People need to be somewhat careful that they understand relevant time bases when taking about deltaT corrections.

 

The links provided below give the offset between Terrestrial Time and UT1. However I would be extremely surprised if anyone in this group actually used UT1 for any time keeping purpose. Rather everyone will access time on the basis of Coordinated Universal Time (UTC). That is the time you get from GPS; it is the time you get from NTP; and it is the time you get from the old short-wave broadcasts such as WWV. This time scale has an identical rate to Terrestrial Time, and is adjusted periodically by the insertion of leap seconds to ensue its difference from UT1 is less than 0.8 secs. You can use UTC signals to derive UT1 at a precision of 0.1 secs by applying the DUT1 correction that is disseminated with UTC signals – but in practice who does that?!

 

Once you appreciate this fact, then almost certainly you are in an environment where the deltaT correction needed to be applied to an observed time is constant between leap seconds. The last leap second was in Jan 2017. The next one hasn’t been announced yet – but my guess (from recent changes in DUT1) is that it won’t be before July 2019, and probably not before the end of 2019.

 

 

Dave Herald
Murrumbateman