Mind the leap second, an AIS ‘gotcha’
Wasn’t I just noodling about celestial mechanics? Well it turns out that for the first time since 1998, the time authorities need to insert a second into the world clock “to make up for the slowing down of the Earth’s rotation”. They’re going to do it at midnight GMT, December 31, and it’s going to affect AIS transponders because atomic time from the GPS system is critical to the signal sharing protocol. ACR warns that all transponders need to be re-synchronized on Jan. 1 or “the GPS signal received by the transponder could fail to identify targets on the AIS display.”
PS There’s more on leap seconds here, including my new favorite obscure department name: The Sub-bureau for Rapid Service and Predictions of Earth Orientation Parameters of the International Earth Rotation Service, located at the U.S. Naval Observatory.