The Atomic Time Scale

Abstract
The atomic time scale A.1 is based on an assumed frequency of 9 192 631 770 cps of Ephemeris time, and is derived from the operation of cesium resonators at 9 laboratories. Coordinated transmissions of time and frequency make the atomic time scale available. The International Committee of Weights and Measures may redefine the unit of time interval, the second, by an atomic transition in 1966.