Recommendation 3 of the 16th CCTF (2004)

Concerning the steering of International Atomic Time (TAI)

The Consultative Committee for Time and Frequency,

considering that

• TAI was defined by the General Conference on Weights and Measures in 1971, complemented by the Consultative Committee for the Definition of the Second in 1980,
• TAI is a realization of Terrestrial Time (TT) as defined, most recently, in Resolution B1.9 (2000) of the International Astronomical Union,
• the scale unit of TAI has significantly deviated from its definition over the past years,
• new primary frequency standards permit the determination of this deviation with adequate uncertainty,
• it is advantageous that TAI provides direct traceability to the SI second,

recommends that

• the procedure of TAI frequency steering be adapted with the aim of ensuring that the estimation of the TAI scale unit conforms to its definition within 3 σ uncertainty,
• this procedure be designed, in collaboration with the Working Group on TAI, to minimize the impact on TAI stability.

DOI : 10.59161/CCTF2004REC3E