@prefix dct: . @prefix ns1: . @prefix ns2: . @prefix rdfs: . @prefix skos: . a skos:Concept ; ns1:creator "European Space Agency", "Spot Image S.A." ; ns1:date "2010-03-23" ; ns1:source ; dct:created "2010-03-23" ; dct:modified "2012-02-14" ; ns2:hasProfile ; rdfs:seeAlso , , ; skos:altLabel "UTC" ; skos:definition "UTC is the time scale that is used worlwide to coordinate technical and scientific activities. It is a compromise between the highly stable atomic time and the irregular Earth rotation. It is kept within 0.9s of UT1 by introducing leap seconds from TAI at irregular intervals. Because of the secular decelleration of the Earth's rotation, TAI, of which the unit of time, corresponds the second of the mean solar day of the epoch 1820, presents an continuous increasing (parabolic) shift with respect to UT1. If legal time was based upon TAI, coincidence with solar day could not be maintained (in a couple of year TAI - UT1 can increase by a few seconds). Therefore international community, for reckoning time, used the intermediate time scale UTC."@en ; skos:exactMatch , , "urn:ogc:def:trs:BIPM::UTC" ; skos:prefLabel "Universal Coordinated Time"@en .