Device to measure time intervals using nucleus or molecular oscillations. These oscillations are extremely constant in time.

A very precise clock that operates using the elements cesium or rubidium. A cesium clock has an error of one second per million years. GPS satellites contain multiple cesium and rubidium clocks.

A clock based upon the transition of the caesium 133 atom. Highly accurate and reliable. Click here to read more information about the atomic clock.

Caesium atomic clocks operate by exposing caesium atoms to microwaves until they start to vibrate at one of their resonant frequencies. By measuring this frequency, which is an unchanging property of matter, a time measure can be established. Caesium atomic clocks are very stable, and accuracies of 1 second in 1.4 million years have been reported.

There are a set of very accurate atomic clocks on the web. Some are super accurate primarily to set other master clocks. You can set your computer’s clock accurately with a free program from WordTimeS [..]

Currently, the most accurate timekeeping devices on earth. These are accurate to 1 second in 1,400,000 years. This information is broadcast throughout the day from a radio transmitter in Ft. Collins, [..]

1. A lessening in amount, particularly the reduction of the amplitude of a wave with distance from the origin. 2. The decrease in the strength of a radar wave resulting from absorption, scattering, an [..]

An extremely accurate reference clock whose operation is based on an atomic process, typically the frequency of electromagnetic radiation associated with a specified energy-level transition in an el [..]