GPS Time Disruptions on 26-Jan-2016

On Tuesday, January 26th 2016 Aalto University Metsähovi Radio Observatory discovered that three out of its four GPS receivers on-site (used for monitoring the performance of four on-site hydrogen (H) maser atomic clocks) performed abrupt 13.0 microsecond time jumps in their "1pps" (one pulse per second) time synchronization outputs. The disruptions lasted for approximately 12 hours during which different GPS receiver units outputted erroneous time signal at different times, preventing their use for microsecond-level time synchronization. The event was later acknowledged by the 2nd Space Operations Squadron at the 50th Space Wing, Schriever Air Force Base, Colorado, USA, as an erroneous time correction parameter upload to GPS satellites.