Universal Time 1
E497213
Universal Time 1 (UT1) is an astronomical time standard based on Earth's actual rotation, closely tracking mean solar time at the prime meridian and used in precise navigation and astronomy.
All labels observed (3)
| Label | Occurrences |
|---|---|
| Universal Time 1 canonical | 2 |
| Universal Time | 1 |
| Universal Time system | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T5150775 — 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: Universal Time 1 Context triple: [Terrestrial Time, distinctFrom, Universal Time 1]
-
A.
Coordinated Universal Time
Coordinated Universal Time (UTC) is the primary global time standard by which the world regulates clocks and time, serving as the basis for most civil time zones.
-
B.
Terrestrial Time
Terrestrial Time is a modern astronomical time standard used for precise calculations of planetary motion and ephemerides, defined in relation to atomic time rather than Earth's rotation.
-
C.
International Atomic Time
International Atomic Time is a high-precision time standard based on the combined output of atomic clocks worldwide, serving as the fundamental reference for modern civil and scientific timekeeping.
-
D.
Zulu time
Zulu time is a standardized time reference used worldwide—especially in aviation, military, and navigation—corresponding to Coordinated Universal Time (UTC) and denoted by the letter "Z."
-
E.
Greenwich Mean Time
Greenwich Mean Time is the mean solar time at the Royal Observatory in Greenwich, London, historically used as the world’s primary reference for timekeeping and the basis for Coordinated Universal Time (UTC).
- 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: Universal Time 1 Target entity description: Universal Time 1 (UT1) is an astronomical time standard based on Earth's actual rotation, closely tracking mean solar time at the prime meridian and used in precise navigation and astronomy.
-
A.
Coordinated Universal Time
Coordinated Universal Time (UTC) is the primary global time standard by which the world regulates clocks and time, serving as the basis for most civil time zones.
-
B.
Terrestrial Time
Terrestrial Time is a modern astronomical time standard used for precise calculations of planetary motion and ephemerides, defined in relation to atomic time rather than Earth's rotation.
-
C.
International Atomic Time
International Atomic Time is a high-precision time standard based on the combined output of atomic clocks worldwide, serving as the fundamental reference for modern civil and scientific timekeeping.
-
D.
Zulu time
Zulu time is a standardized time reference used worldwide—especially in aviation, military, and navigation—corresponding to Coordinated Universal Time (UTC) and denoted by the letter "Z."
-
E.
Greenwich Mean Time
Greenwich Mean Time is the mean solar time at the Royal Observatory in Greenwich, London, historically used as the world’s primary reference for timekeeping and the basis for Coordinated Universal Time (UTC).
- F. None of above. chosen
Statements (46)
| Predicate | Object |
|---|---|
| instanceOf |
astronomical time scale
ⓘ
time standard ⓘ |
| abbreviation |
IERS
ⓘ
UT1 ⓘ |
| abbreviationStyle | UT1 ⓘ |
| appliesTo | Earth ⓘ |
| basedOn | Earth's rotation ⓘ |
| category |
celestial mechanics
ⓘ
timekeeping ⓘ |
| closelyRelatedTo | mean solar time ⓘ |
| comparedWith | Coordinated Universal Time ⓘ |
| coordinateRole | Earth orientation parameter ⓘ |
| definedIn | IERS Conventions ⓘ |
| definedRelativeTo | Earth rotation angle ⓘ |
| dependsOn | variations in Earth's rotation ⓘ |
| differsFrom |
UT0
ⓘ
UT2 ⓘ |
| epochReference | Greenwich midnight ⓘ |
| fullName | Universal Time 1 ⓘ |
| governedBy | International Earth Rotation and Reference Systems Service ⓘ |
| hasProperty | continuous but non-uniform ⓘ |
| isNonUniform | true ⓘ |
| measuredIn |
days
ⓘ
hours ⓘ seconds ⓘ |
| monitoredBy |
IERS Earth Orientation Center
ⓘ
linked to:
IERS Central Bureau
|
| partOf |
Universal Time system
ⓘ
linked to:
Universal Time 1
|
| referenceLongitude | 0 degrees ⓘ |
| referenceMeridian | prime meridian ⓘ |
| relatedTo |
UT0
ⓘ
UT2 ⓘ |
| standardizedBy | International Astronomical Union ⓘ |
| successorOf | Greenwich Mean Time ⓘ |
| symbol | UT1 ⓘ |
| timeScaleClass | Earth rotation time scale ⓘ |
| timeScaleType | solar time scale ⓘ |
| tracks | mean solar time at the prime meridian ⓘ |
| usedFor |
Earth orientation studies
ⓘ
astronomy ⓘ precise navigation ⓘ spacecraft tracking ⓘ |
| usedIn |
VLBI measurements
ⓘ
geodesy ⓘ radio astronomy ⓘ satellite orbit determination ⓘ |
| usedToDefine | leap seconds in Coordinated Universal Time ⓘ |
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: Universal Time 1 Description of subject: Universal Time 1 (UT1) is an astronomical time standard based on Earth's actual rotation, closely tracking mean solar time at the prime meridian and used in precise navigation and astronomy.
Referenced by (4)
Full triples — surface form annotated when it differs from this entity's canonical label.
subject linked to:
TT
linked to: Universal Time 1
subject linked to:
Universal Time 1
linked to: Universal Time 1