手法を比較

	天体測量（年周視差）	パルサータイミングアレイ
分野	天文学	天文学
系統	Process / pipeline	Process / pipeline
提唱年	1838	1979
提唱者	Friedrich Wilhelm Bessel	Stephen Detweiler
種類	Astrometric distance measurement	Observational timing method
原典	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.
別名	Stellar Parallax, Trigonometric Parallax, Parallax Distance Method	PTA, Millisecond Pulsar Timing, Pulsar Timing Residuals
関連	3	3
概要	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.