Re: [LEAPSECS] [Non-DoD Source] Re: no more listening to leap seconds?

[Matsakis, Demetrios N CIV NAVOBSY, N3TS]

Well, I can't match Tom's poetry but I note that the deregulation of 
power-line-time makes the WWV-series even more critical.  So far, though, I 
haven't seen super-large changes in the timing of the 60 Hz signals coming into 
the USNO.  Seems like there was a net 30 second drop in June.

-Original Message-
From: LEAPSECS  On Behalf Of Tom Van Baak
Sent: Friday, August 10, 2018 5:55 PM
To: Leap Second Discussion List 
Subject: [Non-DoD Source] Re: [LEAPSECS] no more listening to leap seconds?

Hi Steve,

>From what I understand the same "threat" occurred in 2017 with the FY18 
>budget. In the end, the budget ended up greater even than what was asked. So 
>no cuts were made. Who knows what will happen this time. Still, it's always a 
>concern; for the staff, for the time service, for the users. The greater issue 
>is to maintain a comprehensive national or global time dissemination system, 
>with deep and multiple levels of accuracy, redundancy, security, and 
>resiliency.

My guess is we will still be able to "hear" leap seconds -- just tune into 
Google and listen to the sound of innocent SI seconds being compressed or 
stretched to levels not seen since medieval timekeeping. The unpredictable 
clock arrest, which starts sometime around midnight, the prolonged shrieks of 
pain from the rack. The horror; the smell of leap seconds in the morning; 
Charlie don't leap.

/tvb

- Original Message - 
From: "Steve Allen" 
To: "Leap Second Discussion List" 
Sent: Friday, August 10, 2018 1:25 PM
Subject: [LEAPSECS] no more listening to leap seconds?


> This crossing over from time-nuts list, but it may mean that
> listening to leap seconds will become a thing of the past.
> If I understand this summary of the NIST budget request then
> radio stations WWV, and WWVH are set to be shut down.
> 
> https://www.nist.gov/director/fy-2019-presidential-budget-request-summary/fundamental-measurement-quantum-science-and
> 
> --
> Steve Allen  WGS-84 (GPS)
> UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
> 1156 High Street   Voice: +1 831 459 3046 Lng -122.06015
> Santa Cruz, CA 95064   http://www.ucolick.org/~sla/   Hgt +250 m
> ___
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Re: [LEAPSECS] [Non-DoD Source] D.H. Sadler in 1954

[Matsakis, Demetrios N CIV NAVOBSY, N3TS]

I was surprised to find phrases in the Lick web pages:  "CCIR ignored the 
advice that astronomers " and "squelched astronomers who insisted that leap 
seconds would cause trouble".   

I realize their author is not the only person with a strong emotional bias, but 
even so I question the tone of these web pages because they are inconsistent 
with the following:

1. There was a progression in thought as technology advanced and atomic clocks 
proved their reliability.

2. It should be obvious that ephemeris time would need a flywheel system to get 
practical time to the users, and GMT could be part of that.  Today individual 
labs realize UTC(k) for the same reason - to flywheel before the monthly 
computations of UTC are published.  WWVB, GPS, and your local cell towers are 
all part of the system as well.  (Even so, I think everyone today agrees that 
Ephemeris time was a mistake.)

3.  According to references in Nelson et al’s Metrologia article, which was 
peer-reviewed, it looks to me like the switch to UTC was by universal agreement 
among the institutions.  The IAU, URSI, CIPM(=CGPM), and CCIR(= ITU) all agreed 
to the current system in the late 60's, and I would guess that the timing of 
their resolutions probably depended more on the (generally) 3-year spacing of 
their general assemblies than anything else.  Note that many of those groups 
had overlapping membership.  It would however be unusual if all individual 
members of these bodies ever agreed to any resolution, even if passed "by 
consensus".

For more trivia, the dynamic  Gernot Winkler of the USNO was both a practical 
clock man and astronomer.  He was not the only one, and he was a very active 
member of the IAU who chaired commissions, served on working groups, etc.  He 
told me personally that he and Essen independently came up with the idea of 
leap seconds.   He also said a big reason was to win the support of the 
mariners, who in the pre-GNSS days actually did celestial navigation and who in 
the pre-internet days could not easily get access to tables that incorporated 
the difference between UT1 and UTC.



From: LEAPSECS [leapsecs-boun...@leapsecond.com] on behalf of Steve Allen 
[s...@ucolick.org]
Sent: Wednesday, March 14, 2018 12:16 AM
To: Leap Second Discussion List
Subject: [Non-DoD Source] [LEAPSECS] D.H. Sadler in 1954

In 1954 D.H. Sadler produced a monograph on the changes in time
that had been resolved at the 1952 IAU General Assembly.
His writeup is clearer than almost anything else for the next 60 years.
It was published in Occasional Notices of the RAS, and it has been hard
to find until now.
https://www.ucolick.org/~sla/leapsecs/twokindsoftime.html
This is one of the series of documents produced starting in 1948 and
proceeding through the next 20 years where astronomers explained that
two kinds of time would be needed to satisfy all applications.

--
Steve Allen  WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street   Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064   http://www.ucolick.org/~sla/   Hgt +250 m
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Re: [LEAPSECS] [Non-DoD Source] Re: new delta-T data point

[Matsakis, Demetrios N CIV NAVOBSY, N3TS]

>From the table in the reference provided by Paul Hirose's post 
>(http://astro.ukho.gov.uk/nao/lvm/) , the uncertainty in delta-T is 0.4 hours. 
> At a latitude of 31 degrees, I compute a (1-sigma) distance of 500 km, which 
>the internet tells me is about as far away as Alexandria.   Judging from the 
>eclipse trajectory as shown, it would have required a ~ 2.5-sigma deviation to 
>miss Canaan entirely, and another sigma of deviation to miss the Nile delta as 
>well, although the curvature of the plot means less and less of northern Egypt 
>would remain in the path as the visibility area moves west.   Thebes is 
>outside of the depicted path already.   I guess their sigma is reasonable, as 
>their figure 10 shows 180 seconds variation of Delta-T in modern times (since 
>1550).

But it certainly seems that if it was visible in Canaan, it should have been 
visible in the delta.

-Original Message-
From: LEAPSECS [mailto:leapsecs-boun...@leapsecond.com] On Behalf Of 
Poul-Henning Kamp
Sent: Friday, November 03, 2017 3:21 PM
To: Leap Second Discussion List; Steve Allen
Subject: [Non-DoD Source] Re: [LEAPSECS] new delta-T data point


In message <20171103173224.ga10...@ucolick.org>, Steve Allen writes:

>I'm a bit disturbed by the plotted path of that eclipse because it is 
>very wide and includes the entire Nile delta as well as modern 
>Palestine, Israel, Jordan, and Baghdad at sunset.  Unless weather 
>prevented it, somebody else should have made a record of that eclipse.

And they probably did, but it didn't survive or we havnt torn down the city 
built on top of it later.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [LEAPSECS] [Non-DoD Source] Re: new delta-T data point

[Matsakis, Demetrios N CIV NAVOBSY, N3TS]

The quote below (from biblegateway.com) may imply a meteor shower also took a 
toll on their adversaries.Perhaps someone should scan the area for 
meteorites suitably below ground?

...   having marched all night from Gilgal.  10 So the Lord routed them before 
Israel, killed them with a great slaughter at Gibeon, chased them along the 
road that goes to Beth Horon, and struck them down as far as Azekah and 
Makkedah.  11 And it happened, as they fled before Israel and were on the 
descent of Beth Horon, that the Lord cast down large hailstones from heaven on 
them as far as Azekah, and they died. There were more who died from the 
hailstones than the children of Israel killed with the sword.

12 Then Joshua spoke to the Lord in the day when the Lord delivered up the 
Amorites before the children of Israel, and he said in the sight of Israel:


"Sun, stand still over Gibeon;
And Moon, in the Valley of Aijalon."

13 
So the sun stood still,
And the moon stopped,
Till the people had revenge
Upon their enemies.

Is this not written in the Book of Jasher? So the sun stood still in the midst 
of heaven, and did not hasten to go down for about a whole day.  14 And there 
has been no day like that, before it or after it, that the Lord heeded the 
voice of a man; for the Lord fought for Israel.


-Original Message-
From: LEAPSECS [mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Steve Allen
Sent: Friday, November 03, 2017 1:32 PM
To: Leap Second Discussion List
Subject: [Non-DoD Source] Re: [LEAPSECS] new delta-T data point

On Mon 2017-10-30T16:23:57-0700 Tom Van Baak hath writ:
> In the news...
>
> https://academic.oup.com/astrogeo/article/58/5/5.39/4159289/Solar-ecli
> pse-of-1207-BC-helps-to-date ( 
> https://academic.oup.com/astrogeo/article-pdf/58/5/5.39/20098470/atx17
> 8.pdf )

Alas for Delta T on date -1206 October 30, that annular eclipse moves almost 
entirely along a parallel of latitude, so Delta T pretty much only affects the 
endpoint where the eclipse happened at sunset.

I'm a bit disturbed by the plotted path of that eclipse because it is very wide 
and includes the entire Nile delta as well as modern Palestine, Israel, Jordan, 
and Baghdad at sunset.  Unless weather prevented it, somebody else should have 
made a record of that eclipse.

--
Steve Allen  WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street   Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064   http://www.ucolick.org/~sla/   Hgt +250 m
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Re: [LEAPSECS] [Non-DoD Source] midyear leap roundup

[Matsakis, Demetrios]

I'm surprised nobody reacted to some of the things in Steve's email.  It's 
probably because 8 years is a long time (7 now).

With regards to the last paragraph, the support for Steve's inference seems 
rather weak.   I feel an obligation to point out that as far as I have seen my 
employer, the U.S. Government, isn't the kind to "hold grudges" on these 
matters .  I suggest that with regards to the governments that supported Method 
D (more study), the U.S. State Department might be more interested in working 
with them on the War on Terror than in holding a grudge on a moot point. 

Also, the US position was to support Method A, not to abolish leap seconds 
immediately.If it had been accepted as-is at WRC-15, there would have been 
a little over five year's notice.  However the WRC could have made it longer if 
it so desired.


-Original Message-
From: LEAPSECS [mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Steve Allen
Sent: Saturday, June 18, 2016 12:52 AM
To: Leap Second Discussion List
Subject: [Non-DoD Source] [LEAPSECS] midyear leap roundup

Last week saw the Science of Time symposium at Harvard with many of the Time 
Lords in attendance.  The subject matter was far broader than just leap 
seconds, but it gave a glimpse into the situation after last year's ITU-R 
WRC-15 meeting.

For 15 years the subject of leap seconds had been ITU-R Question 236/7, and 
that is no longer open.  So the ITU-R has no action to perform until the 2023 
WRC.  Folks at Science of Time indicated that actions other than in the ITU-R 
had to wait until that process had failed.

In the mean time the BIPM expects to produce a document that (unlike ITU-R 
TF.460) actually defines the construction of a time scale.  It makes sense that 
we should be able to see that years in advance of the
2023 WRC.

Looking back, leading up to the WRC had been various Conference Preparatory 
Meetings (CPM) that produced the draft document with the methods for dealing 
with leap seconds (A, B, C, and, much later, D) to be submitted to WRC-15.  
During a several month period leading up to that document the logs for leap 
second web pages showed a two-week periodicity with thousands of HTTP GETs 
being funnelled through a weblog hosted on a server accessible via a VPN.  That 
seemed to confirm that the ITU-R process operates in a very closed fashion.  We 
can hope that from now on the process will be more open.

Subsequent to the WRC-15 meeting the web logs have indicated etentes between 
the US and the countries who submitted method D (which said "make no change") 
to the WRC-15.  I surmise that the Department of State holds a grudge against 
any country which dared to oppose the "abolish leap seconds immediately" 
position of the US.

--
Steve Allen  WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street   Voice: +1 831 459 3046 Lng -122.06015
Santa Cruz, CA 95064   http://www.ucolick.org/~sla/   Hgt +250 m
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[LEAPSECS] Ton Van Baak on PBS tonight!

[Matsakis, Demetrios]

Look for a TV show on National Geographic or PBS called "Genius by Stephen 
Hawking". Episode 1: Can We Time Travel?

It is at 9 PM in Washington DC

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[LEAPSECS] Dr. Gernot Winkler

[Matsakis, Demetrios]

Dr. Gernot Winkler passed on April 30.   To this list he is well-known as the 
person who, along with Dr. Essen of NPL. initiated the current system of leap 
seconds in UTC.  To us in the U.S. Naval Observatory's Time Service Department, 
Gernot was an inspiring leader in every way.  A strong and supportive manager, 
aided by his Von-Braun accent, he always encouraged us to do our best.  One of 
his favorite techniques was to praise someone behind his back about something 
very specific, because he knew the word would get to him.   He would follow our 
progress, and would welcome us into his small, densely-packed but 
well-organized office to talk to us about it.

As a role-model  he was an intellectual giant who was happy to share.  I 
learned timekeeping from his technical review articles, and very much enjoyed 
learning philosophy from his almost-as-technical essays on not just the nature 
of time but of such things as deism, determinism, realism, subjectivism, 
monism, positivism, etc. Very recently I even downloaded a table from his 
website (http://gmrwinkler.net/­), for a viewgraph on whether the future exists.

I still don’t know if there is a future, but I’m pretty sure there was a past 
because when Gernot was running Time Service, which then included what is now 
the Earth Orientation department, he would ensure that everything worked.   In 
fact, a few years ago I told him that it seemed like under his watch everything 
went smoothly.  He gave me a funny look, and replied that every minute of every 
day was a struggle.And it’s good he was struggling – because the department 
and the USNO grew and prospered with him.   One of his achievements, for 
example, was to convince the Air Force to use Navy clocks to determine GPS 
time. Another was funding and assistance for all kinds of innovations, such 
as masers, VLBI for Earth Orientation measurements, and TWSTT.

Gernot came a long way from where he grew up in Austria.  To the end he was 
intellectually vibrant, following the latest developments in science and 
society.   But I wouldn’t expect anything less from a draftee who had the 
courage to apply the German army’s own rules to trap a Nazi general in a 
cable-car over the Alps, and more importantly had the ability to do this and 
survive.

His final good-bye is attached, along with an email from his son Victor.



Friends

It is with deep sadness that I am writing to you. This past Saturday (April 30, 
2016) at 2:45AM, our father Gernot Winkler passed away in his home. My sister 
Trixi and I were with him. I have never felt this kind of grief before, but it 
is really a testament to the kind of person who my father was: I could not have 
done better.

My father was born 17 October 1922 in Frohnleiten Austria. He and my mother 
were married in 1952. My sister and I were very fortunate to have them as 
parents. My mother Renate passed away on 31 March 2014, my father never stopped 
missing mom. In the two years since then, he was in failing health but he 
insisted on continuing to live in his house. He, my sister and I all were 
clear-headed about the situation, and collectively we made it work for dad. He 
last drove his car in January 2016, and since then his decline accelerated.

Please join me in having either an egg salad or tuna sandwich for lunch 
...Gernot loved his tuna fish and egg salad.

The most important point in this email is the enclosure, which dad wrote and 
revised over many many years.

Please feel free to contact myself or my sister Trixi. I am sorry if this news 
finds a roundabout path to you, but that’s just the circumstances of this 
period.

Peace.

Vic Winkler
Trixi (Winkler) Summers

v...@vicwinkler.com   (703) 622 7111
trixisumm...@gmail.com


GoodbyFromGMRW.pdf
Description: GoodbyFromGMRW.pdf
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Re: [LEAPSECS] The leap second, deep space and how we keep time -Brooks

[Matsakis, Demetrios]

Oops - I was referring to the predictions.Of course, any  group of people 
will have disagreements about all kinds of things, and that can be healthy.   
But I am not aware of anyone disagreeing with me on that one point.   

-Original Message-
From: LEAPSECS [mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Greg 
Hennessy
Sent: Wednesday, January 28, 2015 4:50 PM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] The leap second, deep space and how we keep time -Brooks

On 01/28/2015 01:42 PM, Matsakis, Demetrios wrote:
 To Steve mostly,

 It would be misleading to reference the comment in Wall Street Journal 
 article, because people might conclude that staff at the USNO
 disagree among themselves.   This is not the case, at least this
 time.

Are you sure the USNO staff don't disagree among themselves? :) I think some of 
them like arguing. :) :)

Greg

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Re: [LEAPSECS] The leap second, deep space and how we keep time -Brooks

[Matsakis, Demetrios]

The marketplace.org article quotes Bob Tjoelker as saying his team, and 
deep-space missions in general, can handle leap seconds.   I've known Bob 
Tjoelker for years.   He's a super-scientist designing super-clocks.  Since 
some of those clocks are space-qualified, he is literally a rocket scientist.   
But it should also be noted that the marketplace.org article did not point out 
that most of us are not at his level.   Also, they chose not to quote him about 
concerns he expressed about other systems.

As an example, last week some GPS receivers (of different models) apparently 
implemented the coming leap second as soon as GPS  began broadcasting its 
leapsecond-pending flag.  While their jumps could have been due to something 
else, and the receivers did not jump with the last leap second, the coincidence 
raises strong suspicions that the receivers were misprogrammed.This failure 
was discovered because the receivers' associated NTP servers gave out the wrong 
time.  For reference see 
http://lists.ntp.org/pipermail/pool/2015-January/007272.html.

Equally unfortunate is that 30 servers in the NTP pool inserted a leap second 
last Dec 31.  Even if a DNS-based reference helps with some of these issues, 
there would remain a host of other opportunities for failure, such as systems 
mis-programmed so they insert leap seconds after 23:59:59 local time instead of 
UTC.

As always these are my personal opinions, and not those of my employer or the 
US Government.   In that sense I note that NASA is very good at proactively 
preventing mistakes, and I suspect this consideration contributed to its 
anti-leapsecond position, which itself contributed the American government's 
decision to support the proposal calling for the elimination of future leap 
seconds after the suitable waiting period.

-Original Message-
From: LEAPSECS [mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Brooks 
Harris
Sent: Sunday, January 25, 2015 11:35 AM
To: Leap Second Discussion List
Subject: [LEAPSECS] The leap second, deep space and how we keep time -Brooks

The leap second, deep space and how we keep time 
http://www.marketplace.org/topics/world/leap-second-deep-space-and-how-we-keep-time

Much less stupid than many popular reports...

-Brooks
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[LEAPSECS] Comments on predictions for this century

[Matsakis, Demetrios]

Tom,

I don't have any special predictive insights, but when I look at the data 
things appear to be fairly flat.Although the length of day (LOD) has 
dropped below 86400 in the recent summers, it didn't last year.   As my 
viewgraphs indicate, the best predictor for this kind of variation  is that the 
LOD will increase by the recent historical tidal amount from where it has 
been over the last few years - not from where 20th century models had predicted 
it to be at this time.  The LOD could just as easily increase or decrease from 
that baseline.   There is a common belief (not your belief) that after a 
decadal fluctuation the Earth will rapidly slow down or speed up to catch up 
in its rotation angle.  But that's not how it works.   If a pendulum is made to 
suddenly turn slower, say by changing its length, it will simply go back to its 
old rate once its length is restored.  It won't try to catch up its 
phase/position to where it would have been.  Another way to put it is that the 
physi
 cs is in the motion of the Earth, not in its rotational position/angle.  

Poul-Henning, 

I think you are on the right track with the sea level computations.   The 
Chapanov and Gambis paper agrees that the melting of ice is very important, 
although they find thermal expansion of the seawater to be fairly negligible.  
As you and many on this listserve know, the picture is complicated because as 
the glacial ice melts, the arctic land masses bear less weight.  So over 
centuries the Earth's magna pushes them up , leading to glacial rebound.   The 
matter pushing them up is coming from just below, but it in turn is replenished 
by magna from below the equatorial areas - so that the Earth gets rounder and 
therefore speeds up just like a twirling ballerina does when she brings in her 
arms.   So while the Earth is being slowed by the redistribution of water from 
arctic to ocean,  it is being sped up by the motion of much heavier material 
from the equator.   At least that's the hand-waiving argument for 
less-than-expected long-term LOD increase.   I am unaware of any authoritative c
 omputations about whether the very recent rotational speed-up is due to what 
is loosely called global warming or if it is a classical decadal fluctuation 
related to the motion of the Earth's core.   Also of interest might be changes 
in the net velocity of the upper atmosphere winds - the December 2014 
Scientific American had an interesting article about the effects of the jet 
stream on the weather over the last few years.I'm not the authority here.

Steve,

I have pasted your  email at the very end of this one.  It's a shame that in 
this regard your extensive and lovingly worked-out web pages may spread 
disinformation.You are right that predictions are hard when they are about 
the future.But if you really feel the need to show those models, perhaps 
you could add a prominent note indicating that they are all wrong about the 
near future - and that one reasonable analysis predicts that the effect would 
be  1 minute by 2100.   Unfortunately, my finding is too trivial to put in a 
refereed journal, and yes, I too could be wrong either way. 

All,

Let me apologize if I have talked down to many of you.And by the way, the 
opinions and ideas expressed here are my own and not necessarily those of my 
employer or the US government.

-Original Message-
From: LEAPSECS [mailto:leapsecs-boun...@leapsecond.com] On Behalf Of 
leapsecs-requ...@leapsecond.com
Sent: Thursday, January 15, 2015 6:58 AM
To: leapsecs@leapsecond.com
Subject: LEAPSECS Digest, Vol 100, Issue 13

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Today's Topics:

   1. Re: This year's Y2K: 'Leap second' threatens to breakthe
  Internet -Brooks (Tom Van Baak)


--

Message: 1
Date: Thu, 15 Jan 2015 03:57:57 -0800
From: Tom Van Baak t...@leapsecond.com
To: Leap Second Discussion List leapsecs@leapsecond.com
Subject: Re: [LEAPSECS] This year's Y2K: 'Leap second' threatens to
breaktheInternet -Brooks
Message-ID: 7826ACEC0E984E7ABB0DDEBC018E8A76@pc52
Content-Type: text/plain; charset=iso-8859-1

Poul-Henning Kamp writes:
 That reminds me, has anybody tried to do the math on climate change ?
 
 The main effect is (probably?) going to be the thermal expansion of 
 the worlds oceans.
 
 I did a quick back of the envelope calculation modeling the earth as a 
 sphere radius 6367 km, covered by a 4 km thick shell of water.
 
 

[LEAPSECS] Changing the name of UTC

[Matsakis, Demetrios]

With regards to Gerard's question (below), I think the answer is that his 
timescale is one of a large class of possible timescales that could be given 
any name desired as soon as anybody had a use for it.   It would be trivial to 
compute the calendar dates he talks about of course,  but it's not clear to me 
who would care about such a timescale.Pulsar astronomers, for example, 
would not use it.   To reduce observations with the best precise time 
available, they want Terrestrial Time (TT), which is computed by the BIPM as a 
time series in the form TT-UTC.   No matter what is done with UTC, astronomers 
who need the precision should use the BIPM tables to take care of not just leap 
seconds but certain more subtle corrections to UTC.   On the other hand, what 
is needed by lawyers, insurance companies, historians, etc. is the calendar 
date and appropriate legal time associated with the events of interest - they 
wouldn't care about SI seconds.

I'd like to take the opportunity to ask this crowd what they think of the 
statements below:

1. Those who are in favor of UTC redefinition currently oppose the name change 
(emphasis on currently)

2. Those who are against UTC redefinition insist that the name should be 
changed.

3. There is no one who says he/she would support UTC redefinition, but ONLY IF 
the name is also changed.

Are there any significant exceptions to this generalization?I was told by a 
British source that a certain stakeholder had indicated he did not care 
either way about the redefinition, but if a redefinition were to occur this 
stakeholder thought the name should be changed.   I believe this story, but it 
is a fact that these sources are working under very strict constraints set by 
their bosses in the UK government, with very close oversight by the same.

I have also observed the cases wherein webmasters are believed to be opposed 
the redefinition have not corrected errors on their web pages even when they 
are aware of them.I'm unaware of web pages put up by groups in favor of the 
redefinition, but if anyone knows of such omissions on the pro-redefinition 
side I'd be curious and maybe could use my influence to correct.   I'm not 
interested in minor errors, but in errors of fact that are either significant 
in themselves or which as presented allow misinterpretation by others. 

Back to the name change, a list of arguments each way is below.   Pro means in 
favor of a name change.   Have I missed any arguments?

Pro: Keeping the name UTC would cause confusion.

Con: Keeping the name UTC would reduce confusion.

Pro: UTC would be ambiguous if the name were kept, because UT1-UTC would be 
unbounded.

Con: UTC would be still be uniquely defined if the name were kept.   That's 
because integrated step function is well defined, and UT1-UTC  would be 
something like that.

Pro: A presentation from a representative of the appropriate committee of the 
International Standards Organization says the name should be changed.

Con: The ISO has 290 committees, which people frequently disagree with and are 
not bound to follow.  In this case the advisory opinion goes against the 
standard metrological practice of not changing names.  The best example is UTC 
itself when  frequency steers to UT1 were eliminated.   Also the meter, which 
went from a physical meter bar in Paris to the product of the speed of light 
with the SI second.  And the kg, which is about to be redefined but no one is 
suggesting a name change.  Another example where changing the name would have 
caused confusion is the 2006 redefinition of the term planet. 

Special Con: GMT was redefined in 1925 with a 12 hour shift so the day would 
change at midnight instead of noon, with no name change.   Although the GMT 
redefinition did lead to some confusion, there is no way the UK would have 
considered abandoning the name GMT.

Pro's answer to special CON: The Universal Times were set up several years 
later, partly in response to the GMT shift (I don't know the details). 

Pro: Universal in UTC means rotation of the Earth (as in UT0, UT1, and UT2)

Con: Universal in UTC means universally used (as are the numerical UT's by the 
way)

Pro's answer to CON: Universal was meant to mean rotation at the time the name 
was selected

Con's reply to Pro's answer to CON: The two ideas were not contradictory back 
then, given that the C in UTC means coordinated between laboratories.   
Therefore even written descriptions, if they exist and support the PRO 
arguments, would not be relevant.

P.S. I only receive daily digests, so I apologize if someone sent an email 
today that I seem to be ignoring.

-Original Message-

Message: 2
Date: Wed, 15 Oct 2014 11:20:35 -0400
From: Gerard Ashton ashto...@comcast.net
To: 'Leap Second Discussion List' leapsecs@leapsecond.com
Subject: [LEAPSECS] Name of proleptic leap-secondless UTC
Message-ID: 000e01cfe88b$91c99880$b55cc980$@comcast.net
Content-Type: text/plain;   

Re: [LEAPSECS] Earth speeding up?

[Matsakis, Demetrios]

Indeed, Greenland is a textbook case of glacial rebound.   As its ice cap has 
been melting away, the land mass has been noticeably rising.

-Original Message-
From: Poul-Henning Kamp [mailto:p...@phk.freebsd.dk] 
Sent: Tuesday, April 15, 2014 11:41 AM
To: Leap Second Discussion List; Matsakis, Demetrios
Subject: Re: [LEAPSECS] Earth speeding up?

In message e517a9af6a49aa479d731ec5f891c0bbfe81d...@echo.usno.navy.mil, Mats 
akis, Demetrios writes:

The best hand-waiving arguments I've heard for these recent decadal 
fluctuations is that the oblateness of the Earth is changing, possibly 
due to the ice caps changing.

Well, I'd somewhat doubt that.

The Arctic is sea-ice, so no net change in gravity or weight there.

Antartica ?   Probably not.  Our measurements of ice volume would
have to be spectacularly wrong, in which case we will soon have other and much 
more pressing problems than leap seconds.

But Greenland might be relevant, it's close to the pole, significantly 
assymetrical, and loosing a lot of mass (far too) quickly.

But again, I have a hard time coming up with a purely geometrical effect, given 
what we know about the ice volume in play.

A more likely explanation would an effect on the mantel-core interface under 
Greenland, which would make it anybodys guess what will happen.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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[LEAPSECS] Real April Fools' Joke: GMT Abolished

[Matsakis, Demetrios]

http://www.timeanddate.com/news/time/paris-meridian-gmt-obsolete.html

-Original Message-
From: leapsecs-boun...@leapsecond.com [mailto:leapsecs-boun...@leapsecond.com] 
On Behalf Of leapsecs-requ...@leapsecond.com
Sent: Thursday, April 03, 2014 12:01 PM
To: leapsecs@leapsecond.com
Subject: LEAPSECS Digest, Vol 91, Issue 1

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Contents of LEAPSECS digest...


Today's Topics:

   1. Forgetting summer time (David Malone)
   2. Re: Forgetting summer time (Rob Seaman)
   3. Re: Forgetting summer time (Poul-Henning Kamp)
   4. Re: Forgetting summer time (David Malone)


--

Message: 1
Date: Wed, 2 Apr 2014 22:35:19 +0100
From: David Malone dwmal...@maths.tcd.ie
Subject: [LEAPSECS] Forgetting summer time
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 20140402213519.ga38...@walton.maths.tcd.ie
Content-Type: text/plain; charset=us-ascii

I've only seen this reported in the UK news, and not Ireland apocryphal, but 
it's a good story:


http://www.telegraph.co.uk/news/worldnews/europe/ireland/10739277/Device-exploded-in-bombers-face-after-he-forgot-about-clocks-changing.html

David.


--

Message: 2
Date: Wed, 2 Apr 2014 15:50:19 -0700
From: Rob Seaman sea...@noao.edu
Subject: Re: [LEAPSECS] Forgetting summer time
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 83de3f3b-ec2a-4010-a903-f38dae919...@noao.edu
Content-Type: text/plain; charset=us-ascii

On Apr 2, 2014, at 2:35 PM, David Malone dwmal...@maths.tcd.ie wrote:

 I've only seen this reported in the UK news, and not Ireland 
 apocryphal, but it's a good story:
 
   
 http://www.telegraph.co.uk/news/worldnews/europe/ireland/10739277/Devi
 ce-exploded-in-bombers-face-after-he-forgot-about-clocks-changing.html

More than a little suspicious of the April 1 date...

...but going along as a hypothetical, do we understand what the police's theory 
would be?  It sounds like they are saying the bomb went off at the time 
specified, but the bomber had failed to leave the area because his watch 
remained set an hour behind the new local time?

This assumes that the bomb was triggered by a timekeeping device.  Fair enough 
I suppose (having remarkably little expertise in this area).  Such a device is 
either a countdown timer or an alarm clock.  (At least in the movies.)  If the 
former it isn't obvious why the change to summer time would matter as long as 
the bomber was self consistent.  If the latter I guess the thought is that the 
alarm clock was itself of the kind that automatically resets to summer time?  
(In the U.S. these are annoyingly called atomic clocks.  What do they call 
them in the UK?)  In any event, there is nothing in the report or the various 
echoes on the web to suggest any evidence of this.

So if not a joke (in poor taste) escaped into the wild, perhaps this is just a 
naive assumption due to happening on the date of such a transition?  Are there 
other examples of such stories?  Aside from millions of variations of getting 
to work an hour late?

Rob



--

Message: 3
Date: Thu, 03 Apr 2014 06:01:01 +
From: Poul-Henning Kamp p...@phk.freebsd.dk
Subject: Re: [LEAPSECS] Forgetting summer time
To: Leap Second Discussion List leapsecs@leapsecond.com,  Rob Seaman
sea...@noao.edu
Message-ID: 93191.1396504...@critter.freebsd.dk
Content-Type: text/plain; charset=ISO-8859-1

In message 83de3f3b-ec2a-4010-a903-f38dae919...@noao.edu, Rob Seaman writes:

This assumes that the bomb was triggered by a timekeeping device.  
[...]

A surprisingly popular choice is old mobile phones without SIM card:

Usually you can still use the alarm function, and there is good drive current 
to the vibrator motor.

The missing SIM card would be the key here:  Without that the phone doesn't set 
its clock from the  network.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.


--

Message: 4
Date: Thu, 3 Apr 2014 08:59:12 +0100
From: David Malone dwmal...@maths.tcd.ie
Subject: Re: [LEAPSECS] Forgetting summer time
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 20140403075912.ga57...@walton.maths.tcd.ie
Content-Type: text/plain; charset=us-ascii

On Wed, Apr 02, 2014 at 03:50:19PM -0700, Rob Seaman wrote:
 

[LEAPSECS] Daylight Time snafus

[Matsakis, Demetrios]

Sometimes it doesn't matter how much notice is given.  This morning I got an 
email from someone asking why his clock just jumped to daylight time.I've 
had many emails from people whose clocks incorporate a change late, which could 
be due to radio reception problems among other things.   I've also gotten some 
from people whose clocks are pre-programmed with the old American daylight time 
rules, or European ones.   But this is a first for early daylight.

As always programming errors are the default guess.   Last leap year we even 
suspected one product had an issue related to February 29.  Only the 
manufacturers know for sure.



Message: 2
Date: Mon, 24 Feb 2014 06:09:17 -0700
From: Rob Seaman sea...@noao.edu
Subject: [LEAPSECS] Short notice for DST changes
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 777b74ea-dbef-429a-bac9-15524b06f...@noao.edu
Content-Type: text/plain; charset=us-ascii

For five years running the Chilean government has provided very short notice of 
changes to the local daylight saving time rules.  This year only 2.5 weeks 
advance notice (shifting off DST was scheduled for March 8):
  
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Re: [LEAPSECS] LEAPSECS Digest, Vol 88, Issue 31

[Matsakis, Demetrios]

Not my issue, but the last day of the 20th century is technically December 31, 
2000.I wish it weren't.   When this controversy passed  in 1701, Isaac 
Newton is quoted has having rejoiced that the issue was finally behind us.

Also, I would add November 18, 1858 as the first day in the Modified Julian 
Date system, although  MJD was not introduced until much later.

Apologies if this email comes out of sequence - I am only signed up for daily 
batches.

-Original Message-
From: leapsecs-boun...@leapsecond.com [mailto:leapsecs-boun...@leapsecond.com] 
On Behalf Of leapsecs-requ...@leapsecond.com
Sent: Tuesday, January 14, 2014 5:34 AM
To: leapsecs@leapsecond.com
Subject: LEAPSECS Digest, Vol 88, Issue 31

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When replying, please edit your Subject line so it is more specific than Re: 
Contents of LEAPSECS digest...


Today's Topics:

   1. Re: presentations from AAS Future of Time sessions
  (Michael Deckers)
   2. Re: presentations from AAS Future of Time sessions (Brooks Harris)
   3. Re: presentations from AAS Future of Time sessions
  (John Hawkinson)
   4. Re: presentations from AAS Future of Time sessions (Rob Seaman)
   5. Re: presentations from AAS Future of Time sessions (Zefram)


--

Message: 1
Date: Mon, 13 Jan 2014 17:29:00 +
From: Michael Deckers michael.deck...@yahoo.com
Subject: Re: [LEAPSECS] presentations from AAS Future of Time sessions
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 52d4225c.2050...@yahoo.com
Content-Type: text/plain; charset=UTF-8; format=flowed


   On 2014-01-12 03:28, Brooks Harris quoted from RFC 5905:

 Then, and very importantly,  Figure 4: Interesting Historic NTP Dates 
 states the relationship to First day UNIX -

  +-++-+---+--+
  | Date| MJD| NTP | NTP Timestamp | Epoch|
  | || Era | Era Offset|  |
  +-++-+---+--+
  | 1 Jan -4712 | -2,400,001 | -49 | 1,795,583,104 | 1st day Julian   |
  | 1 Jan -1| -679,306   | -14 | 139,775,744   | 2 BCE|
  | 1 Jan 0 | -678,491   | -14 | 171,311,744   | 1 BCE|
  | 1 Jan 1 | -678,575   | -14 | 202,939,144   | 1 CE |
  | 4 Oct 1582  | -100,851   | -3  | 2,873,647,488 | Last day Julian  |
  | 15 Oct 1582 | -100,840   | -3  | 2,874,597,888 | First day|
  | || |   | Gregorian|
  | 31 Dec 1899 | 15019  | -1  | 4,294,880,896 | Last day NTP Era |
  | || |   | -1   |
  | 1 Jan 1900  | 15020  | 0   | 0 | First day NTP|
  | || |   | Era 0|
  | 1 Jan 1970  | 40,587 | 0   | 2,208,988,800 | First day UNIX   |
  | 1 Jan 1972  | 41,317 | 0   | 2,272,060,800 | First day UTC|
  | 31 Dec 1999 | 51,543 | 0   | 3,155,587,200 | Last day 20th|
  | || |   | Century  |
  | 8 Feb 2036  | 64,731 | 1   | 63,104| First day NTP|
  | || |   | Era 1|
  +-++-+---+--+

   Please note that this table has to be read with caution.

   Besides the typo -678,491 for -678,941, one has to realize that
   1 Jan -4712 is meant as a date in the Julian calendar, but
   all the other dates in column 1 must be taken as Gregorian calendar
   dates, even those before 1582-10-15 -- else the entries in
   columns 2,3,4 become incorrect. And this makes the entry
   in column 5 for the date 1582-10-04 incorrect.

   Michael Deckers.



--

Message: 2
Date: Mon, 13 Jan 2014 10:37:28 -0800
From: Brooks Harris bro...@edlmax.com
Subject: Re: [LEAPSECS] presentations from AAS Future of Time sessions
To: leapsecs@leapsecond.com
Message-ID: 52d43268.70...@edlmax.com
Content-Type: text/plain; charset=iso-8859-1; Format=flowed

On 2014-01-13 09:29 AM, Michael Deckers wrote:

   On 2014-01-12 03:28, Brooks Harris quoted from RFC 5905:

 Then, and very importantly,  Figure 4: Interesting Historic NTP Dates 
 states the relationship to First day UNIX -

  +-++-+---+--+
  | Date| MJD| NTP | NTP Timestamp | Epoch|
  | || Era | Era Offset |  |
  

Re: [LEAPSECS] LEAPSECS Digest, Vol 72, Issue 3

[Matsakis, Demetrios]

Rumors that the USNO tried to insert a leap decade as an experiment are not 
exactly correct.  See the message in http://tycho.usno.navy.mil/ntp.html.  One 
of the 50-odd emails we got indicated that it would take working all night to 
undo the damage.  A few responded that it was a good lesson for them - they 
would now configure their NTP to get time from multiple sources for 
error-checking.

I'm not sure if there is a moral for this listserve.We all know that 
equipment can break, and humans can make mistakes.

Those who are against leap seconds will say that this is yet another example 
showing that even so-called experts can make mistakes, so we should KISS-away 
all potential programming hazards.

Those who support keeping leap seconds will say that if the world can survive a 
12-year rollback, how could one measly second make a difference?

And I suppose many on this list will have even more to say ...



From: leapsecs-boun...@leapsecond.com [leapsecs-boun...@leapsecond.com] on 
behalf of leapsecs-requ...@leapsecond.com [leapsecs-requ...@leapsecond.com]
Sent: Wednesday, November 21, 2012 12:00 PM
To: leapsecs@leapsecond.com
Subject: LEAPSECS Digest, Vol 72, Issue 3

Send LEAPSECS mailing list submissions to
leapsecs@leapsecond.com

To subscribe or unsubscribe via the World Wide Web, visit
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You can reach the person managing the list at
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When replying, please edit your Subject line so it is more specific
than Re: Contents of LEAPSECS digest...


Today's Topics:

   1. yesterday USNO said it was year 2000 (Steve Allen)
   2. Re: yesterday USNO said it was year 2000 (David Malone)


--

Message: 1
Date: Tue, 20 Nov 2012 09:46:48 -0800
From: Steve Allen s...@ucolick.org
Subject: [LEAPSECS] yesterday USNO said it was year 2000
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 20121120174647.gb4...@ucolick.org
Content-Type: text/plain; charset=us-ascii

Various messages in admin support forums are indicating fallout
from the event recorded here
http://mailman.nanog.org/pipermail/nanog/2012-November/053449.html
wherein the USNO's NTP servers tick and tock briefly jumped 12 years
into the past.

--
Steve Allen s...@ucolick.orgWGS-84 (GPS)
UCO/Lick Observatory--ISB   Natural Sciences II, Room 165Lat  +36.99855
1156 High StreetVoice: +1 831 459 3046   Lng -122.06015
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


--

Message: 2
Date: Wed, 21 Nov 2012 11:20:27 +
From: David Malone dwmal...@maths.tcd.ie
Subject: Re: [LEAPSECS] yesterday USNO said it was year 2000
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 20121121112028.571fa73...@walton.maths.tcd.ie

 Various messages in admin support forums are indicating fallout
 from the event recorded here
 http://mailman.nanog.org/pipermail/nanog/2012-November/053449.html
 wherein the USNO's NTP servers tick and tock briefly jumped 12 years
 into the past.

Not just that, but Android 4.2 doesn't know about December:

http://www.pcmag.com/article2/0,2817,2412287,00.asp

David.


--

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End of LEAPSECS Digest, Vol 72, Issue 3
***
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Re: [LEAPSECS] LEAPSECS Digest, Vol 72, Issue 3

[Matsakis, Demetrios]

Rumors that the USNO tried to insert a leap decade as an experiment are not 
exactly correct.  See the message in http://tycho.usno.navy.mil/ntp.html.  One 
of the 50-odd emails we got indicated that it would take working all night to 
undo the damage.  A few responded that it was a good lesson for them - they 
would now configure their NTP to get time from multiple sources for 
error-checking.

I'm not sure if there is a moral for this listserve.We all know that 
equipment can break, and humans can make mistakes.

Those who are against leap seconds will say that this is yet another example 
showing that even so-called experts can make mistakes, so we should KISS-away 
all potential programming hazards.

Those who support keeping leap seconds will say that if the world can survive a 
12-year rollback, how could one measly second make a difference?

And I suppose many on this list will have even more to say.



From: leapsecs-boun...@leapsecond.com [leapsecs-boun...@leapsecond.com] on 
behalf of leapsecs-requ...@leapsecond.com [leapsecs-requ...@leapsecond.com]
Sent: Wednesday, November 21, 2012 12:00 PM
To: leapsecs@leapsecond.com
Subject: LEAPSECS Digest, Vol 72, Issue 3

Send LEAPSECS mailing list submissions to
leapsecs@leapsecond.com

To subscribe or unsubscribe via the World Wide Web, visit
http://six.pairlist.net/mailman/listinfo/leapsecs
or, via email, send a message with subject or body 'help' to
leapsecs-requ...@leapsecond.com

You can reach the person managing the list at
leapsecs-ow...@leapsecond.com

When replying, please edit your Subject line so it is more specific
than Re: Contents of LEAPSECS digest...


Today's Topics:

   1. yesterday USNO said it was year 2000 (Steve Allen)
   2. Re: yesterday USNO said it was year 2000 (David Malone)


--

Message: 1
Date: Tue, 20 Nov 2012 09:46:48 -0800
From: Steve Allen s...@ucolick.org
Subject: [LEAPSECS] yesterday USNO said it was year 2000
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 20121120174647.gb4...@ucolick.org
Content-Type: text/plain; charset=us-ascii

Various messages in admin support forums are indicating fallout
from the event recorded here
http://mailman.nanog.org/pipermail/nanog/2012-November/053449.html
wherein the USNO's NTP servers tick and tock briefly jumped 12 years
into the past.

--
Steve Allen s...@ucolick.orgWGS-84 (GPS)
UCO/Lick Observatory--ISB   Natural Sciences II, Room 165Lat  +36.99855
1156 High StreetVoice: +1 831 459 3046   Lng -122.06015
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


--

Message: 2
Date: Wed, 21 Nov 2012 11:20:27 +
From: David Malone dwmal...@maths.tcd.ie
Subject: Re: [LEAPSECS] yesterday USNO said it was year 2000
To: Leap Second Discussion List leapsecs@leapsecond.com
Message-ID: 20121121112028.571fa73...@walton.maths.tcd.ie

 Various messages in admin support forums are indicating fallout
 from the event recorded here
 http://mailman.nanog.org/pipermail/nanog/2012-November/053449.html
 wherein the USNO's NTP servers tick and tock briefly jumped 12 years
 into the past.

Not just that, but Android 4.2 doesn't know about December:

http://www.pcmag.com/article2/0,2817,2412287,00.asp

David.


--

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End of LEAPSECS Digest, Vol 72, Issue 3
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Re: [LEAPSECS] Two clocks are better than one

[Matsakis, Demetrios]

Although I believe I included amateur astronomer concerns uncritically
in my URSI report on the leap seconds, I have always wondered how many
astronomers who are at the level of needing to correct for UT1 would not
be competent to do so.   I would guess that most would consider doing so
part of the fun.After all, there is a horologist in everyone who is
technically advanced.

-Original Message-
From: leapsecs-boun...@leapsecond.com
[mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Rob Seaman
Sent: Wednesday, April 13, 2011 2:40 PM
To: Leap Second Discussion List
Subject: [LEAPSECS] Two clocks are better than one


 I agree they are unware of the discussion. Nor will they be affected
by the discussion.

This is a rather smug assertion.  What about, for instance, *amateur*
astronomers?  These are likely the most prevalent citizen scientists on
the planet - perhaps hundreds of thousands or millions of backyard
astronomers for each basement horologist.


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Re: [LEAPSECS] Looking-glass, through

[Matsakis, Demetrios]

I can't help with the flying cars, but UTC does deliver a frequency
that is the most precisely and accurately measured quantity known to
humans.  Time is the integral of that frequency, and over one
leapsecond-less day a frequency error of 1.E-12 corresponds to a time
error of 86400*1.E-12 = 86 nanoseconds.

The USNO and BIPM web pages give our algorithms, though it takes a bit
of clicking.  The basic idea is that each clock's systematic errors in
time, frequency and/or frequency drift are corrected for and the result
goes into a weighted average.

-Original Message-
From: leapsecs-boun...@leapsecond.com
[mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Sanjeev Gupta
Sent: Friday, January 14, 2011 2:23 AM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] Looking-glass, through


On Fri, Jan 14, 2011 at 13:47, Tom Van Baak t...@leapsecond.com wrote:


You really didn't expect 250 diffeent atomic clocks around
the world to all agree at the ns level at all times did you?

 
tounge-in-cheek
Why not?  nano is 10E-9, and I see references to people trying for
clocks with 10E-12 on this list.  
 
And what good is the atom part of an atomic clock, if it can't even
handle nano?
/foot-in-mouth
 
Still waiting for the flying cars I was promised ...
-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane


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Re: [LEAPSECS] Saint Crispin's Day

[Matsakis, Demetrios]

It wouldn't surprise me if you have your kids build one of those for a science 
fair project!



From: Tom Van Baak
Sent: Tue 10/26/2010 2:14 AM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] Saint Crispin's Day


...
And no, my lab isn't near as good as NIST; but I do keep
an eye out for cesium fountains and ion clocks on eBay.

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[LEAPSECS] UTC Redefinition Advanced

[Matsakis, Demetrios]

I have now heard from two sources that the revised ITU-R draft
recommendation TF.460-6 passed a major hurdle in Geneva last week.  It
will be sent by SG7 to the January 2012 Radiocommunication Assembly
meeting.  At the Radiocommunication Assembly only countries that belong
to the ITU-R can vote and a 75% majority is required for passage of a
recommendation.  I don't have the wording, but I presume it calls for
the elimination of all future leap seconds after several (5?) years
notice.

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[LEAPSECS] FW: comments on DRR TF.460-6

[Matsakis, Demetrios]

I asked an unquestioned expert on celestial navigation about its UT
requirements.  This was his response:


For observed stars that are near the celestial equator or at low
declinations, the error can be up to 0.25 nm per uncorrected second.
This
is a systematic error, i.e., all lines of position for a fix are shifted
in
the same direction, either east or west (although not necessarily by the
same amount).  Given that  marine sextant sights by an experienced
observer
under good conditions typically have errors of around an arcminute, or 1
nm,
anything more than  about a four-second uncorrected UT1 time error would
dominate the error of a fix.

Stars near the celestial poles, like Polaris, work well for azimuth or
latitude determinations because those observations are quite insensitive
to
time errors, but they don't provide a longitude component.  If you want
accurate longitude, you can't get around the need to know UT1 at no
worse
than the several-second level.


 
 From: ashtongj
 Sent: Tue 9/21/2010 11:17 AM
 To: Leap Second Discussion List
 Subject: Re: [LEAPSECS] comments on DRR TF.460-6
 
 Tony asked Are there any requirements for mean solar time other than
 astronomy and celectial navigation?
 
 
 Land surveyors still use sun and star sights to find azimuth. While
GPS
 can also be used for this function, the total station (theodolite and
 laser distance meter combined) is an indispensable piece of capital
 equipment. Smaller firms and single-person firms can avoid the expense
 of GPS equipment by doing sun and star shots and not bidding on
projects
 where GPS is essential. Land surveying GPS requires a site relatively
 free of trees. Trees of course can also interfere with astronomical
 observations, but there could be gaps that would be sufficient for
 astronomical observations but inadequate for GPS.
 
 The tree cover problem can be overcome through the time and expense of
 setting up a GPS line of known direction and traversing to the wooded
area.
 
 The problem of not being able to obtain DUT1 directly from audible
 shortwave time broadcasts could be overcome by obtaining delta UT1
from
 the internet. I don't know if any of the software surveyors use to
 reduce their results limit delta UT1 to  0.9 s or not.
 
 Observe that the Astronomical Almanac still publishes Polaris tables,
 suggesting that someone out there is still obtaining directions from
 Polaris. I understand, although I haven't done the math myself, that
 depending on the position of Polaris, the time accuracy required to
 obtain an azimuth accuracy of 1 arcsecond ranges from 4 seconds to a
few
 minutes. One could easily argue that by the time the error becomes
great
 enough to create real problems, star sights will be totally abandoned.
 But the time accuracy requirement for other bodies is stricter, and it
 may not be possible to observe Polaris because of local obstructions.
 
 Gerry
 
 On 2010-09-21 8:26 AM, Tony Finch wrote:
 On Mon, 20 Sep 2010, Robert Seaman wrote:
 
 To say that leap seconds were devised to keep the UTC time scale in
 close alignment with earth time making UTC useful for celestial
 navigation is to suggest two unsupported assertions.  First that no
 other requirements for earth time exist, and second that UTC is
 responsive only to the evolving needs of those who used to have a
 requirement for celestial navigation.
 
 Are there any requirements for mean solar time other than astronomy
and
 celectial navigation?
 
 Tony.
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Re: [LEAPSECS] UTC is derived from TAI

[Matsakis, Demetrios]

The concept of whether TAI is a product in itself, or just a step to generate 
UTC, has led to some disagreements over time.
 
However, there is only one UTC, which has many realizations.  The true UTC is 
determined not from the realizations, but from the clocks behind those 
realizations.  
 


From: Steve Allen
Sent: Sun 3/14/2010 8:54 PM
To: Leap Second Discussion List
Subject: [LEAPSECS] UTC is derived from TAI


UTC is derived from TAI

Type that phrase into google and look at the results, from
IERS, ITU, G. Petit, E.F. Arias, wikipedia
These deserve to be treated as authoritative sources.

But isn't it the case that hidden in that phrase is something that
deserves a great deal of explanation?

There is only one TAI, and it comes next month from BIPM Circular T.
There are many UTCs.  Therefore the UTC that this phrase refers to can
only be the undecorated, true, just plain UTC which is also not
known until next month from Circular T.

As a practical matter, TAI is derived from all the various versions
of UTC(k) which are maintained by the contributing national labs.
So the only UTC which is available right now is one of the various
versions of UTC(k), not just plain UTC.

I suppose this is all just part of the explanation of why the general
notion of precision time scales is so poorly understood.

--
Steve Allen s...@ucolick.orgWGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99855
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06015
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
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Re: [LEAPSECS] UTC is derived from TAI

[Matsakis, Demetrios]

It is everywhere and it is nowhere.

It is expressed in its difference with the realizations, yet it is of the same 
substance as they are.

It is a prediction of the future and a concept of the now, yet a thing of the 
past.



 



From: Steve Allen
Sent: Sun 3/14/2010 9:41 PM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] UTC is derived from TAI


On Sun 2010-03-14T21:11:58 -0400, Matsakis, Demetrios hath writ:
 However, there is only one UTC, which has many realizations.  The
 true UTC is determined not from the realizations, but from the clocks
 behind those realizations.

At the end of the flower sermon Buddha said
I possess the true Dharma eye, the marvelous mind of Nirvana, the
true form of the formless, the subtle dharma gate that does not
rest on words or letters but is a special transmission outside of
the scriptures.
yet I find that for the sake of practicality I must ask:

How do I get this one, true UTC?  Where do I find it?
How can I share it with others?

--
Steve Allen s...@ucolick.orgWGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99855
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06015
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
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[LEAPSECS] Windows Time's Great Leap Forward

[Matsakis, Demetrios]

Microsoft's NTP package gives no notice of a pending leap second, even
when acting as a server.  Here are some pastes from Microsoft's web
site:

The Windows Time service does not indicate the value of the Leap
Indicator when the Windows Time service receives a packet that includes
a leap second. (The Leap Indicator indicates whether an impending leap
second is to be inserted or deleted in the last minute of the current
day.) Therefore, after the leap second occurs, the NTP client that is
running Windows Time service is one second faster than the actual time.
This difference is resolved at the next time synchronization.

When the Windows Time service is working as an NTP server 

No method exists to include a leap second for the Windows Time service.


See http://support.microsoft.com/kb/909614
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Re: [LEAPSECS] temporal turf wars

[Matsakis, Demetrios]

I agree with Tom about GPS.   Over the past decade both GPS's delivered 
prediction of UTC(USNO) and GPS time have been getting closer and closer to 
UTC(USNO), modulo 1 second  and as measured by the RMS.  That is mostly due to 
improved GPS clocks, but tighter steering was implemented about ten years ago, 
and other algorithm improvements have also been made.  GPS III's times will 
adhere even closer to UTC(USNO) - because clocks, algorithms, and official 
specs are being improved.

While I can't speak for the USNO's sister-institution, I do remember the paper referenced below.  It was presented at a PTTI meeting by someone who at that time was an employee of NIST and this must be why they include it in their reprint library.  I am quite sure that it does not now represent nor ever has represented any official position of NIST in any way.  However, USNO did at one time host a web page that included UTC(tvb)! 


From: Tom Van Baak
Sent: Sat 1/3/2009 5:36 AM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] temporal turf wars



An interesting NIST document from 2000 gives insight into the turf wars
about precision time scales.

http://tf.nist.gov/general/pdf/1429.pdf

The document makes it clear that GPS time was never designed to follow
UTC(USNO) (and by implication, TAI).


I think you're misreading that sentence. GPS is in fact steered to
the USNO MC which is steered to UTC. But I think the steering
parameters are quite different between the two though. I also
suspect there have been improvements in the past ten years.
Demetrios can explain more, if needed.


The document also clarifies the distinction between (raw) GPS time and
GPS time corrected by the offset given in subframe 4 page 18.


The GPS ICD 200 describes the A0 and A1 correction. I believe
most (all?) GPS timing receiver implement the correction. Steve, you'd
have fun with a GPS timing receiver like a Thunderbolt or an M12;
all those subframe parameters can be dumped over the serial port
and played with.


The document also coins the term UTC(GPS) with very interesting
footnotes disclaiming the validity of the use of such a term.


I doubt Al coined that term; I recall seeing it long before. But like
the editor implies, people realized it was not a valid term and so
you rarely see it any more. Maybe marketing people still use it.
I remember being gently corrected by the BIPM and I stopped
using it myself. I think UTC(tvb) is ok, though ;-)

/tvb


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Re: [LEAPSECS] WP7A status

[Matsakis, Demetrios]

There is a mistake in the viewgraphs, which the authors will correct in
any other reports they generate.  This is the reference to URSI.

I was the person who chaired the URSI Commission J working group, and
later chaired the URSI-wide working group on the matter.  Every report
noted that no significant opposition or support for a change came from
within URSI.

The first survey I did, now outdated, reached through the internet to
anyone who chose to respond.  I did receive more negative opinions than
positive ones from the general public.  But the absolute numbers were
small, and none were URSI-related.   Then that commission WG completed
its job, and I chaired an URSI-wide group that did a second survey, 3
years later.  This went only to URSI and the only responses we received
were abstentions. 

On the basis of six years of non-expression of interest from their
constituency, the URSI secretariat made a unanimous decision to not
respond to the ITU-R's Special Rapporteur Group's letter, and my working
group was disbanded.

Historians may note that this provides two rare instances of a committee
being formed, doing its job on time, and then terminating itself.

-Original Message-
From: leapsecs-boun...@leapsecond.com
[mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Poul-Henning Kamp
Sent: Tuesday, December 16, 2008 11:08 AM
To: Leap Second Discussion List
Subject: [LEAPSECS] WP7A status


http://www.navcen.uscg.gov/cgsic/meetings/48thmeeting/Reports/Timing%20S
ubcommittee/48-LS%2020080916.pdf

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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Re: [LEAPSECS] WP7A status

[Matsakis, Demetrios]

I am unaware of URSI having made any official response.  As far as URSI
is concerned, my WG reports are all I know of.

I hope I don't offend anyone by adding that the most vocal scientists I
know of on this subject, in other venues, do not even attend the URSI
General Assemblies.

-Original Message-
From: leapsecs-boun...@leapsecond.com
[mailto:leapsecs-boun...@leapsecond.com] On Behalf Of Poul-Henning Kamp
Sent: Tuesday, December 16, 2008 12:33 PM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] WP7A status

In message
5be518100a3b5041bfadc26754c50353b2c...@echoex.timenet.usno.navy.mil,
Matsakis, Demetrios writes:

On the basis of six years of non-expression of interest from their 
constituency, the URSI secretariat made a unanimous decision to not 
respond to the ITU-R's Special Rapporteur Group's letter, and my 
working group was disbanded.

Does that non-response leave the earlier response standing ?


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by
incompetence.
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