INTERNATIONAL EARTH ROTATION SERVICE (IERS) 
  	       SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE

BUREAU CENTRAL DE L'IERS
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, 17 July 1998
                                                           

                                              Bulletin C 16
                                
                                              To authorities responsible for                  
                                              the measurement and distribution                
                                              of time                                         


                                   UTC TIME STEP
                            on the 1st of January 1999
                      

       A positive leap second will be introduced at the end of December 1998.
       The sequence of dates of the UTC second markers will be:		
		
                          1998 December 31,     23h 59m 59s
                          1998 December 31,     23h 59m 60s
                          1999 January   1,      0h  0m  0s
              
  The difference between UTC and the International Atomic Time TAI is:
  
  from 1997 July 1,    0h UTC, to 1999 January 1, 0h UTC  : UTC-TAI = - 31s
  from 1999 January 1, 0h UTC, until further notice       : UTC-TAI = - 32s

       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 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			
                                              Central Bureau of IERS