Parallax

Description

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 22. Chapters: Binocular disparity, Hipparcos, Nano-JASMINE, Parallax occlusion mapping, Parallax scanning, Parallax scrolling, Parsec, Stellar parallax. Excerpt: Hipparcos, a satellite with the Hipparcos Catalogue and other star datasets, was a scientific mission of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permits the accurate determination of proper motions and parallaxes of stars, allowing a determination of their distance and tangential velocity. When combined with radial-velocity measurements from spectroscopy, this pinpoints all six quantities needed to determine the motion of stars. The Hipparcos Catalogue, a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. The word "Hipparcos" is an acronym for "High precision parallax collecting satellite" and a reference to the ancient Greek astronomer Hipparchus of Nicaea, noted for trigonometry and the precession of the equinoxes. By the second half of the 20th century, the accurate measurement of star positions from the ground was running into essentially insurmountable barriers to improvements in accuracy, especially for large-angle measurements and systematic terms. Problems were dominated by the effects of the Earth's atmosphere, but were compounded by complex optical terms, thermal and gravitational instrument flexures, and the absence of all-sky visibility. A formal proposal to make these exacting observations from space was first put forward in 1967. Although originally proposed to the French space... (Description from external book data)

listed in Nature | 6 similar books linked from this page.