DUT1

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Time scale with correction

title: "DUT1" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["time-scales"] description: "Time scale with correction" topic_path: "general/time-scales" source: "https://en.wikipedia.org/wiki/DUT1" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Time scale with correction ::

::figure[src="https://upload.wikimedia.org/wikipedia/commons/f/fb/Leapsecond.ut1-utc.svg" caption="Graph showing the difference in seconds between [[UT1]] and [[UTC]] over time. A vertical transition indicates the use of a [[leap second]]. The red portion of the graph indicates predicted values."] ::

DUT1 is a time correction equal to the difference between Universal Time (UT1), which is defined by Earth's rotation, and Coordinated Universal Time (UTC), which is defined by a network of precision atomic clocks, with a precision of +/- 0.1s.

:DUT1 = UT1 − UTC (with a precision of +/- 0.1s)

UTC is maintained via leap seconds, such that DUT1 remains within the range −0.9 s

Daily observed values of UT1− UTC for the past week, and daily forecast values for the coming year, are published by IERS Bulletin A, with more digits than for DUT1. Final values are published in the monthly IERS Bulletin B. DUT1 forecasts are published in IERS Bulletin D.

Several time signal services broadcast values of DUT1. CHU (Canada), HLA (South Korea), MSF (United Kingdom), and WWV (United States) transmit DUT1 with 0.1 s precision. In Russia, RWM, RTZ and the longwave RBU transmit DUT1 with 0.1 s precision and an additional correction dUT1 in 0.02 s increments.

Notes

References

ITU-R Recommendation TF.460-4: Standard-frequency and time-signal emissions. International Telecommunication Union.

References

(1996-07-17). "Bulletin D – Product metadata".
(2024-11-15). "Leap second and UT1−UTC information".
"Time Signal Transmitter".

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::