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






BUREAU CENTRAL DE L'IERS
OBSERVATOIRE DE PARIS                                   Paris, 6 January 1997
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
                                                        Bulletin C 13
                                



                                                        To authorities responsible for                  
                                                        the measurement and distribution                
                                                        of time                                         












                                    UTC TIME STEP
                      

                             on the  1st of  July 1997
              





 A positive leap second will be introduced at the end of June 1997.
 The sequence of dates of the UTC second markers will be:


		

                      1997 June       30,    23h 59mn 59s
                      1997 June       30,    23h 59mn 60s
                      1997 July        1,     0h  0mn  0s


 The difference between UTC and the International Atomic Time TAI is:


   from 1996 January 1, 0h UTC, until 1997 July 1, 0h UTC: UTC-TAI = - 30s
   from 1997 July 1, 0h UTC, until further notice        : UTC-TAI = - 31s


 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.








                                                 Martine FEISSEL	
                                                 Director			
                                                 Central Bureau of IERS