Time metrology

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action="https://www.bipm.org/en/time-metrology?p_p_id=com_liferay_login_web_portlet_LoginPortlet&p_p_lifecycle=1&p_p_state=normal&p_p_mode=view&_com_liferay_login_web_portlet_LoginPortlet_javax.portlet.action=%2Flogin%2Flogin&_com_liferay_login_web_portlet_LoginPortlet_mvcRenderCommandName=%2Flogin%2Flogin&p_auth=ZtY6EyEz" class="form sign-in-form " data-fm-namespace="_com_liferay_login_web_portlet_LoginPortlet_" id="_com_liferay_login_web_portlet_LoginPortlet_loginForm" method="post" name="_com_liferay_login_web_portlet_LoginPortlet_loginForm" autocomplete="on" > <fieldset class="input-container" disabled="disabled"> <legend class="sr-only">Sign In</legend> <input class="field form-control" id="_com_liferay_login_web_portlet_LoginPortlet_formDate" name="_com_liferay_login_web_portlet_LoginPortlet_formDate" type="hidden" value="1740577907282" /> <input class="field form-control" id="_com_liferay_login_web_portlet_LoginPortlet_saveLastPath" name="_com_liferay_login_web_portlet_LoginPortlet_saveLastPath" type="hidden" value="false" /> <input class="field form-control" id="_com_liferay_login_web_portlet_LoginPortlet_redirect" name="_com_liferay_login_web_portlet_LoginPortlet_redirect" type="hidden" value="" /> <input class="field form-control" id="_com_liferay_login_web_portlet_LoginPortlet_doActionAfterLogin" name="_com_liferay_login_web_portlet_LoginPortlet_doActionAfterLogin" type="hidden" value="false" /> <div class="inline-alert-container lfr-alert-container"></div> <div class="alert alert-danger" id="_com_liferay_login_web_portlet_LoginPortlet_cookieDisabled" style="display: none;"> Authentication failed. Please enable browser cookies and try again. </div> <fieldset class="" > <legend class="sr-only"> Sign In </legend> <div class="show " id="Content" role="presentation"> <div class="panel-body"> <div class="form-group input-text-wrapper"> <label class=" control-label" for="_com_liferay_login_web_portlet_LoginPortlet_login"> Email Address </label> <input class="field clearable form-control" id="_com_liferay_login_web_portlet_LoginPortlet_login" name="_com_liferay_login_web_portlet_LoginPortlet_login" type="text" value="" /> </div> <div class="form-group input-text-wrapper"> <label class=" control-label" for="_com_liferay_login_web_portlet_LoginPortlet_password"> Password </label> <input class="field form-control" id="_com_liferay_login_web_portlet_LoginPortlet_password" name="_com_liferay_login_web_portlet_LoginPortlet_password" type="password" value="" /> </div> <span id="_com_liferay_login_web_portlet_LoginPortlet_passwordCapsLockSpan" style="display: none;">Caps Lock is on.</span> </div> </div> </fieldset> <div class="button-holder " > <button class="btn btn-primary" id="_com_liferay_login_web_portlet_LoginPortlet_mzue" type="submit" > <span class="lfr-btn-label">Sign In</span> </button> </div> </fieldset> </form> <script> AUI().use( 'liferay-form', function(A) { (function() { var $ = AUI.$;var _ = AUI._; Liferay.Form.register( { id: '_com_liferay_login_web_portlet_LoginPortlet_loginForm' , fieldRules: [ { body: '', custom: false, errorMessage: '\u0054\u0068\u0065\u0020\u0050\u0061\u0073\u0073\u0077\u006f\u0072\u0064\u0020\u0066\u0069\u0065\u006c\u0064\u0020\u0069\u0073\u0020\u0072\u0065\u0071\u0075\u0069\u0072\u0065\u0064\u002e', fieldName: '_com_liferay_login_web_portlet_LoginPortlet_password', validatorName: 'required' } , { body: '', custom: false, errorMessage: '\u0054\u0068\u0065\u0020\u004c\u006f\u0067\u0069\u006e\u0020\u0066\u0069\u0065\u006c\u0064\u0020\u0069\u0073\u0020\u0072\u0065\u0071\u0075\u0069\u0072\u0065\u0064\u002e', fieldName: '_com_liferay_login_web_portlet_LoginPortlet_login', validatorName: 'required' } , { body: '', custom: false, errorMessage: '', fieldName: '_com_liferay_login_web_portlet_LoginPortlet_login', validatorName: 'email' } ] , onSubmit: function(event) { event.preventDefault(); } , validateOnBlur: false } ); var onDestroyPortlet = function(event) { if (event.portletId === 'com_liferay_login_web_portlet_LoginPortlet') { delete Liferay.Form._INSTANCES['_com_liferay_login_web_portlet_LoginPortlet_loginForm']; } }; Liferay.on('destroyPortlet', onDestroyPortlet); A.all('#_com_liferay_login_web_portlet_LoginPortlet_loginForm .input-container').removeAttribute('disabled'); Liferay.fire( '_com_liferay_login_web_portlet_LoginPortlet_formReady', { formName: '_com_liferay_login_web_portlet_LoginPortlet_loginForm' } ); })(); }); </script> <div class="c-mt-3 navigation"> <span class="text-4" > <a href="https://www.bipm.org/en/time-metrology?p_p_id=com_liferay_login_web_portlet_LoginPortlet&p_p_lifecycle=0&p_p_state=maximized&p_p_mode=view&_com_liferay_login_web_portlet_LoginPortlet_mvcRenderCommandName=%2Flogin%2Fforgot_password&saveLastPath=false" target="_self" class=" lfr-icon-item taglib-icon" id="_com_liferay_login_web_portlet_LoginPortlet_ctvk____" > <span class="taglib-text ">Password forgotten</span> </a> </span> </div> </div> <script type="text/javascript"> (function() {var $ = AUI.$;var _ = AUI._; var form = document.getElementById('_com_liferay_login_web_portlet_LoginPortlet_loginForm'); if (form) { form.addEventListener('submit', (event) => { if (!navigator.cookieEnabled) { document.getElementById( '_com_liferay_login_web_portlet_LoginPortlet_cookieDisabled' ).style.display = ''; return; } submitForm(form); }); var password = form.querySelector('#_com_liferay_login_web_portlet_LoginPortlet_password'); if (password) { password.addEventListener('keypress', (event) => { Liferay.Util.showCapsLock( event, '_com_liferay_login_web_portlet_LoginPortlet_passwordCapsLockSpan' ); }); } } })(); </script><script> </script> </div> </div> </div> </section> </div> </div> </div> </div> </div> </div> <div class="modal fade modal-full modal-metrology" id="second-nav-metrology" tabindex="-1" role="dialog" aria-hidden="true"> <div class="modal-dialog modal-full__dialog" role="document"> <div class="modal-content modal-full__content"> <div class="container"> <div class="row"> <div class="col-12 col-lg-2"> <button type="button" class="close modal-full__close" data-dismiss="modal" aria-label="Close"> <img src="https://www.bipm.org/o/bipm-theme/images/picto/picto-close.svg" /> </button> </div> <div class="col-12 col-lg-10"> <div id="secondary-nav" class="header-second-nav"> <ul class="header-second-nav__list"> <li class="header-second-nav__items header-second-nav__items--connexion connexion"> <div class="sign-in-header" data-dismiss="modal" data-toggle="modal" data-target="#second-nav-sign-in"> <p class="header-second-nav__content">Sign in</p> <div class="header-second-nav__picto"></div> </div> </li> <li class="header-second-nav__items header-second-nav__items--metrology metrology-areas-header" data-dismiss="modal" data-toggle="modal" data-target="#second-nav-metrology"> <p class="header-second-nav__content">Metrology areas</p> <div class="header-second-nav__picto"></div> </li> <li class="header-second-nav__items header-second-nav__items--quicks quick-links-header" data-dismiss="modal" data-toggle="modal" data-target="#second-nav-quicklinks"> <p class="header-second-nav__content">Quick links</p> <div class="header-second-nav__picto"></div> </li> <li class="header-second-nav__items header-second-nav__items--languages languages-header"> <div class="portlet-content"> <a data-senna-off="true" class="language-entry-long-text" href="/fr/time-metrology"> français </a> </div> </li> </ul> </div> </div> </div> </div> <div class="modal-body modal-full__body modal-metrology__body"> <div class="container"> <p class="modal-full__title">Metrology areas</p> <div class="portlet-boundary portlet-boundary_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_ portlet-static portlet-static-end portlet-barebone portlet-navigation " id="p_p_id_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_"> <span id="p_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology"></span> <section class="portlet" id="portlet_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology"> <div class="portlet-content"> <div class=" portlet-content-container"> <div class="portlet-body"> <div id="navbar_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology"> <ul aria-label="Site Pages" class="nav nav-pills nav-stacked navbar-site" role="menubar"> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58839" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/auv' role="menuitem"> <span class="text-truncate"> AUV: Acoustics, Ultrasound and Vibrations <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437202" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/committees/cc/ccauv" role="menuitem">CCAUV</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_855483" role="presentation"> <a class="dropdown-item" href="http://liferay.bipm.org:8080/en/people?userId=3340064" role="menuitem">BIPM contact: Dr Gianna Panfilo</a> </li> </ul> </li> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58843" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/em' role="menuitem"> <span class="text-truncate"> EM : Electricity and Magnetism <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_909722" role="presentation"> <a class="dropdown-item" href="https://iopscience.iop.org/journal/0026-1394/page/Focus_on_Electrical_Metrology" role="menuitem">Metrologia: Focus on Metrology in Electricity and Magnetism</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437203" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/committees/cc/ccem" role="menuitem">CCEM</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_855484" role="presentation"> <a class="dropdown-item" href="http://liferay.bipm.org:8080/en/people?userId=38861" role="menuitem">BIPM contact: Dr Michael Stock</a> </li> </ul> </li> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58847" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/l' role="menuitem"> <span class="text-truncate"> L: Length <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437205" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/committees/cc/ccl" role="menuitem">CCL</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_855496" role="presentation"> <a class="dropdown-item" href="http://liferay.bipm.org:8080/people?userId=3340064" role="menuitem">BIPM contact: Dr Gianna Panfilo</a> </li> </ul> </li> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58851" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/m' role="menuitem"> <span class="text-truncate"> M: Mass and related quantities <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437206" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/committees/cc/ccm" role="menuitem">CCM</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_909868" role="presentation"> <a class="dropdown-item" href="https://www.bipm.orgliferay.bipm.org:8080/people?userId=663416" role="menuitem">BIPM contact: Dr Hao Fang</a> </li> </ul> </li> <li class="lfr-nav-item nav-item" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58855" role="presentation"> <a class="nav-link text-truncate" href='https://www.bipm.org/en/metrology/pr' role="menuitem"> <span class="text-truncate"> PR: Photometry and Radiometry </span> </a> </li> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58859" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/qm' role="menuitem"> <span class="text-truncate"> QM: Chemistry and Biology <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437010" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/people" role="menuitem">People</a> </li> </ul> </li> <li class="lfr-nav-item nav-item" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58863" role="presentation"> <a class="nav-link text-truncate" href='https://www.bipm.org/en/metrology/ri' role="menuitem"> <span class="text-truncate"> RI: Ionizing radiation </span> </a> </li> <li class="lfr-nav-item nav-item" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58867" role="presentation"> <a class="nav-link text-truncate" href='https://www.bipm.org/en/metrology/t' role="menuitem"> <span class="text-truncate"> T: Thermometry </span> </a> </li> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58871" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/tf' role="menuitem"> <span class="text-truncate"> TF: Time and Frequency <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437208" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/committees/cc/cctf" role="menuitem">CCTF</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_855629" role="presentation"> <a class="dropdown-item" href="http://webtai.bipm.org/database/" role="menuitem">BIPM Time Department Database</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_855487" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/time-ftp" role="menuitem">Time FTP Server</a> </li> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_855502" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/people?userId=654446" role="menuitem">BIPM contact: Dr Patrizia Tavella</a> </li> </ul> </li> <li class="lfr-nav-item nav-item dropdown" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_58875" role="presentation"> <a aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" href='https://www.bipm.org/en/metrology/u' role="menuitem"> <span class="text-truncate"> U <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology_2437207" role="presentation"> <a class="dropdown-item" href="https://www.bipm.org/en/committees/cc/ccu" role="menuitem">CCU</a> </li> </ul> </li> </ul> </div> <script> AUI().use( 'liferay-navigation-interaction', function(A) { (function() { var $ = AUI.$;var _ = AUI._; var navigation = A.one('#navbar_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_metrology'); Liferay.Data.NAV_INTERACTION_LIST_SELECTOR = '.navbar-site'; Liferay.Data.NAV_LIST_SELECTOR = '.navbar-site'; if (navigation) { navigation.plug(Liferay.NavigationInteraction); } })(); }); </script> </div> </div> </div> </section> </div> </div> </div> </div> </div> </div> <div class="modal fade modal-full modal-quicklinks" id="second-nav-quicklinks" tabindex="-1" role="dialog" aria-hidden="true"> <div class="modal-dialog modal-full__dialog" role="document"> <div class="modal-content modal-full__content"> <div class="container"> <div class="row"> <div class="col-12 col-lg-2"> <button type="button" class="close modal-full__close" data-dismiss="modal" aria-label="Close"> <img src="https://www.bipm.org/o/bipm-theme/images/picto/picto-close.svg" /> </button> </div> <div class="col-12 col-lg-10"> <div id="secondary-nav" class="header-second-nav"> <ul class="header-second-nav__list"> <li class="header-second-nav__items header-second-nav__items--connexion connexion"> <div class="sign-in-header" data-dismiss="modal" data-toggle="modal" data-target="#second-nav-sign-in"> <p class="header-second-nav__content">Sign in</p> <div class="header-second-nav__picto"></div> </div> </li> <li class="header-second-nav__items header-second-nav__items--metrology metrology-areas-header" data-dismiss="modal" data-toggle="modal" data-target="#second-nav-metrology"> <p class="header-second-nav__content">Metrology areas</p> <div class="header-second-nav__picto"></div> </li> <li class="header-second-nav__items header-second-nav__items--quicks quick-links-header" data-dismiss="modal" data-toggle="modal" data-target="#second-nav-quicklinks"> 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id="portlet_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_quicklinks"> <div class="portlet-content"> <div class=" portlet-content-container"> <div class="portlet-body"> <div id="navbar_com_liferay_site_navigation_menu_web_portlet_SiteNavigationMenuPortlet_INSTANCE_navigation_quicklinks"> <ul aria-label="Site Pages" class="nav nav-pills nav-stacked navbar-site" role="menubar"> <li class="lfr-nav-item nav-item dropdown" id="layout_3033748" role="presentation"> <a aria-labelledby="layout_3033748" aria-haspopup='true' class="nav-link text-truncate dropdown-toggle" role="menuitem"> <span class="text-truncate"> The 2018 revision of the SI <span class="lfr-nav-child-toggle"><i class="icon-caret-down"></i></span></span> </a> <ul aria-expanded="false" class="child-menu dropdown-menu" role="menu"> <li class="" id="layout_3033749" role="presentation"> <a aria-labelledby="layout_3033749" class="dropdown-item" 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class="hide-accessible sr-only">Time metrology</p> <style type="text/css"> .master-layout-fragment .portlet-header { display: none; } </style> <div class="columns-1" id="main-content" role="main"> <div class="portlet-layout row"> <div class="col-md-12 portlet-column portlet-column-only" id="column-1"> <div class="portlet-dropzone portlet-column-content portlet-column-content-only" id="layout-column_column-1"> <div class="portlet-boundary portlet-boundary_com_liferay_journal_content_web_portlet_JournalContentPortlet_ portlet-static portlet-static-end decorate portlet-journal-content " id="p_p_id_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_8vgiLKqdRLAx_"> <span id="p_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_8vgiLKqdRLAx"></span> <section class="portlet" id="portlet_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_8vgiLKqdRLAx"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">time metrology - INTRO</h2> </div> <div class="autofit-col autofit-col-end"> <div class="autofit-section"> <div class="visible-interaction"> </div> </div> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <div class="" data-fragments-editor-item-id="46722-17632316" data-fragments-editor-item-type="fragments-editor-mapped-item" > <div class="journal-content-article " data-analytics-asset-id="17632314" data-analytics-asset-title="time metrology - INTRO" data-analytics-asset-type="web-content"> <h1 class="title-primary">BIPM technical services: Time Metrology</h1> <p>The BIPM Time Department is responsible for the realization and dissemination of the international time scales UTC, UTCr and TT, used for different applications.</p> <ul class="list-bullet"> <li><b>Coordinated Universal Time (UTC)</b>, is the international reference time scale that forms the basis for the coordinated dissemination of standard frequencies and time signals; UTC is obtained from International Atomic Time (TAI) by the insertion of leap seconds according to the advice of the International Earth Rotation and Reference Systems Service (IERS) to ensure approximate agreement with the time derived from the rotation of the Earth. The formal definition of UTC and TAI was adopted by the CGPM in 2018.<br /> <br /> Physical realizations of UTC – named UTC(k) – are maintained in national metrology institutes or observatories, which contribute to UTC by sending their clock data to the BIPM. Values of <nobr>[<i>UTC</i> – <i>UTC</i>(<i>k</i>)]</nobr> at five-day intervals are published in the monthly BIPM Circular T, For those institutes participating in the CIPM MRA, their results are also published in the form of a key comparison, CCTF-K001.UTC, resulting in a monthly publication of the degrees of equivalence with respect to the reference time scale UTC.</li> <br /> <li><b>Rapid UTC (UTCr) is a rapid solution</b> that allows participating laboratories to monitor the steering of their clocks at shorter intervals than the monthly Circular T. Values of <nobr></nobr>[<i>UTC</i> – <i>UTC</i>(<i>k</i>)] at one-day intervals are published every week, on Wednesdays.</li> <br /> <li><b>TT(BIPM) is a realization of Terrestrial Time</b> as defined by the International Astronomical Union (IAU). It is computed in deferred time, each January, based on a weighted average of the evaluations of the frequency of TAI by the primary and secondary frequency standards. It is mostly used in scientific applications requiring long-term frequency stability and high frequency accuracy.</li> </ul> <i> </i> </div> </div> </div> </div> </div> </section> </div> <div class="portlet-boundary portlet-boundary_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_ portlet-static portlet-static-end decorate portlet-asset-publisher " id="p_p_id_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_INSTANCE_fpLPSXgozCjk_"> <span id="p_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_INSTANCE_fpLPSXgozCjk"></span> <section class="portlet" id="portlet_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_INSTANCE_fpLPSXgozCjk"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">Asset Publisher</h2> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <p class="asset-entries-group-label h3">International reference time scale</p> <div class="ekpz__documents_list certificates meetings-list"> <a href="/time-ftp/circular-t" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - International reference </p> </div> <div class="certificates__header"> <a class="title-third" href="/time-ftp/circular-t" target="_blank"> International Atomic Time (TAI) and Coordinated Universal Time (UTC) </a> </div> <div class="certificates__informations"> </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/time-ftp/circular-t" target="_blank"> <span class="meetings-list__list-link-session"></span> Circular T </a></li> </ul> </div> </div> </a> <a href="/time-ftp/utcr" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - International reference </p> </div> <div class="certificates__header"> <a class="title-third" href="/time-ftp/utcr" target="_blank"> Rapid UTC </a> </div> <div class="certificates__informations"> </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/time-ftp/utcr" target="_blank"> <span class="meetings-list__list-link-session"></span> UTC-r </a></li> </ul> </div> </div> </a> <a href="/time-ftp/tt-bipm-" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - International reference </p> </div> <div class="certificates__header"> <a class="title-third" href="/time-ftp/tt-bipm-" target="_blank"> Terrestrial Time </a> </div> <div class="certificates__informations"> </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/time-ftp/tt-bipm-" target="_blank"> <span class="meetings-list__list-link-session"></span> TT(BIPM) </a></li> </ul> </div> </div> </a> </div> </div> </div> </div> </section> </div> <div class="portlet-boundary portlet-boundary_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_ portlet-static portlet-static-end decorate portlet-asset-publisher " id="p_p_id_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_INSTANCE_WBqItPcN1pXR_"> <span id="p_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_INSTANCE_WBqItPcN1pXR"></span> <section class="portlet" id="portlet_com_liferay_asset_publisher_web_portlet_AssetPublisherPortlet_INSTANCE_WBqItPcN1pXR"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">Asset Publisher</h2> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <p class="asset-entries-group-label h3">Comparison</p> <div class="ekpz__documents_list certificates meetings-list"> <a href="https://www.bipm.org/kcdb/comparison?id=735" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - Comparison </p> </div> <div class="certificates__header"> <a class="title-third" href="https://www.bipm.org/kcdb/comparison?id=735" target="_blank"> CCTF-K001.UTC </a> </div> <div class="certificates__informations"> [CIPM MRA] Publication of key comparison results </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="https://www.bipm.org/kcdb/comparison?id=735" target="_blank"> <span class="meetings-list__list-link-session"></span> KCDB - CCTF-K001.UTC </a></li> </ul> </div> </div> </a> </div> <p class="asset-entries-group-label h3">Reference input data and BIPM products</p> <div class="ekpz__documents_list certificates meetings-list"> <a href="/time-ftp" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - Reference data </p> </div> <div class="certificates__header"> <a class="title-third" href="/time-ftp" target="_blank"> BIPM FTP Time server </a> </div> <div class="certificates__informations"> Time-data files and publications </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/bipm-staff/tai"> <span class="meetings-list__list-link-user"></span> tai(a)bipm.org </a> </li> <li> <a class="meetings-list__list-link" href="/time-ftp" target="_blank"> <span class="meetings-list__list-link-session"></span> Click here </a></li> </ul> </div> </div> </a> <a href="https://webtai.bipm.org/database/" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - Reference data </p> </div> <div class="certificates__header"> <a class="title-third" href="https://webtai.bipm.org/database/" target="_blank"> BIPM Time Department Database </a> </div> <div class="certificates__informations"> Laboratories contributing to UTC, their time equipment, time transfer calibration, plots, and guidelines </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/bipm-staff/tai"> <span class="meetings-list__list-link-user"></span> tai(a)bipm.org </a> </li> <li> <a class="meetings-list__list-link" href="https://webtai.bipm.org/database/" target="_blank"> <span class="meetings-list__list-link-session"></span> Click here </a></li> </ul> </div> </div> </a> <a href="https://webtai.bipm.org/database/readme_clb.html" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - Reference data </p> </div> <div class="certificates__header"> <a class="title-third" href="https://webtai.bipm.org/database/readme_clb.html" target="_blank"> Hardware delay characterizations </a> </div> <div class="certificates__informations"> Characterized hardware delays of time transfer equipment </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/bipm-staff/tai"> <span class="meetings-list__list-link-user"></span> tai(a)bipm.org </a> </li> <li> <a class="meetings-list__list-link" href="https://webtai.bipm.org/database/readme_clb.html" target="_blank"> <span class="meetings-list__list-link-session"></span> Read more </a></li> </ul> </div> </div> </a> <a href="https://webtai.bipm.org/api/index.html" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - Reference data </p> </div> <div class="certificates__header"> <a class="title-third" href="https://webtai.bipm.org/api/index.html" target="_blank"> Machine-readable data for time scales </a> </div> <div class="certificates__informations"> Time Department API </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/bipm-staff/tai"> <span class="meetings-list__list-link-user"></span> tai(a)bipm.org </a> </li> <li> <a class="meetings-list__list-link" href="https://webtai.bipm.org/api/index.html" target="_blank"> <span class="meetings-list__list-link-session"></span> Read more </a></li> </ul> </div> </div> </a> <a href="https://webtai.bipm.org/webdb/api/ccl-cctf/" data-senna-off="true"> <div class="meetings-list__item certificates__item"> <div class="meetings-list__content certificates__content"> <div class="meetings-list__header"> <p class="meetings-list__title"> Technical service - Reference data </p> </div> <div class="certificates__header"> <a class="title-third" href="https://webtai.bipm.org/webdb/api/ccl-cctf/" target="_blank"> Machine-readable data for standard frequencies </a> </div> <div class="certificates__informations"> Time Department API </div> <br/> <ul class="meetings-list__list"> <li> <a class="meetings-list__list-link" href="/bipm-staff/tai"> <span class="meetings-list__list-link-user"></span> tai(a)bipm.org </a> </li> <li> <a class="meetings-list__list-link" href="https://webtai.bipm.org/webdb/api/ccl-cctf/" target="_blank"> <span class="meetings-list__list-link-session"></span> Read more </a></li> </ul> </div> </div> </a> </div> </div> </div> </div> </section> </div> <div class="portlet-boundary portlet-boundary_com_liferay_journal_content_web_portlet_JournalContentPortlet_ portlet-static portlet-static-end decorate portlet-journal-content " id="p_p_id_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_wIwOABcrKrDq_"> <span id="p_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_wIwOABcrKrDq"></span> <section class="portlet" id="portlet_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_wIwOABcrKrDq"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">contact Time h3</h2> </div> <div class="autofit-col autofit-col-end"> <div class="autofit-section"> <div class="visible-interaction"> </div> </div> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <div class="" data-fragments-editor-item-id="46722-51243433" data-fragments-editor-item-type="fragments-editor-mapped-item" > <div class="journal-content-article " data-analytics-asset-id="51243431" data-analytics-asset-title="contact Time h3" data-analytics-asset-type="web-content"> <h3>Contact</h3> <div class="list-members-list list-members-list--single"> <div class="list-members-list__item"> <p class="list-members-list__title"><a href="javascript:hidden_email('tai','bipm.org');">tai(a)bipm.org</a></p> <div class="list-members-list__content"> <p>BIPM Time Department</p> </div> </div> </div> <i> </i> </div> </div> </div> </div> </div> </section> </div> <div class="portlet-boundary portlet-boundary_com_liferay_journal_content_web_portlet_JournalContentPortlet_ portlet-static portlet-static-end decorate portlet-journal-content " id="p_p_id_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_SXAZFlNfHUfE_"> <span id="p_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_SXAZFlNfHUfE"></span> <section class="portlet" id="portlet_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_SXAZFlNfHUfE"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">link to time staff</h2> </div> <div class="autofit-col autofit-col-end"> <div class="autofit-section"> <div class="visible-interaction"> </div> </div> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <div class="" data-fragments-editor-item-id="46722-51243653" data-fragments-editor-item-type="fragments-editor-mapped-item" > <div class="journal-content-article " data-analytics-asset-id="51243651" data-analytics-asset-title="link to time staff" data-analytics-asset-type="web-content"> <p><a class="button-secondary" href="/bipm-staff/tai">Staff of the BIPM Time Department</a></p> <i> </i> </div> </div> </div> </div> </div> </section> </div> <div class="portlet-boundary portlet-boundary_com_liferay_journal_content_web_portlet_JournalContentPortlet_ portlet-static portlet-static-end decorate portlet-journal-content " id="p_p_id_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_FkbLwaYE83V2_"> <span id="p_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_FkbLwaYE83V2"></span> <section class="portlet" id="portlet_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_FkbLwaYE83V2"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">Link to Opportunities</h2> </div> <div class="autofit-col autofit-col-end"> <div class="autofit-section"> <div class="visible-interaction"> </div> </div> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <div class="" data-fragments-editor-item-id="46722-51424203" data-fragments-editor-item-type="fragments-editor-mapped-item" > <div class="journal-content-article " data-analytics-asset-id="51424201" data-analytics-asset-title="Link to Opportunities" data-analytics-asset-type="web-content"> <p><a class="button-secondary" href="/opportunities">Opportunities to work with us</a></p> <i> </i> </div> </div> </div> </div> </div> </section> </div> <div class="portlet-boundary portlet-boundary_com_liferay_journal_content_web_portlet_JournalContentPortlet_ portlet-static portlet-static-end decorate portlet-journal-content " id="p_p_id_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_jnq451DAddo0_"> <span id="p_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_jnq451DAddo0"></span> <section class="portlet" id="portlet_com_liferay_journal_content_web_portlet_JournalContentPortlet_INSTANCE_jnq451DAddo0"> <div class="portlet-content"> <div class="autofit-float autofit-row portlet-header"> <div class="autofit-col autofit-col-expand"> <h2 class="portlet-title-text">Link to webtai guidelines</h2> </div> <div class="autofit-col autofit-col-end"> <div class="autofit-section"> <div class="visible-interaction"> </div> </div> </div> </div> <div class=" portlet-content-container"> <div class="portlet-body"> <div class="" data-fragments-editor-item-id="46722-259807262" data-fragments-editor-item-type="fragments-editor-mapped-item" > <div class="journal-content-article " data-analytics-asset-id="259807260" data-analytics-asset-title="Link to webtai guidelines" data-analytics-asset-type="web-content"> <p><a class="button-secondary" href="https://webtai.bipm.org/database/guidelines.html">How to contribute to UTC?</a></p> <i> </i> </div> </div> </div> </div> </div> </section> </div> </div> </div> </div> </div> <form action="#" aria-hidden="true" class="hide" id="hrefFm" method="post" name="hrefFm"><span></span><button hidden type="submit">Hidden</button></form> </div> </main> <footer id="footer" class="footer" role="contentinfo"> <div class="container"> <div class="row 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