[kstar]

There's even a leap second - here's a bit about it, again from Wikipedia:

Announcement of leap seconds

The International Earth Rotation and Reference Systems Service (IERS) announces the insertion of a leap second whenever the difference between UTC and UT1 approaches 0.6 s, to keep the difference between UTC and UT1 from exceeding ±0.9 s. The announcement appears in IERS "Bulletin C", typically published every six months.

After UTC 23:59:59, a positive leap second at 23:59:60 would be counted, before the clock indicates 00:00:00 of the next day. Negative leap seconds are also possible should the Earth's rotation become slightly faster; in that case, 23:59:58 would be followed by 00:00:00. Leap seconds occur only at the end of a UTC month, and have only ever been inserted at the end of June 30 or December 31. Unlike leap days, they occur simultaneously worldwide; for example, the leap second on 31 December 2005 occurred at 23:59:60 UTC. This was 6:59:60 p.m. U.S. Eastern Standard Time and 0:59:60 a.m. on 1 January, 2006 Central European Time.

Historically, leap seconds have been inserted about every 18 months. However, the Earth's rotation rate is unpredictable in the long term, so it is not possible to predict the need for them more than six months in advance. Between January 1972 and December 2005, the IERS gave instructions to insert a leap second on 23 occasions. The interval between 1999-01-01 and 2005-12-31 was the longest period without a leap second since the system was introduced.

Leap seconds are also not included directly in GPS time, although a regularly broadcast message notes how far GPST and UTC are apart.

Some time signal broadcasts give voice announcements

Best,

Kurt