Oxford University Press (OUP), Monthly Notices of the Royal Astronomical Society, 4(427), p. 2780-2787
DOI: 10.1111/j.1365-2966.2012.21946.x
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Using observations of pulsars from the Parkes Pulsar Timing Array (PPTA)project we develop the first pulsar-based time-scale that has aprecision comparable to the uncertainties in International AtomicTime-scales (TAI). Our ensemble of pulsars provides an Ensemble PulsarScale (EPS) analogous to the free atomic time-scale ÉchelleAtomique Libre. The EPS can be used to detect fluctuations in atomictime-scales and therefore can lead to a new realization of TerrestrialTime, TT(PPTA11). We successfully follow features known to affect thefrequency of the TAI, and we find marginally significant differencesbetween TT(PPTA11) and TT(BIPM11). We discuss the various phenomena thatlead to a correlated signal in the pulsar timing residuals and thereforelimit the stability of the pulsar time-scale.