[time-nuts] Thunderbolt Question

[Tom Van Baak]

> I have been using a surplus Thunderbolt for about six months, and it seemed
> to be working  fine.  In January 2012, a message came up in yellow, (LEAP
> PENDING!), I don't know what this means, but since it didn't go away on Feb
> 28, must not be leap year related.

Hi Ed,

Right, in this case the "LEAP" refers to a leap second, not a leap
year. When the next leap second occurs this summer, the yellow
warning will go away.

As you know, leap years are used to keep "days" and "years" in
sync, where a day is earth rotation (about its axis) and a year is
earth revolution (around the sun). Last one was: Feb 29, 2012.

Similarly, leap seconds are used to keep "seconds" and "days" in
sync, where a second is now defined by atomic standards and a
day is earth rotation. Next one is: 19:59:60 EDT, Jun 30, 2012.

Keeping clocks in sync is a significant part of the timekeeping
world. For example, with quartz and GPS it's easy to "discipline"
quartz in order to steer it closer to GPS. This is done by making
slight changes in quartz EFC voltage to change the frequency, to
close the differential time error.

But when it comes to orbits and planets, objects too large for us
to change their rate, objects which have no EFC input, we have
to resort to making artificial, bookkeeping, virtual steps in time
instead of gradual changes in physical rate.

/tvb