Coordinated Universal Time

Coordinated Universal Time

Around the world people need to keep to an agreed timescale. The time measured by the rotation of the Earth about its axis slowly drifts away from UTC this means leap seconds are inserted in order, to keep UTC to within 0.9 seconds of the Earth's time.

Atomic time and UTC are kept through the collection of about forty laboratories worldwide, each labratory housing several atomic clocks. The National Physical Laboratory collaborates on behalf of the UK and it has the responsibility for maintaining the national scale of UTC. The National Physical Laboratory broadcasts time signals from a transmitter at Cumbria.

Anyone with a suitable receiver can set their clock directly against the national atomic clock. Some clocks used for domestic every day use are now available with an in-built receiver.