[LEAPSECS] [time-nuts] Leap second to be introduced at midnight UTC December 31 this year

[Warner Losh]

On Wed, Jul 20, 2016 at 9:27 AM, Martin Burnicki
<martin.burnicki at burnicki.net> wrote:
> Brooks Harris wrote:
>> On 2016-07-20 01:08 AM, Tom Van Baak wrote:
>>> I recall this is a known problem in the Z3801A status reporting, and
>>> possibly other GPS receivers of that era as well. It stems indirectly
>>> from a change years ago in how far in advance IERS and DoD were able
>>> to update the leap second info into the GPS constellation. Nowadays
>>> it's common to get 6 months notice; it wasn't always that much.
>>
>> TF.460-6 says:
>> "2.3    The IERS should decide upon and announce the introduction of a
>> leap-second, such an announcement to be made at least eight weeks in
>> advance."
>>
>> Is there a statement in some document from BIPM or IERS that states
>> their current announcement policy? How, when, and why is it different
>> from 460? I mean, more lead time is a good thing, but what, exactly, is
>> an implementer to expect and what standard would would they look to
>> learn and confirm that?
>
> Each bulletin C from IERS says:
>
> "Leap seconds can be introduced in UTC at the end of the months of
> December  or June, depending on the evolution of UT1-TAI. Bulletin C is
> mailed every six months, either to announce a time step in UTC or to
> confirm that there will be no time step at the next possible date."

That's not an official standards document. That's IERS telling us how often
they will publish their Bulletin C with not a lot of precision. Sometimes it's
sent out on July 1, other times later, for example.

Warner