Leap Second Warning
A leap second will be inserted into Coordinated Universal Time (UTC) on 30 June 2012 23:59:59 in order to sustain synchronization of UTC with Earth rotation. All UTC clocks that advance from 59 sec of a minute to 00 sec of the following minute must be set back by one sec on 1 July 2012 00:00:00. The UTC sequence is as follows.
30 June 2012 23:59:59
30 June 2012 23:59:60
Followed by:
1 July 2012 00:00:00
The consequence of failing to accommodate this event is that orbit in-plane motion and corresponding Earth orientation will both become inaccurate by at least one second until the leap second is properly implemented. This will also affect estimating orbits using time sequences of observations spanning this leap second event. Satellite locations in LEO might be inaccurate by several kilometers and in GEO by several tens of kilometers.