2016 leap second

Thread Starter

nsaspook

Joined Aug 27, 2009
10,939
5, 4, 3, 2, 1, 1, -> 2017 :) Just enough time for a extra sip of that drink in 2016.

https://datacenter.iers.org/eop/-/somos/5Rgv/latest/16
INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)

SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE

SERVICE DE LA ROTATION TERRESTRE DE L'IERS
OBSERVATOIRE DE PARIS
61, Av. de l'Observatoire 75014 PARIS (France)
Tel. : +33 1 40 51 23 35
e-mail : services.iers@obspm.fr
http://hpiers.obspm.fr/eop-pc


Paris, 6 July 2016

Bulletin C 52

To authorities responsible for the measurement and distribution of time


UTC TIME STEP
on the 1st of January 2017


A positive leap second will be introduced at the end of December 2016.
The sequence of dates of the UTC second markers will be:

2016 December 31, 23h 59m 59s
2016 December 31, 23h 59m 60s
2017 January 1, 0h 0m 0s

The difference between UTC and the International Atomic Time TAI is:

from 2015 July 1, 0h UTC, to 2017 January 1 0h UTC : UTC-TAI = - 36s
from 2017 January 1, 0h UTC, until further notice : UTC-TAI = - 37s


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.


Christian Bizouard
Head
Earth Orientation Center of IERS
Observatoire de Paris, France
 

wayneh

Joined Sep 9, 2010
17,201
Care to lay odds on whether this will be mentioned during the usual "Rockin' New Year's Eve" broadcast?

On the one hand it sounds like something they'd pounce on as a time filler, but on the other hand it doesn't mesh well with a screaming crowd in Times Square.
 

RichardO

Joined May 4, 2013
2,270
Drat. I hate resetting my watch every time the earth slows down. ;)

Some trivia. A few years ago I was on a tour of NIST in Boulder, Colorado. We actually got to stand right next to NIST-F1 while one of the builders explained how it worked! At the time NIST-F1 was the time standard for the U.S. It has since been replaced by NIST-2 which is more accurate.

The time standard is only turned every 2 weeks to verify that the hydrogen maser clocks are still accurate. We were told the the maser's were typically accurate enough to go a month without re-calibrating.
 

WBahn

Joined Mar 31, 2012
28,193
Interestingly, there is no one master clock that keeps the time. At NIST there is an ensemble of roughly a dozen clocks (the number changes from time to time) and the official UTC(NIST) time is a weighted average of these clocks, with the most stable/accurate clocks getting a higher weighting. In turn, all of this data is fed to the International Bureau of Weights and Measures in France which combines the data from a total of over 300 atomic clocks around the world and performs a similar weighted-average to establish the official International Atomic Time and the derived Coordinated Universal Time.

When I was working at NIST (in a completely different division) I went down to the Time and Frequency Division's section that maintained the U.S. time keepers and, like RichardO, was surprised that it was possible to not only look through a window and see some of the actual clocks, but if you could catch on of the folks in that division you could go inside and stand right next to the thing while they described it. I asked them about that and they said that the clocks were sufficiently sturdy (they actually looked pretty fragile to me) that it was unlikely that someone could mess them up, but that it really wasn't that big a deal because even if they did it would be detected when they were next tuned and the affected clock would simply be removed from the ensemble until it has been repaired and returned to service; so the only real risk was the time and cost of repairing/recertifying the clock and it was felt that the positive public relations impact of allowing the average Joe to be able to stand right next to one of the atomic clocks outweighed that risk, especially since (at that time in 1988) a clock had yet to be messed with. I didn't know enough to ask at the time, but I suspect that the clock on display was likely the clock with the lowest weighting in the average, but perhaps not.

Post-9/11 they have significantly restricted access to NIST, but they still give guided tours. At the time I was there anyone could just walk into the building (the main building in this case) and go on their own self-guided tours.
 

Art

Joined Sep 10, 2007
806
How does theGPS receiver know what the difference is between GPS & UTC? Is that also transmitted from the satellites?
 

Thread Starter

nsaspook

Joined Aug 27, 2009
10,939
How does theGPS receiver know what the difference is between GPS & UTC? Is that also transmitted from the satellites?
GPS time is transmitted and converted to UTC in the receiver using leap second coding from the satellites that's updated from the ground stations and into the local time zone on the display usually.
GPS time is “steered” to maintain a close tie to UTC(USNO) through modulo-whole second offsets (due to leap seconds) • Via daily input of C( S O) CS f UTC(USNO) time into MCS • The Legacy (C/A) navigation message broadcast by every GPS satellite provides information to convert between GPS time and UTC(USNO) • Contains fine error corrections in GPS time and leap second data including notification of pending leap seconds data including notification of pending leap seconds
https://www.itu.int/dms_pub/itu-r/oth/0a/0e/R0A0E0000960005PDFE.pdf
 

atferrari

Joined Jan 6, 2004
4,684
When I read things like in this thread where standards are qualified as high, low or whatever by someone, the same question comes to mind: qualified comparing it against what even higher standard? Have they an absolute one?

Hope the averaging is not the standard... but just a way to range them somehow.

This morning, when waking up I felt that something was wrong. Now I know, that second I was ahead....
 

wayneh

Joined Sep 9, 2010
17,201
Well I certainly didn't watch every second of it, but I heard zero mention of a leap second when the ball dropped last night, either in New York or New Orleans.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
10,939
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