Time scales

International Time Scales

In addition to the unit second, time and frequency metrology needs also a timescale. A timescale is obtained if scale units are juxtaposed starting on a conventionally chosen epoch and counted. Internationally coordinated timescales are Universal Time Coordinated (UTC) and Temps Atomique International (TAI). Both are computed at the Bureau International des Poids et Mesures (BIPM) with data from approximately 250 clocks distributed in about 50 institutes around the globe. Including METAS.

Swiss Atomic Clocks Ensemble

METAS contributes to UTC with several commercial caesium clocks and a hydrogen maser. This ensemble is kept well shielded from external influences such as vibration or temperature and humidity fluctuations. The clocks are continuously compared to each other. These data are used to compute the local timescales UTC(CH) and TA(CH). UTC(CH) and TA(CH) are the basis for calibration works in the time and frequency laboratory

Official Time in Switzerland

The official time (legal time) in Switzerland is ruled by the Federal Law on metrology. The time zone for Switzerland is Central European Time (CET). CET is one hour ahead of UTC (CET = UTC + 1 h). Together with the other European countries of the CET time zone Switzerland applies Summer Time between the last Sunday of March and the last Sunday of October. Central European Summer Time (CEST) is two hours ahead of UTC (CEST = UTC + 2 h).