Recommendation 2 of the 78th CIPM (1989)

Improvement of the frequency accuracy of primary standards

The Comité International des Poids et Mesures,


  • the need to improve accuracy III the scale unitary interval of International Atomic Time (TAI),
  • the small number of primary caesium standards contributing effectively to TAI,


  • the construction of new primary caesium standards,
  • the improvement of the frequency accuracy of existing primary standards,
  • the study of the systematic differences in frequency between them.

reference The reader should note that the official version of this Resolution is the French text

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