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International Atomic Time (abbreviated TAI, from its French name temps atomique international[1]) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. [2] TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories worldwide. [3]
The development of atomic clocks has led to many scientific and technological advances such as precise global and regional navigation satellite systems, and applications in the Internet, which depend critically on frequency and time standards. Atomic clocks are installed at sites of time signal radio transmitters. [115]
Eastern Time Zone. DST is observed in parts of this time zone. The Eastern Time Zone (ET) is a time zone encompassing part or all of 23 states in the eastern part of the United States, parts of eastern Canada, and the state of Quintana Roo in Mexico. Eastern Standard Time (EST) is five hours behind Coordinated Universal Time (UTC−05:00).
Atlantic. UTC−04:00. UTC−03:00. Atlantic. UTC−03:30. UTC−02:30. Newfoundland. Canada is divided into six time zones. Most areas of the country's provinces and territories operate on standard time from the first Sunday in November to the second Sunday in March and daylight saving time the rest of the year.
NIST physicists Steve Jefferts (foreground) and Tom Heavner with the NIST-F2 cesium fountain atomic clock, a civilian time standard for the United States. NIST-F2 is a caesium fountain atomic clock that, along with NIST-F1, serves as the United States ' primary time and frequency standard. [1] NIST-F2 was brought online on 3 April 2014. [1][2]
Universal Time (UT or UT1) is a time standard based on Earth's rotation. [1] While originally it was mean solar time at 0° longitude, precise measurements of the Sun are difficult. Therefore, UT1 is computed from a measure of the Earth's angle with respect to the International Celestial Reference Frame (ICRF), called the Earth Rotation Angle ...
The history of standard time in the United States began November 18, 1883, when United States and Canadian railroads instituted standard time in time zones. Before then, time of day was a local matter, and most cities and towns used some form of local solar time, maintained by some well-known clock (for example, on a church steeple or in a ...
Israel Standard Time (UTC+2) Israel Summer Time (UTC+3) Grey colours indicate areas which do not follow either IST or IDT. Israel Standard Time (IST) (Hebrew: שעון ישראל Sha'on Yisra'el, lit. 'Clock of Israel') is the standard time zone in Israel. It is two hours ahead of UTC (UTC+02:00).