Pulsar timing

Pulsar timing measures when pulses from rotating neutron stars arrive at a telescope. Variations in their arrival times reveal the stars’ properties and disturbances along or near the line of sight.

Pulse time of arrival: The estimated arrival time of a pulsar pulse at a telescope, measured relative to a pulse template. A sequence of these measurements is the raw material of pulsar timing.
Pulsar timing array: A set of precisely monitored millisecond pulsars used together to detect correlated timing variations. Comparing residuals across the sky searches for low-frequency gravitational waves.
Jocelyn Bell Burnell: An astrophysicist who discovered the first known pulsar while analyzing radio telescope data in 1967. Her discovery made periodic radio pulses available for precision timing studies.
Pulsar astrometry: The measurement of a pulsar’s position, parallax, and proper motion on the sky. Astrometry measures apparent location, while timing infers motion from pulse arrival patterns.
Pulsar timing noise: Irregular, often red-spectrum variations in pulsar rotation that are not captured by simple spin-down models. Intrinsic noise can mask weak gravitational-wave signals in timing residuals.
Timing residual: The difference between an observed pulse arrival time and the time predicted by a pulsar timing model. Residual patterns expose effects missing from the model.
Pulsar planet: A planet orbiting a pulsar, detectable through the reflex motion it induces in the neutron star. Orbital motion shifts pulse arrival times in a repeating pattern.
Antony Hewish: A British radio astronomer who led the group that discovered pulsars and shared the 1974 Nobel Prize in Physics. The Cambridge program he led produced the first pulsar observations.
X-ray pulsar timing: The analysis of X-ray pulse arrival times to study rotating neutron stars and their environments. It applies timing methods to high-energy pulses rather than chiefly radio emission.
Interstellar scintillation: Variations in a pulsar’s observed brightness caused by scattering and interference in the ionized interstellar medium. Changing propagation conditions complicate stable pulse-profile measurements and timing precision.

Linked from 19 pages