Press Release

A leap second on the New Year's Day (30 December 2005)

At 7:59:59 A.M. on 1 January 2006 Hong Kong Time, i.e. the coming New Year's Day, a leap second will be added to Coordinated Universal Time (UTC). The Hong Kong standard time, which is exactly eight hours ahead of UTC, will be delayed by one second accordingly. The whole process will be completed in 2 seconds, i.e., at 8:00:00 A.M. Hong Kong Time on that day.

UTC is a stable and even time scale based on the frequency of atomic oscillations in atomic clocks. This is the current international time scale for civil use.

The astronomical time scale based on the Earth's rotation is another common time scale. As a result of atmospheric circulation and other geophysical events on Earth, the rate of the Earth's rotation is uneven and has been slowing down. Difference between the two time scales arises. The purpose of introducing leap second is to reconcile the two time scales so that their difference is kept less than 0.9 second.

A total of 23 leap seconds have been introduced in UTC since its adoption in 1972. The last adjustment was made on 1 January 1999.

More information on leap seconds can be found at:

http://www.weather.gov.hk/gts/time/basicterms-leapsecond.htm