2023MNRAS.521.2553L

There is a wide demand for high-precision and high-stability time-scales, which are mainly established by atomic clocks. The short-term stability of atomic clocks is good, while the long-term stability is poor. Meanwhile, millisecond pulsars have good long-term stability. It is expected to produce time-scales with high-stability performance by combining pulsars and atomic clocks to keep time. In this paper, a novel joint timekeeping algorithm based on Vondrak-Cepek filtering is proposed. The filter makes a compromise between the fidelity of the observation data and their first derivatives and the smoothness of the filtering results. Also, it can give full play to the long-term stability of pulsars and the short-term stability of atomic clocks. Experiments and results show that the joint timekeeping algorithm improved σ_z of 7.58 × 10^–13 on 6.5-d time interval with respect to that obtained from the pulsar ensemble time-scale algorithm. Also, the joint timekeeping algorithm improved σ_z of 6.94 × 10^–15 on 9.1-yr time interval with respect to that obtained from the atomic ensemble time-scale algorithm. The algorithm proposed in this paper can be applied to scenes requiring high-stability time-scales.