Time service

from Wikipedia, the free encyclopedia
This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

In astrometry and geosciences, the time service is a nationally or internationally regulated service for the exact world time  ( UT and UTC ) and the transmission of time signals by time signal transmitters . Since the full expansion of the GPS , the time stamps sent by the satellites have also made a significant contribution to this.

While there were only local time services in the Middle Ages (mostly only approximated with sundials , occasionally with a midday cannon ), they were - now much more precisely - relocated to individual observatories or operated continuously by observatories during the time of the seafaring discovery . In some cases, the time preservation of such observatories was also officially valid. B. that of the Vienna Urania .

It was not until the beginning of the 20th century that nationally regulated time services emerged, which were taken over either by individual observatories or by physical institutes such as the BIH in Paris. In some countries, central verification offices were also responsible, such as in Germany (?) And Switzerland.

Today, the time services are internationally networked, operate large clock systems with often several atomic clocks or hydrogen masers , whose mutual clock status is compared via radio or (less often) with direct clock transport. Only the combination of many such stations and services forms the internationally binding time system of atomic time  (AT) and universal time (UT1 and UTC). The deviations of the individual time services from the network, which today are only in the range of nanoseconds , are continuously monitored and published periodically. They are identified by a name index, e.g. B. AT (PTB) for the atomic time of the Physikalisch-Technische Bundesanstalt in Braunschweig or UTC (BEV) for the Universal Time of the BEV in Vienna.

The time services are increasingly being organizationally and technically linked to geodetic fundamental stations so that the ongoing monitoring of the earth's rotation can be carried out in interdisciplinary cooperation, together with global services such as the IERS .

See also