In the theory of relativity, it is convenient to express results in terms of a spacetime coordinate system relative to an implied observer. In many (but not all) coordinate systems, an event is specified by one time coordinate and three spatial coordinates. The time specified by the time coordinate is referred to as coordinate time to distinguish it from proper time.
In the special case of an inertial observer in special relativity, by convention the coordinate time at an event is the same as the proper time measured by a clock that is at the same location as the event, that is stationary relative to the observer and that has been synchronised to the observer's clock using the Einstein synchronisation convention.
spacetime coordinate system relative to an implied observer. In many (but not all) coordinate systems, an event is specified by one timecoordinate and three...
Coordinated Universal Time or UTC is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time...
Geocentric CoordinateTime (TCG - Temps-coordonnée géocentrique) is a coordinatetime standard intended to be used as the independent variable of time for all...
Barycentric CoordinateTime (TCB, from the French Temps-coordonnée barycentrique) is a coordinatetime standard intended to be used as the independent...
the MAVEN orbiter project. Coordinated Mars Time (MTC) or Martian CoordinatedTime is a proposed Mars analog to Universal Time (UT1) on Earth. It is defined...
scale realized by TAI. Geocentric CoordinateTime and Barycentric CoordinateTime are scales defined as coordinate times in the context of the general...
proper time is usually represented by the Greek letter τ (tau) to distinguish it from coordinatetime represented by t. Coordinatetime is the time between...
A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude...
Coordinated Lunar Time or LTC is a proposed primary lunar time standard for the Moon. In early April 2024, NASA was asked by the White House to work alongside...
geographic coordinate systems is made necessary by the different geographic coordinate systems in use across the world and over time. Coordinate conversion...
timescales, e.g. coordinated universal time, GPS time, International Atomic Time, etc. Geocentric CoordinateTime (TCG) is a coordinatetime having its spatial...
International Atomic Time (abbreviated TAI, from its French name temps atomique international) is a high-precision atomic coordinatetime standard based on...
approximate it. TT is distinct from the time scale often used as a basis for civil purposes, Coordinated Universal Time (UTC). TT is indirectly the basis of...
coordinates, a coordinate system where a clock at infinite distance from the massive sphere would tick at one second per second of coordinatetime, while closer...
Universal Time was introduced in 1928 to denote GMT as counted from midnight. Today, Universal Time usually refers to Coordinated Universal Time (UTC) or...
In geometry, a Cartesian coordinate system (UK: /kɑːrˈtiːzjən/, US: /kɑːrˈtiːʒən/) in a plane is a coordinate system that specifies each point uniquely...
its origin. A relativistic reference frame includes (or implies) the coordinatetime, which does not equate across different reference frames moving relatively...
Dynamical Time (TDB, from the French Temps Dynamique Barycentrique) is a relativistic coordinatetime scale, intended for astronomical use as a time standard...
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. It may be implemented in...
A cylindrical coordinate system is a three-dimensional coordinate system that specifies point positions by the distance from a chosen reference axis (axis...
determines a coordinate or coordinate block via a coordinate selection rule, then exactly or inexactly minimizes over the corresponding coordinate hyperplane...
to coordinatetime. In an inertial frame in which the object is momentarily at rest, the proper acceleration 3-vector, combined with a zero time-component...
theory of its motion. a modern relativistic coordinatetime scale, implemented by the JPL ephemeris time argument Teph, in a series of numerically integrated...
The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane to define two angles:...
The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with...
other time systems. Unix time differs from both Coordinated Universal Time (UTC) and International Atomic Time (TAI) in its handling of leap seconds. UTC includes...
In geometry, curvilinear coordinates are a coordinate system for Euclidean space in which the coordinate lines may be curved. These coordinates may be...
Pakistan uses one time zone, which is Pakistan Standard Time (PKT). This is UTC+05:00 — that is, five hours ahead of Coordinated Universal Time. 10:31 pm, 7...
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