[LEAPSECS] USNO press release

[Brooks Harris]

"WASHINGTON, DC -- On December 31, 2016, a "leap second" will be added 
to the world's
clocks at 23 hours, 59 minutes and 59 seconds Coordinated Universal Time 
(UTC). This
corresponds to 6:59:59 pm Eastern Standard Time, when the extra second 
will be inserted at the
U.S. Naval Observatory's Master Clock Facility in Washington, DC. "

It seems to me not exactly wrong, but misleading in several respects:

1) Its a *positive* Leap Second
2) "introduced" or "inserted" rather than "added" are better terms 
consistent with ITU-R 460.
3) The Leap Second is not, typically, "added to the worlds clocks" in 
the same way its introduced to UTC. If "world clocks" means "local time" 
the Leap Second will typically be introduced on the local timescales 
simultaneous with its occurrence on UTC.
4) "added .. at 23 hours, 59 minutes and 59 seconds" might be 
misinterpreted to mean *before*, or somehow together with, 23:59:59. 
"Inserted following" might be more clear.
5) there's no mention of what happens in the other USA time zones.

Its always a challenge to write about UTC in a way that's both clear and 
readable. Here's my go:

The International Earth Rotation and Reference Systems Service (IERS) 
has determined a positive Leap Second shall be introduced in the 
Coordinated Universal Time (UTC) timescale at the end of the day on 
2016-December-31. The positive Leap Second will be inserted immediately 
following the second labeled 23:59:59 and labeled 23:59:60. Most world 
clocks will introduce this positive Leap Second on their local 
timescales simultaneous with its occurrence in UTC. The U.S. Naval 
Observatory's Master Clock Facility in Washington, DC will insert this 
positive Leap Second to the Eastern Standard Time (UTC-05:00) timescale 
on 2016-December-31 immediately following the second labeled 06:59:59 pm 
(18:59:59) and will be labeled 06:59:60 pm (18:59:60).

-Brooks

On 2016-07-10 11:26 PM, Jonathan E. Hardis wrote:
> I don't disagree with your interpretation of UTC, but there's no error 
> in the announcement.  The leap second is */added/* */at /*23:59:59. 
>  While the leap second itself is 23:59:60, it's during the interval 
> 23:59:59 when the logic is changed for what the next second should be 
> labelled.
>
>      - Jonathan
>
>
>> On Jul 10, 2016, at 3:39 PM, Paul Hirose <cfuhb-acdgw at earthlink.net 
>> <mailto:cfuhb-acdgw at earthlink.net>> wrote:
>>
>> On 2016-07-08 12:16, I wrote:
>>> Is there a mistake in this announcement?
>>>
>>>
>>> http://www.usno.navy.mil/USNO/tours-events/2016_Leap_Second%20Press%20Release%20-%20Final.pdf
>>>
>>>
>>> WASHINGTON, DC -- On December 31, 2016, a "leap second" will be added to
>>> the world's clocks at 23 hours, 59 minutes and 59 seconds Coordinated
>>> Universal Time (UTC).
>>
>> The mistake is in the first sentence. Nothing unusual happens at 
>> 23:59:59. One second later, at 23:59:60, the leap second begins. In 
>> other words, UTC will do this:
>>
>> 23:59:59.9
>> 23:59:60.0
>> 23:59:60.1
>> ...
>> 23:59:60.9
>> 00:00:00.0
>>
>> I have informed the author of the press release.
>>
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>
>
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