INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)


SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE




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  : services.iers@obspm.fr


Paris, 8 July 2011




Bulletin C 42


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 December 2011.
The difference between Coordinated Universal Time UTC and the
International Atomic Time TAI is :


from 2009 January 1, 0h UTC, until further notice : UTC-TAI = -34 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
Observatoire de Paris, France




IMPORTANT: After years of discussions, a proposal to fundamentally redefine
UTC will come to a conclusive vote in January 2012 at the ITU-R in Geneva.


This proposal would halt the intercalary adjustments known as leap seconds
that maintain UTC as a form of Universal Time.


The Earth Orientation Center of the IERS organizes a survey online with the
objective to find out the strength of opinion for maintaining or changing
the present system.


Link to the questionnaire:


http://hpiers.obspm.fr/eop-pc/index.php?index=questionnaire


Your response is appreciated before 30 August 2011