Timescales

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.

Clock 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 in Switzerland is ruled by the time act and the ordinance on daylight saving time. When daylight saving time is not in force, Central European Time (CET) is applicable. The Central European Time is one hour ahead of UTC (CET = UTC + 1 h).

Together with all surrounding Switzerland observes Summer Time between the last Sundy in March and the last Sunday in October. Central European Summer Time (CEST) is two hours ahead of UTC (CEST = UTC + 2 h).

A list of dates when the switch from CET to CEST occures can be found under this link .