Dear colleagues,On Saturday, 6 December 2025 at approximately 21:13 UTC, the atomic time source (a single cesium beam atomic clock) for all the internet time servers at the NIST Gaithersburg campus failed and exhibited a time step of approximately -10 ms. The affected servers are:Coincidentally, there were unexplained failures in more than one co-located resource, including some used for monitoring and control. The server time-a-g became unavailable due to an unexplained operating system shutdow...