Because the rotation of the earth is slowing slightly, the world's atomic clocks are occasionally adjusted by one second to maintain synchronization. This has occurred 25 times between 1972 and 2012. As the rate of slowing is not constant, the scheduling of leap second events is irregular (only scheduled 6 months in advance). The next event is scheduled for June 30th, 2015 and there are no known issues between CA Common Services and the leap second event.