A Pulsar Time Scale Based on Parkes Observations in 1995-2010

Timing of highly stable millisecond pulsars provides the possibility of independently verifying terrestrial time scales on intervals longer than a year. An ensemble pulsar time scale is constructed based on pulsar timing data obtained on the 64-m Parkes telescope (Australia) in 1995–2010. Optimal Wiener filters were applied to enhance the accuracy of the ensemble time scale. The run of the time-scale difference PTens−TT(BIPM2011) does not exceed 0.8 ± 0.4 μs over the entire studied time interval. The fractional instability of the difference PTens−TT(BIPM2011) over 15 years is σ z = (0.6 ± 1.6) × 10−15, which corresponds to an upper limit for the energy density of the gravitational-wave background Ω g h2 ~ 10−10 and variations in the gravitational potential ~10−15 Hz at the frequency 2 × 10−9 Hz.