Application of Millisecond Pulsar Timing to the Long-term Stability of Clock Ensembles

The 1982 discovery of the 1.6 millisecond pulsar B1937+21 [1] has provided an object with rotational stability comparable to the atomic time standards over periods exceeding a few years [2]. The microwave beams of millisecond pulsars, which are rigidly anchored to rotating neutron stars, can act as precision celestial clocks owing to the combined effects of their large rotational energies, 1050–52 erg, and low energy loss rates. Millisecond pulsars provide an opportunity for astronomical observations to define International Atomic Time (TAI) over long periods.