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)
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
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
Rob Seaman wrote:
... Obviously it would take at least N years to introduce a new
reporting requirement of N years in advance (well, N years minus six
months).
Sorry, maybe I'm being thick but, why? Surely the IERS could announce
all the leap seconds in 2007 through 2016 inclusive this week
Poul-Henning Kamp wrote:
If you have subtle point, I'd love to hear it.
Not even close to a subtle point, I simply cannot figure out what the
graph shows...
Me too. Is this an analysis or a simulation? What are the
assumptions? What predicted intervals does he mean?
The bullet points
Steve Allen wrote:
On Mon 2007-01-01T17:42:11 +, Ed Davies hath writ:
Sorry, maybe I'm being thick but, why? Surely the IERS could announce
all the leap seconds in 2007 through 2016 inclusive this week then
those for 2017 just before the end of this year, and so on. We'd have
immediate 10
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Rob Seaman writes:
Jim Palfreyman wrote:
Just a reminder that UTC has no - none - nada - discontinuities.
Various computer mis-implementations may, but the standard is very
carefully constructed to avoid spring-forward or fall-back gaps
Rob Seaman wrote:
I'm given to wonder how much of the friction on this mailing list is
simply due to the shortcomings in the technology that implements it.
I've appended a message I sent in August with four plots attached. Can
someone tell me whether it is readable now or was successfully
Rob Seaman wrote:
...
An amateur astronomer with a Celestron, the Astronomical Almanac
and an atlas can recover UTC anywhere on Earth.
...
Do you really mean UTC here? I can see that an amateur with a
Celestron could recover UT (for some flavour of UT, I'm not sure
which - UT0?, then
Rob Seaman wrote:
Doubt I can lay my hands on the copy of ISO 8601 from my Y2K remediation
days. Anybody want to comment on whether it actually attempts to convey
the Gregorian algorithm within its pages?
Yes, it does.
This International Standard uses the Gregorian calendar for the
Ed Davies scripsit:
If only the 24:00 for end of day notation wasn't in the way
we could look at positive leap seconds as just being the
result of deeming certain days to be a second longer than
most and just use 24:00:00. We wouldn't have to muck with
the lengths of any of the hours or minutes
Markus Kuhn wrote:
With the 24-h notation, it is a very useful and well-established
convention that 00:00 refers to midnight at the start of a date, while
24:00 refers to midnight at the end of a date. Thus, both today 24:00
and tomorrow 00:00 are fully equivalent representations of the same
Rob Seaman wrote:
All proposals (other than rubber seconds or rubber days)
face the same quadratically accelerating divergence between clock and Earth.
By rubber seconds you, presumably, mean non-SI seconds. What do you
mean by rubber days? I'd guess you mean days which are
James Maynard wrote:
I wonder, though, whether those in the other camp would find it
acceptable to have the standard time and frequency stations not only
broadcast UTC and DUT1 (= UT1 - UTC, to 0.1 s resolution), but also to
broadcast DTAI (= TAI - UTC, 1 s resolution)?
A full
Rob Seaman wrote:
I hope we can all continue this discussion in a more positive manner.
I'm of the opinion that messages on this list (no matter how
tricky :-) are always positive. Timekeeping is a fundamental
issue. It would be remarkable if there weren't diverse opinions.
Any negative
Markus Kuhn wrote:
A new Internet-Draft with implementation guidelines on how to handle UTC
leap seconds in Internet protocols was posted today on the IETF web
site:
Coordinated Universal Time with Smoothed Leap Seconds (UTC-SLS),
Markus Kuhn, 18-Jan-06. (36752 bytes)
Ed Davies:
Appendix A argues against putting the adjustment interval after the
leap second (method 4a) by pointing out that some time signals
contain announcements of the leap second before it happens but not
after.
Rob Seaman:
Right, ...
Ed Davies:
I think a stronger argument against
Michael Deckers wrote:
I believe I'm now grasping what you mean: the rate of UTC is the same
as the rate of TAI (since 1972), that is, the derivative
d( UTC )/d( TAI ) = 1. ...
This conversation is making something of a meal of a simple
point. You can treat UTC as a real in either of
Michael Deckers wrote:
Sort of like, is it a particle or a wave? :-)
At the risk of being misunderstood as sarcastic: if
users of UTC were really expected to understand such
strange concepts (Schrodinger time) I would plead for the
immediate abolishment of UTC. Why cannot UTC
Markus Kuhn wrote:
Ed Davies wrote on 2006-01-13 11:45 UTC:
The use of the 23:59:60 notation is described in ISO 8601.
Is it also specified in TF.460?
It originally comes from ITU-R TF.460, which is a standard for radio
time signals.
OK, thanks.
Ed.
Wow, things have got really stirred up around here. Lots of interesting
points but I'll just concentrate on one...
Poul-Henning Kamp wrote:
Well, the BIPM doesn't really want anybody to use TAI, their director
said as much last year, and I can see where he is coming from on that
one.
Since
Poul-Henning Kamp wrote:
What a weird concept...
Why not go the full distance and define a timescale for each
particular kind of time-piece:
and give each of them their own unique way of coping with leapseconds ?
Ignoring the ridiculous parody - no, it's not a weird concept.
Rob Seaman wrote:
I said:
all parties must certainly agree that civil time (as we know it) IS
mean solar time.
Ed says:
saying that it IS civil time is probably a bit strong.
Probably a bit strong is not precisely a staunch denial.
It's not meant to be a staunch denial. I'm mostly
Keith Winstein wrote:
Some minor glitches:
(a) My Garmin 12XL GPS receiver (software version 4.53) did not register
the leap second on its time display. It went from 58 to 59 to 00, and
stayed one second ahead for the next few minutes until I rebooted it.
Then it came up
period;
and for connected purposes.
Well, at least we'd be in sync with most of the rest of the EC. Don't know
if it'll get anywhere, of course.
Ed Davies.
BBC article, Leap second proposal sparks row:
http://news.bbc.co.uk/1/hi/sci/tech/4420084.stm
I found this bit particularly amusing:
The decision stemmed from the work 200 years previously of the first
English Astronomer Royal, John Flamsteed, who calculated that the
Earth rotated on its
The BBC web site has an article about the leap second debate:
http://news.bbc.co.uk/1/hi/sci/tech/4271810.stm
Ed Davies.
to their own little time-
zone not being good enough), have a clock stable enough to
do so and yet are not connected by any mechanism which could
potentially provide leap-second information?
Presumably there are a few but I find them hard to imagine.
Ed Davies
with the difference going
over 0.9 second is, I think, a relatively minor point but
it does need to be considered.
Ed Davies.
.
Ed Davies.
Steve Allen wrote:
...
Basically, as a result of this case it has been established that the
law in the United States must be in the public domain, and this holds
true even if the law incorporates an external document merely by
reference. So, if NIST tries again to modify the US Code in this
, lighting
up times, etc.
Others?
Ed Davies.
Markus Kuhn wrote:
When the scheduled transmission time
arrives for a packet, it is handed with high timing accuracy to the
analog-to-digital converter,
I assume you mean digital-to-analog.
...
[In fact, since short-wave transmitters frequently switch between
programmes at the full hour,
Markus Kuhn wrote:
A point that was made repeatedly at Torino is that the term UT
traditionally meant in astronomy a time scale defined by the Earth's
rotation, and that therefore a leap-second free uniform atomic time
should not be called UTC, even if doing so would of course avoid the
need
Ed Davies wrote on 2003-05-27 13:56 UTC:
Slightly more relevantly: I was a bit surprised that you did not
put more emphasis on the need to distinguish the different types
of time scales an application program can ask for from an operating
system, as your ctime library highlights.
Markus Kuhn
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