Common use of Key results and conclusions Clause in Contracts

Key results and conclusions. The objective of incorporating optical clocks into international timescales as secondary representations of the second, via the submission of data to the BIPM, was achieved, with the target number of submissions being met. Although these submissions came from fewer laboratories and clocks than originally anticipated, other clocks collected large amounts of data with high uptime, which they will be able to use in their first submissions to the BIPM once peer-reviewed publications describing updated uncertainty budgets are available. The new recommended values for standard frequencies approved by the CCTF in 2021, which were strongly influenced by work in this project, were used for the first time for the calculation of TAI in Circular T no. 412 (April 2022). This allowed optical clocks to steer TAI with lower uncertainty, as the recommended frequency values for six secondary representations of the second now have uncertainties at the limit set by caesium fountain primary frequency standards. The update therefore resulted in a significant increase in the weight of optical clocks in TAI (Figure 18).