Astrometry
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way.
History
The history of astrometry is linked to the history of
In the 10th century,
In the 16th century,
Being very difficult to measure, only about 60 stellar parallaxes had been obtained by the end of the 19th century, mostly by use of the filar micrometer. Astrographs using astronomical photographic plates sped the process in the early 20th century. Automated plate-measuring machines[9] and more sophisticated computer technology of the 1960s allowed more efficient compilation of star catalogues. Started in the late 19th century, the project Carte du Ciel to improve star mapping could not be finished but made photography a common technique for astrometry.[10] In the 1980s, charge-coupled devices (CCDs) replaced photographic plates and reduced optical uncertainties to one milliarcsecond. This technology made astrometry less expensive, opening the field to an amateur audience.[citation needed]
In 1989, the
Applications
Apart from the fundamental function of providing astronomers with a reference frame to report their observations in, astrometry is also fundamental for fields like celestial mechanics, stellar dynamics and galactic astronomy. In observational astronomy, astrometric techniques help identify stellar objects by their unique motions. It is instrumental for keeping time, in that UTC is essentially the atomic time synchronized to Earth's rotation by means of exact astronomical observations. Astrometry is an important step in the cosmic distance ladder because it establishes parallax distance estimates for stars in the Milky Way.
Astrometry has also been used to support claims of
Astrometric measurements are used by
Astronomers use astrometric techniques for the tracking of
50000 Quaoar and 90377 Sedna are two Solar System objects discovered in this way by Michael E. Brown and others at Caltech using the Palomar Observatory's Samuel Oschin telescope of 48 inches (1.2 m) and the Palomar-Quest large-area CCD camera. The ability of astronomers to track the positions and movements of such celestial bodies is crucial to the understanding of the Solar System and its interrelated past, present, and future with others in the Universe.[19][20]
Statistics
A fundamental aspect of astrometry is error correction. Various factors introduce errors into the measurement of stellar positions, including atmospheric conditions, imperfections in the instruments and errors by the observer or the measuring instruments. Many of these errors can be reduced by various techniques, such as through instrument improvements and compensations to the data. The results are then analyzed using statistical methods to compute data estimates and error ranges.[21]
Computer programs
- XParallax viu (Free application for Windows)
- Astrometrica (Application for Windows)
- Astrometry.net (Online blind astrometry)
See also
- Astrometric binary
- Barycentric celestial reference system
- Ephemeris
- Equatorium
- Geodetic astronomy
- Gaia spacecraft — launched December 2013
- Hipparcos Space Astrometry Mission (ESA—1989-93)
- International Earth Rotation and Reference Systems Service
- List of astrometric solvers
- Methods of detecting extrasolar planets - Astrometry
- Spherical astronomy
- Celestial cartography
- Star catalogue
- United States Naval Observatory
- United States Naval Observatory Flagstaff Station
- Time standard
References
- ISBN 3-540-67436-5.
- ISBN 978-0-387-71668-8.
- ^ p. 110, Kanas 2007.
- .
- ISBN 0-8153-0322-X.
- ISBN 0-521-64216-7.
- ISBN 0-7923-4066-3.
- JSTOR 113159.
- ^ CERN paper on plate measuring machine USNO StarScan
- ^ H.H. Turner, 1912 The Great Star Map, Being a Brief General Account of the International Project Known as the Astrographic Chart (John Murray)
- ^ Staff (27 February 2019). "The Hipparcos Space Astrometry Mission". European Space Agency. Retrieved 2007-12-06.
- ^ Jatan Mehta (2019). "From Hipparchus to Gaia". thewire.in. Retrieved 27 January 2020.
- ^ Carme Jordi (2019). "Gaia : the first 3D map of the milky way". pourlascience.fr. Retrieved 27 January 2020.
- ISBN 3-540-42380-X.
- doi:10.1038/462705a
- ^ "ESA - Space Science - Gaia overview".
- ^ "Infant exoplanet weighed by Hipparcos and Gaia". 20 August 2018. Retrieved 21 August 2018.
- ^ Trujillo, Chadwick; Rabinowitz, David (1 June 2007). "Discovery of a candidate inner Oort cloud planetoid" (PDF). European Space Agency. Archived (PDF) from the original on 26 October 2007. Retrieved 2007-12-06.
- SPACE.com. Retrieved 2007-12-06.
- ^ Clavin, Whitney (15 May 2004). "Planet-Like Body Discovered at Fringes of Our Solar System". NASA. Archived from the original on 30 November 2007. Retrieved 2007-12-06.
- ISBN 978-3-540-42380-5.
error correction astrometry.
Further reading
- Kovalevsky, Jean; Seidelman, P. Kenneth (2004). Fundamentals of Astrometry. Cambridge University Press. ISBN 0-521-64216-7.
External links
- MPC Guide to Minor Body Astrometry
- Astrometry Department of the U.S. Naval Observatory
- USNO Astrometric Catalog and related Products Archived 2015-08-26 at the Wayback Machine
- "Hall of Precision Astrometry". University of Virginia Department of Astronomy. Archived from the original on 2006-08-26. Retrieved 2006-08-10.
- Planet-Like Body Discovered at Fringes of Our Solar System (2004-03-15)
- Mike Brown's Caltech Home Page
- Scientific Paper describing Sedna's discovery
- The Hipparcos Space Astrometry Mission — on ESA