Ashley Yakeley wrote:
I'd like to see an elastic civil second to which SI nanoseconds are
added or removed. Perhaps this could be done annually: at the
beginning of 2008, the length of the civil second for the year 2009
would be set, with the goal of approaching DUT=0 at the end of 2009.
This was
Zefram wrote:
...
The historical trend is towards using uniform time units. It seems
curious now that when the atomic clock was invented astronomers opposed
calling it a time standard.
Well, it seems curious to everybody except Rob Seaman :-)
...
It is much like the ancient Egyptians (IIRC)
Zefram scripsit:
Projecting into the future, one can foresee the eventual abandonment of
timezones in favour of the universal use of Universal Time.
I think that's over the top. Bureaucratically it is just too annoying
if the large majority of people have a work shift that overlaps legal
Steve Allen wrote:
On Mon 2007-01-01T21:19:04 +, Ed Davies hath writ:
Why does the One sec at predicted intervals line suddenly
diverge in the early 2500's when the other lines seem to just
be expanding in a sensible way?
...
I suspect that the divergence of the one line indicates that the
On Jan 1, 2007, at 22:56, Steve Allen wrote:
Then let's improve the infrastructure for communicating the best
estimation of earth orientation parameters. Then in a world of
ubiquitous computing anyone who wants to estimate the current
rubber-second-time is free to evaluate the splines or
Warner Losh scripsit:
There's an exception for IERS to
step in two weeks in advance if the earth's rotation rate hickups.
So if I understand this correctly, there could be as many as 14
consecutive days during which |DUT1| 0.9s before the emergency leap
second can be implemented;
Then let's improve the infrastructure for communicating the best
estimation of earth orientation parameters. Then in a world of
ubiquitous computing anyone who wants to estimate the current
rubber-second-time is free to evaluate the splines or polynomials
(or whatever is used) and come
On Jan 2, 2007, at 05:15, Zefram wrote:
A technical issue: broadcast time signals are phase-locked with the
carrier, which is at some exact number of hertz. If the time
pulses are
every civil second, and that is now 1.00015 s (as it was in 1961),
it can't be synchronised with the (say) 60
In message [EMAIL PROTECTED], John Cowan writes:
Warner Losh scripsit:
There's an exception for IERS to
step in two weeks in advance if the earth's rotation rate hickups.
So if I understand this correctly, there could be as many as 14
consecutive days during which |DUT1| 0.9s before the
Warner Losh scripsit:
There's an exception for IERS to
step in two weeks in advance if the earth's rotation rate hickups.
So if I understand this correctly, there could be as many as 14
consecutive days during which |DUT1| 0.9s before the emergency leap
second can be implemented;
On Jan 2, 2007, at 11:40, Warner Losh wrote:
The second technical problem is that the length of a second is
implicitly encoded in the carrier for many of the longwave time
distribution stations. 10MHz is at SI seconds. For rubber seconds,
the broadcast would drift into adjacent bands reserved
Warner Losh scripsit:
There's no provision for emergency leapseconds. They just have to be
at the end of the month, and annoucned 8 weeks in advance. IERS has
actually exceeded this mandate by announcing them ~24 weeks in advance
in recent history.
So much the worse. That means that if
In message [EMAIL PROTECTED], Tony Fin
ch writes:
On Tue, 2 Jan 2007, Warner Losh wrote:
Curiously, BIH is currently, at least in the document I have, expected
to predict what the value of DUT1 is to .1 second at least a month in
advance so that frequency standard broadcasts can prepare for
In message: [EMAIL PROTECTED]
John Cowan [EMAIL PROTECTED] writes:
: Warner Losh scripsit:
:
: There's no provision for emergency leapseconds. They just have to be
: at the end of the month, and annoucned 8 weeks in advance. IERS has
: actually exceeded this mandate by announcing
Warner Losh wrote:
The IERS bulletin C is a little different than the ITU TF.460:
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
Warner Losh wrote:
Right now DUT1 is
+0.0s until further notice. From the last few B's, it looks like this
is decreasing at about 300ms per year. This suggests that the next
leap second will be end of 2008.
The way DUT1 is behaving at the
M. Warner Losh wrote:
GPS is also used for UTC today. Many ntpd's are stratum 1 tied to a
GPS receiver.
I imagine two parallel time infrastructures, one synchronised to TAI,
the other to rubber mean universal time. Stratum 0 devices for the
latter would probably have to use radio.
So, sure,
In message [EMAIL PROTECTED], Ashley Yakeley writes:
M. Warner Losh wrote:
GPS is also used for UTC today. Many ntpd's are stratum 1 tied to a
GPS receiver.
I imagine two parallel time infrastructures, one synchronised to TAI,
the other to rubber mean universal time. Stratum 0 devices for the
Ed Davies wrote:
Still, it's a strange assumption, given that TF.640 allows, I
understand, leaps at the end of any month. Unofficially, the
wording seems to be:
A positive or negative leap-second should be the last second
of a UTC month, but first preference should be given to the end
of
Magnus Danielson wrote:
The detailed introduction of the frequency
corrections in various sources was different, and getting a coherent view of
where UTC actually where was difficult. Since then we have grown to depend on
UTC transmission to a higher degree than we did back then. Infact, for
From: Ashley Yakeley [EMAIL PROTECTED]
Subject: Re: [LEAPSECS] A lurker surfaces
Date: Tue, 02 Jan 2007 15:21:14 -0800
Message-ID: [EMAIL PROTECTED]
Ashley,
Magnus Danielson wrote:
The detailed introduction of the frequency
corrections in various sources was different, and getting a
Magnus Danielson wrote:
The budget isn't there and the govrements already pay
good money for the systems in place and is looking to get as much out of it as
possible.
Yes, you're probably right, they're likely to prefer to patch up
something ultimately broken cheaply than fix it properly.
I
Ed Davies wrote:
However, it's a horrible article and really needs reorganization
as some of the paragraphs have suffered serious mission creep.
I edited quite a lot of time-related articles last year, and couldn't
figure out what to do with it. I started off with the articles on
astronomical
From: Ashley Yakeley [EMAIL PROTECTED]
Subject: Re: [LEAPSECS] A lurker surfaces
Date: Tue, 02 Jan 2007 16:40:23 -0800
Message-ID: [EMAIL PROTECTED]
Ashley,
Magnus Danielson wrote:
The budget isn't there and the govrements already pay
good money for the systems in place and is looking to
On 2 Jan 2007 at 12:40, Warner Losh wrote:
The interval math in UTC that's hard today would be significantly
harder with rubber seconds. But it is just software, eh?
In short, it is an interestingly naive idea that was tried in the
1960's and failed when there were only dozens of high
On 2 Jan 2007 at 19:40, Poul-Henning Kamp wrote:
Has anybody calculated how much energy is required to change
the Earths rotation fast enough to make this rule relevant ?
Superman could do it. Or perhaps he could nudge the Earth's rotation
just enough to make the length of a mean solar day
On 2 Jan 2007 at 11:47, Ashley Yakeley wrote:
The obvious solution is to transmit rubber time on a rubber frequency.
Are rubber duckies involved?
--
== Dan ==
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On 2 Jan 2007 at 11:56, Ashley Yakeley wrote:
GPS is TAI. I'm not proposing abandoning TAI for those applications
that need it.
It's a few seconds off from TAI, isn't it? It was synchronized to
UTC in 1980 (I think), but without subsequent leap seconds, so it's
now different from both TAI and
Daniel R. Tobias replies to Poul-Henning Kamp:
Has anybody calculated how much energy is required to change
the Earths rotation fast enough to make this rule relevant ?
Superman could do it. Or perhaps he could nudge the Earth's rotation
just enough to make the length of a mean solar day
Magnus Danielson wrote:
If you do want a new timescale, I think rubber seconds isn't going
to be the solution.
One might point out that many time scales do rely on rubbery seconds,
e.g., sidereal time and apparent solar time. If might be
enlightening to step back from the tendentious and
Poul-Henning Kamp wrote:
That's an interesting piece of data in our endless discussions
about how important DUT1 really is...
The point is that by allowing it to grow without reasonable bound,
DUT1 would gain an importance it never had before.
- Original Message -
From: Ed Davies [EMAIL PROTECTED]
To: LEAPSECS@ROM.USNO.NAVY.MIL
Sent: Tuesday, January 02, 2007 3:55 PM
Subject: [LEAPSECS] Wikipedia article
Thanks to those who confirmed the ITU text on when leap seconds can
be applied.
I've made two small edits to the
In message: [EMAIL PROTECTED]
Daniel R. Tobias [EMAIL PROTECTED] writes:
: On 2 Jan 2007 at 11:56, Ashley Yakeley wrote:
:
: GPS is TAI. I'm not proposing abandoning TAI for those applications
: that need it.
:
: It's a few seconds off from TAI, isn't it? It was synchronized to
:
From: Rob Seaman [EMAIL PROTECTED]
Subject: Re: [LEAPSECS] A lurker surfaces
Date: Tue, 2 Jan 2007 20:45:14 -0700
Message-ID: [EMAIL PROTECTED]
Rob,
Magnus Danielson wrote:
If you do want a new timescale, I think rubber seconds isn't going
to be the solution.
One might point out that
From: Steve Allen [EMAIL PROTECTED]
Subject: Re: [LEAPSECS] A lurker surfaces
Date: Tue, 2 Jan 2007 21:35:24 -0800
Message-ID: [EMAIL PROTECTED]
On Tue 2007-01-02T22:16:19 -0700, M. Warner Losh hath writ:
changed in later revisions to be the same as GPS time. There's an
extreme reluctance
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