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<span>Uses</span> </div> </a> <ul id="toc-Uses-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Mechanism" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Mechanism"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Mechanism</span> </div> </a> <button aria-controls="toc-Mechanism-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Mechanism subsection</span> </button> <ul id="toc-Mechanism-sublist" class="vector-toc-list"> <li id="toc-Time_zones" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Time_zones"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Time zones</span> </div> </a> <ul id="toc-Time_zones-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Daylight_saving_time" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Daylight_saving_time"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Daylight saving time</span> </div> </a> <ul id="toc-Daylight_saving_time-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-History" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#History"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>History</span> </div> </a> <button aria-controls="toc-History-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle History subsection</span> </button> <ul id="toc-History-sublist" class="vector-toc-list"> <li id="toc-Current_number_of_leap_seconds" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Current_number_of_leap_seconds"> <div class="vector-toc-text"> <span class="vector-toc-numb">4.1</span> <span>Current number of leap seconds</span> </div> </a> <ul id="toc-Current_number_of_leap_seconds-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Rationale" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Rationale"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Rationale</span> </div> </a> <ul id="toc-Rationale-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Future" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Future"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>Future</span> </div> </a> <ul id="toc-Future-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>See also</span> </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">8</span> <span>References</span> </div> </a> <button aria-controls="toc-References-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle References subsection</span> </button> <ul id="toc-References-sublist" class="vector-toc-list"> <li id="toc-Notes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Notes"> <div class="vector-toc-text"> <span class="vector-toc-numb">8.1</span> <span>Notes</span> </div> </a> <ul id="toc-Notes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Citations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Citations"> <div class="vector-toc-text"> <span class="vector-toc-numb">8.2</span> <span>Citations</span> </div> </a> <ul id="toc-Citations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-General_and_cited_sources" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#General_and_cited_sources"> <div class="vector-toc-text"> <span class="vector-toc-numb">8.3</span> <span>General and cited sources</span> </div> </a> <ul id="toc-General_and_cited_sources-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">9</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Toggle the table of contents</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Coordinated Universal Time</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 147 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-147" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">147 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/Geko%C3%B6rdineerde_Universele_Tyd" title="Gekoördineerde Universele Tyd – Afrikaans" lang="af" hreflang="af" data-title="Gekoördineerde Universele Tyd" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-als mw-list-item"><a href="https://als.wikipedia.org/wiki/UTC" title="UTC – Alemannic" lang="gsw" hreflang="gsw" data-title="UTC" data-language-autonym="Alemannisch" data-language-local-name="Alemannic" class="interlanguage-link-target"><span>Alemannisch</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%AA%D9%88%D9%82%D9%8A%D8%AA_%D8%B9%D8%A7%D9%84%D9%85%D9%8A_%D9%85%D9%86%D8%B3%D9%82" title="توقيت عالمي منسق – Arabic" lang="ar" hreflang="ar" data-title="توقيت عالمي منسق" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-an mw-list-item"><a href="https://an.wikipedia.org/wiki/Tiempo_Universal_Coordinau" title="Tiempo Universal Coordinau – Aragonese" lang="an" hreflang="an" data-title="Tiempo Universal Coordinau" data-language-autonym="Aragonés" data-language-local-name="Aragonese" class="interlanguage-link-target"><span>Aragonés</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/Tiempu_Coordin%C3%A1u_Universal" title="Tiempu Coordináu Universal – Asturian" lang="ast" hreflang="ast" data-title="Tiempu Coordináu Universal" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-gn mw-list-item"><a href="https://gn.wikipedia.org/wiki/%C3%81ra_pav%E1%BA%BD_omohend%C3%A1va" title="Ára pavẽ omohendáva – Guarani" lang="gn" hreflang="gn" data-title="Ára pavẽ omohendáva" data-language-autonym="Avañe'ẽ" data-language-local-name="Guarani" class="interlanguage-link-target"><span>Avañe'ẽ</span></a></li><li class="interlanguage-link interwiki-av mw-list-item"><a href="https://av.wikipedia.org/wiki/UTC" title="UTC – Avaric" lang="av" hreflang="av" data-title="UTC" data-language-autonym="Авар" data-language-local-name="Avaric" class="interlanguage-link-target"><span>Авар</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/%C3%9Cmumd%C3%BCnya_vaxt%C4%B1" title="Ümumdünya vaxtı – Azerbaijani" lang="az" hreflang="az" data-title="Ümumdünya vaxtı" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-azb mw-list-item"><a href="https://azb.wikipedia.org/wiki/%D8%AF%D9%88%D9%86%DB%8C%D8%A7%D9%86%DB%8C%D9%86_%D8%A7%DB%8C%D8%B3%D8%AA%D8%A7%D9%86%D8%AF%D8%A7%D8%B1%D8%AF_%D8%B2%D8%A7%D9%85%D8%A7%D9%86%DB%8C" title="دونیانین ایستاندارد زامانی – South Azerbaijani" lang="azb" hreflang="azb" data-title="دونیانین ایستاندارد زامانی" data-language-autonym="تۆرکجه" data-language-local-name="South Azerbaijani" class="interlanguage-link-target"><span>تۆرکجه</span></a></li><li class="interlanguage-link interwiki-ban mw-list-item"><a href="https://ban.wikipedia.org/wiki/Galah_Universal_Kakoordinasi" title="Galah Universal Kakoordinasi – Balinese" lang="ban" hreflang="ban" data-title="Galah Universal Kakoordinasi" data-language-autonym="Basa Bali" data-language-local-name="Balinese" class="interlanguage-link-target"><span>Basa Bali</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%B8%E0%A6%B0%E0%A7%8D%E0%A6%AC%E0%A6%9C%E0%A6%A8%E0%A7%80%E0%A6%A8_%E0%A6%B8%E0%A6%AE%E0%A6%A8%E0%A7%8D%E0%A6%AC%E0%A6%BF%E0%A6%A4_%E0%A6%B8%E0%A6%AE%E0%A6%AF%E0%A6%BC" title="সর্বজনীন সমন্বিত সময় – Bangla" lang="bn" hreflang="bn" data-title="সর্বজনীন সমন্বিত সময়" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bjn mw-list-item"><a href="https://bjn.wikipedia.org/wiki/Waktu_Universal_Takoordinasi" title="Waktu Universal Takoordinasi – Banjar" lang="bjn" hreflang="bjn" data-title="Waktu Universal Takoordinasi" data-language-autonym="Banjar" data-language-local-name="Banjar" class="interlanguage-link-target"><span>Banjar</span></a></li><li class="interlanguage-link interwiki-zh-min-nan mw-list-item"><a href="https://zh-min-nan.wikipedia.org/wiki/Hia%CC%8Dp-t%C4%93ng_S%C3%A8-k%C3%A0i-s%C3%AE" title="Hia̍p-tēng Sè-kài-sî – Minnan" lang="nan" hreflang="nan" data-title="Hia̍p-tēng Sè-kài-sî" data-language-autonym="閩南語 / Bân-lâm-gú" data-language-local-name="Minnan" class="interlanguage-link-target"><span>閩南語 / Bân-lâm-gú</span></a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/%D0%A3%D0%BD%D1%96%D0%B2%D0%B5%D1%80%D1%81%D0%B0%D0%BB%D1%8C%D0%BD%D1%8B_%D0%BA%D0%B0%D0%B0%D1%80%D0%B4%D1%8B%D0%BD%D0%B0%D0%B2%D0%B0%D0%BD%D1%8B_%D1%87%D0%B0%D1%81" title="Універсальны каардынаваны час – Belarusian" lang="be" hreflang="be" data-title="Універсальны каардынаваны час" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target"><span>Беларуская</span></a></li><li class="interlanguage-link interwiki-be-x-old mw-list-item"><a href="https://be-tarask.wikipedia.org/wiki/%D0%A3%D0%BD%D1%96%D0%B2%D1%8D%D1%80%D1%81%D0%B0%D0%BB%D1%8C%D0%BD%D1%8B_%D0%BA%D0%B0%D0%B0%D1%80%D0%B4%D1%8B%D0%BD%D0%B0%D0%B2%D0%B0%D0%BD%D1%8B_%D1%87%D0%B0%D1%81" title="Унівэрсальны каардынаваны час – Belarusian (Taraškievica orthography)" lang="be-tarask" hreflang="be-tarask" data-title="Унівэрсальны каардынаваны час" data-language-autonym="Беларуская (тарашкевіца)" data-language-local-name="Belarusian (Taraškievica orthography)" class="interlanguage-link-target"><span>Беларуская (тарашкевіца)</span></a></li><li class="interlanguage-link interwiki-bh mw-list-item"><a href="https://bh.wikipedia.org/wiki/%E0%A4%95%E0%A5%8B%E0%A4%91%E0%A4%B0%E0%A5%8D%E0%A4%A1%E0%A4%BF%E0%A4%A8%E0%A5%87%E0%A4%9F%E0%A5%87%E0%A4%A1_%E0%A4%AF%E0%A5%82%E0%A4%A8%E0%A4%BF%E0%A4%B5%E0%A4%B0%E0%A5%8D%E0%A4%B8%E0%A4%B2_%E0%A4%9F%E0%A4%BE%E0%A4%87%E0%A4%AE" title="कोऑर्डिनेटेड यूनिवर्सल टाइम – Bhojpuri" lang="bh" hreflang="bh" data-title="कोऑर्डिनेटेड यूनिवर्सल टाइम" data-language-autonym="भोजपुरी" data-language-local-name="Bhojpuri" class="interlanguage-link-target"><span>भोजपुरी</span></a></li><li class="interlanguage-link interwiki-bcl mw-list-item"><a href="https://bcl.wikipedia.org/wiki/Pankin%C3%A0ban_na_Batayan_kan_Oras" title="Pankinàban na Batayan kan Oras – Central Bikol" lang="bcl" hreflang="bcl" data-title="Pankinàban na Batayan kan Oras" data-language-autonym="Bikol Central" data-language-local-name="Central Bikol" class="interlanguage-link-target"><span>Bikol Central</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BE%D1%80%D0%B4%D0%B8%D0%BD%D0%B8%D1%80%D0%B0%D0%BD%D0%BE_%D1%83%D0%BD%D0%B8%D0%B2%D0%B5%D1%80%D1%81%D0%B0%D0%BB%D0%BD%D0%BE_%D0%B2%D1%80%D0%B5%D0%BC%D0%B5" title="Координирано универсално време – Bulgarian" lang="bg" hreflang="bg" data-title="Координирано универсално време" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bar mw-list-item"><a href="https://bar.wikipedia.org/wiki/Koordiniade_Wejdzeid" title="Koordiniade Wejdzeid – Bavarian" lang="bar" hreflang="bar" data-title="Koordiniade Wejdzeid" data-language-autonym="Boarisch" data-language-local-name="Bavarian" class="interlanguage-link-target"><span>Boarisch</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/Koordinirano_svjetsko_vrijeme" title="Koordinirano svjetsko vrijeme – Bosnian" lang="bs" hreflang="bs" data-title="Koordinirano svjetsko vrijeme" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/UTC" title="UTC – Breton" lang="br" hreflang="br" data-title="UTC" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Temps_universal_coordinat" title="Temps universal coordinat – Catalan" lang="ca" hreflang="ca" data-title="Temps universal coordinat" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Koordinovan%C3%BD_sv%C4%9Btov%C3%BD_%C4%8Das" title="Koordinovaný světový čas – Czech" lang="cs" hreflang="cs" data-title="Koordinovaný světový čas" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-cy mw-list-item"><a href="https://cy.wikipedia.org/wiki/UTC" title="UTC – Welsh" lang="cy" hreflang="cy" data-title="UTC" data-language-autonym="Cymraeg" data-language-local-name="Welsh" class="interlanguage-link-target"><span>Cymraeg</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/UTC" title="UTC – Danish" lang="da" hreflang="da" data-title="UTC" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-se mw-list-item"><a href="https://se.wikipedia.org/wiki/UTC" title="UTC – Northern Sami" lang="se" hreflang="se" data-title="UTC" data-language-autonym="Davvisámegiella" data-language-local-name="Northern Sami" class="interlanguage-link-target"><span>Davvisámegiella</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Koordinierte_Weltzeit" title="Koordinierte Weltzeit – German" lang="de" hreflang="de" data-title="Koordinierte Weltzeit" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-dv mw-list-item"><a href="https://dv.wikipedia.org/wiki/%DE%94%DE%AB.%DE%93%DE%A9.%DE%90%DE%A9." title="ޔޫ.ޓީ.ސީ. – Divehi" lang="dv" hreflang="dv" data-title="ޔޫ.ޓީ.ސީ." data-language-autonym="ދިވެހިބަސް" data-language-local-name="Divehi" class="interlanguage-link-target"><span>ދިވެހިބަސް</span></a></li><li class="interlanguage-link interwiki-dsb mw-list-item"><a href="https://dsb.wikipedia.org/wiki/Koordin%C4%9Browany_sw%C4%9Btowy_cas" title="Koordiněrowany swětowy cas – Lower Sorbian" lang="dsb" hreflang="dsb" data-title="Koordiněrowany swětowy cas" data-language-autonym="Dolnoserbski" data-language-local-name="Lower Sorbian" class="interlanguage-link-target"><span>Dolnoserbski</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/UTC" title="UTC – Estonian" lang="et" hreflang="et" data-title="UTC" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%A3%CF%85%CE%BD%CF%84%CE%BF%CE%BD%CE%B9%CF%83%CE%BC%CE%AD%CE%BD%CE%B7_%CE%A0%CE%B1%CE%B3%CE%BA%CF%8C%CF%83%CE%BC%CE%B9%CE%B1_%CE%8F%CF%81%CE%B1" title="Συντονισμένη Παγκόσμια Ώρα – Greek" lang="el" hreflang="el" data-title="Συντονισμένη Παγκόσμια Ώρα" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Tiempo_universal_coordinado" title="Tiempo universal coordinado – Spanish" lang="es" hreflang="es" data-title="Tiempo universal coordinado" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Universala_Tempo_Kunordigita" title="Universala Tempo Kunordigita – Esperanto" lang="eo" hreflang="eo" data-title="Universala Tempo Kunordigita" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/UTC" title="UTC – Basque" lang="eu" hreflang="eu" data-title="UTC" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B3%D8%A7%D8%B9%D8%AA_%D9%87%D9%85%D8%A7%D9%87%D9%86%DA%AF_%D8%AC%D9%87%D8%A7%D9%86%DB%8C" title="ساعت هماهنگ جهانی – Persian" lang="fa" hreflang="fa" data-title="ساعت هماهنگ جهانی" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fo mw-list-item"><a href="https://fo.wikipedia.org/wiki/UTC" title="UTC – Faroese" lang="fo" hreflang="fo" data-title="UTC" data-language-autonym="Føroyskt" data-language-local-name="Faroese" class="interlanguage-link-target"><span>Føroyskt</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Temps_universel_coordonn%C3%A9" title="Temps universel coordonné – French" lang="fr" hreflang="fr" data-title="Temps universel coordonné" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Ko%C3%B6rdinearre_Wr%C3%A2ldtiid" title="Koördinearre Wrâldtiid – Western Frisian" lang="fy" hreflang="fy" data-title="Koördinearre Wrâldtiid" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target"><span>Frysk</span></a></li><li class="interlanguage-link interwiki-fur mw-list-item"><a href="https://fur.wikipedia.org/wiki/Timp_coorden%C3%A2t_univers%C3%A2l" title="Timp coordenât universâl – Friulian" lang="fur" hreflang="fur" data-title="Timp coordenât universâl" data-language-autonym="Furlan" data-language-local-name="Friulian" class="interlanguage-link-target"><span>Furlan</span></a></li><li class="interlanguage-link interwiki-ga mw-list-item"><a href="https://ga.wikipedia.org/wiki/Am_Uil%C3%ADoch_Comheagartha" title="Am Uilíoch Comheagartha – Irish" lang="ga" hreflang="ga" data-title="Am Uilíoch Comheagartha" data-language-autonym="Gaeilge" data-language-local-name="Irish" class="interlanguage-link-target"><span>Gaeilge</span></a></li><li class="interlanguage-link interwiki-gv mw-list-item"><a href="https://gv.wikipedia.org/wiki/Traa_Cho-chadjin_Cho-oardit" title="Traa Cho-chadjin Cho-oardit – Manx" lang="gv" hreflang="gv" data-title="Traa Cho-chadjin Cho-oardit" data-language-autonym="Gaelg" data-language-local-name="Manx" class="interlanguage-link-target"><span>Gaelg</span></a></li><li class="interlanguage-link interwiki-gd mw-list-item"><a href="https://gd.wikipedia.org/wiki/%C3%80m_Uile-choitcheann_Co-%C3%B2rdanaichte" title="Àm Uile-choitcheann Co-òrdanaichte – Scottish Gaelic" lang="gd" hreflang="gd" data-title="Àm Uile-choitcheann Co-òrdanaichte" data-language-autonym="Gàidhlig" data-language-local-name="Scottish Gaelic" class="interlanguage-link-target"><span>Gàidhlig</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/Tempo_Universal_Coordinado" title="Tempo Universal Coordinado – Galician" lang="gl" hreflang="gl" data-title="Tempo Universal Coordinado" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-inh mw-list-item"><a href="https://inh.wikipedia.org/wiki/UTC" title="UTC – Ingush" lang="inh" hreflang="inh" data-title="UTC" data-language-autonym="ГӀалгӀай" data-language-local-name="Ingush" class="interlanguage-link-target"><span>ГӀалгӀай</span></a></li><li class="interlanguage-link interwiki-gan mw-list-item"><a href="https://gan.wikipedia.org/wiki/%E5%8D%94%E8%AA%BF%E4%B8%96%E7%95%8C%E6%99%82" title="協調世界時 – Gan" lang="gan" hreflang="gan" data-title="協調世界時" data-language-autonym="贛語" data-language-local-name="Gan" class="interlanguage-link-target"><span>贛語</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%ED%98%91%EC%A0%95_%EC%84%B8%EA%B3%84%EC%8B%9C" title="협정 세계시 – Korean" lang="ko" hreflang="ko" data-title="협정 세계시" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/%D5%80%D5%A1%D5%B4%D5%A1%D5%B7%D5%AD%D5%A1%D6%80%D5%B0%D5%A1%D5%B5%D5%AB%D5%B6_%D5%AF%D5%B8%D5%B8%D6%80%D5%A4%D5%AB%D5%B6%D5%A1%D6%81%D5%BE%D5%A1%D5%AE_%D5%AA%D5%A1%D5%B4%D5%A1%D5%B6%D5%A1%D5%AF" title="Համաշխարհային կոորդինացված ժամանակ – Armenian" lang="hy" hreflang="hy" data-title="Համաշխարհային կոորդինացված ժամանակ" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target"><span>Հայերեն</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A5%8D%E0%A4%B5_%E0%A4%A8%E0%A4%BF%E0%A4%B0%E0%A5%8D%E0%A4%A6%E0%A5%87%E0%A4%B6%E0%A4%BE%E0%A4%82%E0%A4%95%E0%A4%BF%E0%A4%A4_%E0%A4%95%E0%A4%BE%E0%A4%B2" title="सार्व निर्देशांकित काल – Hindi" lang="hi" hreflang="hi" data-title="सार्व निर्देशांकित काल" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hsb mw-list-item"><a href="https://hsb.wikipedia.org/wiki/Koordinowany_sw%C4%9Btowy_%C4%8Das" title="Koordinowany swětowy čas – Upper Sorbian" lang="hsb" hreflang="hsb" data-title="Koordinowany swětowy čas" data-language-autonym="Hornjoserbsce" data-language-local-name="Upper Sorbian" class="interlanguage-link-target"><span>Hornjoserbsce</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Koordinirano_svjetsko_vrijeme" title="Koordinirano svjetsko vrijeme – Croatian" lang="hr" hreflang="hr" data-title="Koordinirano svjetsko vrijeme" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/UTC" title="UTC – Ido" lang="io" hreflang="io" data-title="UTC" data-language-autonym="Ido" data-language-local-name="Ido" class="interlanguage-link-target"><span>Ido</span></a></li><li class="interlanguage-link interwiki-ig mw-list-item"><a href="https://ig.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Igbo" lang="ig" hreflang="ig" data-title="Coordinated Universal Time" data-language-autonym="Igbo" data-language-local-name="Igbo" class="interlanguage-link-target"><span>Igbo</span></a></li><li class="interlanguage-link interwiki-ilo mw-list-item"><a href="https://ilo.wikipedia.org/wiki/Panagpapada_ti_Sangalubongan_nga_Oras" title="Panagpapada ti Sangalubongan nga Oras – Iloko" lang="ilo" hreflang="ilo" data-title="Panagpapada ti Sangalubongan nga Oras" data-language-autonym="Ilokano" data-language-local-name="Iloko" class="interlanguage-link-target"><span>Ilokano</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Waktu_Universal_Terkoordinasi" title="Waktu Universal Terkoordinasi – Indonesian" lang="id" hreflang="id" data-title="Waktu Universal Terkoordinasi" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-ia mw-list-item"><a href="https://ia.wikipedia.org/wiki/Universal_Tempore_Coordinate" title="Universal Tempore Coordinate – Interlingua" lang="ia" hreflang="ia" data-title="Universal Tempore Coordinate" data-language-autonym="Interlingua" data-language-local-name="Interlingua" class="interlanguage-link-target"><span>Interlingua</span></a></li><li class="interlanguage-link interwiki-zu mw-list-item"><a href="https://zu.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Zulu" lang="zu" hreflang="zu" data-title="Coordinated Universal Time" data-language-autonym="IsiZulu" data-language-local-name="Zulu" class="interlanguage-link-target"><span>IsiZulu</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/UTC" title="UTC – Icelandic" lang="is" hreflang="is" data-title="UTC" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Tempo_coordinato_universale" title="Tempo coordinato universale – Italian" lang="it" hreflang="it" data-title="Tempo coordinato universale" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%96%D7%9E%D7%9F_%D7%90%D7%95%D7%A0%D7%99%D7%91%D7%A8%D7%A1%D7%9C%D7%99_%D7%9E%D7%AA%D7%95%D7%90%D7%9D" title="זמן אוניברסלי מתואם – Hebrew" lang="he" hreflang="he" data-title="זמן אוניברסלי מתואם" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-jv mw-list-item"><a href="https://jv.wikipedia.org/wiki/Wektu_Universal_Kakoordhinasi" title="Wektu Universal Kakoordhinasi – Javanese" lang="jv" hreflang="jv" data-title="Wektu Universal Kakoordhinasi" data-language-autonym="Jawa" data-language-local-name="Javanese" class="interlanguage-link-target"><span>Jawa</span></a></li><li class="interlanguage-link interwiki-kn mw-list-item"><a href="https://kn.wikipedia.org/wiki/%E0%B2%9C%E0%B2%BE%E0%B2%97%E0%B2%A4%E0%B2%BF%E0%B2%95_%E0%B2%B8%E0%B2%AE%E0%B2%AF%E0%B2%A6_%E0%B2%A8%E0%B2%BF%E0%B2%B0%E0%B3%8D%E0%B2%A6%E0%B3%87%E0%B2%B6%E0%B2%BE%E0%B2%82%E0%B2%95" title="ಜಾಗತಿಕ ಸಮಯದ ನಿರ್ದೇಶಾಂಕ – Kannada" lang="kn" hreflang="kn" data-title="ಜಾಗತಿಕ ಸಮಯದ ನಿರ್ದೇಶಾಂಕ" data-language-autonym="ಕನ್ನಡ" data-language-local-name="Kannada" class="interlanguage-link-target"><span>ಕನ್ನಡ</span></a></li><li class="interlanguage-link interwiki-ka mw-list-item"><a href="https://ka.wikipedia.org/wiki/%E1%83%9B%E1%83%A1%E1%83%9D%E1%83%A4%E1%83%9A%E1%83%98%E1%83%9D_%E1%83%99%E1%83%9D%E1%83%9D%E1%83%A0%E1%83%93%E1%83%98%E1%83%9C%E1%83%98%E1%83%A0%E1%83%94%E1%83%91%E1%83%A3%E1%83%9A%E1%83%98_%E1%83%93%E1%83%A0%E1%83%9D" title="მსოფლიო კოორდინირებული დრო – Georgian" lang="ka" hreflang="ka" data-title="მსოფლიო კოორდინირებული დრო" data-language-autonym="ქართული" data-language-local-name="Georgian" class="interlanguage-link-target"><span>ქართული</span></a></li><li class="interlanguage-link interwiki-ks mw-list-item"><a href="https://ks.wikipedia.org/wiki/%D8%B9%D8%A7%D9%84%D9%85%DB%8C_%D9%88%D9%8E%D9%82%D9%95%D8%AA" title="عالمی وَقٕت – Kashmiri" lang="ks" hreflang="ks" data-title="عالمی وَقٕت" data-language-autonym="कॉशुर / کٲشُر" data-language-local-name="Kashmiri" class="interlanguage-link-target"><span>कॉशुर / کٲشُر</span></a></li><li class="interlanguage-link interwiki-kk mw-list-item"><a href="https://kk.wikipedia.org/wiki/%D0%94%D2%AF%D0%BD%D0%B8%D0%B5%D0%B6%D2%AF%D0%B7%D1%96%D0%BB%D1%96%D0%BA_%D2%AF%D0%B9%D0%BB%D0%B5%D1%81%D1%82%D1%96%D1%80%D1%96%D0%BB%D0%B3%D0%B5%D0%BD_%D1%83%D0%B0%D2%9B%D1%8B%D1%82" title="Дүниежүзілік үйлестірілген уақыт – Kazakh" lang="kk" hreflang="kk" data-title="Дүниежүзілік үйлестірілген уақыт" data-language-autonym="Қазақша" data-language-local-name="Kazakh" class="interlanguage-link-target"><span>Қазақша</span></a></li><li class="interlanguage-link interwiki-sw mw-list-item"><a href="https://sw.wikipedia.org/wiki/Muda_sanifu_wa_dunia" title="Muda sanifu wa dunia – Swahili" lang="sw" hreflang="sw" data-title="Muda sanifu wa dunia" data-language-autonym="Kiswahili" data-language-local-name="Swahili" class="interlanguage-link-target"><span>Kiswahili</span></a></li><li class="interlanguage-link interwiki-ku mw-list-item"><a href="https://ku.wikipedia.org/wiki/Dema_gerd%C3%BBn%C3%AE_ya_bisaz%C3%BBmankir%C3%AE" title="Dema gerdûnî ya bisazûmankirî – Kurdish" lang="ku" hreflang="ku" data-title="Dema gerdûnî ya bisazûmankirî" data-language-autonym="Kurdî" data-language-local-name="Kurdish" class="interlanguage-link-target"><span>Kurdî</span></a></li><li class="interlanguage-link interwiki-ky mw-list-item"><a href="https://ky.wikipedia.org/wiki/%D0%94%D2%AF%D0%B9%D0%BD%D3%A9%D0%BB%D2%AF%D0%BA_%D1%82%D0%B0%D0%BA%D1%82%D0%B0%D0%BB%D0%B3%D0%B0%D0%BD_%D1%83%D0%B1%D0%B0%D0%BA%D1%8B%D1%82" title="Дүйнөлүк такталган убакыт – Kyrgyz" lang="ky" hreflang="ky" data-title="Дүйнөлүк такталган убакыт" data-language-autonym="Кыргызча" data-language-local-name="Kyrgyz" class="interlanguage-link-target"><span>Кыргызча</span></a></li><li class="interlanguage-link interwiki-la mw-list-item"><a href="https://la.wikipedia.org/wiki/UTC" title="UTC – Latin" lang="la" hreflang="la" data-title="UTC" data-language-autonym="Latina" data-language-local-name="Latin" class="interlanguage-link-target"><span>Latina</span></a></li><li class="interlanguage-link interwiki-lv mw-list-item"><a href="https://lv.wikipedia.org/wiki/Univers%C4%81lais_koordin%C4%93tais_laiks" title="Universālais koordinētais laiks – Latvian" lang="lv" hreflang="lv" data-title="Universālais koordinētais laiks" data-language-autonym="Latviešu" data-language-local-name="Latvian" class="interlanguage-link-target"><span>Latviešu</span></a></li><li class="interlanguage-link interwiki-lb mw-list-item"><a href="https://lb.wikipedia.org/wiki/Koordin%C3%A9iert_Weltz%C3%A4it" title="Koordinéiert Weltzäit – Luxembourgish" lang="lb" hreflang="lb" data-title="Koordinéiert Weltzäit" data-language-autonym="Lëtzebuergesch" data-language-local-name="Luxembourgish" class="interlanguage-link-target"><span>Lëtzebuergesch</span></a></li><li class="interlanguage-link interwiki-lez mw-list-item"><a href="https://lez.wikipedia.org/wiki/UTC" title="UTC – Lezghian" lang="lez" hreflang="lez" data-title="UTC" data-language-autonym="Лезги" data-language-local-name="Lezghian" class="interlanguage-link-target"><span>Лезги</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Pasaulinis_koordinuotasis_laikas" title="Pasaulinis koordinuotasis laikas – Lithuanian" lang="lt" hreflang="lt" data-title="Pasaulinis koordinuotasis laikas" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-li mw-list-item"><a href="https://li.wikipedia.org/wiki/UTC" title="UTC – Limburgish" lang="li" hreflang="li" data-title="UTC" data-language-autonym="Limburgs" data-language-local-name="Limburgish" class="interlanguage-link-target"><span>Limburgs</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Egyezm%C3%A9nyes_koordin%C3%A1lt_vil%C3%A1gid%C5%91" title="Egyezményes koordinált világidő – Hungarian" lang="hu" hreflang="hu" data-title="Egyezményes koordinált világidő" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mai mw-list-item"><a href="https://mai.wikipedia.org/wiki/%E0%A4%85%E0%A4%A8%E0%A5%8D%E0%A4%A4%E0%A4%B0%E0%A5%8D%E0%A4%B0%E0%A4%BE%E0%A4%B7%E0%A5%8D%E0%A4%9F%E0%A5%8D%E0%A4%B0%E0%A4%BF%E0%A4%AF_%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A4%AE%E0%A4%BE%E0%A4%A3%E0%A4%BF%E0%A4%95_%E0%A4%B8%E0%A4%AE%E0%A4%AF" title="अन्तर्राष्ट्रिय प्रमाणिक समय – Maithili" lang="mai" hreflang="mai" data-title="अन्तर्राष्ट्रिय प्रमाणिक समय" data-language-autonym="मैथिली" data-language-local-name="Maithili" class="interlanguage-link-target"><span>मैथिली</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BE%D1%80%D0%B4%D0%B8%D0%BD%D0%B8%D1%80%D0%B0%D0%BD%D0%BE_%D1%83%D0%BD%D0%B8%D0%B2%D0%B5%D1%80%D0%B7%D0%B0%D0%BB%D0%BD%D0%BE_%D0%B2%D1%80%D0%B5%D0%BC%D0%B5" title="Координирано универзално време – Macedonian" lang="mk" hreflang="mk" data-title="Координирано универзално време" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%85%E0%B4%A8%E0%B5%8D%E0%B4%A4%E0%B4%BE%E0%B4%B0%E0%B4%BE%E0%B4%B7%E0%B5%8D%E0%B4%9F%E0%B5%8D%E0%B4%B0%E0%B4%B8%E0%B4%AE%E0%B4%AF%E0%B4%95%E0%B5%8D%E0%B4%B0%E0%B4%AE%E0%B4%82" title="അന്താരാഷ്ട്രസമയക്രമം – Malayalam" lang="ml" hreflang="ml" data-title="അന്താരാഷ്ട്രസമയക്രമം" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-mr mw-list-item"><a href="https://mr.wikipedia.org/wiki/%E0%A4%9C%E0%A4%BE%E0%A4%97%E0%A4%A4%E0%A4%BF%E0%A4%95_%E0%A4%B8%E0%A4%AE%E0%A4%A8%E0%A5%8D%E0%A4%B5%E0%A4%BF%E0%A4%A4_%E0%A4%B5%E0%A5%87%E0%A4%B3" title="जागतिक समन्वित वेळ – Marathi" lang="mr" hreflang="mr" data-title="जागतिक समन्वित वेळ" data-language-autonym="मराठी" data-language-local-name="Marathi" class="interlanguage-link-target"><span>मराठी</span></a></li><li class="interlanguage-link interwiki-xmf mw-list-item"><a href="https://xmf.wikipedia.org/wiki/%E1%83%9B%E1%83%9D%E1%83%A1%E1%83%9D%E1%83%A4%E1%83%94%E1%83%9A%E1%83%98%E1%83%A8_%E1%83%99%E1%83%9D%E1%83%9D%E1%83%A0%E1%83%93%E1%83%98%E1%83%9C%E1%83%98%E1%83%A0%E1%83%90%E1%83%A4%E1%83%98%E1%83%9A%E1%83%98_%E1%83%91%E1%83%9D%E1%83%A0%E1%83%AF%E1%83%98" title="მოსოფელიშ კოორდინირაფილი ბორჯი – Mingrelian" lang="xmf" hreflang="xmf" data-title="მოსოფელიშ კოორდინირაფილი ბორჯი" data-language-autonym="მარგალური" data-language-local-name="Mingrelian" class="interlanguage-link-target"><span>მარგალური</span></a></li><li class="interlanguage-link interwiki-ms mw-list-item"><a href="https://ms.wikipedia.org/wiki/Waktu_Universal_Selaras" title="Waktu Universal Selaras – Malay" lang="ms" hreflang="ms" data-title="Waktu Universal Selaras" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-mni mw-list-item"><a href="https://mni.wikipedia.org/wiki/%EA%AF%8C%EA%AF%A8%EA%AF%85%EA%AF%A4%EA%AF%9A%EA%AF%94%EA%AF%81%EA%AF%A4%EA%AF%8C%EA%AF%A6%EA%AF%9C_%EA%AF%80%EA%AF%A3%EA%AF%91%EA%AF%A3%EA%AF%94%EA%AF%97%EA%AF%A4%EA%AF%85%EA%AF%A6%EA%AF%87%EA%AF%A6%EA%AF%97_%EA%AF%87%EA%AF%A5%EA%AF%8F%EA%AF%9D" title="ꯌꯨꯅꯤꯚꯔꯁꯤꯌꯦꯜ ꯀꯣꯑꯣꯔꯗꯤꯅꯦꯇꯦꯗ ꯇꯥꯏꯝ – Manipuri" lang="mni" hreflang="mni" data-title="ꯌꯨꯅꯤꯚꯔꯁꯤꯌꯦꯜ ꯀꯣꯑꯣꯔꯗꯤꯅꯦꯇꯦꯗ ꯇꯥꯏꯝ" data-language-autonym="ꯃꯤꯇꯩ ꯂꯣꯟ" data-language-local-name="Manipuri" class="interlanguage-link-target"><span>ꯃꯤꯇꯩ ꯂꯣꯟ</span></a></li><li class="interlanguage-link interwiki-mn mw-list-item"><a href="https://mn.wikipedia.org/wiki/%D0%9A%D0%BE%D0%BE%D1%80%D0%B4%D0%B8%D0%BD%D0%B0%D1%82%D0%B6%D1%83%D1%83%D0%BB%D1%81%D0%B0%D0%BD_%D0%B4%D1%8D%D0%BB%D1%85%D0%B8%D0%B9%D0%BD_%D1%86%D0%B0%D0%B3" title="Координатжуулсан дэлхийн цаг – Mongolian" lang="mn" hreflang="mn" data-title="Координатжуулсан дэлхийн цаг" data-language-autonym="Монгол" data-language-local-name="Mongolian" class="interlanguage-link-target"><span>Монгол</span></a></li><li class="interlanguage-link interwiki-my mw-list-item"><a href="https://my.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Burmese" lang="my" hreflang="my" data-title="Coordinated Universal Time" data-language-autonym="မြန်မာဘာသာ" data-language-local-name="Burmese" class="interlanguage-link-target"><span>မြန်မာဘာသာ</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/UTC" title="UTC – Dutch" lang="nl" hreflang="nl" data-title="UTC" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-nds-nl mw-list-item"><a href="https://nds-nl.wikipedia.org/wiki/UTC" title="UTC – Low Saxon" lang="nds-NL" hreflang="nds-NL" data-title="UTC" data-language-autonym="Nedersaksies" data-language-local-name="Low Saxon" class="interlanguage-link-target"><span>Nedersaksies</span></a></li><li class="interlanguage-link interwiki-ne mw-list-item"><a href="https://ne.wikipedia.org/wiki/%E0%A4%85%E0%A4%A8%E0%A5%8D%E0%A4%A4%E0%A4%B0%E0%A5%8D%E0%A4%B0%E0%A4%BE%E0%A4%B7%E0%A5%8D%E0%A4%9F%E0%A5%8D%E0%A4%B0%E0%A4%BF%E0%A4%AF_%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A4%AE%E0%A4%BE%E0%A4%A3%E0%A4%BF%E0%A4%95_%E0%A4%B8%E0%A4%AE%E0%A4%AF" title="अन्तर्राष्ट्रिय प्रमाणिक समय – Nepali" lang="ne" hreflang="ne" data-title="अन्तर्राष्ट्रिय प्रमाणिक समय" data-language-autonym="नेपाली" data-language-local-name="Nepali" class="interlanguage-link-target"><span>नेपाली</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E5%8D%94%E5%AE%9A%E4%B8%96%E7%95%8C%E6%99%82" title="協定世界時 – Japanese" lang="ja" hreflang="ja" data-title="協定世界時" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-frr mw-list-item"><a href="https://frr.wikipedia.org/wiki/UTC" title="UTC – Northern Frisian" lang="frr" hreflang="frr" data-title="UTC" data-language-autonym="Nordfriisk" data-language-local-name="Northern Frisian" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Koordinert_universaltid" title="Koordinert universaltid – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Koordinert universaltid" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/UTC" title="UTC – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="UTC" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-nrm mw-list-item"><a href="https://nrm.wikipedia.org/wiki/UTC" title="UTC – Norman" lang="nrf" hreflang="nrf" data-title="UTC" data-language-autonym="Nouormand" data-language-local-name="Norman" class="interlanguage-link-target"><span>Nouormand</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Temps_Universal_Coordenat" title="Temps Universal Coordenat – Occitan" lang="oc" hreflang="oc" data-title="Temps Universal Coordenat" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-uz mw-list-item"><a href="https://uz.wikipedia.org/wiki/UTC" title="UTC – Uzbek" lang="uz" hreflang="uz" data-title="UTC" data-language-autonym="Oʻzbekcha / ўзбекча" data-language-local-name="Uzbek" class="interlanguage-link-target"><span>Oʻzbekcha / ўзбекча</span></a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%B8%E0%A9%B0%E0%A8%AF%E0%A9%8B%E0%A8%9C%E0%A8%A4_%E0%A8%B5%E0%A8%BF%E0%A8%86%E0%A8%AA%E0%A8%95_%E0%A8%B8%E0%A8%AE%E0%A8%BE%E0%A8%82" title="ਸੰਯੋਜਤ ਵਿਆਪਕ ਸਮਾਂ – Punjabi" lang="pa" hreflang="pa" data-title="ਸੰਯੋਜਤ ਵਿਆਪਕ ਸਮਾਂ" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target"><span>ਪੰਜਾਬੀ</span></a></li><li class="interlanguage-link interwiki-pnb mw-list-item"><a href="https://pnb.wikipedia.org/wiki/%D9%85%D8%AA%D9%86%D8%A7%D8%B3%D9%82_%D8%B9%D8%A7%D9%84%D9%85%DB%8C_%D9%88%D9%82%D8%AA" title="متناسق عالمی وقت – Western Punjabi" lang="pnb" hreflang="pnb" data-title="متناسق عالمی وقت" data-language-autonym="پنجابی" data-language-local-name="Western Punjabi" class="interlanguage-link-target"><span>پنجابی</span></a></li><li class="interlanguage-link interwiki-blk mw-list-item"><a href="https://blk.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Pa'O" lang="blk" hreflang="blk" data-title="Coordinated Universal Time" data-language-autonym="ပအိုဝ်ႏဘာႏသာႏ" data-language-local-name="Pa'O" class="interlanguage-link-target"><span>ပအိုဝ်ႏဘာႏသာႏ</span></a></li><li class="interlanguage-link interwiki-pap mw-list-item"><a href="https://pap.wikipedia.org/wiki/Tempu_Universal_Koordin%C3%A1" title="Tempu Universal Koordiná – Papiamento" lang="pap" hreflang="pap" data-title="Tempu Universal Koordiná" data-language-autonym="Papiamentu" data-language-local-name="Papiamento" class="interlanguage-link-target"><span>Papiamentu</span></a></li><li class="interlanguage-link interwiki-ps mw-list-item"><a href="https://ps.wikipedia.org/wiki/%D9%87%D9%85%D8%BA%DA%96%DB%8C_%D9%86%DA%93%DB%8C%D9%88%D8%A7%D9%84_%D9%88%D8%AE%D8%AA" title="همغږی نړیوال وخت – Pashto" lang="ps" hreflang="ps" data-title="همغږی نړیوال وخت" data-language-autonym="پښتو" data-language-local-name="Pashto" class="interlanguage-link-target"><span>پښتو</span></a></li><li class="interlanguage-link interwiki-km mw-list-item"><a href="https://km.wikipedia.org/wiki/%E1%9E%9F%E1%9E%98%E1%9F%92%E1%9E%9A%E1%9E%94%E1%9E%9F%E1%9E%98%E1%9F%92%E1%9E%9A%E1%9E%BD%E1%9E%9B%E1%9E%9B%E1%9F%92%E1%9E%9C%E1%9F%82%E1%9E%84%E1%9E%98%E1%9F%89%E1%9F%84%E1%9E%84%E1%9E%9F%E1%9E%80%E1%9E%9B" title="សម្របសម្រួលល្វែងម៉ោងសកល – Khmer" lang="km" hreflang="km" data-title="សម្របសម្រួលល្វែងម៉ោងសកល" data-language-autonym="ភាសាខ្មែរ" data-language-local-name="Khmer" class="interlanguage-link-target"><span>ភាសាខ្មែរ</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Uniwersalny_czas_koordynowany" title="Uniwersalny czas koordynowany – Polish" lang="pl" hreflang="pl" data-title="Uniwersalny czas koordynowany" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Tempo_Universal_Coordenado" title="Tempo Universal Coordenado – Portuguese" lang="pt" hreflang="pt" data-title="Tempo Universal Coordenado" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-crh mw-list-item"><a href="https://crh.wikipedia.org/wiki/UTC" title="UTC – Crimean Tatar" lang="crh" hreflang="crh" data-title="UTC" data-language-autonym="Qırımtatarca" data-language-local-name="Crimean Tatar" class="interlanguage-link-target"><span>Qırımtatarca</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Ora_universal%C4%83_coordonat%C4%83" title="Ora universală coordonată – Romanian" lang="ro" hreflang="ro" data-title="Ora universală coordonată" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%92%D1%81%D0%B5%D0%BC%D0%B8%D1%80%D0%BD%D0%BE%D0%B5_%D0%BA%D0%BE%D0%BE%D1%80%D0%B4%D0%B8%D0%BD%D0%B8%D1%80%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D0%BE%D0%B5_%D0%B2%D1%80%D0%B5%D0%BC%D1%8F" title="Всемирное координированное время – Russian" lang="ru" hreflang="ru" data-title="Всемирное координированное время" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-sah mw-list-item"><a href="https://sah.wikipedia.org/wiki/UTC" title="UTC – Yakut" lang="sah" hreflang="sah" data-title="UTC" data-language-autonym="Саха тыла" data-language-local-name="Yakut" class="interlanguage-link-target"><span>Саха тыла</span></a></li><li class="interlanguage-link interwiki-sm mw-list-item"><a href="https://sm.wikipedia.org/wiki/Taimi_Tuufaatasia_Lautele" title="Taimi Tuufaatasia Lautele – Samoan" lang="sm" hreflang="sm" data-title="Taimi Tuufaatasia Lautele" data-language-autonym="Gagana Samoa" data-language-local-name="Samoan" class="interlanguage-link-target"><span>Gagana Samoa</span></a></li><li class="interlanguage-link interwiki-sa mw-list-item"><a href="https://sa.wikipedia.org/wiki/%E0%A4%B8%E0%A4%AE%E0%A4%A8%E0%A5%8D%E0%A4%B5%E0%A4%BF%E0%A4%A4%E0%A4%B8%E0%A4%BE%E0%A4%B0%E0%A5%8D%E0%A4%B5%E0%A4%A4%E0%A5%8D%E0%A4%B0%E0%A4%BF%E0%A4%95%E0%A4%B8%E0%A4%AE%E0%A4%AF%E0%A4%83" title="समन्वितसार्वत्रिकसमयः – Sanskrit" lang="sa" hreflang="sa" data-title="समन्वितसार्वत्रिकसमयः" data-language-autonym="संस्कृतम्" data-language-local-name="Sanskrit" class="interlanguage-link-target"><span>संस्कृतम्</span></a></li><li class="interlanguage-link interwiki-sco mw-list-item"><a href="https://sco.wikipedia.org/wiki/Coordinatit_Universal_Time" title="Coordinatit Universal Time – Scots" lang="sco" hreflang="sco" data-title="Coordinatit Universal Time" data-language-autonym="Scots" data-language-local-name="Scots" class="interlanguage-link-target"><span>Scots</span></a></li><li class="interlanguage-link interwiki-stq mw-list-item"><a href="https://stq.wikipedia.org/wiki/UTC" title="UTC – Saterland Frisian" lang="stq" hreflang="stq" data-title="UTC" data-language-autonym="Seeltersk" data-language-local-name="Saterland Frisian" class="interlanguage-link-target"><span>Seeltersk</span></a></li><li class="interlanguage-link interwiki-nso mw-list-item"><a href="https://nso.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Northern Sotho" lang="nso" hreflang="nso" data-title="Coordinated Universal Time" data-language-autonym="Sesotho sa Leboa" data-language-local-name="Northern Sotho" class="interlanguage-link-target"><span>Sesotho sa Leboa</span></a></li><li class="interlanguage-link interwiki-sq mw-list-item"><a href="https://sq.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Albanian" lang="sq" hreflang="sq" data-title="Coordinated Universal Time" data-language-autonym="Shqip" data-language-local-name="Albanian" class="interlanguage-link-target"><span>Shqip</span></a></li><li class="interlanguage-link interwiki-scn mw-list-item"><a href="https://scn.wikipedia.org/wiki/UTC" title="UTC – Sicilian" lang="scn" hreflang="scn" data-title="UTC" data-language-autonym="Sicilianu" data-language-local-name="Sicilian" class="interlanguage-link-target"><span>Sicilianu</span></a></li><li class="interlanguage-link interwiki-si mw-list-item"><a href="https://si.wikipedia.org/wiki/%E0%B7%83%E0%B6%B8%E0%B7%8F%E0%B6%BA%E0%B7%9D%E0%B6%AD_%E0%B7%83%E0%B7%8F%E0%B6%BB%E0%B7%8A%E0%B7%80%E0%B6%AD%E0%B7%8A%E2%80%8D%E0%B6%BB_%E0%B7%80%E0%B7%9A%E0%B6%BD%E0%B7%8F%E0%B7%80" title="සමායෝත සාර්වත්‍ර වේලාව – Sinhala" lang="si" hreflang="si" data-title="සමායෝත සාර්වත්‍ර වේලාව" data-language-autonym="සිංහල" data-language-local-name="Sinhala" class="interlanguage-link-target"><span>සිංහල</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Simple English" lang="en-simple" hreflang="en-simple" data-title="Coordinated Universal Time" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sd mw-list-item"><a href="https://sd.wikipedia.org/wiki/%D8%A8%D8%B1%D8%A7%D8%A8%D8%B1_%D8%B9%D8%A7%D9%84%D9%85%D9%8A_%D9%88%D9%82%D8%AA" title="برابر عالمي وقت – Sindhi" lang="sd" hreflang="sd" data-title="برابر عالمي وقت" data-language-autonym="سنڌي" data-language-local-name="Sindhi" class="interlanguage-link-target"><span>سنڌي</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Koordinovan%C3%BD_svetov%C3%BD_%C4%8Das" title="Koordinovaný svetový čas – Slovak" lang="sk" hreflang="sk" data-title="Koordinovaný svetový čas" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Univerzalni_koordinirani_%C4%8Das" title="Univerzalni koordinirani čas – Slovenian" lang="sl" hreflang="sl" data-title="Univerzalni koordinirani čas" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-so mw-list-item"><a href="https://so.wikipedia.org/wiki/Isuduwaha_Waqtiga_Caalamiga" title="Isuduwaha Waqtiga Caalamiga – Somali" lang="so" hreflang="so" data-title="Isuduwaha Waqtiga Caalamiga" data-language-autonym="Soomaaliga" data-language-local-name="Somali" class="interlanguage-link-target"><span>Soomaaliga</span></a></li><li class="interlanguage-link interwiki-ckb mw-list-item"><a href="https://ckb.wikipedia.org/wiki/%DA%A9%D8%A7%D8%AA%DB%8C_%DA%AF%DB%95%D8%B1%D8%AF%D9%88%D9%88%D9%86%DB%8C%DB%8C_%DA%BE%D8%A7%D9%88%DA%BE%DB%95%D9%86%DA%AF%D8%A7%D9%88" title="کاتی گەردوونیی ھاوھەنگاو – Central Kurdish" lang="ckb" hreflang="ckb" data-title="کاتی گەردوونیی ھاوھەنگاو" data-language-autonym="کوردی" data-language-local-name="Central Kurdish" class="interlanguage-link-target"><span>کوردی</span></a></li><li class="interlanguage-link interwiki-sr badge-Q70893996 mw-list-item" title=""><a href="https://sr.wikipedia.org/wiki/UTC" title="UTC – Serbian" lang="sr" hreflang="sr" data-title="UTC" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Koordinirano_univerzalno_vreme" title="Koordinirano univerzalno vreme – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Koordinirano univerzalno vreme" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-su mw-list-item"><a href="https://su.wikipedia.org/wiki/UTC" title="UTC – Sundanese" lang="su" hreflang="su" data-title="UTC" data-language-autonym="Sunda" data-language-local-name="Sundanese" class="interlanguage-link-target"><span>Sunda</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Koordinoitu_yleisaika" title="Koordinoitu yleisaika – Finnish" lang="fi" hreflang="fi" data-title="Koordinoitu yleisaika" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Koordinerad_universell_tid" title="Koordinerad universell tid – Swedish" lang="sv" hreflang="sv" data-title="Koordinerad universell tid" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/UTC" title="UTC – Tagalog" lang="tl" hreflang="tl" data-title="UTC" data-language-autonym="Tagalog" data-language-local-name="Tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%92%E0%AE%B0%E0%AF%81%E0%AE%99%E0%AF%8D%E0%AE%95%E0%AE%BF%E0%AE%A3%E0%AF%88%E0%AE%A8%E0%AF%8D%E0%AE%A4_%E0%AE%85%E0%AE%A9%E0%AF%88%E0%AE%A4%E0%AF%8D%E0%AE%A4%E0%AF%81%E0%AE%B2%E0%AE%95_%E0%AE%A8%E0%AF%87%E0%AE%B0%E0%AE%AE%E0%AF%8D" title="ஒருங்கிணைந்த அனைத்துலக நேரம் – Tamil" lang="ta" hreflang="ta" data-title="ஒருங்கிணைந்த அனைத்துலக நேரம்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target"><span>தமிழ்</span></a></li><li class="interlanguage-link interwiki-kab mw-list-item"><a href="https://kab.wikipedia.org/wiki/Akud_Amsideg_Ama%C9%A3rad" title="Akud Amsideg Amaɣrad – Kabyle" lang="kab" hreflang="kab" data-title="Akud Amsideg Amaɣrad" data-language-autonym="Taqbaylit" data-language-local-name="Kabyle" class="interlanguage-link-target"><span>Taqbaylit</span></a></li><li class="interlanguage-link interwiki-tt mw-list-item"><a href="https://tt.wikipedia.org/wiki/B%C3%B6tend%C3%B6nya_kile%C5%9Fterelg%C3%A4n_waq%C4%B1t%C4%B1" title="Bötendönya kileşterelgän waqıtı – Tatar" lang="tt" hreflang="tt" data-title="Bötendönya kileşterelgän waqıtı" data-language-autonym="Татарча / tatarça" data-language-local-name="Tatar" class="interlanguage-link-target"><span>Татарча / tatarça</span></a></li><li class="interlanguage-link interwiki-shn mw-list-item"><a href="https://shn.wikipedia.org/wiki/Coordinated_Universal_Time" title="Coordinated Universal Time – Shan" lang="shn" hreflang="shn" data-title="Coordinated Universal Time" data-language-autonym="ၽႃႇသႃႇတႆး " data-language-local-name="Shan" class="interlanguage-link-target"><span>ၽႃႇသႃႇတႆး </span></a></li><li class="interlanguage-link interwiki-te mw-list-item"><a href="https://te.wikipedia.org/wiki/%E0%B0%B8%E0%B0%BE%E0%B0%B0%E0%B1%8D%E0%B0%B5%E0%B0%A4%E0%B1%8D%E0%B0%B0%E0%B0%BF%E0%B0%95_%E0%B0%B8%E0%B0%AE%E0%B0%A8%E0%B1%8D%E0%B0%B5%E0%B0%AF_%E0%B0%B8%E0%B0%AE%E0%B0%AF%E0%B0%82" title="సార్వత్రిక సమన్వయ సమయం – Telugu" lang="te" hreflang="te" data-title="సార్వత్రిక సమన్వయ సమయం" data-language-autonym="తెలుగు" data-language-local-name="Telugu" class="interlanguage-link-target"><span>తెలుగు</span></a></li><li class="interlanguage-link interwiki-th mw-list-item"><a href="https://th.wikipedia.org/wiki/%E0%B9%80%E0%B8%A7%E0%B8%A5%E0%B8%B2%E0%B8%AA%E0%B8%B2%E0%B8%81%E0%B8%A5%E0%B9%80%E0%B8%8A%E0%B8%B4%E0%B8%87%E0%B8%9E%E0%B8%B4%E0%B8%81%E0%B8%B1%E0%B8%94" title="เวลาสากลเชิงพิกัด – Thai" lang="th" hreflang="th" data-title="เวลาสากลเชิงพิกัด" data-language-autonym="ไทย" data-language-local-name="Thai" class="interlanguage-link-target"><span>ไทย</span></a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/%D0%92%D0%B0%D2%9B%D1%82%D0%B8_%D2%B3%D0%B0%D0%BC%D0%BE%D2%B3%D0%B0%D0%BD%D0%B3%D0%B8_%D2%B7%D0%B0%D2%B3%D0%BE%D0%BD%D3%A3" title="Вақти ҳамоҳанги ҷаҳонӣ – Tajik" lang="tg" hreflang="tg" data-title="Вақти ҳамоҳанги ҷаҳонӣ" data-language-autonym="Тоҷикӣ" data-language-local-name="Tajik" class="interlanguage-link-target"><span>Тоҷикӣ</span></a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/E%C5%9Fg%C3%BCd%C3%BCml%C3%BC_Evrensel_Zaman" title="Eşgüdümlü Evrensel Zaman – Turkish" lang="tr" hreflang="tr" data-title="Eşgüdümlü Evrensel Zaman" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target"><span>Türkçe</span></a></li><li class="interlanguage-link interwiki-tyv mw-list-item"><a href="https://tyv.wikipedia.org/wiki/UTC" title="UTC – Tuvinian" lang="tyv" hreflang="tyv" data-title="UTC" data-language-autonym="Тыва дыл" data-language-local-name="Tuvinian" class="interlanguage-link-target"><span>Тыва дыл</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%92%D1%81%D0%B5%D1%81%D0%B2%D1%96%D1%82%D0%BD%D1%96%D0%B9_%D0%BA%D0%BE%D0%BE%D1%80%D0%B4%D0%B8%D0%BD%D0%BE%D0%B2%D0%B0%D0%BD%D0%B8%D0%B9_%D1%87%D0%B0%D1%81" title="Всесвітній координований час – Ukrainian" lang="uk" hreflang="uk" data-title="Всесвітній координований час" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-ur mw-list-item"><a href="https://ur.wikipedia.org/wiki/%D9%85%D8%AA%D9%86%D8%A7%D8%B3%D9%82_%D8%B9%D8%A7%D9%84%D9%85%DB%8C_%D9%88%D9%82%D8%AA" title="متناسق عالمی وقت – Urdu" lang="ur" hreflang="ur" data-title="متناسق عالمی وقت" data-language-autonym="اردو" data-language-local-name="Urdu" class="interlanguage-link-target"><span>اردو</span></a></li><li class="interlanguage-link interwiki-ug mw-list-item"><a href="https://ug.wikipedia.org/wiki/%D9%85%D8%A7%D8%B3_%D9%82%DB%95%D8%AF%DB%95%D9%85%D9%84%D9%89%D9%83_%D8%AF%DB%87%D9%86%D9%8A%D8%A7%DB%8B%D9%89%D9%8A_%D8%B3%D8%A7%D8%A6%DB%95%D8%AA" title="ماس قەدەملىك دۇنياۋىي سائەت – Uyghur" lang="ug" hreflang="ug" data-title="ماس قەدەملىك دۇنياۋىي سائەت" data-language-autonym="ئۇيغۇرچە / Uyghurche" data-language-local-name="Uyghur" class="interlanguage-link-target"><span>ئۇيغۇرچە / Uyghurche</span></a></li><li class="interlanguage-link interwiki-vec mw-list-item"><a href="https://vec.wikipedia.org/wiki/Tenpo_Coorden%C3%A0_Universa%C5%82e" title="Tenpo Coordenà Universałe – Venetian" lang="vec" hreflang="vec" data-title="Tenpo Coordenà Universałe" data-language-autonym="Vèneto" data-language-local-name="Venetian" class="interlanguage-link-target"><span>Vèneto</span></a></li><li class="interlanguage-link interwiki-vep mw-list-item"><a href="https://vep.wikipedia.org/wiki/Mail%27man_koordiniruidud_aig" title="Mail'man koordiniruidud aig – Veps" lang="vep" hreflang="vep" data-title="Mail'man koordiniruidud aig" data-language-autonym="Vepsän kel’" data-language-local-name="Veps" class="interlanguage-link-target"><span>Vepsän kel’</span></a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Gi%E1%BB%9D_Ph%E1%BB%91i_h%E1%BB%A3p_Qu%E1%BB%91c_t%E1%BA%BF" title="Giờ Phối hợp Quốc tế – Vietnamese" lang="vi" hreflang="vi" data-title="Giờ Phối hợp Quốc tế" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target"><span>Tiếng Việt</span></a></li><li class="interlanguage-link interwiki-fiu-vro mw-list-item"><a href="https://fiu-vro.wikipedia.org/wiki/UTC" title="UTC – Võro" lang="vro" hreflang="vro" data-title="UTC" data-language-autonym="Võro" data-language-local-name="Võro" class="interlanguage-link-target"><span>Võro</span></a></li><li class="interlanguage-link interwiki-wuu mw-list-item"><a href="https://wuu.wikipedia.org/wiki/%E5%8D%94%E8%AA%BF%E4%B8%96%E7%95%8C%E6%99%82" title="協調世界時 – Wu" lang="wuu" hreflang="wuu" data-title="協調世界時" data-language-autonym="吴语" data-language-local-name="Wu" class="interlanguage-link-target"><span>吴语</span></a></li><li class="interlanguage-link interwiki-yo mw-list-item"><a href="https://yo.wikipedia.org/wiki/Aj%E1%BB%8Df%E1%BB%8D%CC%80n%C3%A0k%C3%B2_%C3%80s%C3%ACk%C3%B2_K%C3%A1r%C3%ADay%C3%A9" title="Ajọfọ̀nàkò Àsìkò Káríayé – Yoruba" lang="yo" hreflang="yo" data-title="Ajọfọ̀nàkò Àsìkò Káríayé" data-language-autonym="Yorùbá" data-language-local-name="Yoruba" class="interlanguage-link-target"><span>Yorùbá</span></a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/%E4%B8%96%E7%95%8C%E5%8D%94%E8%AA%BF%E6%99%82%E9%96%93" title="世界協調時間 – Cantonese" lang="yue" hreflang="yue" data-title="世界協調時間" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target"><span>粵語</span></a></li><li class="interlanguage-link interwiki-diq mw-list-item"><a href="https://diq.wikipedia.org/wiki/UTC" title="UTC – Zazaki" lang="diq" hreflang="diq" data-title="UTC" data-language-autonym="Zazaki" data-language-local-name="Zazaki" class="interlanguage-link-target"><span>Zazaki</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E5%8D%8F%E8%B0%83%E4%B8%96%E7%95%8C%E6%97%B6" title="协调世界时 – Chinese" lang="zh" hreflang="zh" data-title="协调世界时" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target"><span>中文</span></a></li><li class="interlanguage-link interwiki-zgh badge-Q17506997 badge-featuredlist mw-list-item" title="featured list badge"><a href="https://zgh.wikipedia.org/wiki/%E2%B4%B0%E2%B4%BD%E2%B5%93%E2%B4%B7_%E2%B4%B0%E2%B5%8E%E2%B4%B0%E2%B4%B9%E2%B5%8D%E2%B4%B0%E2%B5%8F_%E2%B4%B0%E2%B5%8E%E2%B5%A3%E2%B4%B7%E2%B4%B0%E2%B5%A2" title="ⴰⴽⵓⴷ ⴰⵎⴰⴹⵍⴰⵏ ⴰⵎⵣⴷⴰⵢ – Standard Moroccan Tamazight" lang="zgh" hreflang="zgh" data-title="ⴰⴽⵓⴷ ⴰⵎⴰⴹⵍⴰⵏ ⴰⵎⵣⴷⴰⵢ" data-language-autonym="ⵜⴰⵎⴰⵣⵉⵖⵜ ⵜⴰⵏⴰⵡⴰⵢⵜ" data-language-local-name="Standard Moroccan Tamazight" class="interlanguage-link-target"><span>ⵜⴰⵎⴰⵣⵉⵖⵜ ⵜⴰⵏⴰⵡⴰⵢⵜ</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1536#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Namespaces"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a 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For the time zone between UTC−1 and UTC+1, see <a href="/wiki/UTC%2B00:00" title="UTC+00:00">UTC+00:00</a>. For other uses, see <a href="/wiki/UTC_(disambiguation)" class="mw-disambig" title="UTC (disambiguation)">UTC (disambiguation)</a>.</div> <p class="mw-empty-elt"> </p> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:World_Time_Zones_Map.png" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/8/88/World_Time_Zones_Map.png/300px-World_Time_Zones_Map.png" decoding="async" width="300" height="162" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/8/88/World_Time_Zones_Map.png/450px-World_Time_Zones_Map.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/8/88/World_Time_Zones_Map.png/600px-World_Time_Zones_Map.png 2x" data-file-width="4000" data-file-height="2157" /></a><figcaption>Current time zones</figcaption></figure> <p><b>Coordinated Universal Time</b> (<b>UTC</b>) is the primary <a href="/wiki/Time_standard" title="Time standard">time standard</a> globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for <a href="/wiki/Civil_time" title="Civil time">civil time</a> and <a href="/wiki/Time_zones" class="mw-redirect" title="Time zones">time zones</a>. UTC facilitates international communication, navigation, scientific research, and commerce. </p><p>UTC has been widely embraced by most countries and is the effective successor to <a href="/wiki/Greenwich_Mean_Time" title="Greenwich Mean Time">Greenwich Mean Time</a> (GMT) in everyday usage and common applications.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>a<span class="cite-bracket">]</span></a></sup> In specialized domains such as scientific research, navigation, and timekeeping, other standards such as <a href="/wiki/UT1" class="mw-redirect" title="UT1">UT1</a> and <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> (TAI) are also used alongside UTC. </p><p>UTC is based on TAI, which is a weighted average of hundreds of <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clocks</a> worldwide. UTC is within about one second of <a href="/wiki/Mean_solar_time" class="mw-redirect" title="Mean solar time">mean solar time</a> at 0° longitude, the currently used <a href="/wiki/Prime_meridian" title="Prime meridian">prime meridian</a>, and is not adjusted for <a href="/wiki/Daylight_saving_time" title="Daylight saving time">daylight saving time</a>. </p><p>The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted as a standard in 1963 and "UTC" became the official abbreviation of Coordinated Universal Time in 1967.<sup id="cite_ref-FOOTNOTEMcCarthy20094_3-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthy20094-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The current version of UTC is defined by the <a href="/wiki/International_Telecommunication_Union" title="International Telecommunication Union">International Telecommunication Union</a>. </p><p>Since adoption, UTC has been adjusted several times, notably adding <a href="/wiki/Leap_seconds" class="mw-redirect" title="Leap seconds">leap seconds</a> in 1972. Recent years have seen significant developments in the realm of UTC, particularly in discussions about eliminating leap seconds from the timekeeping system because leap seconds occasionally disrupt timekeeping systems worldwide. The General Conference on Weights and Measures adopted a resolution to alter UTC with a new system that would eliminate leap seconds by 2035.<sup id="cite_ref-CGPM2022_4-0" class="reference"><a href="#cite_note-CGPM2022-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Etymology">Etymology</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=1" title="Edit section: Etymology"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The official abbreviation for Coordinated Universal Time is <i>UTC</i>. This abbreviation comes as a result of the <a href="/wiki/International_Telecommunication_Union" title="International Telecommunication Union">International Telecommunication Union</a> and the <a href="/wiki/International_Astronomical_Union" title="International Astronomical Union">International Astronomical Union</a> wanting to use the same abbreviation in all languages.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> The compromise that emerged was <i>UTC</i>,<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> which conforms to the pattern for the abbreviations of the variants of Universal Time (UT0, UT1, UT2, UT1R, etc.).<sup id="cite_ref-FOOTNOTEIAU_resolutions1976_7-0" class="reference"><a href="#cite_note-FOOTNOTEIAU_resolutions1976-7"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p><p>McCarthy described the origin of the abbreviation: </p> <blockquote><p>In 1967 the <a href="/wiki/ITU-R#CCIR" title="ITU-R">CCIR</a> adopted the names Coordinated Universal Time and Temps Universel Coordonné for the English and French names with the acronym UTC to be used in both languages. The name "Coordinated Universal Time (UTC)" was approved by a resolution of IAU Commissions 4 and 31 at the 13th General Assembly in 1967 (Trans. IAU, 1968).<sup id="cite_ref-FOOTNOTEMcCarthy20094_3-1" class="reference"><a href="#cite_note-FOOTNOTEMcCarthy20094-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></p></blockquote> <div class="mw-heading mw-heading2"><h2 id="Uses">Uses</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=2" title="Edit section: Uses"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p><a href="/wiki/Time_zone" title="Time zone">Time zones</a> around the world are expressed using <a href="/wiki/UTC_offset" title="UTC offset">positive, zero, or negative offsets from UTC</a>, as in the <a href="/wiki/List_of_UTC_time_offsets" class="mw-redirect" title="List of UTC time offsets">list of time zones by UTC offset</a>. </p><p>The westernmost time zone uses <a href="/wiki/UTC%E2%88%9212:00" title="UTC−12:00">UTC−12</a>, being twelve hours behind UTC; the easternmost time zone uses <a href="/wiki/UTC%2B14:00" title="UTC+14:00">UTC+14</a>, being fourteen hours ahead of UTC. In 1995, the island nation of <a href="/wiki/Kiribati" title="Kiribati">Kiribati</a> moved those of its atolls in the <a href="/wiki/Line_Islands" title="Line Islands">Line Islands</a> from <a href="/wiki/UTC%E2%88%9210" class="mw-redirect" title="UTC−10">UTC−10</a> to <a href="/wiki/UTC%2B14:00" title="UTC+14:00">UTC+14</a> so that Kiribati would all be on the same day. </p><p>UTC is used in many <a href="/wiki/Internet" title="Internet">Internet</a> and <a href="/wiki/World_Wide_Web" title="World Wide Web">World Wide Web</a> standards. The <a href="/wiki/Network_Time_Protocol" title="Network Time Protocol">Network Time Protocol</a> (NTP), designed to synchronise the clocks of computers over the Internet, transmits time information from the UTC system.<sup id="cite_ref-FOOTNOTEHow_NTP_Works2011_8-0" class="reference"><a href="#cite_note-FOOTNOTEHow_NTP_Works2011-8"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> If only milliseconds precision is needed, clients can obtain the current UTC from a number of official internet UTC servers. For sub-microsecond precision, clients can obtain the time from satellite signals. </p><p>UTC is also the time standard used in <a href="/wiki/Aviation" title="Aviation">aviation</a>,<sup id="cite_ref-FOOTNOTEAviation_Time2006_9-0" class="reference"><a href="#cite_note-FOOTNOTEAviation_Time2006-9"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> e.g. for <a href="/wiki/Flight_plan" title="Flight plan">flight plans</a> and <a href="/wiki/Air_traffic_control" title="Air traffic control">air traffic control</a>. In this context it is frequently referred to as Zulu time, as described below. <a href="/wiki/Weather_forecasts" class="mw-redirect" title="Weather forecasts">Weather forecasts</a> and maps all use UTC to avoid confusion about time zones and daylight saving time. The <a href="/wiki/International_Space_Station" title="International Space Station">International Space Station</a> also uses UTC as a time standard. </p><p><a href="/wiki/Amateur_radio" title="Amateur radio">Amateur radio</a> operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up in many time zones.<sup id="cite_ref-FOOTNOTEHorzepa2010_10-0" class="reference"><a href="#cite_note-FOOTNOTEHorzepa2010-10"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Mechanism">Mechanism</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=3" title="Edit section: Mechanism"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>UTC divides time into days, hours, minutes, and <a href="/wiki/Second" title="Second">seconds</a>. Days are conventionally identified using the <a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian calendar</a>, but <a href="/wiki/Julian_day" title="Julian day">Julian day numbers</a> can also be used. Each day contains 24 hours and each hour contains 60 minutes. The number of seconds in a minute is usually 60, but with an occasional <a href="/wiki/Leap_second" title="Leap second">leap second</a>, it may be 61 or 59 instead.<sup id="cite_ref-FOOTNOTEITU_Radiocommunication_Assembly20023_11-0" class="reference"><a href="#cite_note-FOOTNOTEITU_Radiocommunication_Assembly20023-11"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Thus, in the UTC time scale, the second and all smaller time units (millisecond, microsecond, etc.) are of constant duration, but the minute and all larger time units (hour, day, week, etc.) are of variable duration. Decisions to introduce a leap second are announced at least six months in advance in "Bulletin C" produced by the <a href="/wiki/International_Earth_Rotation_and_Reference_Systems_Service" title="International Earth Rotation and Reference Systems Service">International Earth Rotation and Reference Systems Service</a>.<sup id="cite_ref-FOOTNOTEInternational_Earth_Rotation_and_Reference_Systems_Service2011_12-0" class="reference"><a href="#cite_note-FOOTNOTEInternational_Earth_Rotation_and_Reference_Systems_Service2011-12"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009229_13-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009229-13"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> The leap seconds cannot be predicted far in advance due to the unpredictable rate of the rotation of Earth.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009chapter_4_14-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009chapter_4-14"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> </p><p>Nearly all UTC days contain exactly 86,400 <a href="/wiki/International_System_of_Units" title="International System of Units">SI</a> seconds with exactly 60 seconds in each minute. UTC is within about one second of <a href="/wiki/Solar_time#Mean_solar_time" title="Solar time">mean solar time</a> (such as <a href="/wiki/UT1" class="mw-redirect" title="UT1">UT1</a>) at <a href="/wiki/Prime_meridian" title="Prime meridian">0° longitude</a>,<sup id="cite_ref-FOOTNOTEGuinot2011S181_15-0" class="reference"><a href="#cite_note-FOOTNOTEGuinot2011S181-15"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> (at the <a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">IERS Reference Meridian</a>). The <a href="/wiki/Mean_solar_day" class="mw-redirect" title="Mean solar day">mean solar day</a> is slightly longer than 86,400 SI seconds so occasionally the last minute of a UTC day is adjusted to have 61 seconds. The extra second is called a leap second. It accounts for the grand total of the extra length (about 2 milliseconds each) of all the mean solar days since the previous leap second. The last minute of a UTC day is permitted to contain 59 seconds to cover the remote possibility of the Earth rotating faster, but that has not yet been necessary. The irregular day lengths mean fractional Julian days do not work properly with UTC. </p><p>Since 1972, UTC may be calculated by subtracting the accumulated leap seconds from <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> (TAI), which is a <a href="/wiki/Coordinate_time" title="Coordinate time">coordinate time</a> scale tracking notional <a href="/wiki/Proper_time" title="Proper time">proper time</a> on the rotating surface of the <a href="/wiki/Earth" title="Earth">Earth</a> (the <a href="/wiki/Geoid" title="Geoid">geoid</a>). In order to maintain a close approximation to <a href="/wiki/Universal_Time" title="Universal Time">UT1</a>, UTC occasionally has <a href="/wiki/Classification_of_discontinuities" title="Classification of discontinuities">discontinuities</a> where it changes from one linear function of TAI to another. These discontinuities take the form of leap seconds implemented by a UTC day of irregular length. Discontinuities in UTC occurred only at the end of June or December. However, there is provision for them to happen at the end of March and September as well as a second preference.<sup id="cite_ref-FOOTNOTEHistory_of_TAI-UTCc._2009_16-0" class="reference"><a href="#cite_note-FOOTNOTEHistory_of_TAI-UTCc._2009-16"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009217,_227–231_17-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009217,_227–231-17"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup> The International Earth Rotation and Reference Systems Service (IERS) tracks and publishes the difference between UTC and Universal Time, <a href="/wiki/DUT1" title="DUT1">DUT1</a> = UT1 − UTC, and introduces discontinuities into UTC to keep DUT1 in the <a href="/wiki/Interval_(mathematics)" title="Interval (mathematics)">interval</a> (−0.9 s, +0.9 s). </p><p>As with TAI, UTC is only known with the highest precision in retrospect. Users who require an approximation in real time must obtain it from a time laboratory, which disseminates an approximation using techniques such as <a href="/wiki/GPS" class="mw-redirect" title="GPS">GPS</a> or radio <a href="/wiki/Time_signal" title="Time signal">time signals</a>. Such approximations are designated UTC(<i>k</i>), where <i>k</i> is an abbreviation for the time laboratory.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009209_18-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009209-18"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup> The time of events may be provisionally recorded against one of these approximations; later corrections may be applied using the <a href="/wiki/International_Bureau_of_Weights_and_Measures" title="International Bureau of Weights and Measures">International Bureau of Weights and Measures</a> (BIPM) monthly publication of tables of differences between canonical TAI/UTC and TAI(<i>k</i>)/UTC(<i>k</i>) as estimated in real-time by participating laboratories.<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup> (See the article on <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> for details.) </p><p>Because of <a href="/wiki/Time_dilation" title="Time dilation">time dilation</a>, a standard clock not on the geoid, or in rapid motion, will not maintain synchronicity with UTC. Therefore, <a href="/wiki/Telemetry" title="Telemetry">telemetry</a> from clocks with a known relation to the geoid is used to provide UTC when required, on locations such as those of spacecraft. </p><p>It is impossible to compute the exact time interval elapsed between two UTC <a href="/wiki/Timestamp" title="Timestamp">timestamps</a> without consulting a table showing how many leap seconds occurred during that interval. By extension, it is not possible to compute the precise duration of a time interval that ends in the future and may encompass an unknown number of leap seconds (for example, the number of TAI seconds between "now" and 2099-12-31 23:59:59). Therefore, many scientific applications that require precise measurement of long (multi-year) intervals use TAI instead. TAI is also commonly used by systems that cannot handle leap seconds. <a href="/wiki/GPS_time" class="mw-redirect" title="GPS time">GPS time</a> always remains exactly 19 seconds behind TAI (neither system is affected by the leap seconds introduced in UTC). </p> <div class="mw-heading mw-heading3"><h3 id="Time_zones">Time zones</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=4" title="Edit section: Time zones"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main articles: <a href="/wiki/Time_zone" title="Time zone">Time zone</a> and <a href="/wiki/Lists_of_time_zones" title="Lists of time zones">Lists of time zones</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/UTC_offset" title="UTC offset">UTC offset</a> and <a href="/wiki/List_of_UTC_time_offsets" class="mw-redirect" title="List of UTC time offsets">List of UTC time offsets</a></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">"Zulu time" redirects here. For the album by Caspar Brötzmann and Page Hamilton, see <a href="/wiki/Zulutime" title="Zulutime"><i>Zulutime</i></a>. For the time zone of the <a href="/wiki/Zulu_people" title="Zulu people">Zulu people</a>, see <a href="/wiki/South_African_Standard_Time" class="mw-redirect" title="South African Standard Time">South African Standard Time</a>.</div> <p>Time zones are usually defined as differing from UTC by an integer number of hours,<sup id="cite_ref-FOOTNOTESeidelmann19927_20-0" class="reference"><a href="#cite_note-FOOTNOTESeidelmann19927-20"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup> although the laws of each jurisdiction would have to be consulted if sub-second accuracy was required. Several jurisdictions have established time zones that differ by an odd integer number of half-hours or quarter-hours from UT1 or UTC. </p><p>Current <a href="/wiki/Civil_time" title="Civil time">civil time</a> in a particular <a href="/wiki/Time_zone" title="Time zone">time zone</a> can be determined by adding or subtracting the number of hours and minutes specified by the <a href="/wiki/UTC_offset" title="UTC offset">UTC offset</a>, which ranges from <a href="/wiki/UTC%E2%88%9212:00" title="UTC−12:00">UTC−12:00</a> in the west to <a href="/wiki/UTC%2B14:00" title="UTC+14:00">UTC+14:00</a> in the east (see <a href="/wiki/List_of_UTC_offsets" title="List of UTC offsets">List of UTC offsets</a>). </p><p>The time zone using UTC is sometimes denoted <a href="/wiki/UTC%2B00:00" title="UTC+00:00">UTC+00:00</a> or by the letter <i>Z</i>—a reference to the equivalent <a href="/wiki/Nautical_time" title="Nautical time">nautical time zone</a> (GMT), which has been denoted by a <i>Z</i> since about 1950. Time zones were identified by successive letters of the alphabet and the Greenwich time zone was marked by a <i>Z</i> as it was the point of origin. The letter also refers to the "zone description" of zero hours, which has been used since 1920 (see <a href="/wiki/Time_zone#History" title="Time zone">time zone history</a>). Since the <a href="/wiki/NATO_phonetic_alphabet" title="NATO phonetic alphabet">NATO phonetic alphabet</a> word for <i>Z</i> is "Zulu", UTC is sometimes known as "Zulu time". This is especially true in aviation, where "Zulu" is the universal standard.<sup id="cite_ref-FOOTNOTEMilitary_&_Civilian_Time_Designationsn.d._21-0" class="reference"><a href="#cite_note-FOOTNOTEMilitary_&_Civilian_Time_Designationsn.d.-21"><span class="cite-bracket">[</span>20<span class="cite-bracket">]</span></a></sup> This ensures that all pilots, regardless of location, are using the same <a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a>, thus avoiding confusion when flying between time zones.<sup id="cite_ref-FOOTNOTEWilliams2005_22-0" class="reference"><a href="#cite_note-FOOTNOTEWilliams2005-22"><span class="cite-bracket">[</span>21<span class="cite-bracket">]</span></a></sup> See the <a href="/wiki/List_of_military_time_zones" class="mw-redirect" title="List of military time zones">list of military time zones</a> for letters used in addition to <i>Z</i> in qualifying time zones other than Greenwich. </p><p>On electronic devices which only allow the time zone to be configured using maps or city names, UTC can be selected indirectly by selecting cities such as <a href="/wiki/Accra" title="Accra">Accra</a> in <a href="/wiki/Ghana" title="Ghana">Ghana</a> or <a href="/wiki/Reykjav%C3%ADk" title="Reykjavík">Reykjavík</a> in <a href="/wiki/Iceland" title="Iceland">Iceland</a> as they are always on UTC and do not currently use <a href="/wiki/Daylight_saving_time" title="Daylight saving time">daylight saving time</a> (which <a href="/wiki/Greenwich" title="Greenwich">Greenwich</a> and <a href="/wiki/London" title="London">London</a> do, and so could be a source of error).<sup id="cite_ref-FOOTNOTEIceland2011_23-0" class="reference"><a href="#cite_note-FOOTNOTEIceland2011-23"><span class="cite-bracket">[</span>22<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading3"><h3 id="Daylight_saving_time">Daylight saving time</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=5" title="Edit section: Daylight saving time"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></div> <p>UTC does not change with a change of seasons, but <a href="/wiki/Time_zone" title="Time zone">local time</a> or civil time may change if a time zone jurisdiction observes daylight saving time (summer time). For example, local time on the east coast of the United States is five hours behind UTC during winter,<sup id="cite_ref-FOOTNOTE15_U.S._Code_§_2612007_24-0" class="reference"><a href="#cite_note-FOOTNOTE15_U.S._Code_§_2612007-24"><span class="cite-bracket">[</span>23<span class="cite-bracket">]</span></a></sup> but four hours behind while daylight saving is observed there.<sup id="cite_ref-FOOTNOTE15_U.S._Code_§_260a2005_25-0" class="reference"><a href="#cite_note-FOOTNOTE15_U.S._Code_§_260a2005-25"><span class="cite-bracket">[</span>24<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=6" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Universal_time#History" class="mw-redirect" title="Universal time">Universal time § History</a></div> <p>In 1928, the term <i>Universal Time</i> (<i>UT</i>) was introduced by the International Astronomical Union to refer to GMT, with the day starting at midnight.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann200910–11_26-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann200910–11-26"><span class="cite-bracket">[</span>25<span class="cite-bracket">]</span></a></sup> Until the 1950s, broadcast <a href="/wiki/Time_signal" title="Time signal">time signals</a> were based on UT, and hence on the rotation of the Earth. </p><p>In 1955, the <a href="/wiki/Caesium" title="Caesium">caesium</a> <a href="/wiki/Atomic_clock" title="Atomic clock">atomic clock</a> was invented. This provided a form of timekeeping that was both more stable and more convenient than astronomical observations. In 1956, the U.S. <a href="/wiki/National_Bureau_of_Standards" class="mw-redirect" title="National Bureau of Standards">National Bureau of Standards</a> and <a href="/wiki/U.S._Naval_Observatory" class="mw-redirect" title="U.S. Naval Observatory">U.S. Naval Observatory</a> started to develop atomic frequency time scales; by 1959, these time scales were used in generating the <a href="/wiki/WWV_(radio_station)" title="WWV (radio station)">WWV</a> time signals, named for the shortwave radio station that broadcasts them. In 1960, the U.S. Naval Observatory, the Royal Greenwich Observatory, and the <a href="/wiki/National_Physical_Laboratory_(United_Kingdom)" title="National Physical Laboratory (United Kingdom)">UK National Physical Laboratory</a> coordinated their radio broadcasts so that time steps and frequency changes were coordinated, and the resulting time scale was informally referred to as "Coordinated Universal Time".<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009226–227_27-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009226–227-27"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEMcCarthy20093_28-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthy20093-28"><span class="cite-bracket">[</span>27<span class="cite-bracket">]</span></a></sup> </p><p>In a controversial decision, the frequency of the signals was initially set to match the rate of UT, but then kept at the same frequency by the use of atomic clocks and deliberately allowed to drift away from UT. When the divergence grew significantly, the signal was phase shifted (stepped) by 20 <a href="/wiki/Millisecond" title="Millisecond">ms</a> to bring it back into agreement with UT. Twenty-nine such steps were used before 1960.<sup id="cite_ref-FOOTNOTEAriasGuinotQuinn2003_29-0" class="reference"><a href="#cite_note-FOOTNOTEAriasGuinotQuinn2003-29"><span class="cite-bracket">[</span>28<span class="cite-bracket">]</span></a></sup> </p><p>In 1958, data was published linking the frequency for the <a href="/wiki/Caesium_standard" title="Caesium standard">caesium transition</a>, newly established, with the <a href="/wiki/Ephemeris_time" title="Ephemeris time">ephemeris second</a>. The ephemeris second is a unit in the system of time that, when used as the independent variable in the laws of motion that govern the movement of the planets and moons in the solar system, enables the laws of motion to accurately predict the observed positions of solar system bodies. Within the limits of observable accuracy, ephemeris seconds are of constant length, as are atomic seconds. This publication allowed a value to be chosen for the length of the atomic second that would accord with the celestial laws of motion.<sup id="cite_ref-FOOTNOTEMarkowitzHallEssenParry1958_30-0" class="reference"><a href="#cite_note-FOOTNOTEMarkowitzHallEssenParry1958-30"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup> </p><p>The coordination of time and frequency transmissions around the world began on 1 January 1960. UTC was first officially adopted in 1963 as <a href="/wiki/ITU-R#CCIR" title="ITU-R">CCIR</a> Recommendation 374, <i>Standard-Frequency and Time-Signal Emissions</i>, and "UTC" became the official abbreviation of Coordinated Universal Time in 1967.<sup id="cite_ref-FOOTNOTEMcCarthy20094_3-2" class="reference"><a href="#cite_note-FOOTNOTEMcCarthy20094-3"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>In 1961, the <a href="/wiki/International_Time_Bureau" title="International Time Bureau">Bureau International de l'Heure</a> began coordinating the UTC process internationally (but the name Coordinated Universal Time was not formally adopted by the International Astronomical Union until 1967).<sup id="cite_ref-FOOTNOTENelsonMcCarthy200515_31-0" class="reference"><a href="#cite_note-FOOTNOTENelsonMcCarthy200515-31"><span class="cite-bracket">[</span>30<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTENelsonMcCarthyMalysLevine2001515_32-0" class="reference"><a href="#cite_note-FOOTNOTENelsonMcCarthyMalysLevine2001515-32"><span class="cite-bracket">[</span>31<span class="cite-bracket">]</span></a></sup> From then on, there were time steps every few months, and frequency changes at the end of each year. The jumps increased in size to 0.1 seconds. This UTC was intended to permit a very close approximation to UT2.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009226–227_27-1" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009226–227-27"><span class="cite-bracket">[</span>26<span class="cite-bracket">]</span></a></sup> </p><p>In 1967, the <a href="/wiki/SI" class="mw-redirect" title="SI">SI</a> second was redefined in terms of the frequency supplied by a caesium atomic clock. The length of second so defined was practically equal to the second of ephemeris time.<sup id="cite_ref-FOOTNOTEMarkowitz1988_33-0" class="reference"><a href="#cite_note-FOOTNOTEMarkowitz1988-33"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> This was the frequency that had been provisionally used in TAI since 1958. It was soon decided that having two types of second with different lengths, namely the UTC second and the SI second used in TAI, was a bad idea. It was thought better for time signals to maintain a consistent frequency, and that this frequency should match the SI second. Thus it would be necessary to rely on time steps alone to maintain the approximation of UT. This was tried experimentally in a service known as "Stepped Atomic Time" (SAT), which ticked at the same rate as TAI and used jumps of 0.2 seconds to stay synchronised with UT2.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009227_34-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009227-34"><span class="cite-bracket">[</span>33<span class="cite-bracket">]</span></a></sup> </p><p>There was also dissatisfaction with the frequent jumps in UTC (and SAT). In 1968, <a href="/wiki/Louis_Essen" title="Louis Essen">Louis Essen</a>, the inventor of the caesium atomic clock, and G. M. R. Winkler both independently proposed that steps should be of 1 second only.<sup id="cite_ref-FOOTNOTEEssen1968161–165_35-0" class="reference"><a href="#cite_note-FOOTNOTEEssen1968161–165-35"><span class="cite-bracket">[</span>34<span class="cite-bracket">]</span></a></sup> to simplify future adjustments. This system was eventually approved as <a href="/wiki/Leap_second" title="Leap second">leap seconds</a> in a new UTC in 1970 and implemented in 1972, along with the idea of maintaining the UTC second equal to the TAI second. This CCIR Recommendation 460 "stated that (a) carrier frequencies and time intervals should be maintained constant and should correspond to the definition of the <a href="/wiki/SI_second" class="mw-redirect" title="SI second">SI second</a>; (b) step adjustments, when necessary, should be exactly 1 s to maintain approximate agreement with Universal Time (UT); and (c) standard signals should contain information on the difference between UTC and UT."<sup id="cite_ref-FOOTNOTEMcCarthy20095_36-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthy20095-36"><span class="cite-bracket">[</span>35<span class="cite-bracket">]</span></a></sup> </p><p>As an intermediate step at the end of 1971, there was a final irregular jump of exactly 0.107758 TAI seconds, making the total of all the small time steps and frequency shifts in UTC or TAI during 1958–1971 exactly ten seconds, so that <span class="nowrap">1 January 1972 00:00:00 UTC</span> was <span class="nowrap">1 January 1972 00:00:10 TAI</span> exactly,<sup id="cite_ref-FOOTNOTEBlair197432_37-0" class="reference"><a href="#cite_note-FOOTNOTEBlair197432-37"><span class="cite-bracket">[</span>36<span class="cite-bracket">]</span></a></sup> and a whole number of seconds thereafter. At the same time, the tick rate of UTC was changed to exactly match TAI. UTC also started to track UT1 rather than UT2. Some time signals started to broadcast the DUT1 correction (UT1 − UTC) for applications requiring a closer approximation of UT1 than UTC now provided.<sup id="cite_ref-FOOTNOTESeidelmann199285–87_38-0" class="reference"><a href="#cite_note-FOOTNOTESeidelmann199285–87-38"><span class="cite-bracket">[</span>37<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTENelsonLombardiOkayama200546_39-0" class="reference"><a href="#cite_note-FOOTNOTENelsonLombardiOkayama200546-39"><span class="cite-bracket">[</span>38<span class="cite-bracket">]</span></a></sup> </p><p>The current version of UTC is defined by <a href="/wiki/International_Telecommunication_Union" title="International Telecommunication Union">International Telecommunication Union</a> Recommendation (ITU-R TF.460-6), <i>Standard-frequency and time-signal emissions</i>,<sup id="cite_ref-FOOTNOTEITU_Radiocommunication_Assembly2002_40-0" class="reference"><a href="#cite_note-FOOTNOTEITU_Radiocommunication_Assembly2002-40"><span class="cite-bracket">[</span>39<span class="cite-bracket">]</span></a></sup> and is based on <a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a> (TAI) with leap seconds added at irregular intervals to compensate for the accumulated difference between TAI and time measured by <a href="/wiki/Earth%27s_rotation" title="Earth's rotation">Earth's rotation</a>.<sup id="cite_ref-FOOTNOTEChester2015_41-0" class="reference"><a href="#cite_note-FOOTNOTEChester2015-41"><span class="cite-bracket">[</span>40<span class="cite-bracket">]</span></a></sup> Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of the <a href="/wiki/Universal_time#Versions" class="mw-redirect" title="Universal time">UT1 variant of universal time</a>.<sup id="cite_ref-42" class="reference"><a href="#cite_note-42"><span class="cite-bracket">[</span>41<span class="cite-bracket">]</span></a></sup> See the "<a href="#Current_number_of_leap_seconds">Current number of leap seconds</a>" section for the number of leap seconds inserted to date. </p> <div class="mw-heading mw-heading3"><h3 id="Current_number_of_leap_seconds">Current number of leap seconds</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=7" title="Edit section: Current number of leap seconds"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The first leap second occurred on 30 June 1972. Since then, leap seconds have occurred on average about once every 19 months, always on 30 June or 31 December. As of July 2022<sup class="plainlinks noexcerpt noprint asof-tag update" style="display:none;"><a class="external text" href="https://en.wikipedia.org/w/index.php?title=Coordinated_Universal_Time&action=edit">[update]</a></sup>, there have been 27 leap seconds in total, all positive, putting UTC 37 seconds behind TAI.<sup id="cite_ref-FOOTNOTEBulletin_C2022_43-0" class="reference"><a href="#cite_note-FOOTNOTEBulletin_C2022-43"><span class="cite-bracket">[</span>42<span class="cite-bracket">]</span></a></sup> </p><p>A study published in March 2024 in <i><a href="/wiki/Nature_(journal)" title="Nature (journal)">Nature</a></i> concluded that accelerated melting of ice in Greenland and Antarctica due to climate change has decreased Earth's rotational velocity, affecting UTC adjustments and causing problems for computer networks that rely on UTC.<sup id="cite_ref-Nature_20240327_44-0" class="reference"><a href="#cite_note-Nature_20240327-44"><span class="cite-bracket">[</span>43<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Rationale">Rationale</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=8" title="Edit section: Rationale"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <figure class="mw-default-size" typeof="mw:File/Thumb"><a href="/wiki/File:Leapsecond.ut1-utc.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Leapsecond.ut1-utc.svg/220px-Leapsecond.ut1-utc.svg.png" decoding="async" width="220" height="176" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Leapsecond.ut1-utc.svg/330px-Leapsecond.ut1-utc.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/fb/Leapsecond.ut1-utc.svg/440px-Leapsecond.ut1-utc.svg.png 2x" data-file-width="600" data-file-height="480" /></a><figcaption>Graph showing the difference <a href="/wiki/DUT1" title="DUT1">DUT1</a> between UT1 and UTC (in seconds). Vertical segments correspond to leap seconds.</figcaption></figure> <p>Earth's <a href="/wiki/Rotational_speed" class="mw-redirect" title="Rotational speed">rotational speed</a> is very slowly decreasing because of <a href="/wiki/Tidal_acceleration" title="Tidal acceleration">tidal deceleration</a>; this increases the length of the <a href="/wiki/Solar_time" title="Solar time">mean solar day</a>. The length of the SI second was calibrated on the basis of the second of <a href="/wiki/Ephemeris_time" title="Ephemeris time">ephemeris time</a><sup id="cite_ref-FOOTNOTEMarkowitzHallEssenParry1958_30-1" class="reference"><a href="#cite_note-FOOTNOTEMarkowitzHallEssenParry1958-30"><span class="cite-bracket">[</span>29<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-FOOTNOTEMarkowitz1988_33-1" class="reference"><a href="#cite_note-FOOTNOTEMarkowitz1988-33"><span class="cite-bracket">[</span>32<span class="cite-bracket">]</span></a></sup> and can now be seen to have a relationship with the mean solar day observed between 1750 and 1892, analysed by <a href="/wiki/Simon_Newcomb" title="Simon Newcomb">Simon Newcomb</a>. As a result, the SI second is close to <style data-mw-deduplicate="TemplateStyles:r1214402035">.mw-parser-output .sfrac{white-space:nowrap}.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tion{display:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center}.mw-parser-output .sfrac .num{display:block;line-height:1em;margin:0.0em 0.1em;border-bottom:1px solid}.mw-parser-output .sfrac .den{display:block;line-height:1em;margin:0.1em 0.1em}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}</style><span class="sfrac">⁠<span class="tion"><span class="num">1</span><span class="sr-only">/</span><span class="den">86400</span></span>⁠</span> of a mean solar day in the mid‑19th century.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann200987_45-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann200987-45"><span class="cite-bracket">[</span>44<span class="cite-bracket">]</span></a></sup> In earlier centuries, the mean solar day was shorter than 86,400 SI seconds, and in more recent centuries it is longer than 86,400 seconds. Near the end of the 20th century, the length of the mean solar day (also known simply as "length of day" or "LOD") was approximately 86,400.0013 s.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann200954_46-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann200954-46"><span class="cite-bracket">[</span>45<span class="cite-bracket">]</span></a></sup> For this reason, UT is now "slower" than TAI by the difference (or "excess" LOD) of 1.3 ms/day. </p><p>The excess of the LOD over the nominal 86,400 s accumulates over time, causing the UTC day, initially synchronised with the mean sun, to become desynchronised and run ahead of it. Near the end of the 20th century, with the LOD at 1.3 ms above the nominal value, UTC ran faster than UT by 1.3 ms per day, getting a second ahead roughly every 800 days. Thus, leap seconds were inserted at approximately this interval, retarding UTC to keep it synchronised in the long term.<sup id="cite_ref-47" class="reference"><a href="#cite_note-47"><span class="cite-bracket">[</span>46<span class="cite-bracket">]</span></a></sup> The actual <a href="/wiki/Rotation_period" class="mw-redirect" title="Rotation period">rotational period</a> varies on unpredictable factors such as <a href="/wiki/Plate_tectonics" title="Plate tectonics">tectonic motion</a> and has to be observed, rather than computed. </p><p>Just as adding a leap day every four years does not mean the year is getting longer by one day every four years, the insertion of a leap second every 800 days does not indicate that the mean solar day is getting longer by a second every 800 days. It will take about 50,000 years for a mean solar day to lengthen by one second (at a rate of 2 ms per century). This rate fluctuates within the range of 1.7–2.3 ms/cy. While the rate due to <a href="/wiki/Tidal_friction" class="mw-redirect" title="Tidal friction">tidal friction</a> alone is about 2.3 ms/cy, the <a href="/wiki/Post-glacial_rebound" title="Post-glacial rebound">uplift</a> of Canada and <a href="/wiki/Scandinavia" title="Scandinavia">Scandinavia</a> by several metres since the <a href="/wiki/Last_Glacial_Period" title="Last Glacial Period">last ice age</a> has temporarily reduced this to 1.7 ms/cy over the last 2,700 years.<sup id="cite_ref-FOOTNOTEStephensonMorrison1995_48-0" class="reference"><a href="#cite_note-FOOTNOTEStephensonMorrison1995-48"><span class="cite-bracket">[</span>47<span class="cite-bracket">]</span></a></sup> The correct reason for leap seconds, then, is not the current difference between actual and nominal LOD, but rather the <i>accumulation</i> of this difference over a period of time: Near the end of the 20th century, this difference was about <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1214402035"><span class="sfrac">⁠<span class="tion"><span class="num">1</span><span class="sr-only">/</span><span class="den">800</span></span>⁠</span> of a second per day; therefore, after about 800 days, it accumulated to 1 second (and a leap second was then added). </p><p>In the graph of <a href="/wiki/DUT1" title="DUT1">DUT1</a> above, the excess of LOD above the nominal 86,400 s corresponds to the downward slope of the graph between vertical segments. (The slope became shallower in the 1980s, 2000s and late 2010s to 2020s because of slight accelerations of Earth's rotation temporarily shortening the day.) Vertical position on the graph corresponds to the accumulation of this difference over time, and the vertical segments correspond to leap seconds introduced to match this accumulated difference. Leap seconds are timed to keep DUT1 within the vertical range depicted by the adjacent graph. The frequency of leap seconds therefore corresponds to the slope of the diagonal graph segments, and thus to the excess LOD. Time periods when the slope reverses direction (slopes upwards, not the vertical segments) are times when the excess LOD is negative, that is, when the LOD is below 86,400 s. </p> <div class="mw-heading mw-heading2"><h2 id="Future">Future</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=9" title="Edit section: Future"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Leap_second" title="Leap second">Leap second</a></div> <p>As the Earth's rotation continues to slow, positive leap seconds will be required more frequently. The long-term <a href="/wiki/Derivative" title="Derivative">rate of change</a> of LOD is approximately +1.7 ms per century. At the end of the 21st century, LOD will be roughly 86,400.004 s, requiring leap seconds every 250 days. Over several centuries, the frequency of leap seconds will become problematic.<sup id="cite_ref-FOOTNOTEMcCarthySeidelmann2009232_49-0" class="reference"><a href="#cite_note-FOOTNOTEMcCarthySeidelmann2009232-49"><span class="cite-bracket">[</span>48<span class="cite-bracket">]</span></a></sup> A change in the trend of the UT1 – UTC values was seen beginning around June 2019 in which instead of slowing down (with leap seconds to keep the difference between UT1 and UTC less than 0.9 seconds) the Earth's rotation has sped up, causing this difference to increase. If the trend continues, a negative leap second may be required, which has not been used before. This may not be needed until 2025.<sup id="cite_ref-50" class="reference"><a href="#cite_note-50"><span class="cite-bracket">[</span>49<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-51" class="reference"><a href="#cite_note-51"><span class="cite-bracket">[</span>50<span class="cite-bracket">]</span></a></sup> </p><p>Some time in the 22nd century, two leap seconds will be required every year. The current practice of only allowing leap seconds in June and December will be insufficient to maintain a difference of less than 1 second, and it might be decided to introduce leap seconds in March and September. In the 25th century, four leap seconds are projected to be required every year, so the current quarterly options would be insufficient. </p><p>In April 2001, Rob Seaman of the <a href="/wiki/National_Optical_Astronomy_Observatory" title="National Optical Astronomy Observatory">National Optical Astronomy Observatory</a> proposed that leap seconds be allowed to be added monthly rather than twice yearly.<sup id="cite_ref-52" class="reference"><a href="#cite_note-52"><span class="cite-bracket">[</span>51<span class="cite-bracket">]</span></a></sup> </p><p>In 2022 a resolution was adopted by the General Conference on Weights and Measures to redefine UTC and abolish leap seconds, but keep the civil second constant and equal to the SI second, so that <a href="/wiki/Sundial" title="Sundial">sundials</a> would slowly get further and further out of sync with civil time. The leap seconds will be eliminated by 2035. The resolution does not break the connection between UTC and UT1, but increases the maximum allowable difference. The details of what the maximum difference will be and how corrections will be implemented is left for future discussions.<sup id="cite_ref-CGPM2022_4-1" class="reference"><a href="#cite_note-CGPM2022-4"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> This will result in a shift of the sun's movements relative to civil time, with the difference increasing quadratically with time (i.e., proportional to elapsed centuries squared). This is analogous to the shift of <a href="/wiki/Season" title="Season">seasons</a> relative to the yearly calendar that results from the calendar year not precisely matching the <a href="/wiki/Tropical_year" title="Tropical year">tropical year</a> length. This would be a change in civil timekeeping, and would have a slow effect at first, but becoming drastic over several centuries. UTC (and TAI) would be more and more ahead of UT; it would coincide with local mean time along a meridian drifting eastward faster and faster.<sup id="cite_ref-FOOTNOTEIrvine2008_53-0" class="reference"><a href="#cite_note-FOOTNOTEIrvine2008-53"><span class="cite-bracket">[</span>52<span class="cite-bracket">]</span></a></sup> Thus, the time system will lose its fixed connection to the geographic coordinates based on the <a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">IERS meridian</a>. The difference between UTC and UT would reach 0.5 hours after the year 2600 and 6.5 hours around 4600.<sup id="cite_ref-FOOTNOTEAllen2011a_54-0" class="reference"><a href="#cite_note-FOOTNOTEAllen2011a-54"><span class="cite-bracket">[</span>53<span class="cite-bracket">]</span></a></sup> </p><p><a href="/wiki/ITU-R" title="ITU-R">ITU-R</a> Study Group 7 and Working Party 7A were unable to reach consensus on whether to advance the proposal to the 2012 Radiocommunications Assembly; the chairman of Study Group 7 elected to advance the question to the 2012 Radiocommunications Assembly (20 January 2012),<sup id="cite_ref-FOOTNOTESeidelmannSeago2011S190_55-0" class="reference"><a href="#cite_note-FOOTNOTESeidelmannSeago2011S190-55"><span class="cite-bracket">[</span>54<span class="cite-bracket">]</span></a></sup> but consideration of the proposal was postponed by the ITU until the World Radio Conference in 2015.<sup id="cite_ref-FOOTNOTELeap_decision_postponed2012_56-0" class="reference"><a href="#cite_note-FOOTNOTELeap_decision_postponed2012-56"><span class="cite-bracket">[</span>55<span class="cite-bracket">]</span></a></sup> This conference, in turn, considered the question,<sup id="cite_ref-57" class="reference"><a href="#cite_note-57"><span class="cite-bracket">[</span>56<span class="cite-bracket">]</span></a></sup> but no permanent decision was reached; it only chose to engage in further study with the goal of reconsideration in 2023.<sup id="cite_ref-itu.int_58-0" class="reference"><a href="#cite_note-itu.int-58"><span class="cite-bracket">[</span>57<span class="cite-bracket">]</span></a></sup><sup class="noprint Inline-Template" style="margin-left:0.1em; white-space:nowrap;">[<i><a href="/wiki/Wikipedia:Manual_of_Style/Dates_and_numbers#Chronological_items" title="Wikipedia:Manual of Style/Dates and numbers"><span title="The text near this tag is dated. (December 2023)">needs update</span></a></i>]</sup> </p><p>A proposed alternative to the leap second is the leap hour or leap minute, which requires changes only once every few centuries.<sup id="cite_ref-59" class="reference"><a href="#cite_note-59"><span class="cite-bracket">[</span>58<span class="cite-bracket">]</span></a></sup> </p><p>ITU World Radiocommunication Conference 2023 (WRC-23), which was held in Dubai (United Arab Emirates) from 20 November to 15 December 2023 formally recognized the <a rel="nofollow" class="external text" href="https://www.bipm.org/en/cgpm-2022/resolution-4">Resolution 4</a> of the 27th CGPM (2022) which decides that the maximum value for the difference (UT1-UTC) will be increased in, or before, 2035.<sup id="cite_ref-60" class="reference"><a href="#cite_note-60"><span class="cite-bracket">[</span>59<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=10" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239009302">.mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:1px solid var(--border-color-base,#a2a9b1);padding:0.1em;background:var(--background-color-neutral-subtle,#f8f9fa)}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{clear:left;float:left;margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}</style><ul role="navigation" aria-label="Portals" class="noprint portalbox portalborder portalright"> <li class="portalbox-entry"><span class="portalbox-image"><span class="noviewer" typeof="mw:File"><span><img alt="icon" src="//upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Terra.png/28px-Terra.png" decoding="async" width="28" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Terra.png/42px-Terra.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Terra.png/56px-Terra.png 2x" data-file-width="600" data-file-height="600" /></span></span></span><span class="portalbox-link"><a href="/wiki/Portal:Geography" title="Portal:Geography">Geography portal</a></span></li></ul> <ul><li><a href="/wiki/Coordinated_Lunar_Time" class="mw-redirect" title="Coordinated Lunar Time">Coordinated Lunar Time</a></li> <li><a href="/wiki/Coordinated_Mars_Time" class="mw-redirect" title="Coordinated Mars Time">Coordinated Mars Time</a> – Proposed approaches to tracking date and time on the planet Mars<span style="display:none" class="category-annotation-with-redirected-description">Pages displaying short descriptions of redirect targets</span> (MTC)</li> <li><a href="/wiki/Ephemeris_time" title="Ephemeris time">Ephemeris time</a> – Time standard used in astronomical ephemerides</li> <li><a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">IERS Reference Meridian</a> – International prime meridian used for GPS and other systems</li> <li><a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a> – International standards for dates and times</li> <li><a href="/wiki/ITU-R" title="ITU-R">ITU-R</a> – One of the three sectors of the ITU</li> <li><a href="/wiki/List_of_UTC_timing_centers" title="List of UTC timing centers">List of UTC timing centers</a> – Recognized maintainers of atomic clocks from which UTC is calculated</li> <li><a href="/wiki/Terrestrial_Time" title="Terrestrial Time">Terrestrial Time</a> – Time standard for astronomical observations from the Earth</li> <li><a href="/wiki/Universal_Time" title="Universal Time">Universal Time</a> – Time standard based on the slowing rotation of the Earth</li> <li><a href="/wiki/World_Radiocommunication_Conference" title="World Radiocommunication Conference">World Radiocommunication Conference</a> – Convention<span style="display:none" class="category-spaceless-annotation">Pages displaying short descriptions with no spaces</span></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=11" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="mw-heading mw-heading3"><h3 id="Notes">Notes</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=12" title="Edit section: Notes"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist reflist-lower-alpha"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">The pips are no longer broadcast from Greenwich, but from the National Physical Laboratory in Teddington, Surrey, which uses Coordinated Universal Time (UTC) – the successor of GMT – for its reading.<sup id="cite_ref-FOOTNOTEEvers201374_1-0" class="reference"><a href="#cite_note-FOOTNOTEEvers201374-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </span> </li> </ol></div></div> <div class="mw-heading mw-heading3"><h3 id="Citations">Citations</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=13" title="Edit section: Citations"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239543626"><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-FOOTNOTEEvers201374-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEEvers201374_1-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFEvers2013">Evers 2013</a>, p. 74.</span> </li> <li id="cite_note-FOOTNOTEMcCarthy20094-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEMcCarthy20094_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEMcCarthy20094_3-1"><sup><i><b>b</b></i></sup></a> <a href="#cite_ref-FOOTNOTEMcCarthy20094_3-2"><sup><i><b>c</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFMcCarthy2009">McCarthy 2009</a>, p. 4.</span> </li> <li id="cite_note-CGPM2022-4"><span class="mw-cite-backlink">^ <a href="#cite_ref-CGPM2022_4-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-CGPM2022_4-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.bipm.org/documents/20126/64811223/Resolutions-2022.pdf/281f3160-fc56-3e63-dbf7-77b76500990f?version=1.2&t=1668786143360&download=true">"Resolutions of the General Conference on Weights and Measures (27th Meeting)"</a>. <i>Bureau International des Poids et Mesures</i>. 19 November 2022. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20221119231518/https://www.bipm.org/documents/20126/64811223/Resolutions-2022.pdf/281f3160-fc56-3e63-dbf7-77b76500990f?version=1.2&t=1668786143360&download=true">Archived</a> from the original on 19 November 2022<span class="reference-accessdate">. Retrieved <span class="nowrap">19 August</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=Bureau+International+des+Poids+et+Mesures&rft.atitle=Resolutions+of+the+General+Conference+on+Weights+and+Measures+%2827th+Meeting%29&rft.date=2022-11-19&rft_id=https%3A%2F%2Fwww.bipm.org%2Fdocuments%2F20126%2F64811223%2FResolutions-2022.pdf%2F281f3160-fc56-3e63-dbf7-77b76500990f%3Fversion%3D1.2%26t%3D1668786143360%26download%3Dtrue&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://www.bipm.org/en/publications/si-brochure"><i>SI Brochure</i></a> (9th ed.). BIPM. 2019. 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Retrieved <span class="nowrap">17 July</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=NIST+Time+Frequently+Asked+Questions+%28FAQ%29&rft.atitle=Why+is+UTC+used+as+the+acronym+for+Coordinated+Universal+Time+instead+of+CUT%3F&rft.date=2010-02-03&rft_id=https%3A%2F%2Fwww.nist.gov%2Fpml%2Fdiv688%2Futcnist.cfm%23cut&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></span> </li> <li id="cite_note-FOOTNOTEIAU_resolutions1976-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEIAU_resolutions1976_7-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFIAU_resolutions1976">IAU resolutions 1976</a>.</span> </li> <li id="cite_note-FOOTNOTEHow_NTP_Works2011-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEHow_NTP_Works2011_8-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFHow_NTP_Works2011">How NTP Works 2011</a>.</span> </li> <li id="cite_note-FOOTNOTEAviation_Time2006-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEAviation_Time2006_9-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFAviation_Time2006">Aviation Time 2006</a>.</span> </li> <li id="cite_note-FOOTNOTEHorzepa2010-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEHorzepa2010_10-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFHorzepa2010">Horzepa 2010</a>.</span> </li> <li id="cite_note-FOOTNOTEITU_Radiocommunication_Assembly20023-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEITU_Radiocommunication_Assembly20023_11-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFITU_Radiocommunication_Assembly2002">ITU Radiocommunication Assembly 2002</a>, p. 3.</span> </li> <li id="cite_note-FOOTNOTEInternational_Earth_Rotation_and_Reference_Systems_Service2011-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEInternational_Earth_Rotation_and_Reference_Systems_Service2011_12-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFInternational_Earth_Rotation_and_Reference_Systems_Service2011">International Earth Rotation and Reference Systems Service 2011</a>.</span> </li> <li id="cite_note-FOOTNOTEMcCarthySeidelmann2009229-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcCarthySeidelmann2009229_13-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcCarthySeidelmann2009">McCarthy & Seidelmann 2009</a>, p. 229.</span> </li> <li id="cite_note-FOOTNOTEMcCarthySeidelmann2009chapter_4-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcCarthySeidelmann2009chapter_4_14-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcCarthySeidelmann2009">McCarthy & Seidelmann 2009</a>, chapter 4.</span> </li> <li id="cite_note-FOOTNOTEGuinot2011S181-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEGuinot2011S181_15-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFGuinot2011">Guinot 2011</a>, p. S181.</span> </li> <li id="cite_note-FOOTNOTEHistory_of_TAI-UTCc._2009-16"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEHistory_of_TAI-UTCc._2009_16-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFHistory_of_TAI-UTCc._2009">History of TAI-UTC c. 2009</a>.</span> </li> <li id="cite_note-FOOTNOTEMcCarthySeidelmann2009217,_227–231-17"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcCarthySeidelmann2009217,_227–231_17-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcCarthySeidelmann2009">McCarthy & Seidelmann 2009</a>, pp. 217, 227–231.</span> </li> <li id="cite_note-FOOTNOTEMcCarthySeidelmann2009209-18"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcCarthySeidelmann2009209_18-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcCarthySeidelmann2009">McCarthy & Seidelmann 2009</a>, p. 209.</span> </li> <li id="cite_note-19"><span class="mw-cite-backlink"><b><a href="#cite_ref-19">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.bipm.org/en/time-ftp/circular-t">"Circular T"</a>. <i><a href="/wiki/International_Bureau_of_Weights_and_Measures" title="International Bureau of Weights and Measures">International Bureau of Weights and Measures</a></i>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20220630112200/https://www.bipm.org/en/time-ftp/circular-t">Archived</a> from the original on 30 June 2022<span class="reference-accessdate">. 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</li> <li id="cite_note-FOOTNOTEWilliams2005-22"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEWilliams2005_22-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFWilliams2005">Williams 2005</a>.</span> </li> <li id="cite_note-FOOTNOTEIceland2011-23"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEIceland2011_23-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFIceland2011">Iceland 2011</a>.</span> </li> <li id="cite_note-FOOTNOTE15_U.S._Code_§_2612007-24"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTE15_U.S._Code_§_2612007_24-0">^</a></b></span> <span class="reference-text"><a href="#CITEREF15_U.S._Code_§_2612007">15 U.S. Code § 261 2007</a>.</span> </li> <li id="cite_note-FOOTNOTE15_U.S._Code_§_260a2005-25"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTE15_U.S._Code_§_260a2005_25-0">^</a></b></span> <span class="reference-text"><a href="#CITEREF15_U.S._Code_§_260a2005">15 U.S. Code § 260a 2005</a>.</span> </li> <li id="cite_note-FOOTNOTEMcCarthySeidelmann200910–11-26"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcCarthySeidelmann200910–11_26-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcCarthySeidelmann2009">McCarthy & Seidelmann 2009</a>, pp. 10–11.</span> </li> <li id="cite_note-FOOTNOTEMcCarthySeidelmann2009226–227-27"><span class="mw-cite-backlink">^ <a href="#cite_ref-FOOTNOTEMcCarthySeidelmann2009226–227_27-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-FOOTNOTEMcCarthySeidelmann2009226–227_27-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><a href="#CITEREFMcCarthySeidelmann2009">McCarthy & Seidelmann 2009</a>, pp. 226–227.</span> </li> <li id="cite_note-FOOTNOTEMcCarthy20093-28"><span class="mw-cite-backlink"><b><a href="#cite_ref-FOOTNOTEMcCarthy20093_28-0">^</a></b></span> <span class="reference-text"><a href="#CITEREFMcCarthy2009">McCarthy 2009</a>, p. 3.</span> </li> <li 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Retrieved <span class="nowrap">3 September</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=The+New+Indian+Express&rft.atitle=Scientists+propose+%27leap+hour%27+to+fix+time+system&rft.date=2012-05-14&rft_id=https%3A%2F%2Fwww.newindianexpress.com%2Fmagazine%2F2008%2Fdec%2F18%2Fscientists-propose-leap-hour-to-fix-time-system-11669.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></span> </li> <li id="cite_note-60"><span class="mw-cite-backlink"><b><a href="#cite_ref-60">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://www.bipm.org/en/-/2023-12-12-wrc-dubai">BIPM</a></span> </li> </ol></div></div> <div class="mw-heading mw-heading3"><h3 id="General_and_cited_sources">General and cited sources</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=14" title="Edit section: General and cited sources"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin refbegin-hanging-indents refbegin-columns references-column-width" style="column-width: 30em"> <ul><li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAllanAshbyHodge1997" class="citation book cs1">Allan, David W.; Ashby, Neil; Hodge, Clifford C. 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Time Service Dept., <a href="/wiki/U.S._Naval_Observatory" class="mw-redirect" title="U.S. Naval Observatory">U.S. Naval Observatory</a>. c. 2009. Archived from <a rel="nofollow" class="external text" href="http://maia.usno.navy.mil/ser7/tai-utc.dat">the original</a> on 19 October 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">4 January</span> 2009</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=History+of+TAI-UTC&rft.pub=Time+Service+Dept.%2C+U.S.+Naval+Observatory&rft_id=http%3A%2F%2Fmaia.usno.navy.mil%2Fser7%2Ftai-utc.dat&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHorzepa2010" class="citation web cs1">Horzepa, Stan (17 September 2010). <a rel="nofollow" class="external text" href="https://www.arrl.org/news/surfin-time-for-ham-radio">"Surfin': Time for Ham Radio"</a>. American Radio Relay League. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20100923152507/http://www.arrl.org/news/surfin-time-for-ham-radio">Archived</a> from the original on 23 September 2010<span class="reference-accessdate">. Retrieved <span class="nowrap">24 October</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Surfin%27%3A+Time+for+Ham+Radio&rft.pub=American+Radio+Relay+League&rft.date=2010-09-17&rft.aulast=Horzepa&rft.aufirst=Stan&rft_id=https%3A%2F%2Fwww.arrl.org%2Fnews%2Fsurfin-time-for-ham-radio&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHowse1997" class="citation book cs1">Howse, Derek (1997). <span class="id-lock-registration" title="Free registration required"><a rel="nofollow" class="external text" href="https://archive.org/details/greenwichtimelon0000hows"><i>Greenwich Time and the Longitude</i></a></span>. London: Philip Wilson. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/0-85667-468-0" title="Special:BookSources/0-85667-468-0"><bdi>0-85667-468-0</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Greenwich+Time+and+the+Longitude&rft.place=London&rft.pub=Philip+Wilson&rft.date=1997&rft.isbn=0-85667-468-0&rft.aulast=Howse&rft.aufirst=Derek&rft_id=https%3A%2F%2Farchive.org%2Fdetails%2Fgreenwichtimelon0000hows&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFHow_NTP_Works2011" class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.eecis.udel.edu/~mills/ntp/html/warp.html">"How NTP Works"</a>. <i>NTP: The Network Time Protocol</i>. 28 July 2011. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140620171010/http://www.eecis.udel.edu/~mills/ntp/html/warp.html">Archived</a> from the original on 20 June 2014<span class="reference-accessdate">. Retrieved <span class="nowrap">18 June</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=NTP%3A+The+Network+Time+Protocol&rft.atitle=How+NTP+Works&rft.date=2011-07-28&rft_id=https%3A%2F%2Fwww.eecis.udel.edu%2F~mills%2Fntp%2Fhtml%2Fwarp.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span> See heading "NTP Timescale and Data Formats".</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIAU_resolutions1976" class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.iau.org/static/resolutions/IAU1976_French.pdf">"IAU resolutions adopted at the XVIth General Assembly, Grenoble, France, 1976"</a> <span class="cs1-format">(PDF)</span>. 1976. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190502234359/https://www.iau.org/static/resolutions/IAU1976_French.pdf">Archived</a> <span class="cs1-format">(PDF)</span> from the original on 2 May 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">18 June</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=IAU+resolutions+adopted+at+the+XVIth+General+Assembly%2C+Grenoble%2C+France%2C+1976&rft.date=1976&rft_id=https%3A%2F%2Fwww.iau.org%2Fstatic%2Fresolutions%2FIAU1976_French.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span> Resolution no. 3 by Commissions 4 (Ephemerides/Ephémérides) and 31 (Time/L'Heure) (near the end of the document) "recommend that the following notations be used in all languages", UT0(i), UT1(i), UT2(i), UTC, UTC(i), UT, where (i) is institution "i".</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIceland2011" class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20111018222316/http://wwp.greenwichmeantime.com/time-zone/europe/iceland/">"Iceland"</a>. 2011. 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Retrieved <span class="nowrap">18 June</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=IERS+Bulletins&rft.date=2011-07-19&rft.au=International+Earth+Rotation+and+Reference+Systems+Service&rft_id=https%3A%2F%2Fwww.iers.org%2FIERS%2FEN%2FPublications%2FBulletins%2Fbulletins.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFIrvine2008" class="citation news cs1">Irvine, Chris (18 December 2008). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110514005932/http://www.telegraph.co.uk/science/science-news/3817096/Scientists-propose-leap-hour-to-fix-time-system.html">"Scientists propose 'leap hour' to fix time system"</a>. <i>The Telegraph</i>. 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Retrieved <span class="nowrap">2 August</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Standard-frequency+and+time-signal+emissions&rft.pub=International+Telecommunication+Union&rft.date=2002&rft.au=ITU+Radiocommunication+Assembly&rft_id=https%3A%2F%2Fwww.itu.int%2Fdms_pubrec%2Fitu-r%2Frec%2Ftf%2FR-REC-TF.460-6-200202-I%21%21PDF-E.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLangley1999" class="citation web cs1">Langley, Richard B. 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Retrieved <span class="nowrap">17 July</span> 2011</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=A+Few+Facts+Concerning+GMT%2C+UT%2C+and+the+RGO&rft.date=1999-01-20&rft.aulast=Langley&rft.aufirst=Richard+B.&rft_id=https%3A%2F%2Fwww.apparent-wind.com%2Fgmt-explained.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLeap_decision_postponed2012" class="citation news cs1"><a rel="nofollow" class="external text" href="https://www.bbc.co.uk/news/science-environment-16625614">"Leap second decision is postponed"</a>. <i>BBC News</i>. 19 January 2012. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190201130903/https://www.bbc.co.uk/news/science-environment-16625614">Archived</a> from the original on 1 February 2019<span class="reference-accessdate">. Retrieved <span class="nowrap">21 July</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=BBC+News&rft.atitle=Leap+second+decision+is+postponed&rft.date=2012-01-19&rft_id=https%3A%2F%2Fwww.bbc.co.uk%2Fnews%2Fscience-environment-16625614&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMarkowitzHallEssenParry1958" class="citation journal cs1">Markowitz, W.; Hall, R.; Essen, L.; Parry, J. 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Retrieved <span class="nowrap">18 October</span> 2008</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Physical+Review+Letters&rft.atitle=Frequency+of+caesium+in+terms+of+Ephemeris+Time&rft.volume=1&rft.issue=3&rft.pages=105-107&rft.date=1958-08&rft_id=info%3Adoi%2F10.1103%2FPhysRevLett.1.105&rft_id=info%3Abibcode%2F1958PhRvL...1..105M&rft.aulast=Markowitz&rft.aufirst=W.&rft.au=Hall%2C+R.&rft.au=Essen%2C+L.&rft.au=Parry%2C+J.&rft_id=http%3A%2F%2Fwww.leapsecond.com%2Fhistory%2F1958-PhysRev-v1-n3-Markowitz-Hall-Essen-Parry.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFleming1886" class="citation journal cs1">Fleming, Sandford (1886). <a rel="nofollow" class="external text" href="https://library.si.edu/digital-library/book/annualreportofbo18861smit">"Time-reckoning for the twentieth century"</a>. <i>Annual Report of the Board of Regents of the Smithsonian Institution</i> (1): 345–366. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20221005110429/https://library.si.edu/digital-library/book/annualreportofbo18861smit">Archived</a> from the original on 5 October 2022<span class="reference-accessdate">. Retrieved <span class="nowrap">23 July</span> 2018</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Annual+Report+of+the+Board+of+Regents+of+the+Smithsonian+Institution&rft.atitle=Time-reckoning+for+the+twentieth+century&rft.issue=1&rft.pages=345-366&rft.date=1886&rft.aulast=Fleming&rft.aufirst=Sandford&rft_id=https%3A%2F%2Flibrary.si.edu%2Fdigital-library%2Fbook%2Fannualreportofbo18861smit&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span> Reprinted in 1889: <a rel="nofollow" class="external text" href="https://archive.org/details/timereckoningfor00flem"><i>Time-reckoning for the twentieth century</i></a> at the <a href="/wiki/Internet_Archive" title="Internet Archive">Internet Archive</a></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMarkowitz1988" class="citation book cs1">Markowitz, Wm. (1988). 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Retrieved <span class="nowrap">18 June</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Proc.+IEEE&rft.atitle=Astronomical+Time&rft.volume=79&rft.issue=7&rft.pages=915-920&rft.date=1991-07&rft_id=info%3Adoi%2F10.1109%2F5.84967&rft.aulast=McCarthy&rft.aufirst=Dennis+D.&rft_id=https%3A%2F%2Fwww.cl.cam.ac.uk%2F~mgk25%2Fvolatile%2Fastronomical-time.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMcCarthySeidelmann2009" class="citation book cs1"><a href="/wiki/Dennis_McCarthy_(scientist)" title="Dennis McCarthy (scientist)">McCarthy, Dennis D.</a>; Seidelmann, P. Kenneth (2009). <i>TIME From Earth Rotation to Atomic Physics</i>. 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Retrieved <span class="nowrap">17 August</span> 2022</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Note+on+Coordinated+Universal+Time+%28CCTF%2F09-32%29&rft.date=2009-06-02&rft.aulast=McCarthy&rft.aufirst=D.&rft_id=https%3A%2F%2Fwww.bipm.org%2Fdocuments%2F20126%2F28435864%2Fworking-document-ID-3644%2F2a6ce17c-7b50-4164-9bee-64f77bfad895%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMcCarthyGuinot2013" class="citation book cs1"><a href="/wiki/Dennis_McCarthy_(scientist)" title="Dennis McCarthy (scientist)">McCarthy, D.</a>; Guinot, B. (2013). "Time". In Urban, Sean E.; Seidelmann, P. Kenneth (eds.). <i>Explanatory Supplement to the Astronomical Almanac</i> (3rd ed.). 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Archived from <a rel="nofollow" class="external text" href="https://www.usatoday.com/weather/zulu.htm">the original</a> on 21 June 2007<span class="reference-accessdate">. Retrieved <span class="nowrap">25 February</span> 2007</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=USA+Today&rft.atitle=Understanding+and+using+Zulu+time&rft.date=2005-05-17&rft.aulast=Williams&rft.aufirst=Jack&rft_id=https%3A%2F%2Fwww.usatoday.com%2Fweather%2Fzulu.htm&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACoordinated+Universal+Time" class="Z3988"></span></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Coordinated_Universal_Time&action=edit&section=15" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1237033735">@media print{body.ns-0 .mw-parser-output .sistersitebox{display:none!important}}@media screen{html.skin-theme-clientpref-night .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .sistersitebox img[src*="Wiktionary-logo-en-v2.svg"]{background-color:white}}</style><div class="side-box side-box-right plainlinks sistersitebox"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-image"><span class="noviewer" typeof="mw:File"><span><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/40px-Wiktionary-logo-en-v2.svg.png" decoding="async" width="40" height="40" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/60px-Wiktionary-logo-en-v2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/99/Wiktionary-logo-en-v2.svg/80px-Wiktionary-logo-en-v2.svg.png 2x" data-file-width="512" data-file-height="512" /></span></span></div> <div class="side-box-text plainlist">Look up <i><b><a href="https://en.wiktionary.org/wiki/UTC" class="extiw" title="wiktionary:UTC">UTC</a></b></i> in Wiktionary, the free dictionary.</div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://www.worldtimeserver.com/time-zones/utc/"><i>Current</i> UTC time</a></li> <li><a rel="nofollow" class="external text" href="https://www.cl.cam.ac.uk/~mgk25/time/zeitgesetz.en.html">Definition of Coordinated Universal Time in German law – ZeitG §1 (3)</a></li> <li><a rel="nofollow" class="external text" href="https://hpiers.obspm.fr/eop-pc/earthor/utc/TAI-UTC_tab.html">International Earth Rotation Service; list of differences between TAI and UTC from 1961 to present</a></li> <li><a rel="nofollow" class="external text" href="https://www.w3.org/TR/NOTE-datetime">W3C Specification about UTC Date and Time</a> and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><a href="/wiki/RFC_(identifier)" class="mw-redirect" title="RFC (identifier)">RFC</a> <a rel="nofollow" class="external text" href="https://datatracker.ietf.org/doc/html/rfc3339">3339</a>, based on <a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a></li> <li><a rel="nofollow" class="external text" href="https://www.ipses.com/eng/in-depth-analysis/standard-of-time-definition/">Standard of time definition: UTC, GPS, LORAN and TAI</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20131106032206/https://itunews.itu.int/En/4271-What-is-in-a-nameBROn-the-term-Coordinated-Universal-Time.note.aspx">What is in a name? On the term Coordinated Universal Time</a> at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a> (archived 6 November 2013)</li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": 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href="mw-data:TemplateStyles:r1129693374"></div><div role="navigation" class="navbox" aria-labelledby="Time" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Time_topics" title="Template:Time topics"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Time_topics" title="Template talk:Time topics"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Time_topics" title="Special:EditPage/Template:Time topics"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Time" style="font-size:114%;margin:0 4em"><a href="/wiki/Time" title="Time">Time</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Key concepts</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Past" title="Past">Past</a></li> <li><a href="/wiki/Present" title="Present">Present</a></li> <li><a href="/wiki/Future" title="Future">Future</a></li> <li><a href="/wiki/Eternity" title="Eternity">Eternity</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Horology" class="mw-redirect" title="Horology">Measurement</a><br />and <a href="/wiki/Time_standard" title="Time standard">standards</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Chronometry" title="Chronometry">Chronometry</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a class="mw-selflink selflink">UTC</a></li> <li><a href="/wiki/Universal_Time" title="Universal Time">UT</a></li> <li><a href="/wiki/International_Atomic_Time" title="International Atomic Time">TAI</a></li> <li><a href="/wiki/Unit_of_time" title="Unit of time">Unit of time</a></li> <li><a href="/wiki/Orders_of_magnitude_(time)" title="Orders of magnitude (time)">Orders of magnitude (time)</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/System_of_measurement" class="mw-redirect" title="System of measurement">Measurement<br />systems</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Italian_six-hour_clock" title="Italian six-hour clock">Italian six-hour clock</a></li> <li><a href="/wiki/Thai_six-hour_clock" title="Thai six-hour clock">Thai six-hour clock</a></li> <li><a href="/wiki/12-hour_clock" title="12-hour clock">12-hour clock</a></li> <li><a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a></li> <li><a href="/wiki/Relative_hour" title="Relative hour">Relative hour</a></li> <li><a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></li> <li><a href="/wiki/Traditional_Chinese_timekeeping" title="Traditional Chinese timekeeping">Chinese</a></li> <li><a href="/wiki/Decimal_time" title="Decimal time">Decimal</a></li> <li><a href="/wiki/Hexadecimal_time" title="Hexadecimal time">Hexadecimal</a></li> <li><a href="/wiki/Hindu_units_of_time" title="Hindu units of time">Hindu</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric</a></li> <li><a href="/wiki/Roman_timekeeping" title="Roman timekeeping">Roman</a></li> <li><a href="/wiki/Sidereal_time" title="Sidereal time">Sidereal</a></li> <li><a href="/wiki/Solar_time" title="Solar time">Solar</a></li> <li><a href="/wiki/Time_zone" title="Time zone">Time zone</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Calendar" title="Calendar">Calendars</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Calendar#Systems" title="Calendar">Main types</a> <ul><li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a></li> <li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a></li></ul></li> <li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a></li> <li><a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a></li> <li><a href="/wiki/Solar_Hijri_calendar" title="Solar Hijri calendar">Solar Hijri</a></li> <li><a href="/wiki/Chinese_calendar" title="Chinese calendar">Chinese</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu Panchang</a></li> <li><a href="/wiki/Maya_calendar" title="Maya calendar">Maya</a></li> <li><i><a href="/wiki/List_of_calendars" title="List of calendars">List</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Clock" title="Clock">Clocks</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Clock#Types" title="Clock">Main types</a> <ul><li><a href="/wiki/Astronomical_clock" title="Astronomical clock">astronomical</a> <ul><li><a href="/wiki/Astrarium" title="Astrarium">astrarium</a></li></ul></li> <li><a href="/wiki/Atomic_clock" title="Atomic clock">atomic</a> <ul><li><a href="/wiki/Quantum_clock" class="mw-redirect" title="Quantum clock">quantum</a></li></ul></li> <li><a href="/wiki/Hourglass" title="Hourglass">hourglass</a></li> <li><a href="/wiki/Marine_chronometer" title="Marine chronometer">marine</a></li> <li><a href="/wiki/Sundial" title="Sundial">sundial</a></li> <li><a href="/wiki/Watch" title="Watch">watch</a> <ul><li><a href="/wiki/Mechanical_watch" title="Mechanical watch">mechanical</a></li> <li><a href="/wiki/Stopwatch" title="Stopwatch">stopwatch</a></li></ul></li> <li><a href="/wiki/Water_clock" title="Water clock">water-based</a></li></ul></li> <li><a href="/wiki/Cuckoo_clock" title="Cuckoo clock">Cuckoo clock</a></li> <li><a href="/wiki/Digital_clock" title="Digital clock">Digital clock</a></li> <li><a href="/wiki/Grandfather_clock" title="Grandfather clock">Grandfather clock</a></li> <li><i><a href="/wiki/History_of_timekeeping_devices" title="History of timekeeping devices">History</a></i> <ul><li><i><a href="/wiki/Timeline_of_time_measurement_inventions" title="Timeline of time measurement inventions">Timeline</a></i></li></ul></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div class="hlist"><ul><li><a href="/wiki/Chronology" title="Chronology">Chronology</a></li><li><a href="/wiki/History" title="History">History</a></li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomical chronology</a></li> <li><a href="/wiki/Big_History" title="Big History">Big History</a></li> <li><a href="/wiki/Calendar_era" title="Calendar era">Calendar era</a></li> <li><a href="/wiki/Deep_time" title="Deep time">Deep time</a></li> <li><a href="/wiki/Periodization" title="Periodization">Periodization</a></li> <li><a href="/wiki/Regnal_year" title="Regnal year">Regnal year</a></li> <li><a href="/wiki/Timeline" title="Timeline">Timeline</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Philosophy_of_space_and_time" title="Philosophy of space and time">Philosophy of time</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/A_series_and_B_series" title="A series and B series">A series and B series</a></li> <li><a href="/wiki/B-theory_of_time" title="B-theory of time">B-theory of time</a></li> <li><a href="/wiki/Chronocentrism" title="Chronocentrism">Chronocentrism</a></li> <li><a href="/wiki/Duration_(philosophy)" title="Duration (philosophy)">Duration</a></li> <li><a href="/wiki/Endurantism" title="Endurantism">Endurantism</a></li> <li><a href="/wiki/Eternal_return" title="Eternal return">Eternal return</a></li> <li><a href="/wiki/Eternalism_(philosophy_of_time)" title="Eternalism (philosophy of time)">Eternalism</a></li> <li><a href="/wiki/Event_(philosophy)" title="Event (philosophy)">Event</a></li> <li><a href="/wiki/Perdurantism" title="Perdurantism">Perdurantism</a></li> <li><a href="/wiki/Philosophical_presentism" title="Philosophical presentism">Presentism</a></li> <li><a href="/wiki/Temporal_finitism" title="Temporal finitism">Temporal finitism</a></li> <li><a href="/wiki/Temporal_parts" title="Temporal parts">Temporal parts</a></li> <li><i><a href="/wiki/The_Unreality_of_Time" title="The Unreality of Time">The Unreality of Time</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><div class="hlist"><ul><li><a href="/wiki/Category:Time_in_religion" title="Category:Time in religion">Religion</a></li><li><a href="/wiki/Template:Time_in_religion_and_mythology" title="Template:Time in religion and mythology">Mythology</a></li></ul></div></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ages_of_Man" title="Ages of Man">Ages of Man</a></li> <li><a href="/wiki/Destiny" title="Destiny">Destiny</a></li> <li><a href="/wiki/Immortality" title="Immortality">Immortality</a></li> <li><a href="/wiki/The_Dreaming" title="The Dreaming">Dreamtime</a></li> <li><a href="/wiki/K%C4%81la" title="Kāla">Kāla</a></li> <li><a href="/wiki/Time_and_fate_deities" title="Time and fate deities">Time and fate deities</a> <ul><li><a href="/wiki/Father_Time" title="Father Time">Father Time</a></li></ul></li> <li><a href="/wiki/Wheel_of_time" title="Wheel of time">Wheel of time</a> <ul><li><a href="/wiki/Kalachakra" title="Kalachakra">Kalachakra</a></li></ul></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Time_perception" title="Time perception">Human experience</a><br />and <a href="/wiki/Time-use_research" title="Time-use research">use of time</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronemics" title="Chronemics">Chronemics</a></li> <li><a href="/wiki/Generation_time" title="Generation time">Generation time</a></li> <li><a href="/wiki/Mental_chronometry" title="Mental chronometry">Mental chronometry</a></li> <li><a href="/wiki/Duration_(music)" title="Duration (music)">Music</a> <ul><li><a href="/wiki/Tempo" title="Tempo">tempo</a></li> <li><a href="/wiki/Time_signature" title="Time signature">time signature</a></li></ul></li> <li><a href="/wiki/Rosy_retrospection" title="Rosy retrospection">Rosy retrospection</a></li> <li><a href="/wiki/Tense%E2%80%93aspect%E2%80%93mood" title="Tense–aspect–mood">Tense–aspect–mood</a></li> <li><a href="/wiki/Time_management" title="Time management">Time management</a></li> <li><a href="/wiki/Yesterday_(time)" title="Yesterday (time)">Yesterday</a> – <a href="/wiki/Present" title="Present">Today</a> – <a href="/wiki/Tomorrow_(time)" title="Tomorrow (time)">Tomorrow</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Time in <a href="/wiki/Science" title="Science">science</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Geology" title="Geology">Geology</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geological time</a> <ul><li><a href="/wiki/Age_(geology)" class="mw-redirect" title="Age (geology)">age</a></li> <li><a href="/wiki/Chronozone" title="Chronozone">chron</a></li> <li><a href="/wiki/Eon_(geology)" class="mw-redirect" title="Eon (geology)">eon</a></li> <li><a href="/wiki/Epoch_(geology)" class="mw-redirect" title="Epoch (geology)">epoch</a></li> <li><a href="/wiki/Era_(geology)" class="mw-redirect" title="Era (geology)">era</a></li> <li><a href="/wiki/Geological_period" class="mw-redirect" title="Geological period">period</a></li></ul></li> <li><a href="/wiki/Geochronology" title="Geochronology">Geochronology</a></li> <li><a href="/wiki/Geological_history_of_Earth" title="Geological history of Earth">Geological history of Earth</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;"><a href="/wiki/Time_in_physics" title="Time in physics">Physics</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absolute_space_and_time" title="Absolute space and time">Absolute space and time</a></li> <li><a href="/wiki/Arrow_of_time" title="Arrow of time">Arrow of time</a></li> <li><a href="/wiki/Chronon" title="Chronon">Chronon</a></li> <li><a href="/wiki/Coordinate_time" title="Coordinate time">Coordinate time</a></li> <li><a href="/wiki/Instant" title="Instant">Instant</a></li> <li><a href="/wiki/Proper_time" title="Proper time">Proper time</a></li> <li><a href="/wiki/Spacetime" title="Spacetime">Spacetime</a></li> <li><a href="/wiki/Theory_of_relativity" title="Theory of relativity">Theory of relativity</a></li> <li><a href="/wiki/Time_domain" title="Time domain">Time domain</a></li> <li><a href="/wiki/Time_translation_symmetry" class="mw-redirect" title="Time translation symmetry">Time translation symmetry</a></li> <li><a href="/wiki/T-symmetry" title="T-symmetry">Time reversal symmetry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:6.5em;font-weight:normal; text-align:center;">Other fields</th><td class="navbox-list-with-group navbox-list navbox-even" style="padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological dating</a></li> <li><a href="/wiki/Chronobiology" title="Chronobiology">Chronobiology</a> <ul><li><a href="/wiki/Circadian_rhythm" title="Circadian rhythm">Circadian rhythms</a></li></ul></li> <li><a href="/wiki/Chemical_clock" title="Chemical clock">Clock reaction</a></li> <li><a href="/wiki/Glottochronology" title="Glottochronology">Glottochronology</a></li> <li><a href="/wiki/Time_geography" title="Time geography">Time geography</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Leap_year" title="Leap year">Leap year</a></li> <li><a href="/wiki/Memory" title="Memory">Memory</a></li> <li><a href="/wiki/Moment_(unit)" title="Moment (unit)">Moment</a></li> <li><a href="/wiki/Space" title="Space">Space</a></li> <li><a href="/wiki/System_time" title="System time">System time</a></li> <li><i><a href="/wiki/Tempus_fugit" title="Tempus fugit">Tempus fugit</a></i></li> <li><a href="/wiki/Time_capsule" title="Time capsule">Time capsule</a></li> <li><a href="/wiki/Time_immemorial" title="Time immemorial">Time immemorial</a></li> <li><a href="/wiki/Time_travel" title="Time travel">Time travel</a></li></ul> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li><span class="noviewer" typeof="mw:File"><span title="Category"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /></span></span> <a href="/wiki/Category:Time" title="Category:Time">Category</a></li> <li><span class="noviewer" typeof="mw:File"><span title="Commons page"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></span></span> <a href="https://commons.wikimedia.org/wiki/Category:Time" class="extiw" title="commons:Category:Time">Commons</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Time_measurement_and_standards" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="3"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:Time_measurement_and_standards" title="Template:Time measurement and standards"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Time_measurement_and_standards" title="Template talk:Time measurement and standards"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Time_measurement_and_standards" title="Special:EditPage/Template:Time measurement and standards"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Time_measurement_and_standards" style="font-size:114%;margin:0 4em"><a href="/wiki/Time" title="Time">Time measurement</a> and <a href="/wiki/Time_standard" title="Time standard">standards</a></div></th></tr><tr><td class="navbox-abovebelow" colspan="3"><div> <ul><li><a href="/wiki/Chronometry" title="Chronometry">Chronometry</a></li> <li><a href="/wiki/Orders_of_magnitude_(time)" title="Orders of magnitude (time)">Orders of magnitude</a></li> <li><a href="/wiki/Time_metrology" class="mw-redirect" title="Time metrology">Metrology</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">International standards</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a class="mw-selflink selflink">Coordinated Universal Time</a> <ul><li><a href="/wiki/UTC_offset" title="UTC offset">offset</a></li></ul></li> <li><a href="/wiki/Universal_Time" title="Universal Time">UT</a></li> <li><a href="/wiki/%CE%94T_(timekeeping)" title="ΔT (timekeeping)">ΔT</a></li> <li><a href="/wiki/DUT1" title="DUT1">DUT1</a></li> <li><a href="/wiki/International_Earth_Rotation_and_Reference_Systems_Service" title="International Earth Rotation and Reference Systems Service">International Earth Rotation and Reference Systems Service</a></li> <li><a href="/wiki/ISO_31-1" title="ISO 31-1">ISO 31-1</a></li> <li><a href="/wiki/ISO_8601" title="ISO 8601">ISO 8601</a></li> <li><a href="/wiki/International_Atomic_Time" title="International Atomic Time">International Atomic Time</a></li> <li><a href="/wiki/12-hour_clock" title="12-hour clock">12-hour clock</a></li> <li><a href="/wiki/24-hour_clock" title="24-hour clock">24-hour clock</a></li> <li><a href="/wiki/Barycentric_Coordinate_Time" title="Barycentric Coordinate Time">Barycentric Coordinate Time</a></li> <li><a href="/wiki/Barycentric_Dynamical_Time" title="Barycentric Dynamical Time">Barycentric Dynamical Time</a></li> <li><a href="/wiki/Civil_time" title="Civil time">Civil time</a></li> <li><a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a></li> <li><a href="/wiki/Geocentric_Coordinate_Time" title="Geocentric Coordinate Time">Geocentric Coordinate Time</a></li> <li><a href="/wiki/International_Date_Line" title="International Date Line">International Date Line</a></li> <li><a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">IERS Reference Meridian</a></li> <li><a href="/wiki/Leap_second" title="Leap second">Leap second</a></li> <li><a href="/wiki/Solar_time" title="Solar time">Solar time</a></li> <li><a href="/wiki/Terrestrial_Time" title="Terrestrial Time">Terrestrial Time</a></li> <li><a href="/wiki/Time_zone" title="Time zone">Time zone</a></li> <li><a href="/wiki/180th_meridian" title="180th meridian">180th meridian</a></li></ul> </div></td><td class="noviewer navbox-image" rowspan="9" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/Hourglass" title="Hourglass"><img alt="template illustration" src="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/75px-Marine_sandglass_MMM.jpg" decoding="async" width="75" height="175" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/113px-Marine_sandglass_MMM.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/70/Marine_sandglass_MMM.jpg/150px-Marine_sandglass_MMM.jpg 2x" data-file-width="1637" data-file-height="3819" /></a></span><br /><span typeof="mw:File"><a href="/wiki/Time_zone" title="Time zone"><img alt="template illustration" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/75px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png" decoding="async" width="75" height="152" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/113px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/63/Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png/150px-Aleutian_Islands_with_180th_meridian_and_International_Date_Line_%28cropped%29.png 2x" data-file-width="496" data-file-height="1007" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Obsolete standards</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ephemeris_time" title="Ephemeris time">Ephemeris time</a></li> <li><a href="/wiki/Greenwich_Mean_Time" title="Greenwich Mean Time">Greenwich Mean Time</a></li> <li><a href="/wiki/Prime_meridian" title="Prime meridian">Prime meridian</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Time_in_physics" title="Time in physics">Time in physics</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Absolute_space_and_time" title="Absolute space and time">Absolute space and time</a></li> <li><a href="/wiki/Spacetime" title="Spacetime">Spacetime</a></li> <li><a href="/wiki/Chronon" title="Chronon">Chronon</a></li> <li><a href="/wiki/Continuous_signal" class="mw-redirect" title="Continuous signal">Continuous signal</a></li> <li><a href="/wiki/Coordinate_time" title="Coordinate time">Coordinate time</a></li> <li><a href="/wiki/Cosmological_decade" title="Cosmological decade">Cosmological decade</a></li> <li><a href="/wiki/Discrete_time_and_continuous_time" title="Discrete time and continuous time">Discrete time and continuous time</a></li> <li><a href="/wiki/Proper_time" title="Proper time">Proper time</a></li> <li><a href="/wiki/Theory_of_relativity" title="Theory of relativity">Theory of relativity</a></li> <li><a href="/wiki/Time_dilation" title="Time dilation">Time dilation</a></li> <li><a href="/wiki/Gravitational_time_dilation" title="Gravitational time dilation">Gravitational time dilation</a></li> <li><a href="/wiki/Time_domain" title="Time domain">Time domain</a></li> <li><a href="/wiki/Time-translation_symmetry" title="Time-translation symmetry">Time-translation symmetry</a></li> <li><a href="/wiki/T-symmetry" title="T-symmetry">T-symmetry</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Horology" class="mw-redirect" title="Horology">Horology</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Clock" title="Clock">Clock</a></li> <li><a href="/wiki/Astrarium" title="Astrarium">Astrarium</a></li> <li><a href="/wiki/Atomic_clock" title="Atomic clock">Atomic clock</a></li> <li><a href="/wiki/Complication_(horology)" title="Complication (horology)">Complication</a></li> <li><a href="/wiki/History_of_timekeeping_devices" title="History of timekeeping devices">History of timekeeping devices</a></li> <li><a href="/wiki/Hourglass" title="Hourglass">Hourglass</a></li> <li><a href="/wiki/Marine_chronometer" title="Marine chronometer">Marine chronometer</a></li> <li><a href="/wiki/Marine_sandglass" title="Marine sandglass">Marine sandglass</a></li> <li><a href="/wiki/Radio_clock" title="Radio clock">Radio clock</a></li> <li><a href="/wiki/Watch" title="Watch">Watch</a> <ul><li><a href="/wiki/Stopwatch" title="Stopwatch">stopwatch</a></li></ul></li> <li><a href="/wiki/Water_clock" title="Water clock">Water clock</a></li> <li><a href="/wiki/Sundial" title="Sundial">Sundial</a></li> <li><a href="/wiki/Dialing_scales" title="Dialing scales">Dialing scales</a></li> <li><a href="/wiki/Equation_of_time" title="Equation of time">Equation of time</a></li> <li><a href="/wiki/History_of_sundials" title="History of sundials">History of sundials</a></li> <li><a href="/wiki/Schema_for_horizontal_dials" title="Schema for horizontal dials">Sundial markup schema</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Calendar" title="Calendar">Calendar</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Gregorian_calendar" title="Gregorian calendar">Gregorian</a></li> <li><a href="/wiki/Hebrew_calendar" title="Hebrew calendar">Hebrew</a></li> <li><a href="/wiki/Hindu_calendar" title="Hindu calendar">Hindu</a></li> <li><a href="/wiki/Holocene_calendar" title="Holocene calendar">Holocene</a></li> <li><a href="/wiki/Islamic_calendar" title="Islamic calendar">Islamic</a> (lunar Hijri)</li> <li><a href="/wiki/Julian_calendar" title="Julian calendar">Julian</a></li> <li><a href="/wiki/Solar_Hijri_calendar" title="Solar Hijri calendar">Solar Hijri</a></li> <li><a href="/wiki/Astronomical_year_numbering" title="Astronomical year numbering">Astronomical</a></li> <li><a href="/wiki/Dominical_letter" title="Dominical letter">Dominical letter</a></li> <li><a href="/wiki/Epact" title="Epact">Epact</a></li> <li><a href="/wiki/Equinox" title="Equinox">Equinox</a></li> <li><a href="/wiki/Intercalation_(timekeeping)" title="Intercalation (timekeeping)">Intercalation</a></li> <li><a href="/wiki/Julian_day" title="Julian day">Julian day</a></li> <li><a href="/wiki/Leap_year" title="Leap year">Leap year</a></li> <li><a href="/wiki/Lunar_calendar" title="Lunar calendar">Lunar</a></li> <li><a href="/wiki/Lunisolar_calendar" title="Lunisolar calendar">Lunisolar</a></li> <li><a href="/wiki/Solar_calendar" title="Solar calendar">Solar</a></li> <li><a href="/wiki/Solstice" title="Solstice">Solstice</a></li> <li><a href="/wiki/Tropical_year" title="Tropical year">Tropical year</a></li> <li><a href="/wiki/Determination_of_the_day_of_the_week" title="Determination of the day of the week">Weekday determination</a></li> <li><a href="/wiki/Names_of_the_days_of_the_week" title="Names of the days of the week">Weekday names</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Archaeology and geology</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronological_dating" title="Chronological dating">Chronological dating</a></li> <li><a href="/wiki/Geologic_time_scale" title="Geologic time scale">Geologic time scale</a></li> <li><a href="/wiki/International_Commission_on_Stratigraphy" title="International Commission on Stratigraphy">International Commission on Stratigraphy</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Astronomical_chronology" title="Astronomical chronology">Astronomical chronology</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Galactic_year" title="Galactic year">Galactic year</a></li> <li><a href="/wiki/Nuclear_timescale" title="Nuclear timescale">Nuclear timescale</a></li> <li><a href="/wiki/Precession" title="Precession">Precession</a></li> <li><a href="/wiki/Sidereal_time" title="Sidereal time">Sidereal time</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Other <a href="/wiki/Unit_of_time" title="Unit of time">units of time</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Instant" title="Instant">Instant</a></li> <li><a href="/wiki/Flick_(time)" title="Flick (time)">Flick</a></li> <li><a href="/wiki/Shake_(unit)" title="Shake (unit)">Shake</a></li> <li><a href="/wiki/Jiffy_(time)" title="Jiffy (time)">Jiffy</a></li> <li><a href="/wiki/Second" title="Second">Second</a></li> <li><a href="/wiki/Minute" title="Minute">Minute</a></li> <li><a href="/wiki/Moment_(unit)" title="Moment (unit)">Moment</a></li> <li><a href="/wiki/Hour" title="Hour">Hour</a></li> <li><a href="/wiki/Day" title="Day">Day</a></li> <li><a href="/wiki/Week" title="Week">Week</a></li> <li><a href="/wiki/Fortnight" title="Fortnight">Fortnight</a></li> <li><a href="/wiki/Month" title="Month">Month</a></li> <li><a href="/wiki/Year" title="Year">Year</a></li> <li><a href="/wiki/Olympiad" title="Olympiad">Olympiad</a></li> <li><a href="/wiki/Lustrum" title="Lustrum">Lustrum</a></li> <li><a href="/wiki/Decade" title="Decade">Decade</a></li> <li><a href="/wiki/Century" title="Century">Century</a></li> <li><a href="/wiki/Saeculum" title="Saeculum">Saeculum</a></li> <li><a href="/wiki/Millennium" title="Millennium">Millennium</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related topics</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Chronology" title="Chronology">Chronology</a></li> <li><a href="/wiki/Duration_(philosophy)" title="Duration (philosophy)">Duration</a> <ul><li><a href="/wiki/Duration_(music)" title="Duration (music)">music</a></li></ul></li> <li><a href="/wiki/Mental_chronometry" title="Mental chronometry">Mental chronometry</a></li> <li><a href="/wiki/Decimal_time" title="Decimal time">Decimal time</a></li> <li><a href="/wiki/Metric_time" title="Metric time">Metric time</a></li> <li><a href="/wiki/System_time" title="System time">System time</a></li> <li><a href="/wiki/Time_metrology" class="mw-redirect" title="Time metrology">Time metrology</a></li> <li><a href="/wiki/Time_value_of_money" title="Time value of money">Time value of money</a></li> <li><a href="/wiki/Timekeeper" title="Timekeeper">Timekeeper</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox" aria-labelledby="Coordinated_Universal_Time_(UTC)" style="padding:3px"><table class="nowraplinks mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1239400231"><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:UTC_time_offsets" title="Template:UTC time offsets"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:UTC_time_offsets" title="Template talk:UTC time offsets"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:UTC_time_offsets" title="Special:EditPage/Template:UTC time offsets"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Coordinated_Universal_Time_(UTC)" style="font-size:114%;margin:0 4em"><a class="mw-selflink selflink">Coordinated Universal Time</a> (UTC)</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><span class="wrap"><a href="/wiki/UTC_offset" title="UTC offset">UTC offset</a> for <a href="/wiki/Standard_time" title="Standard time">standard time</a> and <a href="/wiki/Daylight_saving_time" title="Daylight saving time">Daylight saving time</a> (DST)<br /><br /><i>Italics: historical or unofficial</i></span></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/180th_meridian" title="180th meridian">180°</a> to <a href="/wiki/90th_meridian_west" title="90th meridian west">90°W</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/UTC%E2%88%9212:00" title="UTC−12:00">−12:00</a></li> <li><a href="/wiki/UTC%E2%88%9211:00" title="UTC−11:00">−11:00</a></li> <li><i><a href="/wiki/UTC%E2%88%9210:30" title="UTC−10:30">−10:30</a></i></li> <li><a href="/wiki/UTC%E2%88%9210:00" title="UTC−10:00">−10:00</a></li> <li><a href="/wiki/UTC%E2%88%9209:30" title="UTC−09:30">−09:30</a></li> <li><a href="/wiki/UTC%E2%88%9209:00" title="UTC−09:00">−09:00</a></li> <li><i><a href="/wiki/UTC%E2%88%9208:30" title="UTC−08:30">−08:30</a></i></li> <li><a href="/wiki/UTC%E2%88%9208:00" title="UTC−08:00">−08:00</a></li> <li><a href="/wiki/UTC%E2%88%9207:00" title="UTC−07:00">−07:00</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/90th_meridian_west" title="90th meridian west">90°W</a> to <a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">0°</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/UTC%E2%88%9206:00" title="UTC−06:00">−06:00</a></li> <li><a href="/wiki/UTC%E2%88%9205:00" title="UTC−05:00">−05:00</a></li> <li><i><a href="/wiki/UTC%E2%88%9204:30" title="UTC−04:30">−04:30</a></i></li> <li><a href="/wiki/UTC%E2%88%9204:00" title="UTC−04:00">−04:00</a></li> <li><a href="/wiki/UTC%E2%88%9203:30" title="UTC−03:30">−03:30</a></li> <li><a href="/wiki/UTC%E2%88%9203:00" title="UTC−03:00">−03:00</a></li> <li><a href="/wiki/UTC%E2%88%9202:30" title="UTC−02:30">−02:30</a></li> <li><a href="/wiki/UTC%E2%88%9202:00" title="UTC−02:00">−02:00</a></li> <li><a href="/wiki/UTC%E2%88%9201:00" title="UTC−01:00">−01:00</a></li> <li><i><a href="/wiki/UTC%E2%88%9200:44" title="UTC−00:44">−00:44</a></i></li> <li><i><a href="/wiki/UTC%E2%88%9200:25:21" title="UTC−00:25:21">−00:25:21</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/IERS_Reference_Meridian" title="IERS Reference Meridian">0°</a> to <a href="/wiki/90th_meridian_east" title="90th meridian east">90°E</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/UTC%2B00:00" title="UTC+00:00">+00:00</a></li> <li><i><a href="/wiki/UTC%2B00:20" title="UTC+00:20">+00:20</a></i></li> <li><i><a href="/wiki/UTC%2B00:30" title="UTC+00:30">+00:30</a></i></li> <li><a href="/wiki/UTC%2B01:00" title="UTC+01:00">+01:00</a></li> <li><i><a href="/wiki/UTC%2B01:24" title="UTC+01:24">+01:24</a></i></li> <li><i><a href="/wiki/UTC%2B01:30" title="UTC+01:30">+01:30</a></i></li> <li><a href="/wiki/UTC%2B02:00" title="UTC+02:00">+02:00</a></li> <li><i><a href="/wiki/UTC%2B02:30" title="UTC+02:30">+02:30</a></i></li> <li><a href="/wiki/UTC%2B03:00" title="UTC+03:00">+03:00</a></li> <li><a href="/wiki/UTC%2B03:30" title="UTC+03:30">+03:30</a></li> <li><a href="/wiki/UTC%2B04:00" title="UTC+04:00">+04:00</a></li> <li><a href="/wiki/UTC%2B04:30" title="UTC+04:30">+04:30</a></li> <li><i><a href="/wiki/UTC%2B04:51" title="UTC+04:51">+04:51</a></i></li> <li><a href="/wiki/UTC%2B05:00" title="UTC+05:00">+05:00</a></li> <li><a href="/wiki/UTC%2B05:30" title="UTC+05:30">+05:30</a></li> <li><i><a href="/wiki/UTC%2B05:40" title="UTC+05:40">+05:40</a></i></li> <li><a href="/wiki/UTC%2B05:45" title="UTC+05:45">+05:45</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/90th_meridian_east" title="90th meridian east">90°E</a> to <a href="/wiki/180th_meridian" title="180th meridian">180°</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/UTC%2B06:00" title="UTC+06:00">+06:00</a></li> <li><a href="/wiki/UTC%2B06:30" title="UTC+06:30">+06:30</a></li> <li><a href="/wiki/UTC%2B07:00" title="UTC+07:00">+07:00</a></li> <li><i><a href="/wiki/UTC%2B07:20" title="UTC+07:20">+07:20</a></i></li> <li><i><a href="/wiki/UTC%2B07:30" title="UTC+07:30">+07:30</a></i></li> <li><a href="/wiki/UTC%2B08:00" title="UTC+08:00">+08:00</a></li> <li><i><a href="/wiki/UTC%2B08:30" title="UTC+08:30">+08:30</a></i></li> <li><i><a href="/wiki/UTC%2B08:45" title="UTC+08:45">+08:45</a></i></li> <li><a href="/wiki/UTC%2B09:00" title="UTC+09:00">+09:00</a></li> <li><a href="/wiki/UTC%2B09:30" title="UTC+09:30">+09:30</a></li> <li><i><a href="/wiki/UTC%2B09:45" title="UTC+09:45">+09:45</a></i></li> <li><a href="/wiki/UTC%2B10:00" title="UTC+10:00">+10:00</a></li> <li><a href="/wiki/UTC%2B10:30" title="UTC+10:30">+10:30</a></li> <li><a href="/wiki/UTC%2B11:00" title="UTC+11:00">+11:00</a></li> <li><i><a href="/wiki/UTC%2B11:30" title="UTC+11:30">+11:30</a></i></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/180th_meridian" title="180th meridian">180°</a> to <a href="/wiki/90th_meridian_west" title="90th meridian west">90°W</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/UTC%2B12:00" title="UTC+12:00">+12:00</a></li> <li><a href="/wiki/UTC%2B12:45" title="UTC+12:45">+12:45</a></li> <li><a href="/wiki/UTC%2B13:00" title="UTC+13:00">+13:00</a></li> <li><a href="/wiki/UTC%2B13:45" title="UTC+13:45">+13:45</a></li> <li><a href="/wiki/UTC%2B14:00" title="UTC+14:00">+14:00</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Time_zone" title="Time zone">Time zone</a> data sources</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"><a href="/wiki/Tz_database" title="Tz database">tz database</a></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Lists_of_time_zones" title="Lists of time zones">Lists of time zones</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/List_of_time_zones_by_country" title="List of time zones by country">Time zones by country</a></li> <li><a href="/wiki/List_of_UTC_offsets" title="List of UTC offsets">Time zones by UTC offset</a></li> <li><a href="/wiki/Military_time_zone" title="Military time zone">Military time zone</a></li> <li><a href="/wiki/List_of_time_zone_abbreviations" title="List of time zone abbreviations">Time zone abbreviations</a></li> <li><a href="/wiki/Daylight_saving_time_by_country" title="Daylight saving time by country">Daylight saving time by country</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related topics</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Abolition_of_time_zones" title="Abolition of time zones">Abolition of time zones</a></li></ul> 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Template:Time_topics"," 6.01% 71.321 13 Template:Cite_journal"," 5.89% 69.901 1 Template:Short_description"," 4.95% 58.736 1 Template:Efn"," 3.97% 47.077 2 Template:Pagetype"]},"scribunto":{"limitreport-timeusage":{"value":"0.726","limit":"10.000"},"limitreport-memusage":{"value":28772865,"limit":52428800},"limitreport-logs":"anchor_id_list = table#1 {\n [\"CITEREF15_U.S._Code_§_260a2005\"] = 1,\n [\"CITEREF15_U.S._Code_§_2612007\"] = 1,\n [\"CITEREFAgnew2024\"] = 1,\n [\"CITEREFAllanAshbyHodge1997\"] = 1,\n [\"CITEREFAllen2011a\"] = 1,\n [\"CITEREFAllen2011b\"] = 1,\n [\"CITEREFAriasGuinotQuinn2003\"] = 1,\n [\"CITEREFAviation_Time2006\"] = 1,\n [\"CITEREFBlair1974\"] = 1,\n [\"CITEREFBulletin_C2022\"] = 1,\n [\"CITEREFChester2015\"] = 1,\n [\"CITEREFCreet1990\"] = 1,\n [\"CITEREFEssen1968\"] = 1,\n [\"CITEREFEvers2013\"] = 1,\n [\"CITEREFFinklemanAllenSeagoSeaman2011\"] = 1,\n [\"CITEREFFleming1886\"] = 1,\n [\"CITEREFGuinot2011\"] = 1,\n [\"CITEREFHistory_of_TAI-UTCc._2009\"] = 1,\n [\"CITEREFHorzepa2010\"] = 1,\n [\"CITEREFHow_NTP_Works2011\"] = 1,\n [\"CITEREFHowse1997\"] = 1,\n [\"CITEREFIAU_resolutions1976\"] = 1,\n [\"CITEREFITU_Radiocommunication_Assembly2002\"] = 1,\n [\"CITEREFIceland2011\"] = 1,\n [\"CITEREFInternational_Earth_Rotation_and_Reference_Systems_Service2011\"] = 1,\n [\"CITEREFIrvine2008\"] = 1,\n [\"CITEREFLangley1999\"] = 1,\n [\"CITEREFLeap_decision_postponed2012\"] = 1,\n [\"CITEREFMarkowitz1988\"] = 1,\n [\"CITEREFMarkowitzHallEssenParry1958\"] = 1,\n [\"CITEREFMcCarthy1991\"] = 1,\n [\"CITEREFMcCarthy2009\"] = 1,\n [\"CITEREFMcCarthyGuinot2013\"] = 1,\n [\"CITEREFMcCarthySeidelmann2009\"] = 1,\n [\"CITEREFMilitary_\u0026amp;_Civilian_Time_Designationsn.d.\"] = 1,\n [\"CITEREFNelsonLombardiOkayama2005\"] = 1,\n [\"CITEREFNelsonMcCarthy2005\"] = 1,\n [\"CITEREFNelsonMcCarthyMalysLevine2001\"] = 1,\n [\"CITEREFSeaman2001\"] = 1,\n [\"CITEREFSeaman2003\"] = 1,\n [\"CITEREFSeidelmann1992\"] = 1,\n [\"CITEREFSeidelmannSeago2011\"] = 1,\n [\"CITEREFStephensonMorrison1995\"] = 1,\n [\"CITEREFUnited_States_Naval_Observatoryn.d.\"] = 1,\n [\"CITEREFUniversal_Timen.d.\"] = 1,\n [\"CITEREFWilliams2005\"] = 1,\n}\ntemplate_list = table#1 {\n [\"!\"] = 1,\n [\"Annotated link\"] = 10,\n [\"As of\"] = 1,\n [\"Citation\"] = 1,\n [\"Cite book\"] = 8,\n [\"Cite conference\"] = 2,\n [\"Cite journal\"] = 13,\n [\"Cite news\"] = 3,\n [\"Cite press release\"] = 3,\n [\"Cite web\"] = 27,\n [\"Efn\"] = 1,\n [\"Further\"] = 1,\n [\"Harvnb\"] = 1,\n [\"IETF RFC\"] = 1,\n [\"Internet Archive\"] = 1,\n [\"Main\"] = 2,\n [\"Notelist\"] = 1,\n [\"Nowrap\"] = 2,\n [\"Portal\"] = 1,\n [\"Pp-move-indef\"] = 1,\n [\"Pp-pc\"] = 1,\n [\"Redirect\"] = 2,\n [\"Refbegin\"] = 1,\n [\"Refend\"] = 1,\n [\"Reflist\"] = 1,\n [\"See also\"] = 2,\n [\"Sfn\"] = 50,\n [\"SfnRef\"] = 9,\n [\"Sfnref\"] = 3,\n [\"Sfrac\"] = 2,\n [\"Short description\"] = 1,\n [\"Snd\"] = 1,\n [\"Time measurement and standards\"] = 1,\n [\"Time topics\"] = 1,\n [\"UTC time offsets\"] = 1,\n [\"Update after\"] = 1,\n [\"Use dmy dates\"] = 1,\n [\"Webarchive\"] = 1,\n [\"Wiktionary\"] = 1,\n}\narticle_whitelist = table#1 {\n}\n"},"cachereport":{"origin":"mw-web.codfw.main-f69cdc8f6-sw5fn","timestamp":"20241124053328","ttl":66406,"transientcontent":true}}});});</script> <script type="application/ld+json">{"@context":"https:\/\/schema.org","@type":"Article","name":"Coordinated Universal Time","url":"https:\/\/en.wikipedia.org\/wiki\/Coordinated_Universal_Time","sameAs":"http:\/\/www.wikidata.org\/entity\/Q1536","mainEntity":"http:\/\/www.wikidata.org\/entity\/Q1536","author":{"@type":"Organization","name":"Contributors to Wikimedia projects"},"publisher":{"@type":"Organization","name":"Wikimedia Foundation, Inc.","logo":{"@type":"ImageObject","url":"https:\/\/www.wikimedia.org\/static\/images\/wmf-hor-googpub.png"}},"datePublished":"2001-10-13T07:38:05Z","image":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/8\/88\/World_Time_Zones_Map.png","headline":"principal time standard that underlies civil times on Earth"}</script> </body> </html>