required
more time for updates in satellite software, they have not said that it
cannot be done.
Michael Deckers.
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until 2135.
On the other hand, ITU-R might come up with a scheme where the
approximation
of (UT1 - UTC) is only given modulo 100 s in radio signals, so that
2 digits
would suffice for the integral part.
Michael Deckers.
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nd CCIR's) tradition of murky statements
about UTC.
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try to avoid to introduce an official
approximation of UT1 - UTC with a resolution of whole seconds
and whose values change only at the end of a UTC month.
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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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for a
reference time scale cannot reliably be predicted, anything beyond a
necessarily incomplete list of possibilities (a discontinuous step,
change in the rate d(UTC)/d(TT), using predictions of UT1 - UTC, etc)
would be wasted effort.
Michael Deckers
s to 0.7 s; and by then,
leap seconds will have been "suspended".
Michael Deckers.
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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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ot;. To my eyeball I
just don't see that in the historical LOD plot.
The relationship between LOD and the El Niño events is
not so easy to spot, see eg
[https://link.springer.com/chapter/10.1007/1345_2022_167]
Michael Deckers.
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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.
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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&qu
(NFA)"
found at http://syrte.obspm.fr/iauWGnfa/NFA Glossary.html.
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.
Michael Deckers.
__
.
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ver, since the
amplitude of UT1 - UT2 is about 34 ms, dUT1 must be adjusted
for annual variations of UT1 - UTC.
I have seen the term "dUT1" to be used for ΔUT1 = UT1 - UTC
(and that is how I read it in the paper you quoted), and
also for the rate d(UT1) -- but these are different
].
A few of them transmit DUT1 (and even dUT1).
Michael Deckers.
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.
The reason why the CIPM (for now) sticks to the requirement that
|UTC - UT1| be bounded is most probably the argument brought forward
by some people from ISO who say that, without explicit bound on
|UTC - UT1|, UTC had to change its name so that "polysemy" is avoided.
Micha
seconds will not be noticed for 2000 years.
The CGPM resolution to be adopted in November, online at
[https://www.bipm.org/documents/20126/66742098/Draft-Resolutions-2022.pdf/2e8e53df-7a14-3fc8-8a04-42dd47df1a04]
only requires continuity of UTC - TAI for 100 years.
Michael Deckers
upwards (is advanced).
Michael Deckers.
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to +0.4 s due
to a leap second (Bulletin C36)
On 2009-03-12, there was a switch of DUT1 from +0.4 s to +0.3 s
(Bulletin D102)
Your graph only has one switch, on 2009-01-01 from -0.6 s to +0.3 s
Michael Deckers.
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to abolish leap seconds for quite a while.
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iers.org/data/latestVersion/38_EOP_C01.1900-NOW_V2013_0138.txt])
from 4 µs to 30 µs since J2020.40 = 2020-05-26.6 may be a related
effect.
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to
0.1 s). And its prediction for the (seasonally smoothed) length
of day after 2021.5 is d(UTC)/d(UT2) ~= 1 + 0.13 ms/d.
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ition of UTC in an open manner, and that it adheres
to rational design and decision processes. The recent revision
of the SI has been largely transparent and guided by good practices.
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Bulletins D139, D134, and D129 each
came earlier than predicted by the preceding Bulletin D;
Bulletin D129 (of 2016-04-15) was even significantly earlier
(45 d) than predicted by Bulletin D128 (of 2016-02-19).
Michael Deckers.
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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 wo
t have preferred
the latter.
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the prediction
of UT1 as given in the Bulletins.
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g mit DCF77: 1959 – 2009 und darüber hinaus".
in: PTB Mitteiliungen, 2009 Heft 3. 2009-09 Braunschweig.
online at
[https://www.ptb.de/cms/fileadmin/internet/publikationen
/ptb_mitteilungen/mitt2009/Heft3/PTB-Mitteilungen_2009_Heft_3.pdf]
Micha
961-01-01 definitely was a downward jump (it is also included
as such in the SOFA function iauDat()). Did I make a sign error?
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apply to prior years;
a step in UT2 may have influenced the disseminated time signals
which followed UT2, and the step causes jumps in some differences
such as A3 - UT2, but it does not not cause a step in UT1 or in
any (integrated) atomic time scale.
as J1958.0. Couldn't that mean that the change on
1961-01-01 was designed to have no effect on A3 as published by
the BIH?
Michael Deckers.
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an uncertainty of a few ms per year at the time, it should be
possible to verify whether they all agreed at J1958.0 or at
1960-01-01T20 -- it is unlikely that they all ever agreed on more
than one instant.
Michael Deckers.
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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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been by a different amount, and not by an integral multiple
of 1 µs.
HTH
Michael Deckers.
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:59:60+14 to just before
2017-01-01T14:00:00+14 during that leap second.
HTH.
Michael Deckers.
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UTC is used globally to date all kinds
of observations in astronomy, geodesy, meteorology, space
technology; and it is widely taken as the time base for
computers. The previous time scale definition that lasted
for more than 50 years was that of UT, defin
bit
surprising that most average citizens oppose such a change.
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to
anything in contemporary documents.
The history is tangled, but none of it matters except to historians.
I think that 1974 is just a typo for 1964; I do not see any error
in the history.
Michael Deckers.
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can only say
something about TAI - UTC for TAI on or after 1972-01-01T00:00:10, but
nothing (correct) for smaller values of TAI.
Michael Deckers.
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close to UT2 was an enormous help.
But of course passion can't be replaced by anything else.
Maybe money?
I do not see which point you want to make here.
Michael Deckers.
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at:
[rsta.royalsocietypublishing.org/content/369/1953/4131.full.pdf]
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of durations), but it also makes many
meaningless operations possible (such as subtracting
a sedimentation rate from a clock reading).
Michael Deckers.
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researched, reliable account of the history
of UTC and other time scales, based on the primary sources.
It is the result of an enormous labor in extracting the facts
from a mixture with myth and hearsay.
Michael Deckers.
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institutes to TAI
are independent from the UTC(k) and are denoted by TA(k) in
Circular T by the BIPM. The recommendation explains it as:
TA(k): Atomic Time-scale, as realized by the institute “k”;
Michael Deckers.
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(as used in
satellite dynamics) is a different value altogether, namely
d(TCG)/d(UT1)·(86 400 SI seconds) at the geocenter. Neither
quantity is used as a unit to express UT1; instead, both
are derived from expressions of UT1, TAI, and TCG in SI units.
Michael Deckers
of the quantity; any extra
information on the nature of the quantity should
be attached to the quantity symbol and not to the
unit symbol.
Reference:
[SI brochure 2006]:
http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf
Michael Deckers
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
. And this makes the entry
in column 5 for the date 1582-10-04 incorrect.
Michael Deckers.
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to recorded history yet.
Or you mean a year before 1960 but then it is not clear to me
which time scale you use for determining the years (instead
of UTC) and which to measure their lengths (instead of TAI).
Michael Deckers.
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On 2012-01-21 23:27, Poul-Henning Kamp remarked:
This is not a current standard C interface, this is *new*
C interface that does it right.
Ooops, sorry! I overlooked that.
Michael Deckers.
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or perl or..
functions to get current UTC.
Thanks!
Michael Deckers.
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it into Standard C will be hard
-- it has been tried on several
occasions without success.
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as.
To set the scale, the finest resolution possible with
the time of day register in IBM zArchitecture machines
is 2^-52 µs =~ 0.2 zs, which is 3 orders of magnitude
below your proposal.
Michael Deckers.
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information
networks and in programming interfaces. Having both guides
could make the decision in 2015 even more rational.
Michael Deckers.
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, PTB, is quoted
as being in favor of a continuous civil time
without leaps, but not under the name UTC.
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is not physically
realized? And why is TAI not suitable for dissemination
even though TAI - 35 s apparently is? This is all
sheer nonsense.
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tall enough to be lopped off?
The document says that spectrum utilization is an important
concern of ITU-R. No wonder they care so much about
the 10..100 nHz band with all that leap second cross talk!
Michael Deckers.
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-- eg, when UTC was 2008-12-31T23:59:60 (beginning of a
positive leap second), UTC[Google] was 2008-12-31T23:59:59.
I have never seen an equally clear statement for
the value of type time_t to be returned by POSIX calls
of time(), even with parameters left unspecified.
Michael Deckers
.
Michael Deckers.
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and d(TAI) of TAI.)
Michael Deckers.
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decisions.
Michael Deckers.
NB. Having studied several papers of Dr Felicitas Arias, I am sure that
my critique does not apply to her position and her writings.
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..and chaired by list members is announced in
http://data.iers.org/products/2/14839/orig/message_191.txt
(Sorry iff this has already been posted here.)
Michael Deckers.
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http
? And this
document bears the logo of the BIPM and is signed by its director!
Michael Deckers.
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values as an option.
Michael Deckers.
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with second field values = 60.
However, I have never seen that notation being applied in
practice in Germany, not even by the PTB. Has it ever been
used on a perceivable level in Denmark?
Michael Deckers.
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for UTC + 2 h, ...).
Thanks.
Michael Deckers.
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technical issues have been raised in the
discussion about this matter that I am wondering whether
the ITU-R people may still be aware of the importance of their
decision: they are going to revise the agreement of 1884.
Michael Deckers
etc is misleading, in my
opinion.
Michael Deckers.
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to be based on the 1992 Supplement. A more current and
freely available description is in Kaplan's excellent summary at
[http://www.usno.navy.mil/USNO/astronomical-applications
/publications/Circular_179.pd].
Michael Deckers
never added to the SI, nor will they ever be. One of the
principles of the SI system is to have one and only one unit per
dimension, or at least, per quantity. And the BIPM try very hard,
even in the presence of °C and K, Hz and Bq and rad/s, Sv and Gy.
Michael Deckers
the method of its fundamental reproduction.
This will doubtless happen to the second in due time, as it will
happen within a few years for kg and A, probably for K, and
possibly also for mol.
Michael Deckers.
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kept UTC?
Michael Deckers.
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time scale, for example, you prohibit
correct comparison of timestamps with nanosecond precision during
positive leap seconds. This is the typical design inconsistency
that can cause implementation errors and, ulitmately, viruses.
Michael Deckers
details and I hope this comment is
still not too abstract.
Michael Deckers.
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during 1995..1998.
Michael Deckers.
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of UTC?
Finally, if I want to know where I am after 86 400 s,
I would use an inertial coordinate system for time and space --
the rotating geoid with UTC or TAI is not (part of) one of those.
Michael Deckers.
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to
a formal review by the ITU working group.
Michael Deckers.
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on this incoherence: the rate of UTC is a fundamental
vehicle for synchronization and is used as such in
innumerable applications, while the phase is erratic.
The suspicion is that a less erratic phase would not
hurt as many applications as the incoherence could.
Michael Deckers
scribblings.
To put it in provocative terms: we (eg, the people on this list)
do not agree on what a world-wide civil time scale should
accomplish. I think we do not even agree on what a quantifiable
time scale really is.
Michael Deckers
and future,
for any timescale, and for fairly arbitrary resolutions (just
resolutions 1 year are not (yet) possible);
+ it has been adopted widely in the computer arena.
Michael Deckers.
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]. The new name denotes a
new concept, the old concept has retained its name.
Michael Deckers.
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the current
draft revision of TF.460 indicate that it does not try.
Yes, you are of course right. My point is that even UT1
does not try. Sidereal time is no longer an affine
function of UT1.
Michael Deckers.
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.
Since sidereal time is still well-defined (based on both UT1 and
TT), any definition of a mean sun could resurrect mean solar time
in the original sense, if desired. For the time being, it would not
deviate appreciably from UT1 (because that's how UT1 was redefined).
Michael Deckers
an approximation of UT1.
Michael Deckers.
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matter, in my opinion. So this might be the real
terminological challenge: we need a new name for the time
scale defined in the way that UTC currently is.
Michael Deckers.
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http
On 2010-08-09 22:17, Poul-Henning Kamp wrote:
In message4c607952.2090...@yahoo.com, Michael Deckers writes:
I am confused: there is no time scale specified in the Danish law
quoted. Do you mean that the reference in the footnote is supposed
to include the Danish text
term in math. TAI - UTC (after 1972) may then be called
a step function, which is a piecewise constant function.
Michael Deckers.
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On 2010-03-10 17:54, Steve Allen wrote:
On Wed 2010-03-10T16:05:28 +, Michael Deckers hath writ:
On 2010-03-09 17:34, Zefram wrote:
Apparently not. I'm inclined to use the phrase faux linear time.
These timescales are really encodings of UTC-wise broken-down time
with at
most 90 ns error!
Thanks for the comments!
Michael Deckers.
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