Sammenlign metoder

	Astrometri (Parallakse)	Pulsar Timing Array
Fagfelt	Astronomi	Astronomi
Familie	Process / pipeline	Process / pipeline
Opprinnelsesår	1838	1979
Opphavsperson	Friedrich Wilhelm Bessel	Stephen Detweiler
Type	Astrometric distance measurement	Observational timing method
Opprinnelig kilde	ESA (1997). The Hipparcos and Tycho Catalogues. Astrometric and photometric star catalogue. European Space Agency Technical Reports, SP-1200.	Sazhin, M. V. (1978). Opportunities for detecting ultralong gravitational waves. Soviet Astronomy, 22, 36-38.
Alias	Stellar Parallax, Trigonometric Parallax, Parallax Distance Method	PTA, Millisecond Pulsar Timing, Pulsar Timing Residuals
Relaterte	3	3
Sammendrag	Astrometric parallax is the foundational geometric method for measuring distances to nearby stars, based on observing the apparent shift in a star's position as Earth orbits the Sun. First successfully demonstrated by Friedrich Wilhelm Bessel in 1838 for the star 61 Cygni, parallax remains the most direct and reliable distance measurement in astronomy, anchoring the entire cosmic distance ladder.	A pulsar timing array uses multiple millisecond pulsars as a distributed network of gravitational wave detectors across the galaxy. Proposed theoretically by Stephen Detweiler in 1979, this method exploits the extraordinary timing precision of pulsars to detect the subtle spacetime distortions caused by gravitational waves. In 2023, the first evidence for a stochastic background of gravitational waves was announced using pulsar timing arrays.