A power outage on Dec. 19 at the National Institute of Standards and Technology (NIST) campus in Boulder, Colo., disrupted operation of the NIST-F4 atomic clock.
Hurricane force winds and dry conditions prompted the National Weather Service to issue a rare “particularly dangerous situation” fire weather warning. In response, energy provider Xcel Energy preemptively cut power to much of Boulder County to reduce the risk of downed power lines sparking wildfires.
During the prolonged outage, a failure in a backup generator disrupted networking equipment responsible for distributing time signals from NIST’s atomic clocks. The disruption affected radio broadcasts and internet time servers used by nearly every internet-connected device, including the one you are reading this article on.
Jeff Sherman, who leads NIST’s Time Realization and Distribution Group reported Sunday that a backup time scale system using additional atomic clocks on the Boulder campus was successfully brought online. This restored NIST’s offset from Coordinated Universal Time (UTC) to “the level of a few nanoseconds (billionths of a second),” well within the system’s normal precision. Sherman concluded that “the Boulder Internet Time Service is now providing accurate time.”
“Offset from UTC” is the important part here.
The NIST-F4 cesium fountain atomic clock, is one of the primary tools use to define the second helping ongoing calibration of global time (UTC)
Though NIST-F4, a cesium fountain atomic clock, is among the most accurate time providers in the world. It is what defines the ultra-precise timekeeping that drives modern technology where nanoseconds matter, including GPS, managing the power grid, financial trading and synchronizing the clocks on nearly every internet connected device, including your mobile phone.
Ten atomic clocks globally, including additional ones in the U.S. maintained by the Naval Observatory, contribute to UTC time computed by the International Bureau of Weights and Measures in the Paris suburbs.
Dr. Judah Levine designed and implemented NIST’s implementation of the UTC timescale along with three backup timescales maintained at the Boulder, CO campus
I recently visited the NIST campus in Boulder. I was fortunate to run into Judah Levine just before his retirement from the Network Synchronization Project after 56 years at NIST. He led me through the NIST-7 that provided reference time until 1999, now on display in the lobby.
NIST-7, the cesium beam atomic clock in use at NIST during the 1990s
Levine described how turning the cylinder of that atomic-beam clock vertical and slowing the caeseum atoms by cooling them with a laser slows the atoms to allow longer interaction with detectors enabling precision that beam clocks can’t match.
