This article explains how the National Institute of Standards and Technology (NIST) contributes to the global timekeeping system by maintaining highly accurate frequency standards. NIST-F1, a cesium fountain clock, is the primary frequency standard in the United States and has an uncertainty of less than 1 part in 10^15. NIST uses these standards to help calculate Coordinated Universal Time (UTC), which is managed by the International Bureau of Weights and Measures (BIPM). NIST generates its own version of UTC, called UTC(NIST), based on a real-time scale called AT1, which combines data from multiple atomic clocks.
The article also provides detailed data from 2006 showing how UTC(NIST) is adjusted relative to AT1. These adjustments include time offsets and frequency corrections, which are updated regularly to keep UTC(NIST) aligned with the global UTC standard. Leap seconds are also accounted for in these calculations. The data includes specific values for each month, allowing precise calculation of the difference between UTC(NIST) and AT1 at any given time. This information is important for maintaining accurate timekeeping in scientific, technological, and communication systems.
Keywords: frequency standards, time scale, UTC(NIST)
