international atomic time การใช้

• TT indirectly underlies UTC, via International Atomic Time ( TAI ).
• These clocks collectively define a continuous and stable time scale, International Atomic Time ( TAI ).
• International Atomic Time ( TAI ) was set equal to UT2 at 1 January 1958 0 : 00 : 00.
• This is kept in sync with the official civilian time reference maintained by NIST and contributes to the International Atomic Time.
• One is called International Atomic Time, or TAI, which is computed by the International Bureau of Weights and Measures in Paris.
• Practical examples include the International Atomic Time standard and its relationship with the Barycentric Coordinate Time standard used for interplanetary objects.
• ET was given a new name, Terrestrial Time ( TT ), and for most purposes ET = TT = International Atomic Time + 32.184 SI seconds.
• It is also answered that two timescales that do not follow leap seconds are already available, International Atomic Time ( TAI ) and Global Positioning System ( GPS ) time.
• The International Atomic Time ( TAI ) time standard and its derivatives ( such as the Coordinated Universal Time ( UTC ) ) are based on weighted averages of atomic clocks worldwide.
• In the synchronous grid of Continental Europe, the deviation between network phase time and UTC ( based on International Atomic Time ) is calculated at 08 : 00 each day in a control center in Switzerland.
• Thus, civil broadcast standards for time and frequency usually follow International Atomic Time closely, but occasionally step ( or " leap " ) in order to prevent them from drifting too far from mean solar time.
• Atomic clocks are far more accurate than any previous timekeeping device, and are used to calibrate other clocks and to calculate the International Atomic Time; a standardized civil system, Coordinated Universal Time, is based on atomic time.
• The SI second was defined in terms of the caesium atom in 1967, and in 1971 the name International Atomic Time ( TAI ) was assigned to a time scale based on SI seconds with no leap seconds.
• More precisely, it was defined that TT instant 1977-01-01T00 : 00 : 32.184 exactly and TCG instant 1977-01-01T00 : 00 : 32.184 exactly correspond to the International Atomic Time ( TAI ) instant 1977-01-01T00 : 00 : 00.000 exactly.
• Since 1972, UTC is calculated by subtracting the accumulated leap seconds from International Atomic Time ( TAI ), which is a coordinate time scale tracking notional proper time on the rotating surface of the Earth ( the geoid ).
• Losing only a second of accuracy every 1.6 million years, it remains the most accurate commercial clock in the world, and accounts for 82 % of the data used to keep the International Atomic Time Standard ( as of 2006 ).
• TWSTFT is being evaluated as an alternative to be used by the Bureau International des Poids et Mesures in the determination of International Atomic Time ( TAI ), as a complement to the current standard method of simultaneous observations of GPS transmissions.
• Therefore, time standards that change the date after precisely 86, 400 SI seconds, such as the International Atomic Time ( TAI ), will get increasingly ahead of time standards tied to the mean solar day, such as Greenwich Mean Time ( GMT ).
• The current version of UTC is defined by International Telecommunications Union Recommendation ( ITU-R TF . 460-6 ), " Standard-frequency and time-signal emissions " and is based on International Atomic Time ( TAI ) with leap seconds added at irregular intervals to compensate for the slowing of Earth's rotation.
• PTP typically uses the same epoch as Unix time ( Midnight, 1 January 1970 ) . | group = note } } While the Unix time is based on Coordinated Universal Time ( UTC ) and is subject to leap seconds, PTP is based on International Atomic Time ( TAI ).