TT
E116187
TT (Terrestrial Time) is a modern astronomical time standard used as the independent time variable in ephemerides and precise celestial mechanics, defined to provide a uniform time scale for observations from Earth's surface.
All labels observed (1)
| Label | Occurrences |
|---|---|
| TT canonical | 1 |
Statements (46)
| Predicate | Object |
|---|---|
| instanceOf |
astronomical time scale
ⓘ
time standard ⓘ |
| abbreviation | TT ⓘ |
| application |
lunar ephemerides
ⓘ
planetary ephemerides ⓘ satellite orbit determination ⓘ |
| category |
astronomical standard
ⓘ
timekeeping system ⓘ |
| closelyRelatedTo | Barycentric Dynamical Time ⓘ |
| coordinateOrigin | Earth's center of mass ⓘ |
| coordinateRelation | closely related to Geocentric Coordinate Time ⓘ |
| coordinateTimeType | terrestrial coordinate time ⓘ |
| definedBy | International Astronomical Union ⓘ |
| definedFor | uniform time scale for observations from Earth's surface ⓘ |
| definedToBe | uniform at the geoid ⓘ |
| distinctFrom |
Coordinated Universal Time
ⓘ
Universal Time 1 ⓘ
surface form:
Universal Time
|
| domain |
astrometry
ⓘ
celestial mechanics ⓘ space navigation ⓘ |
| epochReference | TAI + 32.184 seconds ⓘ |
| frameOfReference | Earth geoid ⓘ |
| governingBody | International Astronomical Union ⓘ |
| introducedTo | provide consistent time argument for ephemerides ⓘ |
| notAffectedBy | irregularities of Earth's rotation ⓘ |
| offsetFromTAI | 32.184 seconds ⓘ |
| rateDefinition | same rate as International Atomic Time ⓘ |
| realizationMethod | derived from International Atomic Time with fixed offset ⓘ |
| referenceSystem | geocentric ⓘ |
| relatedTo | International Atomic Time ⓘ |
| replaced | Ephemeris Time in modern ephemerides ⓘ |
| replacedByInPractice | TT realized from TAI ⓘ |
| scaleType | continuous time scale without leap seconds ⓘ |
| standardizedIn |
IAU 1991 Resolution A4
ⓘ
surface form:
IAU 1991 resolutions
IAU 2000 resolutions ⓘ IAU 2006 resolutions ⓘ |
| successorOf | Ephemeris Time ⓘ |
| symbol | TT ⓘ |
| timeArgumentFor | apparent geocentric ephemerides ⓘ |
| timeScaleClass | theoretical time scale ⓘ |
| unit | SI second ⓘ |
| usedAs | independent time variable in ephemerides ⓘ |
| usedBy |
astronomers
ⓘ
space agencies ⓘ timekeeping institutions ⓘ |
| usedIn | precise celestial mechanics ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.