On 2023-12-22 22:35, Seaman, Robert Lewis - (rseaman) wrote:
E pur si muove
Natura non facit saltus -- why should UTC?
UTC may no longer serve as a kind of solar time (after 2026 or 2035, or
somebody said 2040 the other day), but civil time will continue to have
engineering
On 2023-12-21 18:22, Poul-Henning Kamp wrote:
My Tl;dr version of the resolution is:
. Please keep DUT1 less than 100 seconds.
I do not read that from the text. The original [page 399] says:
" recognizing
.
k) that the maximum value for the difference
On 2023-11-26 06:59, Steve Allen wrote:
This week began the meeting of ITU-R WRC 23.
..and it ended on 2023-12-15. The ITU-R news channel
[https://www.itu.int/en/mediacentre/Pages/PR-2023-12-15-WRC23-closing-ceremony.aspx]
mentions a "key outcome"of WRC23:
" ∙ Endorsement of
On 2023-11-26 06:59, Steve Allen wrote:
This week began the meeting of ITU-R WRC 23.
After closure of work related to resolution 655 of WRC 2015
at the World Radio Conference 2023 in Dubai, the BIPM has added
the web page
[https://www.bipm.org/en/-/2023-12-12-wrc-dubai]
On 2023-11-26 17:38, Michael Deckers wrote:
online at [https://www.itu.int/oth/R0A0807/en]
when he meant: nline at
[https://www.itu.int/pub/publications.aspx?lang=en=R-REP-TF.2511-2022]
Michael Deckers.
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On 2023-11-26 06:59, Steve Allen wrote:
This week began the meeting of ITU-R WRC 23. One preparation for this
meeting was a document issued early this year
The future of Coordinated Universal Time
https://www.itu.int/en/itunews/Documents/2023/2023-02/2023_ITUNews02-en.pdf
This looks at
On 2023-08-26 17:58, John Sauter via LEAPSECS wrote:
According to the IERS, today, for the first time since the
establishment of the modern definition of UTC in 1973, the quantity
UT1-UTC crosses zero while increasing. If this continues we will have
a negative leap second, probably some
On 2023-06-20 12:21, Michael Deckers via LEAPSECS referenced:
[https://link.springer.com/chapter/10.1007/1345_2022_167]
which was already cited by Richard Langley on 2023-06-17.
Sorry for the duplication.
MD.
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On 2023-06-16 01:48, Tom Van Baak wrote about the relationship of
LOD with El Niño:
Attached is an LOD plot I made a while ago. A random web google link
says "The five strongest El Niño events since 1950 were in the winters
of 1957-58, 1965-66, 1972-73, 1982-83 and 1997-98". To my
On 2023-06-16 13:46, jimlux wrote:
10 terasquare meters
You mean 10 square megameters = 10 Mm²; SI suffixes
apply to named units, not to its powers.
Michael Deckers.
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On 2023-03-20 19:36, Michael Deckers wrote:
This seems to be lenient enough to allow for not scheduling
a negative leap second even in the case that the difference
(UT1 - UTC) should go a bit below -1 s before 2035.
when he meant "a bit above +1 s"
MD.
On 2023-03-20 07:54, Jürgen Appel via LEAPSECS wrote:
In your Conclusion, you say "the CGPM resolution also stipulates that no
change to current practices can occur before 2035."
This is not how I read read the CGPM document on the BIPM website:
"The General Conference on Weights and
On 2022-12-04 17:01, Steve Allen wrote:
On Sun 2022-12-04T16:30:01+ Tony Finch hath writ:
So if you agree with Donald Sadler, has already GMT concluded.
I do agree, and I also disagree, for Sadler was in large part
responsible for another tacit change to GMT. Like others engaged
On 2022-11-21 14:19, Seaman, Robert Lewis - (rseaman) wrote:
In a post-leap-second world, precision values for dUT1 either become more
critical or less. Or rather, they become no-less important scientifically but
perhaps negligible politically. For
On 2022-11-20 15:15, Tony Finch asked:
(Do any of
the national broadcast signals actually follow the ITU spec?)
Lists of UTC time signals with details about the coding are in
the Annual reports of the BIPM time department, at
[https://www.bipm.org/en/time-ftp/annual-reports].
On 2022-11-14 19:48, Steve Allen wrote:
The NYT article ends with Arias ruminating about how someday
there will have to be a leap minute or leap hour.
Of course, nobody will propose leap minutes or leap hours in UTC
after 2135 just to decrease the difference UTC - UT1.
The
On 2022-07-26 05:08, Steve Allen wrote:
The CNET article includes a quote from correspondence which
repeats a trick that has been performed since the 1960s, that
being to produce a significant underestimate of the difference
between solar and atomic time by saying that the absence of
leap
Another first has happened: Bulletin D141 at
[https://datacenter.iers.org/data/latestVersion/17_BULLETIN_D17.txt]
specifies that DUT1 jumps from -0.2 s to -0.1 s on 2021-07-21T00Z.
This is the first time ever (since 1972) that the approximation
UTC + DUT1 of UT1 makes a jump
On 2021-01-08 19:57, John Sauter via LEAPSECS wrote:
I attach a plot of historical values of DUT1 based on the old issues of
Bulletin A kept on the IERS' web site.
I think the graph of DUT1 is not quite correct, for instance:
On 2009-01-01, there was a switch of DUT1 from -0.6 s to
The latest Bulletin A
[https://datacenter.iers.org/data/latestVersion/6_BULLETIN_A_V2013_016.txt]
predicts that d(UT2)/d(TAI) = 1 after 2021-11-13, ie
the rates of UTT2 and TAI are expected to agree for the
next year. This has never happened since 1961. We may
not need to
On 2020-08-08 10:46, John Sauter via LEAPSECS wrote:
UT2 captures the seasonal change in the length of day, so it can be
ignored for long-term estimates. The important number, therefore, is
-0.00010, which I will call the UT1 slope.
Perhaps "slope of UT2 - UTC (as predicted by the
On 2020-07-07 22:37, Steve Allen wrote:
The earth has accelerated so that it is spinning as fast as it was
during World War 2, and before that, the 1890s.
Yes, Bulletin A vol 33 no 027 predicts that 2020 will be the
first year since 1972 without change of DUT1 (= UT1 - UTC up to
On 2020-02-04 21:16, Steve Allen wrote:
The first time that the 4th meeting of the CCDS happened was in 1966,
but that meeting is not found in any official record. The meeting
ended with a vote to recommend that the CGPM should adopt an SI second
based on cesium, but the circumstances of
On 2020-02-04 13:44, Tony Finch wrote:
The IERS Bulletins C state a value of UTC-TAI "until further notice".
However the machine-readable files from IERS and NIST give an expiry date
of a few days less than 6 months after the announced (lack of) leap
second, or a bit more than 11 months
On 2020-02-02 22:30, Steve Allen wrote:
On Sun 2020-02-02T17:59:20+ Michael Deckers hath writ:
The maximum deviation |UTC - UT1| <= 0.9 s as stipulated in
1974 by CCIR Rec. 460-1 has never been violated until now.
That violates the agreement that the difference between
UTC and UT1 would
On 2020-02-01 23:59, Steve Allen wrote:
In every instance where a document
specified a maximum deviation that agreement was later violated.
The maximum deviation |UTC - UT1| <= 0.9 s as stipulated in
1974 by CCIR Rec. 460-1 has never been violated until now.
In one case it was
On 2019-06-05 05:28, Steve Allen wrote:
I have plowed through enough of Bulletin Horaire to find the complete
history of UT2.
https://www.ucolick.org/~sla/leapsecs/seasonal.html
Missing from the earlier version of the plots on this web page was the
story of how exactly the BIH performed
On 2019-02-01 17:56, Steve Allen wrote:
The PTB-controlled broadcasts were pure SI
seconds thus making those broadcasts a form of Stepped Atomic Time
which was approved as experimental by CCIR Rec 374-1 in 1966.
The DCF77 service started on 1959-01-01 and sent astronomically
On 2019-01-22 05:17, Steve Allen wrote:
Curiously there is not a big jump in the value of UT2 - A3 at that
same date which would have been caused by changing from the old
expression for UT2 - UT1 to the new expression. I surmise that this
means Stoyko and Guinot did correct the old values
On 2019-01-21 00:42, Steve Allen wrote:
Of course there was a time step. The BIH had to deal with totally
hetergeneous data from an ever changing set of contributors. Almost
every year for the BIH there was a systematic offset from the times of
other years. But until the cesium standard
On 2019-01-20 17:19, Steve Allen wrote:
Those pages are a response to Recommendation 2 from the second CCDS
meeting held 1961-04-11/1961-04-12. At the CCDS meeting BIH presented
an initial effort to integrate and compare all the cesium standards
for which data were available, and BIH was
On 2019-01-20 00:50, Steve Allen wrote:
I took a closer read and cross reference of the relevant
issues of Bulletin Horaire and finalized my web page.
The epoch at which TAI was set is definitely 1961-01-01T20:00:00 UT2
Arias and Guinot say in "Coordinated Universal Time UTC:
On 2019-01-18 17:11, Michael H Deckers wrote:
.. insert a step of 0.2 s in their time signal about every 71 days.
when he meant "about every 77 days".
Michael Deckers.
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On 2018-08-15 11:49, Zefram wrote:
Time Service Announcement 14 #8 (1971-10-08) discusses the irregular
leap (still called a "step") at the end of 1971, but weirdly gives a
different size for that step from that which is implied by tai-utc.dat.
The announcement states a step size of 107600
On 2018-07-20 18:05, Stephen Scott wrote:
While there is no perfect answer, it seems that Microsoft Azure
servers got it right for the last one, incorporating the leap second
just before midnight local time.
No, they didn't.
A leap second describes a discontinuity in the
On 2018-07-21 01:08, Steve Allen wrote:
At that same meeting IAU Comm 31 was led to yield that they had no
influence over the leap seconds that the CCIR had instituted, and IAU
Comm 31 was pressed to produce a statement declaring that leap seconds
were "the optimum solution."
On 2015-02-05 11:16, Peter Vince wrote:
Yes, I took part in the initial meeting of professionals (so-called
stakeholders), where the issues were indeed thoroughly discussed, and well
understood (apart from some unfortunate absences - no-one from the military was
there, for example).
On 2015-01-26 20:05, Brooks Harris wrote:
As a practical matter of modern timekeeping the UTC timescale started at
1972-01-01T00:00:00Z (UTC). NTP, POSIX, 1588/PTP and others refer to epochs and
timescales they call UTC that occur earlier than 1972-01-01, so this confuses
matters. But those
On 2015-01-25 14:58, Rob Seaman wrote:
Please let me know about typos, suggestions, etc. Needless to say this
remains a prototype.
...
MM before after encoded crc IP Decodedflags
On 2014-11-06 13:10, Steffen Nurpmeso wrote
in defense of the description by the German metrology
laboratory in [https://www.ptb.de/cms/en/fachabteilungen
/abt4/fb-44/ag-441/coordinated-universal-time-utc.html]:
Hm, indeed a sloppy translation of the original German text
Die
On 2014-11-04 22:26, Steve Allen quoted Bernard Guinot
about the unit for the difference TAI - UT1:
Guinot explained this using the term graduation second
in section 2.2 of 1995 Metrologia 31 431
http://iopscience.iop.org/0026-1394/31/6/002
He points out that the way the IAU has written
On 2014-11-04 22:26, Steve Allen wrote:
Guinot explained this using the term graduation second
in section 2.2 of 1995 Metrologia 31 431
http://iopscience.iop.org/0026-1394/31/6/002
He points out that the way the IAU has written the definitions of the
time scales uses a subtly ambiguous
On 2014-11-05 11:28, Steffen Nurpmeso wrote:
Oh, the German Physikalisch-Technische Bundesanstalt (PTB) also
has a general -- at least -- overview of the set of problems.
(English: [1] and all around that; oops, not everything is
translated, what a shame! I hope it's not due to lack of
On 2014-11-05 16:27, Zefram wrote:
... UTC is always
an integral number of seconds offset from TAI, and so by construction
UTC(NPL) is always an integral number of seconds offset from TAI(NPL).
Hence each of the marks also occurs at the
On 2014-11-04 12:34, Zefram wrote:
UT1 always ticks a second for that ERA increase, but Warner's point
is that the second of UT1 isn't an *SI* second. The time taken for
that ERA increase, and hence the duration of a UT1 second, very rarely
exactly matches an SI second. The second of UT1
On 2014-11-01 23:31, Steve Allen wrote:
In the appropriate contexts there are days of Terrestrial Time,
International Atomic Time, Barycentric Coordinate Time, Geocentric
Coordinate time, GPS system time, BeiDou system time, etc. Each of
those days is 86400 SI seconds in its own reference
On 2014-11-02 19:04, Warner Losh wrote:
On Nov 2, 2014, at 11:21 AM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
For instance, the differential rate d(TAI - UT1)/d(UT1) is
published as LOD by the IERS as a dimensionless number
with unit ms/d. To compute this, one
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