Rapid UTC (UTCr)

Why Rapid UTC?

Bridging the gap between monthly UTC publications

The UTC results are computed monthly and published in Circular T. Participating laboratories, however, need more frequent information to monitor how their local real-time realizations of UTC are performing.

Rapid UTC, or UTCr, responds to this operational need. Produced every week using clock and time-transfer data from the previous week, UTCr provides a provisional approximation of UTC that laboratories can use between the definitive monthly UTC results.

The weekly cycle

From new clock data to Rapid UTC

The BIPM uses clock and time-transfer data from the previous week to provide participating laboratories with a rapid weekly solution.

How Rapid UTC supports UTC

UTC and UTCr serve closely related but distinct roles within international timekeeping. The comparison below shows how they differ in their publication cycle, data, results and principal role.

Rapid UTC data and documentation

Access the latest UTCr results and supporting technical information.

Does Rapid UTC replace UTC?

No. UTCr is a provisional weekly approximation of UTC that provides participating laboratories with more frequent information between monthly UTC publications. It complements UTC; it does not replace the definitive UTC results or the traceability information published in Circular T.

How often is UTCr published?

UTCr is published every Wednesday and provides daily values for participating laboratories.

Who uses UTCr?

UTCr is used by National Metrology Institutes and designated time laboratories that maintain local real-time realizations of UTC.

Why is UTCr available more quickly than UTC?

UTCr is produced each week using clock and time-transfer data from the previous week. The monthly UTC computation uses the complete dataset for the relevant period and provides the results and traceability information published in Circular T.