This HTML5 document contains 16 embedded RDF statements represented using HTML+Microdata notation.

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Namespace Prefixes

PrefixIRI
n5http://qudt.org/vocab/quantitykind/
dctermshttp://purl.org/dc/terms/
n4http://qudt.org/vocab/sou/
n3http://qudt.org/schema/qudt/
n2http://qudt.org/vocab/unit/
n8http://qudt.org/vocab/dimensionvector/
rdfshttp://www.w3.org/2000/01/rdf-schema#
n9http://qudt.org/2.1/vocab/
rdfhttp://www.w3.org/1999/02/22-rdf-syntax-ns#
xsdhhttp://www.w3.org/2001/XMLSchema#

Statements

Subject Item
n2:HR_Sidereal
rdf:type
n3:Unit
rdfs:label
Sidereal Hour
rdfs:isDefinedBy
n9:unit
dcterms:description
Sidereal time is a time-keeping system astronomers use to keep track of the direction to point their telescopes to view a given star in the night sky. A mean sidereal day is about 23 h 56 m 4.1 s in length. However, due to variations in the rotation rate of the Earth, the rate of an ideal sidereal clock deviates from any simple multiple of a civil clock. In practice, the difference is kept track of by the difference UTC-UT1, which is measured by radio telescopes and kept on file and available to the public at the IERS and at the United States Naval Observatory. A Sidereal Hour is \(1/24^{th}\) of a Sidereal Day. A mean sidereal day is 23 hours, 56 minutes, 4.0916 seconds (23.9344699 hours or 0.99726958 mean solar days), the time it takes Earth to make one rotation relative to the vernal equinox. (Due to nutation, an actual sidereal day is not quite so constant.) The vernal equinox itself precesses slowly westward relative to the fixed stars, completing one revolution in about 26,000 years, so the misnamed sidereal day ("sidereal" is derived from the Latin sidus meaning "star") is 0.0084 seconds shorter than Earth's period of rotation relative to the fixed stars.
n3:hasDimensionVector
n8:A0E0L0I0M0H0T1D0
n3:informativeReference
http://en.wikipedia.org/wiki/Sidereal_time
n3:symbol
hr{sidereal}
n3:hasQuantityKind
n5:Time
n3:applicableSystem
n4:CGS-EMU n4:CGS-GAUSS n4:IMPERIAL n4:SI n4:USCS n4:CGS
n3:conversionMultiplier
3590.17
n3:ucumCode
h