CAPE CANAVERAL, Florida -- A leap second will be added on Saturday June 30, 2012 so that International Atomic Time will stay in sync with the the astronomical time of the Earth which is ever so slightly slowing its rotation.
The official bulletin was issued by the Earth Orientation Center of the International Earth Rotation and Reference Systems Service in Paris, France to atomic time keepers around the globe, inlcuding the U.S. Naval Observatory.
The last time a Leap Second was introduced was at the end of December 2008.
The instructions given for introduction of the 2012 June 30 Leap Second to time keepers are as follows:
A positive leap second will be introduced at the end of June 2012. The sequence of dates of the UTC second markers will be: 2012 June 30, 23h 59m 59s 2012 June 30, 23h 59m 60s 2012 July 1, 0h 0m 0s The difference between UTC and the International Atomic Time TAI is: from 2009 January 1, 0h UTC, to 2012 July 1 0h UTC : UTC-TAI = - 34s from 2012 July 1, 0h UTC, until further notice : UTC-TAI = - 35s 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.