Research on Space/ground Based Pulsar Timescale for PNT

The comprehensive Positioning Navigation Timing (PNT) system is a multi-source information fusion system with Global Navigation Satellite System (GNSS) as the core. The high-precision millisecond pulsar timing can enhance the long-term stability of the GNSS time benchmark and maintain a space-time benchmark for future deep-space users. In this paper, the method of establishing space and ground-based pulsar time is studied. The ground radio timing data from the International Pulsar Timing Array (IPTA), the X-ray timing data from the Neutron star Interior Composition Explorer (NICER) in space, and the simulation data from the 500-m spherical radio telescope (Five-hundred-meter Aperture Spherical radio Telescope, FAST) for three millisecond pulsars are used to analyze the stability of ground/space-based pulsar time. The research results show that the annual stability of the PSR J0437-4715 ground-based pulsar time based on IPTA data is 3.30 × 10–14, and the 10-year stability is 1.23 × 10–15, respectively; The existence of pulsar red noise could reduce the time stability of the pulsar; The annual stability of the PSR J1939+2134 ground-based pulsar time is 6.51 × 10–12; We find that the accuracy of the pulse Time of Arrival(TOA) is an important factor that restricts the stability of space-based pulsar time. Based on NICER space X-ray timing data, the stability of the pulsar time for PSR J1824-2452A is 1.36 × 10–13 in one year; Finally, the simulation analysis for FAST's data without considering the influence of red noise is completed, and we find that the PSR J1939+2134 ground-based pulsar time based on FAST has an annual stability of 2.55 × 10–15, a 10-year stability of 1.39 × 10–16, and a 20-year stability of 5.08 × 10–17. It demonstrates that powerful pulsar observation capabilities of FAST will help to improve the accuracy of ground-based pulsar time.