Time Realization and Distribution Group

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href="/web/20230830171857/https://www.nist.gov/pml">Physical Measurement Laboratory</a> /<a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division">Time and Frequency Division</a> </div> <div class="nist-section-header__sub"> <div class="nist-section-header__main grid-container"> <div class="grid-row"> <div class="nist-section-header__title tablet-lg:grid-col-4"> <h1 class="nist-page__title">Time Realization and Distribution Group</h1> </div> <div class="nist-section-header__desc tablet-lg:grid-col-8"> <div class="text-with-summary"> <p>The Time Realization and Distribution group distributes standard time and frequency signals generated by the Coordinated Universal Time scale, UTC(NIST), maintained at the NIST laboratories in Boulder, Colorado. UTC(NIST) is the U. S. national standard for time-of-day, time interval, and frequency.</p> </div> </div> </div> </div> </div> </div> <div class="grid-container margin-top-4"> <div class="grid-row grid-gap-6"> <aside class="nist-page__region nist-page__region--sidebar-first tablet-lg:grid-col-4 desktop-lg:grid-col-3"> <div>  <div data-elastic-exclude="" class="nist-block"> <nav> <ul class="usa-sidenav usa-accordion "> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml" data-drupal-link-system-path="">Laboratory Homepage</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division" data-drupal-link-system-path="">Division Homepage</a> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20230830171857/http://time.gov/" data-drupal-link-system-path="">Official United States Time</a> </li> <li class="usa-sidenav__item usa-sidenav__item--parent"> <a href="/web/20230830171857/https://www.nist.gov/org/time-and-frequency-division/groups" class="usa-current" data-drupal-link-system-path="">Groups</a> <button class="usa-accordion__button" aria-expanded="true" aria-controls="menu-time-and-frequency-4"><span class="usa-sr-only">Expand or Collapse</span></button> <ul id="menu-time-and-frequency-4" class="usa-sidenav__sublist usa-accordion"> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/atomic-devices-and-instrumentation" data-drupal-link-system-path="">Atomic Devices and Instrumentation</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/ion-storage" data-drupal-link-system-path="">Ion Storage</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/neutral-atom-optical-clocks" data-drupal-link-system-path="">Neutral Atom Optical Clocks</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-and-frequency-metrology" data-drupal-link-system-path="">Phase Noise Metrology</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/precision-photonic-synthesis" data-drupal-link-system-path="">Precision Photonic Synthesis</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/quantum-nonlinear-nanophotonics" data-drupal-link-system-path="">Quantum & Nonlinear Nanophotonics</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-services" class="usa-current" data-drupal-link-system-path="">Time Realization and Distribution</a> </li> </ul> </li> <li class="usa-sidenav__item"> <a href="https://web.archive.org/web/20230830171857/https://tf.nist.gov/general/publications.htm" data-drupal-link-system-path="">Publications</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/staff/division/5961" data-drupal-link-system-path="">Staff Directory</a> </li> <li class="usa-sidenav__item usa-sidenav__item--parent"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution" data-drupal-link-system-path="">Time Distribution</a> <button class="usa-accordion__button" aria-expanded="false" aria-controls="menu-time-and-frequency-7"><span class="usa-sr-only">Expand or Collapse</span></button> <ul id="menu-time-and-frequency-7" class="usa-sidenav__sublist usa-accordion"> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/automated-computer-time-service-acts" data-drupal-link-system-path="">Automated Computer Time Service (ACTS)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/services/gps-data-archive" data-drupal-link-system-path="">GPS Data Archive</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/time-distribution/gps-time-transfer" data-drupal-link-system-path="">GPS Time Transfer</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/internet-time-service-its" data-drupal-link-system-path="">Internet Time Service (ITS)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwv" data-drupal-link-system-path="">Radio Station WWV</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwvb" data-drupal-link-system-path="">Radio Station WWVB</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwvh" data-drupal-link-system-path="">Radio Station WWVH</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/programs-projects/frequency-measurement-and-analysis-service-fmas" data-drupal-link-system-path="">Remote Frequency Calibrations (FMAS)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/programs-projects/time-measurement-and-analysis-service-tmas" data-drupal-link-system-path="">Remote Time Calibrations (TMAS)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwv/telephone-time-day-service" data-drupal-link-system-path="">Telephone Time-of-Day (TTDS)</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/two-way-satellite-time-and-frequency-transfer" data-drupal-link-system-path="">Two-Way Satellite Time and Frequency Transfer (TWSTFT)</a> </li> </ul> </li> <li class="usa-sidenav__item usa-sidenav__item--parent"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization" data-drupal-link-system-path="">Time Realization</a> <button class="usa-accordion__button" aria-expanded="false" aria-controls="menu-time-and-frequency-8"><span class="usa-sr-only">Expand or Collapse</span></button> <ul id="menu-time-and-frequency-8" class="usa-sidenav__sublist usa-accordion"> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization/leap-seconds" data-drupal-link-system-path="">Leap Seconds</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization/cesium-fountain-atomic-clocks" data-drupal-link-system-path="">Cesium Fountain Atomic Clocks</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization/time-scale-data-and-bulletin-archive" data-drupal-link-system-path="">Time Scale Data and Bulletin Archive</a> </li> <li class="usa-sidenav__item"> <a href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization/utcnist-time-scale-0" data-drupal-link-system-path="">UTC(NIST) Time Scale</a> </li> </ul> </li> </ul> </nav> </div>  </div> </aside> <div class="nist-page__region nist-page__region--content tablet-lg:grid-col-8 desktop-lg:grid-col-9"> <div class="nist-block"> <div class="paragraph paragraph--type--hero paragraph--view-mode--default"> <div class="nist-hero grid-row grid-gap-2"> <div class="nist-hero__item tablet:grid-col-12 "> <div class="nist-hero__item-inner"> <div class="nist-hero__image"> <a href=""> <picture> <source srcset="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/1200_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.webp?itok=bjCBOE-K 1x, /web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/2400_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.webp?itok=Tki57h5D 2x" media="(min-width: 1200px)" type="image/webp" width="1200" height="799"/> <source srcset="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/600_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.webp?itok=uWp9hRF7 1x, /web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/1200_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.webp?itok=bjCBOE-K 2x" media="(min-width: 480px)" type="image/webp" width="600" height="399"/> <source srcset="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/300_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.webp?itok=m8NpNho3 1x, /web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/600_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.webp?itok=uWp9hRF7 2x" media="(min-width: 0px)" type="image/webp" width="300" height="200"/> <img loading="eager" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/1200_wide/public/images/2023/05/20/time-realization-and-distribution-group.png.jpg?itok=bjCBOE-K" width="1200" height="799" alt="time realization and distribution group members" typeof="foaf:Image"/> </picture> </a> </div> <div class="nist-hero__caption"> <a href=""> <div class="text">Time Realization and Distribution Group</div> </a> </div> </div> </div> </div> </div> <div class="nist-content-row nist-content-row--width-legible paragraph paragraph--type--text paragraph--view-mode--default"> <div class="nist-block text-long"><p>One of NIST's mission essential functions is to provide the United States with official sources of time and frequency. Our group fulfills this mission by operating and continuously analyzing a large ensemble of commercial atomic clocks. Briefly, an atomic clock measures the passage of time by counting oscillations of an electronic signal kept resonant with a state transition in an atom, engineered for insensitivity to the surrounding environment or perturbing effects like magnetic field fluctuations.</p> <p>The stability and robustness of the derived timing signal, called <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="b2d9874a-d7ae-4aae-bf26-749f4095459f" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization/utcnist-time-scale-0" title="UTC(NIST) Time Scale">UTC(NIST)</a>, is enhanced by averaging across the clock ensemble. The accuracy of UTC(NIST) is ensured by regular comparisons with primary frequency references---devices like the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="2886c60e-2b45-48c9-845b-67f69b40e58e" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization/cesium-fountain-atomic-clocks" title="NIST’s Cesium Fountain Atomic Clocks">cesium atomic fountain</a> that attempt to realize a microwave frequency closely based on the definition of the International System (SI) second in terms of an unperturbed state transition in the cesium atom---and by regular comparisons with other national metrology laboratories. We keep UTC(NIST) closely aligned with the international atomic time scale Coordinated Universal Time (UTC); our typical time offsets are at the 1 nanosecond level with frequency offsets of about 1 x 10<sup>-15</sup>.</p> <p>We distribute NIST time and frequency signals freely to the public (e.g. <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="7f3ea4b1-a4dc-4fb8-ab17-8e78e6a217e4" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/internet-time-service-its" title="NIST Internet Time Service (ITS)">the Internet Time Service</a>, <a href="https://web.archive.org/web/20230830171857/https://time.gov/">time.gov website</a>, <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="1dac7986-4597-4d1f-9dce-523e0d53d147" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwv" title="Radio Station WWV">WWV</a>, <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="7adae22d-3710-4706-9ef2-8dbb1f049181" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwvb" title="Radio Station WWVB">WWVB</a>, and <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="c9215bba-0c4a-4c1b-ab72-3a4a5b051045" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution/radio-station-wwvh" title="Radio Station WWVH">WWVH</a> radio stations). For customers who need UTC(NIST) at higher accuracies or that require a controlled or calibrated transfer medium, we offer remote calibration services (e.g. <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="d613428d-8936-4bd0-a944-e9694b5b2204" href="/web/20230830171857/https://www.nist.gov/programs-projects/time-measurement-and-analysis-service-tmas" title="Time Measurement and Analysis Service (TMAS)">TMAS</a>, <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="55c190c4-f711-412e-8424-834ba9f5db46" href="/web/20230830171857/https://www.nist.gov/programs-projects/frequency-measurement-and-analysis-service-fmas" title="Frequency Measurement and Analysis Service (FMAS)">FMAS</a>) and direct links (e.g. <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="bc8bbac3-cd6e-4a22-b78a-2cba7e7683fa" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-services/time-over-fiber" title="Time Over Fiber">Time over Fiber</a>, Time over Satellite). We publish measurements of UTC(NIST) against timing signals from the <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="8ab67339-90bc-40d5-bd63-a9eb5ddbd772" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/services/gps-data-archive" title="GPS Data Archive">Global Positioning System (GPS)</a>, other global satellite navigation systems (GNSS), and support time transfer methods using GNSS satellites as transfer oscillators. We also offer calibration services for oscillators, commercial atomic clocks, and <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="7903f3de-5a68-4b37-be3b-eb342b909fbc" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-services/calibrations-services-time-and-frequency-division" title="Calibrations Services in the Time and Frequency Division">GPS/GNSS receivers</a>. The group supports US industry and other agencies with <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="312716a4-a83c-4fdb-b6e8-22d4626c5af5" href="/web/20230830171857/https://www.nist.gov/tpo/partnerships/cooperative-research-and-development-agreement-crada" title="Cooperative Research and Development Agreement (CRADA)">Collaborative Research and Development Agreements (CRADAs)</a> and <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="d630ed34-bf08-458e-9703-4f998773ccae" href="/web/20230830171857/https://www.nist.gov/tpo/partnerships" title="Partnerships">technology transfer partnerships</a>.</p> <p>Finally, the group incorporates state-of-the-art developments in time and frequency metrology, such as <a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="7337be56-acdc-49b3-a9f6-43bec7c2ad5f" href="/web/20230830171857/https://www.nist.gov/programs-projects/trapped-sr-ion-clock-secondary-realization-si-second" title="Trapped Sr+ ion clock; a secondary realization of the SI second">optical atomic clocks</a>, and supports NIST laboratory research programs.</p> <ul><li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="b4d1767e-6658-4abb-b863-8d8b77c933eb" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-distribution" title="Time Distribution">Time Distribution</a></li> <li><a data-entity-substitution="canonical" data-entity-type="node" data-entity-uuid="1e3a9302-75d1-4e3e-a259-793826e42647" href="/web/20230830171857/https://www.nist.gov/pml/time-and-frequency-division/time-realization" title="Time Realization">Time Realization</a></li> </ul></div> </div> <div class="nist-content-row nist-content-row--width-legible paragraph paragraph--type--text paragraph--view-mode--default"> <div class="nist-block text-long"><h2 class="nist-block__title">NBS/NIST Radio Stations: The Story of an Old Timer</h2> <div class="grid-row grid-gap"> <div class="grid-col-3"> <figure class="align-center nist-image"><img alt="NBS/DOC" height="257" loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/480_x_480_limit/public/images/2017/02/27/nbs-commerce.jpg?itok=FSjn8Gn4" typeof="foaf:Image" width="480"><figcaption class="nist-image__caption"><div class="nist-image__caption-content" data-caption-editable="true"> </div> </figcaption></figure></div> <div class="grid-col-9"> <p>This <a href="https://web.archive.org/web/20230830171857/https://www.nist.gov/pml/nbsnist-radio-stations-story-old-timer">series of webpages</a> will lead you on a journey on the history of the NBS/NIST radio stations. You can watch a <a href="https://web.archive.org/web/20230830171857/https://www.nist.gov/video/nist-colloquium-nbsnist-radio-stations-story-old-timer">video</a> as well.</p> </div> </div></div> </div> <div class="paragraph paragraph--type--dynamic-content-list-ou paragraph--view-mode--default"> <div class="nist-block "> <h2 class="nist-block__title"> <div class="string">News and Updates</div> </h2> <div class="viewsreference"><div class="views-element-container"><div class="js-view-dom-id-93f63c4091b9ab80d98d819e2b596e2daf280620dcb47d0b8820428dc94571d7"> <div> <article role="article" about="/news-events/news/2021/11/nist-recommends-steps-boost-resilience-us-timekeeping" typeof="schema:Article" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/news-events/news/2021/11/nist-recommends-steps-boost-resilience-us-timekeeping" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2021/11/29/resilient_time_image_%28002%29.png?itok=6wlqig_f" width="100" height="32" alt="A small rectangular device with a display screen and buttons sits next to a spool of yellow fiber. " typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/news-events/news/2021/11/nist-recommends-steps-boost-resilience-us-timekeeping"><span property="schema:name">NIST Recommends Steps to Boost Resilience of U.S. Timekeeping</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2021-11-29T12:00:00Z">November 29, 2021</time> </div> </div> </header> <div class="nist-teaser__content"> <div property="schema:text" class="text-with-summary"> The nation should bolster research and development of systems that distribute accurate time via fiber-optic cable and radio as part of the effort to back up GPS </div> </div> </div> </article> </div> <div> <article role="article" about="/news-events/news/2018/06/nist-atomic-clock-comparison-confirms-key-assumptions-einsteins-elevator" typeof="schema:Article" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/news-events/news/2018/06/nist-atomic-clock-comparison-confirms-key-assumptions-einsteins-elevator" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2018/05/31/18pml021_einstein-elevator-withtext-4000px-wide-hr.jpg?itok=d3ksi8Xf" width="88" height="100" alt="Cartoon with man standing on falling blue cube representing Earth, decorated with clumps of clock faces, with yellow sun at right." typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/news-events/news/2018/06/nist-atomic-clock-comparison-confirms-key-assumptions-einsteins-elevator"><span property="schema:name">NIST Atomic Clock Comparison Confirms Key Assumptions of ‘Einstein’s Elevator’</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2018-06-04T12:00:00Z">June 4, 2018</time> </div> </div> </header> <div class="nist-teaser__content"> <div property="schema:text" class="text-with-summary"> By comparing different types of remote atomic clocks, physicists at the National Institute of Standards and Technology (NIST) have performed the most accurate </div> </div> </div> </article> </div> <div> <article role="article" about="/news-events/news/2017/11/nists-next-generation-atomic-clocks-may-support-official-timekeeping" typeof="schema:Article" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/news-events/news/2017/11/nists-next-generation-atomic-clocks-may-support-official-timekeeping" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2017/11/16/17pml022_levine-with-time-scale-by-j-burrus_175x170.jpg?itok=K_0prB5m" width="66" height="100" alt="Man with gray hair standing beside computer with digital clock display" typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/news-events/news/2017/11/nists-next-generation-atomic-clocks-may-support-official-timekeeping"><span property="schema:name">NIST’s Next-Generation Atomic Clocks May Support Official Timekeeping</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2017-11-16T12:00:00Z">November 16, 2017</time> </div> </div> </header> <div class="nist-teaser__content"> <div property="schema:text" class="text-with-summary"> For more than a decade, the National Institute of Standards and Technology (NIST) has been unveiling experimental next-generation atomic clocks. These clocks </div> </div> </div> </article> </div> <footer> <div class="link-list"><a href="/web/20230830171857/https://www.nist.gov/news-events/news-updates/org/6601">View All News and Updates</a></div> </footer> </div> </div> </div> </div> </div> <div class="paragraph paragraph--type--dynamic-content-list-ou paragraph--view-mode--default"> <div class="nist-block "> <h2 class="nist-block__title"> <div class="string">Projects and Programs</div> </h2> <div class="viewsreference"><div class="views-element-container"><div class="js-view-dom-id-734edabf40e01e8c2f05377e5f5f2a59a097506754349c06f2bf80e6780c335a"> <div> <article role="article" about="/programs-projects/frequency-measurement-and-analysis-service-fmas" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/programs-projects/frequency-measurement-and-analysis-service-fmas" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2016/08/30/nistfmas_1.jpg?itok=UyLlE4-2" width="100" height="78" alt="NIST FMAS" typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/programs-projects/frequency-measurement-and-analysis-service-fmas"><span>Frequency Measurement and Analysis Service (FMAS)</span> </a></h3> <div class="nist-teaser__type"> <div class="nist-badge display-inline-block margin-y-1 nist-badge--blue boolean">Ongoing</div> </div> </header> <div class="nist-teaser__content"> <div class="text-long"> The NIST Frequency Measurement and Analysis Service (FMAS) makes it easy to measure and calibrate any quartz, rubidium, cesium, or hydrogen maser frequency </div> </div> </div> </article> </div> <div> <article role="article" about="/programs-projects/time-measurement-and-analysis-service-tmas" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/programs-projects/time-measurement-and-analysis-service-tmas" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2017/12/08/nistdo_chassis.png?itok=4Ns8TBSa" width="100" height="55" alt="NIST disciplined clock chassis" typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/programs-projects/time-measurement-and-analysis-service-tmas"><span>Time Measurement and Analysis Service (TMAS)</span> </a></h3> <div class="nist-teaser__type"> <div class="nist-badge display-inline-block margin-y-1 nist-badge--blue boolean">Ongoing</div> </div> </header> <div class="nist-teaser__content"> <div class="text-long"> The NIST Time Measurement and Analysis Service (TMAS) was designed to serve any organization that is required to maintain an accurate local time standard. The </div> </div> </div> </article> </div> <div> <article role="article" about="/programs-projects/trapped-sr-ion-clock-secondary-realization-si-second" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/programs-projects/trapped-sr-ion-clock-secondary-realization-si-second" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2023/05/16/trap-assembly.png?itok=UYBPt7pO" width="100" height="60" alt="trap assembly" typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/programs-projects/trapped-sr-ion-clock-secondary-realization-si-second"><span>Trapped Sr+ ion clock; a secondary realization of the SI second</span> </a></h3> <div class="nist-teaser__type"> <div class="nist-badge display-inline-block margin-y-1 nist-badge--blue boolean">Ongoing</div> </div> </header> <div class="nist-teaser__content"> <div class="text-long"> NIST is constructing a high-uptime optical frequency reference based on a single trapped Sr + ion. The goal of this project is to provide long-term ≤ 1x10 -16 </div> </div> </div> </article> </div> <footer> <div class="link-list"><a href="/web/20230830171857/https://www.nist.gov/laboratories/projects-programs/org/6601">View All Projects/Programs</a></div> </footer> </div> </div> </div> </div> </div> <div class="paragraph paragraph--type--dynamic-content-list-ou paragraph--view-mode--default"> <div class="nist-block "> <h2 class="nist-block__title"> <div class="string">Publications</div> </h2> <div class="viewsreference"><div class="views-element-container"><div class="js-view-dom-id-b7483701d2eecfd414c24d3577a47bd784913e1d05544e7daa1d45045bf3559a"> <div> <article role="article" about="/publications/vhfuhf-detection-using-high-angular-momentum-rydberg-states" class="nist-teaser"> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/publications/vhfuhf-detection-using-high-angular-momentum-rydberg-states"><span>VHF/UHF detection using high angular momentum Rydberg states</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2023-05-12T12:00:00Z">May 12, 2023</time> </div> </div> <div class="nist-teaser__type"> <div class="nist-field nist-field--label-inline text-long"> <div class="nist-field__label">Author(s)</div> <div class="nist-field__item"><span class="nist-author">Roger Brown</span></div> </div> </div> </header> <div class="nist-teaser__content"> <div class="text-with-summary"> We demonstrate resonant detection of rf electric fields from 240 MHz to 900 MHz (VHF/UHF) using electromagnetically induced transparency with orbital angular </div> </div> </div> </article> </div> <div> <article role="article" about="/publications/measuring-frequency-accuracy-and-stability-wwv-and-wwvh" class="nist-teaser"> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/publications/measuring-frequency-accuracy-and-stability-wwv-and-wwvh"><span>Measuring the Frequency Accuracy and Stability of WWV and WWVH</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2023-03-01T12:00:00Z">March 1, 2023</time> </div> </div> <div class="nist-teaser__type"> <div class="nist-field nist-field--label-inline text-long"> <div class="nist-field__label">Author(s)</div> <div class="nist-field__item"><span class="nist-author">Michael A. Lombardi</span></div> </div> </div> </header> <div class="nist-teaser__content"> <div class="text-with-summary"> Radio station WWV, famous for the "at the tone ...." announcements broadcast at the top of each minute, is known to shortwave listeners and radio amateurs </div> </div> </div> </article> </div> <div> <article role="article" about="/publications/measuring-timing-accuracy-satellite-time-and-location-stl-receivers" class="nist-teaser"> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/publications/measuring-timing-accuracy-satellite-time-and-location-stl-receivers"><span>Measuring the Timing Accuracy of Satellite Time and Location (STL) Receivers</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2023-01-23T12:00:00Z">January 23, 2023</time> </div> </div> <div class="nist-teaser__type"> <div class="nist-field nist-field--label-inline text-long"> <div class="nist-field__label">Author(s)</div> <div class="nist-field__item">Peter Johnson, <span class="nist-author">Andrew Novick</span>, <span class="nist-author">Michael A. Lombardi</span></div> </div> </div> </header> <div class="nist-teaser__content"> <div class="text-with-summary"> We present measurements of the timing accuracy and stability of Satellite Time and Location (STL) receivers with respect to UTC(NIST), the coordinated universal </div> </div> </div> </article> </div> <div> <article role="article" about="/publications/multi-source-common-view-disciplined-clock-fail-safe-clock-critical-infrastructure" class="nist-teaser"> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/publications/multi-source-common-view-disciplined-clock-fail-safe-clock-critical-infrastructure"><span>Multi-Source Common-View Disciplined Clock: A Fail-Safe Clock for Critical Infrastructure Systems</span> </a></h3> <div class="nist-teaser__date"> <div class="daterange"><time datetime="2022-01-10T12:00:00Z">January 10, 2022</time> </div> </div> <div class="nist-teaser__type"> <div class="nist-field nist-field--label-inline text-long"> <div class="nist-field__label">Author(s)</div> <div class="nist-field__item"><span class="nist-author">Michael A. Lombardi</span></div> </div> </div> </header> <div class="nist-teaser__content"> <div class="text-with-summary"> The multi-source common-view disciplined clock (MSCVDC) is a recent NIST invention designed to support critical infrastructure timing systems that require a </div> </div> </div> </article> </div> <footer> <div class="link-list"><a href="/web/20230830171857/https://www.nist.gov/publications/search/all">View All Publications</a></div> </footer> </div> </div> </div> </div> </div> <div class="paragraph paragraph--type--dynamic-content-list-ou paragraph--view-mode--default"> <div class="nist-block "> <h2 class="nist-block__title"> <div class="string">Awards</div> </h2> <div class="viewsreference"><div class="views-element-container"><div class="js-view-dom-id-2903facfb86294e4111523ffa083637a25ad71c38998498f44216fd099fde023"> <div> <article role="article" about="/awards/2023-distinguished-associate-award-vladislav-gerginov" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/awards/2023-distinguished-associate-award-vladislav-gerginov" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2023/04/26/Gerginov.png?itok=L6HKOoSg" width="100" height="56" alt="Vladi Gerginov" typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/awards/2023-distinguished-associate-award-vladislav-gerginov"><span>2023 Distinguished Associate Award - Vladislav Gerginov</span> </a></h3> </header> <div class="nist-teaser__content"> <div class="text-long"> For long-term and extraordinary contributions in support of NIST’s atomic clock and sensing programs. </div> </div> </div> </article> </div> <div> <article role="article" about="/awards/distinguished-ptti-service-award-michael-lombardi" class="nist-teaser"> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/awards/distinguished-ptti-service-award-michael-lombardi"><span>Distinguished PTTI Service Award - Michael A. Lombardi</span> </a></h3> </header> <div class="nist-teaser__content"> <div class="text-long"> Mr. Lombardi was recognized for system development and leadership in the successful delivery of the U.S. time and frequency standards </div> </div> </div> </article> </div> <div> <article role="article" about="/nist-awards/2020-edward-uhler-condon-award-glenn-nelson" class="nist-teaser"> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/nist-awards/2020-edward-uhler-condon-award-glenn-nelson"><span>2020 - Edward Uhler Condon Award---Glenn Nelson</span> </a></h3> </header> <div class="nist-teaser__content"> <div class="string-long">For his exemplary historical review article commemorating the 100th anniversary of NIST radio station WWV.</div> </div> </div> </article> </div> <div> <article role="article" about="/awards/2019-distinguished-associate-award-jian-yao" class="nist-teaser"> <div class="nist-teaser__image"> <div class="entity-reference"> <a href="/web/20230830171857/https://www.nist.gov/awards/2019-distinguished-associate-award-jian-yao" hreflang="en"><img loading="lazy" src="/web/20230830171857im_/https://www.nist.gov/sites/default/files/styles/thumbnail/public/images/2020/06/22/JianYaoPhoto%20-%20Copy.png?itok=1ER5fZCU" width="79" height="100" alt="Jian Yao" typeof="foaf:Image"/> </a> </div> </div> <div class="nist-teaser__content-wrapper"> <header> <h3 class="nist-teaser__title"><a href="/web/20230830171857/https://www.nist.gov/awards/2019-distinguished-associate-award-jian-yao"><span>2019 Distinguished Associate Award - Jian Yao</span> </a></h3> </header> <div class="nist-teaser__content"> <div class="text-long"> For creating and networking the world's best optical atomic clocks for a 100-fold improvement in precision timekeeping over state of the art </div> </div> </div> </article> </div> <footer> <div class="link-list"><a href="/web/20230830171857/https://www.nist.gov/awards/org/6601">View All Awards</a></div> </footer> </div> </div> </div> </div> </div> </div> </div> </div> </div> <div class="grid-row"> <div class="nist-resource-block nist-resource-block--first tablet:grid-col"> <div class="nist-resource-block__title-bar"> <div class="nist-resource-block__title"> <div class="nist-resource-block__icon"> <img aria-hidden="true" role="img" alt="decorative icon" src="/web/20230830171857im_/https://www.nist.gov/themes/custom/nist_www/img/resource-icons/link-icon-2x.png"/> </div> <h2> <div class="string">SIM Time Scale</div> </h2> </div> </div> <div class="nist-resource-block__content"> <div class="nist-block"> <div class="text-long"><p>To support time and frequency metrology throughout the Americas, the Sistema Interamericano de Metrologia (SIM) Time and Frequency Metrology Working Group (TFMWG) maintains the SIM time scale (SIMT), the first continuously maintained multi-national ensemble time scale that is generated and published in real time (updated every hour). SIMT complements the world's official time scale, Coordinated Universal Time (UTC), by providing real time support to operational timing and calibration systems in the SIM region. The stability of SIMT is superior to most SIM local time scales and SIMT also provides a good approximation of UTC timing accuracy (±15 ns).</p> <p><a href="https://web.archive.org/web/20230830171857/http://tf.nist.gov/sim/">View website >></a></p></div> </div> </div> </div> <div class="nist-resource-block nist-resource-block--second nist-resource-block--green tablet:grid-col"> <div class="nist-resource-block__title-bar"> <div class="nist-resource-block__title"> <div class="nist-resource-block__icon"> <img aria-hidden="true" role="img" alt="decorative icon" src="/web/20230830171857im_/https://www.nist.gov/themes/custom/nist_www/img/resource-icons/product-icon-2x.png"/> </div> <h2> <div class="string">Standard Reference Instruments (SRI)</div> </h2> </div> </div> <div class="nist-resource-block__content"> <div class="nist-block"> <div class="text-long"><p><span>NIST is consolidating its provision of reference instrumentation and devices into a new Standard Reference Instrumentation (SRI) program.</span></p> <p><a href="https://web.archive.org/web/20230830171857/https://www.nist.gov/sri"><span>View website>></span></a></p></div> </div> </div> </div> </div> <div class="grid-container"> <div class="nist-page__region nist-page__region--content-bottom"> <div class="nist-block nist-block--contact"> <h2 class="nist-block__title">Contacts</h2> <div class="nist-contact"> <h3 class="nist-contact__heading">Group Leader</h3> <ul class="nist-contact__items"> <li role="article" about="/people/michael-lombardi" class="nist-contact__item"> <div class="nist-contact__name"><a href="/web/20230830171857/https://www.nist.gov/people/michael-lombardi" title="View staff profile page">Michael A. 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