astrometry (literal star measurement) is the geometrical subrange of the astronomy and as such the counterpart to astrophysics. It covers the measurement and computation of Gestirnspositionen (so-called. Sternörter) and their movements (see also celestial mechanics). Up toAstrometry and spherical astronomy the majority of the entire astronomy constituted establishment of the astrophysics, which took place around 1850 after invention of the spectroscopy.
After [de Vegt ¹] astrometry is the science of the geometrical structure of the universe (place, movement and distance of the Gestirne)or the measurement of the sky. At the same time it gives coordinates - basis for geodesy - thus the measurement of the earth.
Table of contents
means tasks of the astrometry of concrete today:
- Production of catalogs with exact positions and independent movements of stars
- structure of fundamental three-dimensional axes of astronomy and geosciences
- structure of spatial astronomical data bases
- development of measuring methods and instruments
- execution of the relevant measurements and international measuring campaigns
- reduction of the measurements and standardization of the appropriate procedures.
The most important institution forthese aspects is the astronomical computing institute (AIR) in Heidelberg. It operates astrometry, stellar dynamics and astronomical services in the form of Ephemeriden and yearbooks, calendar bases and Bibliografien.
historical and cross connections
up to arising astrophysics after1850 - particularly by the spectrographic analysis and the astrophotography - were astrometry equivalently to astronomy at all [K.Schütte]. Only in the 20-century one began to speak starting from 1950 the those from astrometry or Positionsastronomie to - contrary to astrophysics,Astronomy dominated.
Since the development of electrooptical sensors such as CCD, of astrometry satellites as HIPPARCOS and the VLBI - Interferometrie experiences astrometry one Renaissance. Their cross connections to geodesy become stronger, the meaning of highly precise coordinate systems increase. International tasks such as monitoringsinterdisciplinary and young astronomer will give new career opportunities to the earth rotation with radio astronomy and government inspection department, space travel and satellite projects such as Galileo or GAIA. In the definition of the time systems astronomers with physics and further 3-4 disciplines must cooperate.
twoto four-dimensional astrometry
of the 2-D - part of astrometry ranks among the spherical astronomy and concerns themselves only with the idea direction of sources of light from space - theoretically, instrumentation, reference of the coordinate systems and for various corrections of the apparent direction of celestial objects(Planet, stars, galaxies) on their true direction.
The Sternörter becomes three-dimensional by measurement of parallaxes - those apparent annual shifts, which can be recognized from opposite points of the Earth's orbit. From this star distances can up to 100 light-years, with HIPPARCOS and other methods are derived still far beyond that.
one could finally call 4-D the stellar dynamics, which rely on independent movements. One receives it from exact Sternörtern from far apart to lying epochs. Their addition of the spatial speed vectorthe radial velocity, a result and thus the transition gives the spectrographic analysis to astrophysics. Similarly it stands around distance regulations by means of Fotometrie.
- Julius fair: A view into the most general term net of astrometry. Publishing house Beyer, Langensalza 1907.
- Rudolf Sigl: Geodetic astronomy. Publishing house yielding man, 3.überarb. Edition, 300 p., ISBN 387907190X, Heidelberg 1991.
- P.Bro, H.Schuh: New developments of astrometry and their meaning for geodesy. ZfV Jg.124, p.343-350, Stuttgart 1999.