550700

Time is precisely controlled in the United States by the most accurate clock in North America, the atomic clock of the US National Institute of Standards and Technology, Time and Frequency Division in Boulder, Colorado.  A team of atomic physicists continually measures every second of every day to an accuracy of ten billionths of a second per day. These physicists have created an international standard, measuring a second as 9,192,631,770 vibrations of a cesium 133 atom in a vacuum. This clock receives a signal from the WWVB radio transmitter located in Fort Collins, Colorado, where the exact time signal is continuously broadcast throughout the United States at 60 kHz to take advantage of stable longwave radio paths found in that frequency range. The built-in antenna system in this clock will receive the WWVB signal anywhere in North America where long-wave reception is undisturbed. A microprocessor activates the receiver and processes the time signal from Fort Collins overnight. Even adjustment for daylight savings time and leap second are automatic. Dial: 6-1/8". Base: 8-13/16". Depth: 1-7/8".