The NIST-F2 atomic clock represents "official" U.S. time and the loses only 1 second every 300,000,000 years - Reeko's Mad Scientist Lab
The United States’ method of keeping time was already very accurate but today, took a giant leap forward with the introduction of the NIST-F2 atomic clock. Scientists at the National Institute of Standards and Technology (NIST) have been building the NIST-F2 for about 10 years in hopes of replacing the aging F1 which has been used to keep the official U.S. time since 1999. The NIST-F2 clock is used to keep the official time in the United States and is shared with the International Bureau of Weights and Measures in Paris, France.