INTERNATIONAL EARTH ROTATION SERVICE (IERS) SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE SERVICE DE LA ROTATION TERRESTRE OBSERVATOIRE DE PARIS 61, Av. de l'Observatoire 75014 PARIS (France) Tel. : 33 (0) 1 40 51 22 26 FAX : 33 (0) 1 40 51 22 91 Internet : iers@obspm.fr Paris, 11 January 2001 Bulletin C 21 To authorities responsible for the measurement and distribution of time INFORMATION ON UTC - TAI NO positive leap second will be introduced at the end of June 2001. The difference between UTC and the International Atomic Time TAI is : from 1999 January 1, 0h UTC, until further notice : UTC-TAI = - 32 s Leap seconds can be introduced in UTC at the end of the months of December or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every six months, either to announce a time step in UTC, or to confirm that there will be no time step at the next possible date. Daniel GAMBIS Director Earth Orientation Center of IERS