer/"> Four-Channel Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/danish154/six-channel-photometer/"> Six-Channel uvby-Hβ Photometer </a></li></ul></li><li class=""><a href="/public/teles-instr/lasilla/tarot/"> Télescope à Action Rapide pour les Objets Transitoires </a></li><li class=""><a href="/public/teles-instr/lasilla/1mschmidt/"> ESO 1-metre Schmidt telescope </a></li><li class="submenu"><a href="/public/teles-instr/lasilla/152metre/"> ESO 1.52-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-360" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/152metre/bandc/"> Boller and Chivens Spectrograph </a></li><li class=""><a href="/public/teles-instr/lasilla/152metre/coude/"> Coudé Spectrograph </a></li><li class=""><a href="/public/teles-instr/lasilla/152metre/echelec/"> ECHELEC </a></li><li class=""><a href="/public/teles-instr/lasilla/152metre/rv-cass-spectrograph/"> RV Cass Spectrograph </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/1metre/"> ESO 1-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-365" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/1metre/fideos/"> FIDEOS </a></li><li class=""><a href="/public/teles-instr/lasilla/1metre/infrared-photometer/"> Infrared Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/1metre/single-channel-photometer/"> Single-Channel Photometer </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/05metre/"> ESO 0.5-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-369" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/05metre/single-channel-photometer/"> Single-Channel Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/05metre/double-channel-photometer/"> Double-Channel Photometer </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/coude/"> Coudé Auxiliary Telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-372" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/coude/ces/"> CES </a></li></ul></li><li class=""><a href="/public/teles-instr/lasilla/marly/"> MarLy 1-metre telescope </a></li><li class="submenu current"><a href="/public/teles-instr/lasilla/09metre/"> Dutch 0.9-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-375" class="submenu-aim sublevel selected current current-leaf"><li class=" current current-leaf"><a href="/public/teles-instr/lasilla/09metre/walraven/"> Walraven Photometer </a></li></ul></li><li class=""><a href="/public/teles-instr/lasilla/t70/"> Swiss T70 telescope </a></li><li class="submenu"><a href="/public/teles-instr/lasilla/bochum/"> Bochum 0.61-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-378" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/bochum/bochum-scanner/"> Bochum Scanner </a></li><li class=""><a href="/public/teles-instr/lasilla/bochum/bochum-photometer/"> Bochum Photometer </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/lasilla/danish05/"> Danish 0.5-metre telescope <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-381" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/lasilla/danish05/danish-two-channel-hb-photometer/"> Two-Channel Hβ Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/danish05/danish-four-channel-uvby-photometer/"> Four-Channel uvby Photometer </a></li><li class=""><a href="/public/teles-instr/lasilla/danish05/danish-six-channel-uvby-hb-photometer/"> Six-Channel uvby–Hβ Photometer </a></li></ul></li><li class=""><a href="/public/teles-instr/lasilla/gpo/"> Grand Prisme Objectif telescope </a></li><li class=""><a href="/public/teles-instr/lasilla/swiss04/"> Swiss 0.4-metre telescope </a></li><li class=""><a href="/public/teles-instr/lasilla/marseille/"> Marseille 0.36-metre telescope </a></li><li class=""><a href="/public/teles-instr/lasilla/grb/"> GRB Monitoring System </a></li><li class=""><a href="/public/teles-instr/lasilla/mascara/"> MASCARA </a></li><li class=""><a href="/public/teles-instr/lasilla/blackgem/"> BlackGEM </a></li><li class=""><a href="/public/teles-instr/lasilla/extra/"> ExTrA </a></li><li class=""><a href="/public/teles-instr/lasilla/test-bed/"> Test-Bed Telescope </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/apex/"> APEX <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-393" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/apex/apex-2a/"> APEX–2A </a></li><li class=""><a href="/public/teles-instr/apex/artemis/"> ArTéMiS </a></li><li class=""><a href="/public/teles-instr/apex/aszca/"> ASZCa </a></li><li class=""><a href="/public/teles-instr/apex/champ-plus/"> CHAMP+ </a></li><li class=""><a href="/public/teles-instr/apex/concerto/"> CONCERTO </a></li><li class=""><a href="/public/teles-instr/apex/flash/"> FLASH </a></li><li class=""><a href="/public/teles-instr/apex/flash-plus/"> FLASH+ </a></li><li class=""><a href="/public/teles-instr/apex/laboca/"> LABOCA </a></li><li class=""><a href="/public/teles-instr/apex/mpi_11thz/"> MPI_1.1THz </a></li><li class=""><a href="/public/teles-instr/apex/p-artemis/"> P-ArTéMiS </a></li><li class=""><a href="/public/teles-instr/apex/pi230/"> PI230 </a></li><li class=""><a href="/public/teles-instr/apex/polka/"> PolKa </a></li><li class=""><a href="/public/teles-instr/apex/saboca/"> SABOCA </a></li><li class=""><a href="/public/teles-instr/apex/sepia/"> SEPIA </a></li><li class=""><a href="/public/teles-instr/apex/shefi/"> SHeFI </a></li></ul></li><li class="submenu"><a href="/public/teles-instr/alma/"> ALMA <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-409" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/alma/antennas/"> Antennas </a></li><li class=""><a href="/public/teles-instr/alma/transporters/"> Transporters </a></li><li class=""><a href="/public/teles-instr/alma/interferometry/"> Interferometry </a></li><li class=""><a href="/public/teles-instr/alma/receiver-bands/"> Receiver Bands </a></li><li class=""><a href="/public/teles-instr/alma/residencia/"> ALMA Residencia </a></li></ul></li><li class=""><a href="/public/teles-instr/elt/"> ELT </a></li><li class="submenu"><a href="/public/teles-instr/technology/"> Technology for Telescopes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-416" class="submenu-aim sublevel"><li class=""><a href="/public/teles-instr/technology/active_optics/"> Active Optics </a></li><li class=""><a href="/public/teles-instr/technology/adaptive_optics/"> Adaptive Optics </a></li><li class=""><a href="/public/teles-instr/technology/ifu/"> Integral Field Units </a></li><li class=""><a href="/public/teles-instr/technology/interferometry/"> Interferometry </a></li><li class=""><a href="/public/teles-instr/technology/spectroscopy/"> Spectroscopy </a></li><li class=""><a href="/public/teles-instr/technology/polarimetry/"> Polarimetry </a></li></ul></li><li class=""><a href="/public/teles-instr/instruments/"> Instruments </a></li> </ul> </div> </div> </li> <li><a href="/public/science/">Discoveries<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-424" class="submenu-aim"> <li class=""><a href="/public/science/key-discoveries/"> ESO Key Astronomical Discoveries </a></li><li class=""><a href="/public/science/exoplanets/"> Exoplanets </a></li><li class=""><a href="/public/science/gravitationalwaves/"> Gravitational Wave Sources </a></li><li class="submenu"><a class="no-link children" href="#"> Black Holes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-428" class="submenu-aim sublevel"><li class=""><a href="https://www.eso.org/public/science/event-horizon/"> First image of a black hole </a></li><li class=""><a href="https://www.eso.org/public/science/EHT-MilkyWay/"> First image of the Milky Way central black hole </a></li><li class=""><a href="https://www.eso.org/public/science/gc/"> More about the black hole at the galactic centre </a></li></ul></li><li class=""><a href="/public/science/grb/"> Gamma-Ray Bursts </a></li><li class=""><a href="/public/science/archive/"> Science Archive </a></li> </ul> </div> </div> </li> <li><a href="/public/events/">Events<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-434" class="submenu-aim"> <li class=""><a href="/public/events/press-evt/"> Press Events </a></li><li class="submenu"><a href="/public/events/special-evt/"> Special Events <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-436" class="submenu-aim sublevel"><li class=""><a href="https://www.eso.org/public/events/special-evt/60years/"> ESO at 60 </a></li><li class=""><a href="/public/events/special-evt/eeltblast/"> ELT Groundbreaking </a></li><li class=""><a href="/public/events/special-evt/cafe-and-kosmos/"> Café & Kosmos in Munich </a></li><li class=""><a href="/public/events/special-evt/awesome-universe/"> Awesome Universe </a></li><li class=""><a href="/public/events/special-evt/100ha/"> 100 Hours of Astronomy </a></li><li class=""><a href="/public/events/special-evt/theeye/"> The Eye 3D </a></li><li class=""><a href="/public/events/special-evt/imax-hidden-universe/"> IMAX® 3D Film Hidden Universe </a></li><li class=""><a href="/public/outreach/bond/"> Bond at Paranal </a></li></ul></li><li class="submenu"><a href="/public/events/exhibitions/"> Exhibitions <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-445" class="submenu-aim sublevel"><li class=""><a href="/public/events/exhibitions/perma_exhibitions/"> ESO Permanent Exhibitions </a></li><li class=""><a href="https://www.esof.eu/"> EuroScience Open Forum (ESOF) </a></li></ul></li><li class="submenu"><a href="/public/events/astro-evt/"> Astronomical Events <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-448" class="submenu-aim sublevel"><li class=""><a href="/public/events/astro-evt/solareclipse2019/"> Total Solar Eclipse 2019 </a></li><li class=""><a href="/public/events/astro-evt/mcnaught2007/"> The Comet McNaught 2007 </a></li><li class=""><a href="/public/events/astro-evt/deepimpact/"> Deep Impact - 04.07.2005 </a></li><li class=""><a href="https://www.eso.org/public/outreach/eduoff/vt-2004/"> The Venus Transit - 08.11.2004 </a></li><li class=""><a href="/public/events/astro-evt/leonids99/"> The Leonids - 17.11.1999 </a></li><li class=""><a href="/public/events/astro-evt/eclipse99/"> Solar Eclipse at ESO HQ - 11.08.1999 </a></li><li class=""><a href="/public/events/astro-evt/leonids98/"> The Leonids - 11.1998 </a></li><li class=""><a href="/public/events/astro-evt/pathfinder/"> Mars Pathfinder - 1997 </a></li><li class=""><a href="/public/events/astro-evt/hyakutake/"> Comet Hyakutake - 1997 </a></li><li class=""><a href="/public/events/astro-evt/sl9/"> SL-9 and Jupiter - 1994 </a></li><li class=""><a href="/public/events/astro-evt/hale-bopp/"> Comet Hale Bopp - 1994 </a></li></ul></li> </ul> </div> </div> </li> <li><a href="/public/outreach/">Outreach<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-460" class="submenu-aim"> <li class="submenu"><a href="/public/outreach/eduoff/"> Education <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-461" class="submenu-aim sublevel"><li class=""><a href="/public/products/education/"> Educational Material </a></li><li class=""><a href="https://www.scienceinschool.org/" target="_blank" rel="noopener noreferrer"> Science in School </a></li><li class=""><a href="/public/outreach/eduoff/teacherschools/"> Teacher Schools </a></li><li class="submenu"><a href="/public/outreach/eduoff/prev-programmes/"> Previous Programmes <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-465" class="submenu-aim sublevel"><li class=""><a href="https://www.eso.org/public/outreach/eduoff/prev-programmes/catch-a-star/"> Catch a Star </a></li><li class=""><a href="/public/outreach/eduoff/liu/"> Life in the Universe </a></li><li class=""><a href="/public/outreach/eduoff/pos/"> Physics On Stage </a></li></ul></li><li class=""><a href="http://kids.alma.cl/?lang=en"> ALMA Kids </a></li></ul></li><li class="submenu"><a href="/public/outreach/partnerships/"> Partnerships <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-470" class="submenu-aim sublevel"><li class=""><a href="/public/outreach/partnerships/translators/"> Volunteer Translators </a></li><li class=""><a href="/public/outreach/partnerships/eson/"> ESO Science Outreach Network </a></li><li class="submenu"><a href="/public/outreach/partnerships/chile/"> Collaborations in Chile <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-473" class="submenu-aim sublevel"><li class=""><a href="/public/outreach/partnerships/chile/2010/"> 2010 </a></li><li class=""><a href="/public/outreach/partnerships/chile/2009/"> 2009 </a></li></ul></li><li class=""><a href="/public/outreach/partnerships/organisations/"> ESO Outreach Partner Organisations </a></li><li class=""><a href="/public/outreach/partnerships/educators/"> Informal Educators </a></li><li class=""><a href="/public/outreach/partnerships/photo-ambassadors/"> ESO Photo Ambassadors </a></li><li class=""><a href="/public/outreach/partnerships/music-ambassadors/"> ESO Music Ambassadors </a></li></ul></li><li class=""><a href="https://www.eso.org/public/outreach/first-picture-of-a-black-hole/blog/"> Taking the First Picture of a Black Hole </a></li><li class=""><a href="/public/outreach/gems/"> Cosmic Gems </a></li><li class=""><a href="/public/outreach/social/"> Social Media </a></li><li class=""><a href="/public/outreach/for_planetariums/"> For Planetariums </a></li><li class=""><a href="https://www.eso.org/public/outreach/webcams/"> Webcams </a></li><li class=""><a href="/public/outreach/your_eso_pictures/"> Your ESO Pictures </a></li><li class=""><a href="/public/outreach/astroprize/"> European Astronomy Journalism Prize </a></li><li class="submenu"><a href="/public/outreach/department/"> Our Team <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-487" class="submenu-aim sublevel"><li class=""><a href="/public/outreach/department/students/"> Students and Visitors </a></li><li class=""><a href="https://supernova.eso.org/join-us/"> Join us </a></li></ul></li><li class=""><a href="https://supernova.eso.org/"> ESO Supernova </a></li><li class=""><a href="/public/outreach/art/"> Art at ESO </a></li><li class=""><a href="/public/outreach/data2dome/"> Data2Dome </a></li><li class=""><a href="https://www.eso.org/public/blog/"> ESOblog </a></li><li class=""><a href="/public/outreach/starsateso/"> Stars@ESO </a></li><li class=""><a href="/public/outreach/ai-disclaimer/"> AI Disclaimer </a></li> </ul> </div> </div> </li> <li><a href="/public/products/">Products<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-496" class="submenu-aim"> <li class="submenu"><a class="no-link children" href="#"> Audiovisual and multimedia <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-497" class="submenu-aim sublevel"><li class=""><a href="/public/products/models3d/"> 3D models </a></li><li class=""><a href="/public/products/applications/"> Apps </a></li><li class=""><a href="/public/products/media/"> DVDs and CDs </a></li><li class=""><a href="/public/products/imaxfilms/"> IMAX movies </a></li><li class=""><a href="/public/products/minisites/"> Mini-sites </a></li><li class=""><a href="/public/products/music/"> Music </a></li><li class=""><a href="/public/products/planetariumshows/"> Planetarium shows </a></li><li class=""><a href="/public/products/presentations/"> Presentations </a></li><li class=""><a href="/public/products/soundscapes/"> Soundscapes </a></li><li class=""><a href="https://www.eso.org/public/products/virtualbackgrounds/"> Virtual Backgrounds </a></li><li class=""><a href="/public/products/virtualtours/"> Virtual Tours </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> Periodicals <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-509" class="submenu-aim sublevel"><li class=""><a href="/public/products/messengers/"> Messenger </a></li><li class=""><a href="/public/products/capjournals/"> CAPjournal </a></li><li class=""><a href="/public/products/schools/"> Science in School </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> Print products <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-513" class="submenu-aim sublevel"><li class=""><a href="/public/products/annualreports/"> Annual Reports </a></li><li class=""><a href="/public/products/books/"> Books </a></li><li class=""><a href="/public/products/brochures/"> Brochures </a></li><li class=""><a href="/public/products/bulletins/"> Bulletins </a></li><li class=""><a href="/public/products/calendars/"> Calendars </a></li><li class=""><a href="/public/products/conf_posters/"> Conference posters </a></li><li class=""><a href="/public/products/flyers/"> Flyers </a></li><li class=""><a href="/public/products/handouts/"> Handouts </a></li><li class=""><a href="/public/products/maps/"> Maps </a></li><li class=""><a href="/public/products/presskits/"> Press kits </a></li><li class=""><a href="/public/products/reports/"> Reports </a></li><li class=""><a href="/public/products/postcards/"> Postcards </a></li><li class=""><a href="/public/products/stickers/"> Stickers </a></li><li class=""><a href="/public/products/print_posters/"> Printed posters </a></li><li class=""><a href="/public/products/papermodels/"> Paper models </a></li></ul></li><li class="submenu"><a href="/public/products/merchandise/"> Merchandise <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-529" class="submenu-aim sublevel"><li class=""><a href="/public/products/merchandise/"> Merchandise </a></li><li class=""><a href="/public/products/apparel/"> Apparel </a></li><li class=""><a href="/public/products/mountedimages/"> Mounted images </a></li><li class=""><a href="/public/products/stationery/"> Stationery </a></li></ul></li><li class="submenu"><a class="no-link children" href="#"> Electronic products <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-534" class="submenu-aim sublevel"><li class=""><a href="/public/products/electroniccards/"> Electronic cards </a></li><li class=""><a href="/public/products/elec_posters/"> Electronic posters </a></li><li class=""><a href="/public/products/epublications/"> ePublications </a></li><li class=""><a href="https://www.eso.org/public/products/virtualbackgrounds/"> Virtual Backgrounds </a></li></ul></li><li class=""><a href="/public/products/education/"> Educational material </a></li><li class=""><a href="/public/products/exhibitions/"> Exhibition material </a></li><li class=""><a href="/public/products/logos/"> Logos </a></li><li class=""><a href="/public/shop/"> Order in ESOshop </a></li> </ul> </div> </div> </li> <li><a href="/public/industry/">Business@ESO<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-543" class="submenu-aim"> <li class=""><a href="/public/industry/cp.html"> Procurement at ESO </a></li><li class=""><a href="https://www.eso.org/public/industry/events/"> Industry Events </a></li><li class="submenu"><a href="/public/industry/techtrans/"> Technology Transfer <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-546" class="submenu-aim sublevel"><li class=""><a href="/public/industry/techtrans/technology-developed-by-industry-or-institutes/"> Technology Developed by Industries </a></li><li class=""><a href="/public/industry/techtrans/develeso/"> Novel technologies by ESO </a></li><li class=""><a href="/public/industry/techtrans/developments/"> ESO know-how </a></li></ul></li><li class="submenu"><a href="/public/industry/projects/"> Future Projects <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-550" class="submenu-aim sublevel"><li class=""><a href="/public/industry/projects/elt/"> Working with the ELT </a></li></ul></li><li class="submenu"><a href="/public/industry/safety.html"> Safety <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-552" class="submenu-aim sublevel"><li class=""><a href="/public/industry/safety/emergency.html"> Emergency & Evacuation </a></li><li class=""><a href="/public/industry/safety/traffic.html"> Traffic & Parking at ESO </a></li><li class=""><a href="/public/industry/safety/contractors.html"> Contractors at ESO </a></li></ul></li><li class=""><a href="/public/industry/contact/"> Contact Information </a></li> </ul> </div> </div> </li> <li><a href="https://recruitment.eso.org/">Career Opportunities<span class="fa fa-angle-down level0-children-arrows"></span></a> <span class="mobile-children"> <span class="fa fa-angle-down"></span> </span> <div class="level1-wrapper"> <div class="level1"> <ul id="submenu-aim-557" class="submenu-aim"> <li class=""><a href="https://recruitment.eso.org/"> Recruitment </a></li><li class="submenu"><a href="/public/jobs/conditions/"> Employment Conditions <span class="desktop-children topmenu-arrow fa fa-angle-right"></span></a><span class="mobile-children"><span class="fa fa-angle-down"></span></span><ul id="submenu-aim-559" class="submenu-aim sublevel"><li class=""><a href="/public/jobs/conditions/intstaff/"> International Staff Members </a></li><li class=""><a href="/public/jobs/conditions/localstaff/"> Local Staff Members (Spanish / English) </a></li><li class=""><a href="/public/jobs/conditions/fellows/"> Fellows </a></li><li class=""><a href="/public/jobs/conditions/students/"> Students </a></li><li class=""><a href="/public/jobs/conditions/paidassoc/"> Paid Associates </a></li></ul></li><li class=""><a href="/public/jobs/working-at-eso/"> Working at ESO </a></li><li class=""><a href="/public/jobs/other-information/"> Other Information </a></li><li class=""><a href="/public/jobs/how_to_use/"> How to use this site </a></li> </ul> </div> </div> </li> </ul> </div> </nav> <div id="content" class=""> <div id="eso-side-logo"> <a href="/public/"> <div data-spy="affix" class="affix"> <div class="sprites-esologo"></div> <span>European<br>Southern<br>Observatory</span> </div> </a> </div> <div class="container " id="body"> <div class="row no-page"> <div class="col-md-12"> </div> </div> <div class="row page"> <div class="col-md-12 one-column"> <div id="edit-info-block"> <div id="page-edit-success" class="alert alert-success alert-dismissible" role="alert" style="display: none"> <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">×</span></button> Page saved successfully </div> <div id="page-edit-failure" class="alert alert-danger alert-dismissible" role="alert" style="display: none"> <button type="button" class="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">×</span></button> Couldn't save page :( Please try again. </div> </div> <div class='page-content'> <div id="editable-content"> <h1>Walraven Photometer (decommissioned)</h1> <div class="row"> <div class="col-md-8"> <p dir="ltr"><a href="/public/images/090_dutch_lasilla_1979/"><img style="float: right; padding: 7px 0px 0px 20px;" src="/public/archives/images/medium/090_dutch_lasilla_1979.jpg" border="0" /></a>The Walraven Photometer was designed by Theodore Walraven at Leiden Observatory in the Netherlands, and mounted at the Cassegrain focus of the 36-inch photometric telescope known as the “Lightcollector”, located at the Leiden Southern Station in South Africa in 1958.</p> <p dir="ltr">In 1978 the Leiden Observatory Foundation (LUF) and ESO struck an agreement to move the telescope to ESO’s <a href="http://www.eso.org/public/teles-instr/lasilla/">La Silla Observatory</a>, sharing it equally. The Walraven Photometer was flown back to the Netherlands for long-needed modifications, and the telescope was shipped directly to Chile, seeing first light again in March 1979. After moving to La Silla the “Lightcollector” became known as the <a href="http://www.eso.org/public/teles-instr/lasilla/09metre/">Dutch 0.9-metre telescope</a>.</p> <p dir="ltr">The Walraven Photometer, which had been fully integrated and built around the telescope for greater stability, was modified in such a way that its lower part became detachable. This allowed access to the Cassegrain focus, also to visitor instruments, without affecting its stability.</p> <p dir="ltr">Making use of a clever polarisation optics filter, which provided the possibility to measure simultaneously in five photometric bands, the Walraven Photometer was originally designed with the purpose of studying early-type stars. As it turned out, the location of the photometric passbands also made it very useful for the classification and study of physical parameters of <a href="https://en.wikipedia.org/wiki/Stellar_classification">A, F and G stars</a>. Between South Africa and Chile the Walraven Photometer was used to study OB stars in the Milky Way Galaxy and the Magellanic Clouds, Pulsating variables such as <a href="https://en.wikipedia.org/wiki/Cepheid_variable">Cepheids</a> and <a href="https://en.wikipedia.org/wiki/RR_Lyrae_variable">RR Lyrae stars</a>, stellar metallicity, <a href="https://en.wikipedia.org/wiki/Stellar_kinematics#OB_associations">OB associations</a> as well as <a href="https://en.wikipedia.org/wiki/Cataclysmic_variable_star">cataclysmic and X-ray variables</a> — all because of its near ultraviolet sensitivity.</p> <p dir="ltr">The Walraven Photometer played an important role in data collection for the preparation of ESA's <a href="https://en.wikipedia.org/wiki/Hipparcos">HIPPARCOS</a> satellite.</p> <p dir="ltr">In 1987 the Walraven Photometer was used in photometric measurements of <a href="https://en.wikipedia.org/wiki/SN_1987A">SN 1987A</a>, to monitor the energy distribution of the supernova in near ultraviolet (<a href="http://www.eso.org/public/news/eso8704/">eso8704</a>).</p> <p dir="ltr">Due to its unique design, the Walraven Photometer was highly stable and time-efficient, due to the possibility of using 5 simultaneous channels. Its <a href="https://en.wikipedia.org/wiki/Photometry_(astronomy)">photometric system</a> measured light from the visible to the near ultraviolet, with passbands at the effective wavelengths of 542 nm (V), 427 nm (B), 385 nm (L), 362 nm (U) and 323 nm (W). For this reason it is also known as the Walraven VBLUW Photometer.</p> <p dir="ltr">The Walraven Photometer was decommissioned from the Dutch 0.9-metre telescope in 1991. After 2006 it was returned to Leiden and it is now in the <a href="https://en.wikipedia.org/wiki/Museum_Boerhaave">Boerhaave Museum for the History of Science</a>.</p> </div> <div class="col-md-4"> <table class="table table-bordered" width="100%"> <tbody> <tr> <td> <h3>Walraven Photometer at the Dutch 0.9-metre telescope</h3> <p><small>This table lists the global capabilities of the instrument.</small></p> <table class="table"> <tbody> <tr> <td valign="top" width="80"><strong>Name:</strong></td> <td valign="top">Decommissioned</td> </tr> <tr> <td valign="top" width="80"><strong>Telescope:</strong></td> <td valign="top">Dutch 0.9-metre telescope</td> </tr> <tr> <td valign="top" width="80"><strong>Focus:</strong></td> <td valign="top">Cassegrain f/13.7</td> </tr> <tr> <td valign="top"><strong>Type:</strong></td> <td valign="top">Simultaneous 5 channel photometer</td> </tr> <tr> <td valign="top"><strong>Wavelength coverage:</strong></td> <td valign="top">310–648 nm</td> </tr> <tr> <td valign="top"><strong>Spatial resolution:</strong></td> <td valign="top">0.06mm/″ [standard diaphragm was 16.5″ (1mm)]</td> </tr> <tr> <td valign="top"><strong>Spectral resolution:</strong></td> <td valign="top">0.14 (V) - 0.07 (W)</td> </tr> <tr> <td valign="top"><strong>First Light:</strong></td> <td valign="top"> <p dir="ltr">1958 South Africa<br />1979 La Silla, Chile</p> </td> </tr> <tr> <td valign="top"><strong>Science goal:</strong></td> <td valign="top"> <ul> <li dir="ltr">Classification of OB stars (E(B-V), temperatures, absolute magnitudes, distances)</li> <li dir="ltr">Physical properties of A, F and G stars (temperatures, log geff, stellar metallicity, E(B-V))</li> <li dir="ltr">Variable Stars (all bands simultaneously)</li> </ul> </td> </tr> <tr> <td valign="top"><strong>Active Optics:</strong></td> <td valign="top">No</td> </tr> <tr> <td valign="top"><strong>Images taken with the instrument:</strong></td> <td valign="top"><a href="http://www.eso.org/public/images/archive/search/?ranking=0&fov=0&release_id=&minimum_size=0&description=&published_until_year=0&credit=&published_until_month=0&title=&subject_name=&instrument=102&published_until_day=0&published_since_day=0&published_since_month=0&id=&published_since_year=0">Link</a></td> </tr> <tr> <td valign="top"><strong>Images of the instrument:</strong></td> <td valign="top"><a href="/public/images/archive/search/?adv=&subject_name=Walraven">Link</a></td> </tr> <tr> <td valign="top"><strong>Press Releases with the instrument:</strong></td> <td valign="top"><a href="/public/news/eso8704/">Link</a></td> </tr> <tr> <td valign="top"><strong>Consortium:</strong></td> <td valign="top"> <ul> <li dir="ltr">ESO</li> <li dir="ltr">Leids Universiteits Fonds</li> </ul> </td> </tr> </tbody> </table> </td> </tr> </tbody> </table> </div> </div> </div> </div> </div> </div> </div>  <div class="row footernote"> <div class="col-xs-12 col-md-3"> <a href="mailto:information@eso.org">Send us your comments!</a> </div> <div class="col-xs-12 col-md-3"> <a href="/public/outreach/newsletters/esonews/">Subscribe to receive news from ESO in your language</a> </div> <div class="col-xs-12 col-md-3"> <a href="https://www.cdn77.com">Accelerated by CDN77</a> </div> <div class="col-xs-12 col-md-3"> <a href="/public/about-eso/privacy/">Terms & Conditions</a> </div> </div> <link href="/public/archives/djp/css/extras.d3e54451ebbb.css" rel="stylesheet" type="text/css" /> <script type="text/javascript">var MEDIA_URL = "/public/archives/"</script> <script type="text/javascript" src="/public/archives/djp/js/main.04a7335af5a0.js" charset="utf-8"></script> </div>  <div id="social-share" class="hidden-print"> <div class="link facebook" data-toggle="tooltip" data-placement="right" title="Share on Facebook"> <a href="https://www.facebook.com/sharer/sharer.php?u=https://www.eso.org/public/teles-instr/lasilla/09metre/walraven/" target="_blank" rel="noopener noreferrer"><i class="fa-brands fa-facebook-f" aria-hidden="true"></i></a> </div> <div class="link twitter" data-toggle="tooltip" data-placement="right" title="Share on X/Twitter"> <a href="https://twitter.com/intent/tweet?url=https://www.eso.org/public/teles-instr/lasilla/09metre/walraven/&text=The Walraven Photometer&via=ESO" target="_blank" rel="noopener noreferrer"><i class="fa-brands fa-x-twitter"></i></i></a> </div> <div class="link pinterest" data-toggle="tooltip" data-placement="right" title="Share on Pinterest"> <a href="https://pinterest.com/pin/create/button/?url=https://www.eso.org/public/teles-instr/lasilla/09metre/walraven/&media=&description=The Walraven Photometer" target="_blank" rel="noopener noreferrer"><i class="fa-brands fa-pinterest-p" aria-hidden="true"></i></a> </div> <div class="link print" data-toggle="tooltip" data-placement="right" title="Print"> <a href="javascript:window.print()" target="_blank" rel="noopener noreferrer"><i class="fa fa-print" aria-hidden="true"></i></a> </div> <div class="link email" data-toggle="tooltip" data-placement="right" title="Share by email"> <a href="mailto:%20?subject=ESO — The Walraven Photometer&body=https://www.eso.org/public/teles-instr/lasilla/09metre/walraven/" target="_blank" rel="noopener noreferrer"><i class="fa-regular fa-envelope" aria-hidden="true"></i></a> </div> </div> <script> $('[data-toggle="tooltip"]').tooltip(); </script> <input type='hidden' name='csrfmiddlewaretoken' value='HRMqvXzfYHv8Odj84p2XPp5S0Lo7hv5nqCJzP8gneJnEcofKUT9OozeaBJ68mSHc' /> </body> </html>

CINXE.COM

The Walraven Photometer | ESO