leap second

Leap seconds are used to adjust the time scale UTC to the apparent motion of the Sun, i.e. to Earth rotation. They are introduced in such a way that UT1-UTC stays smaller than 0.9 s in absolute value.

The decision to introduce a leap second in UTC to meet this condition is the responsibility of the IERS. Leap seconds are announced in IERS Bulletin C.

Related terms:

• Coordinated Universal Time
• Universal Time (UT1)

Related links:

• IERS Bulletin C
• Earth orientation data
• Leap seconds