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 |
How this entity was disambiguated
This entity first appeared as the object of triple T982996 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: TT Context triple: [International Atomic Time, closelyRelatedTo, TT]
-
A.
TT
TT is the common abbreviation for the Isle of Man TT, a famous and notoriously dangerous annual motorcycle racing event held on the Isle of Man.
-
B.
TM
TM is the New York Stock Exchange ticker symbol for Toyota Motor Corporation, the Japanese multinational automotive manufacturer.
-
C.
TTA
TTA (Telecommunications Technology Association) is South Korea’s primary standards organization for information and communication technologies, contributing to global telecom standards development.
-
D.
TD
TD is the two-letter ISO 3166-1 alpha-2 country code assigned to Chad.
-
E.
the T
The T is the public transit system serving the Greater Boston area, operated by the Massachusetts Bay Transportation Authority.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: TT Target entity description: 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.
-
A.
TT
TT is the common abbreviation for the Isle of Man TT, a famous and notoriously dangerous annual motorcycle racing event held on the Isle of Man.
-
B.
TM
TM is the New York Stock Exchange ticker symbol for Toyota Motor Corporation, the Japanese multinational automotive manufacturer.
-
C.
TTA
TTA (Telecommunications Technology Association) is South Korea’s primary standards organization for information and communication technologies, contributing to global telecom standards development.
-
D.
TD
TD is the two-letter ISO 3166-1 alpha-2 country code assigned to Chad.
-
E.
the T
The T is the public transit system serving the Greater Boston area, operated by the Massachusetts Bay Transportation Authority.
- F. None of above. chosen
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 ⓘ
linked to:
Universal Time 1
|
| 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 resolutions
ⓘ
linked to:
IAU 1991 Resolution A4
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 ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: TT Description of subject: 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.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.