To determine your local time add or subtract the difference between UTC and your local Time Zone. An atomic clock keeps time using the naturally occurring frequencies of atoms, such as cesium, hydrogen, or rubidium. Atomic clocks are extremely accurate because these generated frequencies are highly stable, constant, and virtually unaffected by factors such as temperature, air pressure, or humidity. The official definition of an Earth Second. This definition was agreed upon in 1967.
Atomic clocks based on the cesium atom are the primary means for accurate timekeeping.
This page links directly to NIST and displays the current time reported by the NIST Atomic Clock. However, due to network delays over the Internet there is a fractional second margin of error. Do not use this time to synchronize clocks requiring sub-second accuracy.