What are International Atomic Time (TAI) and Coordinated Universal Time (UTC)?
International Atomic Time (TAI) is an international time scale that is computed by taking the weighted average of more than 300 atomic clocks. These clocks are located at more than 60 timing laboratories around the world. The most stable clocks receive the most weight in the calculation, but the maximum weight assigned to any clock is limited to A / N, where A = 2.5 and N is the number of clocks. Thus, if N = 300, the maximum weight is 0.83 %. While the stability of TAI is achieved by this weighted average, the accuracy of TAI is derived from data from primary frequency standards, which are clocks built at several national metrology institutes. TAI is computed by the International Bureau of Weights and Measures (BIPM) located near Paris, France. Coordinated Universal Time (UTC) is based on TAI, but it is adjusted by leap seconds to account for the difference between the definition of the second and the rotation of Earth. This correction keeps UTC in conjunction with the apparent positi
