Abstract
The international time scales, International Atomic Time (TAI) and Coordinated Universal Time (UTC), are elaborated at the Bureau International des Poids et Mesures (BIPM), thanks to the contribution of 57 national time laboratories that maintain local realizations of UTC. The Iberoamerican contribution to TAI has increased in the last years. Ten laboratories in America and one in Spain participate to the calculation of TAI, increasing its stability with the data of industrial atomic clocks and improving its accuracy with frequency measurements of a caesium source developed and maintained at one laboratory. This paper summarizes the characteristics of the reference time scales and describes the contributions of the Iberoamerican time laboratories to them.
