Millisecond pulsars: nature´s most stable clocks

The author describes the role pulsars might play in time and frequency technology. Millisecond pulsars are rapidly rotating neutron stars: some 20 km in diameter, 1.4 times as massive as the Sun, and spinning as fast as several thousand radians per second. Radio noise generated in a pulsar´s magnetosphere by a highly beamed process is detectable over interstellar distances, as a periodic sequence of pulses. High-precision comparisons between pulsar time and terrestrial atomic time show that over intervals of several years, some millisecond pulsars have fractional stabilities comparable to those of the best atomic clocks. The author briefly reviews the physics of pulsars, discusses the techniques of pulsar timing measurements, and summarizes the results of careful studies of pulsar stabilities