4 Principles and Applications of Pulsar Timing
It became clear soon after their discovery that pulsars are excellent celestial clocks. The period of the
first pulsar [119] was found to be stable to one part in
over a few months. Following the discovery of
the millisecond pulsar B1937+21 [19
] it was demonstrated that its period could be measured
to one part in
or better [84]. This unrivaled stability leads to a host of applications
including uses as time keepers, probes of relativistic gravity and natural gravitational wave
detectors.