Re: UT1 confidence

2007-01-18 Thread Steve Allen
On Thu 2007-01-18T00:40:56 -0700, M. Warner Losh hath writ:
 Thus UT1 is not, strictly speaking, a form of solar time

This was the point made by Aoki et al. in 1982
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1982A%26A...105..359A
when they replaced Newcomb's expressions (which had been based on
observations of the sun) with a new interpretation of what Newcomb had
actually done.  Then in 2000 Capitaine et al.
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000A%26A...355..398C
further removed the sun from the equation.  Despite being so openly
acknowledged in the literature this deviation from solar time eluded
even Jean Meeus until around 2005; look for a pointed example in his
next book on computational astronomy.

The current expression for UT1 will do well enough for civil time
until leap seconds would have to be happening every month.
One might wonder whether, in the light of modern measurements, Newcomb
would opine that his expression was supposed to be solar time.  The
slop of a full second in UTC made the original meaning of UT1 moot,
and the geophysicists took the advantage.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
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Re: UT1 confidence

2007-01-18 Thread Steve Allen
On Wed 2007-01-17T21:47:50 -, Robert Jones hath writ:
 Does anyone know where I can find what the predicted effects of global
 warming on rotation due to weight redistribution are likely to be and the
 potential rate of change over the next few decades or centuries, perhaps
 till all the ice has gone.

In the Torino proceedings we see people who work with the IERS who
did not make the best possible short term projections of rotation.
It's less than a decade since the models of oceanic circulation became
good enough that Richard Gross could demonstrate that the annual wobble
of UT2 was mostly due to ocean currents.
There are still ruminations that melting the arctic would trigger a
shutdown of the north Atlantic currents that convey heat north and
thus precipitate an ice age.

I'd love to see this prediction, too, but I would not expect to put
too much confidence in it.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
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Re: UT1 confidence

2007-01-17 Thread Steve Allen
On Wed 2007-01-17T12:31:14 -0700, Warner Losh hath writ:
 It has been remarked that the current state of the art is that 100ms
 accuracy can be predicted about a year in advance only and that the
 models are constantly undergoing refinement.  It has been estimated
 that IERS could issue leap seconds, with today's technology, about 3-5
 years out and still be in a 95% or 99% band of certainty that the 0.9s
 margin is maintained.  However, I can't find papers that show these
 models or point to any better data than hearsay...

The best that I know of were the ones presented at the Colloquium that
the WP7A SRG held in Torino in May 2003.  There was a time when the
host institution (IEN) was providing the proceedings online, but the
contents of that URL went away sometime around a year ago.  (I wonder
if they may not have liked the conclusion that was reached.)

In the spirit of promulgation I provide what they once did at
http://www.ucolick.org/~sla/leapsecs/torino/ITU.shtml

The conclusion was originally a powerpoint drafted in real time, it is
http://www.ucolick.org/~sla/leapsecs/torino/closure.pdf

The indications of how well predictions of UT1 might be done are found
in three presentations to which Felicitas Arias contributed.
There are two which were powerpoint
http://www.ucolick.org/~sla/leapsecs/torino/guinot.pdf
http://www.ucolick.org/~sla/leapsecs/torino/arias_2.pdf
and one which is a more verbose writeup of one of the powerpoints
http://www.ucolick.org/~sla/leapsecs/torino/arias_3.pdf

The plots by Arias indicate how well UT1 could have been predicted
over two and three year intervals for the 40 year interval starting
around 1960.  It is based on those plots that I have voiced no
concerns for the pointing of our telescopes if leap seconds were
published five years in advance.  I'm not ready to go for ten.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: The Martian Chronicles

2007-01-15 Thread Steve Allen
On Mon 2007-01-15T08:53:19 -0700, Rob Seaman hath writ:
 Any comments on the practicality of space-rating such timepieces?

GPS uses rubidium cells, and Galileo will.
I've seen ruminations about flying a cesium resonator and an ion trap
on ISS with a goal of redefining the SI second by allowing a long term
calibration of the continually probe-able on earth ion against the
it always falls down on earth cesium.

 Also - what are the actual use cases requiring a common time scale,
 rather than establishing a separate Martian civil cesium standard and
 simply tracking the deltas?

Robert A. Nelson.
Look up his numerous presentations on a Mars version of GPS in CGSIC,
PTTI, etc., and more recently IAU in Prague
http://tycho.usno.navy.mil/IAU31/nelson.ppt
(Which, by the way, includes the calculation that deviation between
Mars coordinate time and Earth coordinate time is about 25 ms
peak to peak.)

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Introduction of long term scheduling

2007-01-12 Thread Steve Allen
On Fri 2007-01-12T18:35:55 +, Tony Finch hath writ:
 According to the slides linked from Dave Mills's Timekeeping in the
 Interplanetary Internet page, they are planning to sync Mars time to UTC.
 http://www.eecis.udel.edu/~mills/ipin.html

Neverminding the variations on Mars with its rather more eccentric
orbit, the deviations from uniformity of rate of time on earth alone
create an annual variation of almost 2 ms between TT and TDB.  This is
also ignoring variations in time signal propagation through the solar
wind when Mars is near superior conjunction.

To some applications 2 ms in a year is nothing.  From an engineering
standpoint a variation of 2 ms in a year on Mars is certainly better
than any time scale that could be established there in lieu of landing
a cesium chronometer.  To other applications 2 ms in a year may be
intolerably large.

So the question remains: At what level do distributed systems need
access to a time scale which is uniform in their reference frame?
And my question: Can something as naive as POSIX time_t really serve
all such applications, even the ones on earth, for the next 600 years?

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Introduction of long term scheduling

2007-01-06 Thread Steve Allen
On Sat 2007-01-06T19:36:19 +, Poul-Henning Kamp hath writ:
 There are two problems:

 1. We get too short notice about leap-seconds.

 2. POSIX and other standards cannot invent their UTC timescales.

This is not fair, for there is a more fundamental problem:

No two clocks can ever stay in agreement.

And the question that POSIX time_t does not answer is:

What do you want to do about that?

In some applications, especially the one for which it was designed,
there is nothing wrong with POSIX time_t.  POSIX is just fine to
describe a clock which is manually reset as necessary to stay within
tolerance.

There are now other applications.
For some of those POSIX cannot do the job -- with or without leap seconds.

Yes, there is a cost of doing time right, and leap seconds are not to
blame for that cost.  They are a wake up call from the state of denial.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Introduction of long term scheduling

2007-01-05 Thread Steve Allen
On Fri 2007-01-05T21:14:19 -0700, Rob Seaman hath writ:
 Which raises the question of how concisely one can express a leap
 second table.

Gosh, Rob, I remember toggling in the boot program and starting
up the paper tape reader or the 12-inch floppy disc drive, but now
I'm not really sure I understand the need for compactness except in
formats which are specific to devices with very limited capacity.
I routinely carry around 21 GB of rewriteable storage.  It's
hard to imagine that the current generation of GPS receivers
has less than 100 MB and I expect that by the time Galileo is
flying it will be routine for handheld devices to have GB.

I would much prefer to see the IERS produce a rather verbose,
self-describing (to a machine), and extensible set of data products.
Devices which prefer a more compact version are free to compile the
full form into something suitable and specific to their limited needs.
Most devices will be satisfied with only the leap second table.

A leap second table in a working format is just one form of the
navigator's log containing information for the conversion of the
ship's chronometer to and from other, more universal time scales.
Leap seconds are step functions, but in general the chronometer
offsets are likely to be splines of higher order.
That's something which might benefit from having a well-defined
API and a number of examples of code which uses the information
to varying degrees of accuracy.

Some devices will never have clocks guaranteed to be set to within a
second of real time, and for that purpose the POSIX time_t API is
just dandy.  Other applications with access to other time sources
will want to use algorithms of more sophistication according to
their individual needs.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Introduction of long term scheduling

2007-01-01 Thread Steve Allen
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 year scheduling.

For reasons never explained publicly this notion was shot down very
early in the process of the WP7A SRG.  It would almost certainly
exceed the current 0.9 s limit, and in so doing it would violate the
letter of ITU-R TF.460.

The IERS may not be a single entity so much as a confederation of
organizations competing for scientific glory and using the umbrella to
facilitate funding from each of their national governments.  Even if
the IERS were monolithic they would have to obtain approval for such a
change from the ITU-R, IAU, IUGG, and FAGS.  Given the tri/quadrennial
meeting schedules it seems unlikely that the IERS could obtain
approval much before year 2010.

 Maybe we can turn this question round.  Suppose the decision was made
 to simplistically schedule a positive leap second every 18 months for
 the next decade, what would be the effect of the likely worst case
 error?  First, what could the worst case error be?

McCarthy pretty much answered this question in 2001 as I reiterate here
http://www.ucolick.org/~sla/leapsecs/McCarthy.html

 As Rob has pointed out recently on the list, 1 second in time equates
 to 15 seconds of arc in right ascension at the celestial equator for
 telescope pointing.
...
 For the professionals I'm not so sure but

Give us a few years of warning and I think we can cope.  No telescope
I know uses ICRS, we're all still using FK5 and/or FK4.  That means we
astronomers already know (or at least ought to know *) that we all
have to do a software update.

 For celestial navigation on the Earth, a nine second error in time
 would equate to a 4.1 km error along the equator.  Worth considering.

The format of the almanacs would be changed along with the change
in UTC such that by including one more addition there would be
no worse error than now.  This would be a change much smaller in
magnitude than what the Admiralty did in 1833.

 Is it really likely to be a problem, though?

I think not.  It's hard to prove not.
None of the agencies involved has the funding to mount a survey
which would motivate all affected parties to investigate.

(*) While standing near the UTC poster at ADASS I was accosted by a
software engineer whose PI had instructed that all observation times
be reduced to heliocentric UTC.  Upon discussion it became clear
that the PI had not clearly distinguished between heliocentric and
barycentric.  Furthermore, there was no concept that UTC is only
defined at the surface of the earth and that the only suitable time
scales are TCB and TDB.  (TDB would be the natural result because
ticks along with UTC and because that's what the JPL ephemerides use.)
The need for pedagogy never ends.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Introduction of long term scheduling

2007-01-01 Thread Steve Allen
On Mon 2007-01-01T19:29:19 +, Poul-Henning Kamp hath writ:
 McCarthy pretty much answered this question in 2001 as I reiterate here
 http://www.ucolick.org/~sla/leapsecs/McCarthy.html

 What exactly is the Y axis on this graph ?

Only McCarthy can say for sure.
Maybe someone elsewho was at the GSIC meeting could give a better idea.

My impression is that McCarthy generated a pseudorandom sequence of
LOD values based on the known power spectrum of the LOD fluctutations
and then applied the current UT1 prediction filters to that to see
how wrong UT1-UTC was likely to get.  I suspect it was a rather
back of the envelope kind of calculation that was not repeated
because the notions of scheduling that it posited were shot down.

As a routine matter of operation the IERS would undoubtedly want
to put some effort into verifying that new software for making such
predictions was well reviewed and tested.

Oh, and the lawyer in me just asserted a loophole in my previous post.

One could say that it was never possible for the BIH/IERS to guarantee
that its leap second scheduling could meet the 0.7 s and then later
0.9 s specification because they could not be held responsible for
things that the earth might do.  As such the IERS could conceivably
start unilaterally issuing full decade scheduling of leap seconds and
claim that it *was* acting in strict conformance with ITU-R TF.460.

In civil matters this is the sort of action which would later be
tested in court if it were found to have adverse effects.  In the
matter of earth rotation it seems unlikely that there could be any
penalties, and if there were a general consensus that this be the
right thing to do then the IERS could probably act with impunity in
advance of official approval from all agencies.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Introduction of long term scheduling

2007-01-01 Thread Steve Allen
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?

Upon looking closer I see a 200 year periodicity in the plot.
I begin to suspect that rather than run a pseudorandom sequence of LOD
based on the power spectrum he instead took the past 2 centuries of
LOD variation around the linear trend and just kept repeating those
variations added to an ongoing linear trend.

I suspect that the divergence of the one line indicates that the LOD
has become long enough that 1 s can no longer keep up with the
divergence using whatever predicted interval he chose.  I suspect that
the chosen interval was every three months, for it is in about the
year 2500 that the LOD will require 4 leap seconds per year.

As for the other questions, McCarthy had been producing versions of this
plot since around 1999, but the published record of them is largely
in PowerPoint.  Dr. Tufte has provided postmortems of both  Challenger
and Columbia as testaments to how little that medium conveys.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: A lurker surfaces

2007-01-01 Thread Steve Allen
On Tue 2007-01-02T01:48:26 -0500, John Cowan hath writ:
 Well, okay.  Does the rubberiness go down all the way?  Is a civil
 nanosecond one-billionth of a civil second, then?  If so, how do we
 build clocks that measure these intervals?

Let's not.

Let's continue the valid and agreeable notion of transmitting seconds
and frequencies based on a coordinate time scale tied to the ITRS at a
specified depth in the gravitational+rotational+tidal potential.  The
best practical implementation of such is undeniably the estimation
given by TAI.

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 up with output devices to display that.

And let's create an interface better than POSIX time_t which allows
those applications which need precise time to do a good job at it.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: A lurker surfaces

2006-12-31 Thread Steve Allen
On Sun 2006-12-31T07:59:35 +, Poul-Henning Kamp hath writ:
 Rob, If you feel uncomfortable with calling leapseconds
 discontinuities, then we can use the term arrhythmia instead.

The point of my allegory about unplanned pregnancies is that
all practically available time scales have arrhythmias.
Almost everything has jumps at some point during power on self test,
and the national time bureaus (and the GPS almanac) publish their
current estimate of their deviation from regularity.  If you can
handle leap seconds, then you can handle reality.  The decision made
37 years ago was that the reality of most systems didn't/couldn't care
about seconds, and that's the part that now is getting scrutiny.

What tweaks me is that I get the impression that a lot of folks are
perfectly willing to accept those irregularities and to let Dave Mills
diddle with the rates of their system clocks so long as they never
have to admit the existence of a named leap second.  It's as if
everything is okay so long as the baby never comes to term -- everyone
can live in denial about those things going on behind the scenes --
but as soon as the county recorder gets that birth certificate with
Mr.  Astronomer named as father the social order of the world breaks
down.

I see this as a form of denial.  Almost all applications may be
capable of tolerating the level of irregularity in the currently
practically available time scales, but they are irregular.

What happens in a world with terabit per second information streams
coming over fibers from sources whose clocks, even if they are
ion-trap clocks (especially if so), are different tidal potentials
that vary diurnally?  (Of course the glib answer is that if the
optical fiber engineers do manage to notice this first then they will
win the Nobel prize just as surely as Penzias and Wilson did after
they found that cleaning pigeon shit out of their microwave horns did
not manage to make the background noise go away.)

What happens in a world where systems begin to be sensitive to the
effective leap microseconds or variations in length of seconds which
happen even if Dave Mills is conditioning their clocks?

It's my expectation that if all systems are allowed to deny the
reality of precision time keeping we will eventually find ourselves
living in a timekeeping world that resembles C.M. Kornbluth's story
The Marching Morons.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Mechanism to provide tai-utc.dat locally

2006-12-29 Thread Steve Allen
On Fri 2006-12-29T07:43:56 +, Tony Finch hath writ:
 Astronomers still count Julian
 years (365.25 days instead of exact years) when dealing with long MJD
 intervals.

Such intervals are almost always expressed in the IAU's time scale of
Terrestrial Time (TT) which is taken to be a more uniform measure than
any practically available time scale, including TAI.  As such it is a
simplification for the sake of human cognition that comes close to the
notion of year without any intent to match observable or political
reality.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Mechanism to provide tai-utc.dat locally

2006-12-29 Thread Steve Allen
On Thu 2006-12-28T18:31:43 -0700, M. Warner Losh hath writ:
 Let's turn the question around.  What would the harm be if |DUT1| were
 1.1s?  1.5s?  2.0s?  Contrast this with the harm and difficulty that
 the current 6 month scheduling window affords.

I have previously indicated that I believe this proposal is workable
even with a full decade of lookahead.
http://www.mail-archive.com/leapsecs@rom.usno.navy.mil/msg01351.html

I don't think there is much harm.  From a technological standpoint
I think we can handle it if we are given a decade of advance warning.

Because the current form could not accommodate the new magnitude it
would demand discontinuation of DUT1 signals in the broadcasts of
time, but this is not harm.  I believe that there is not one person
objecting that the broadcasts of DUT1 are being used by anyone.

For our existing telescopes at Lick, no harm.  The biggest is
literally battleship-era technology -- built by the foundries looking
for post-war reasons to keep producing large steel objects, and it
steers about as well as a battleship.  I do not believe we have any
software that would fail with larger values of DUT1.

For celestial navigation, no harm other than to require use of one
more correction in the almanacs.  The projected values of UT1 as
published in annual almanacs would almost certainly be as accurate
as the DUT1 broadcasts have been.  As seen in vol 2 of MNRAS, the
Admiralty forced worse changes of procedure on sailors 174 years ago.

For the newest telescope now being built at Lick there might be harm,
but we can't tell.  It's pointing will rely on ingesting the file
ftp://maia.usno.navy.mil/ser7/mark3.out
using software for which we will not have the source code.

This could be an issue for us and for any other agency using that
file because nobody can guarantee the formatting rules of the
file provided by USNO.  If it is being produced by Fortran then
it will fill its field widths as soon as UT1 - UTC reaches -10
seconds.  This would be a problem for interpreting software which
was relying on space separation rather than fixed-width fields.
We intend to request that the vendor rely on obtaining the data from
a file whose format is formally specified instead of hoping that
the USNO can and will continue providing that old format which is
not an official IERS data product (it predates the IERS).

But I would be uncomfortable with this proposal unless I were
to see more definitive changes in the responsibility for UTC.
The final words in the summary of the 2003 Torino colloquium were
Responsibility for disseminating UT1 information should remain
solely with IERS.
The time scale(s) in use by most of the world should not be held by an
organization which cannot openly publish the characteristics.  I think
that the ITU should not only get out of the business of distributing
UT1, but out of the time scale business altogether.

I think that the ITU-R document should restrict itself to naming a
time scale whose characteristics are entirely under the control of
another agency -- an agency which can openly publish the
specifications.  Right now the ITU-R document reads
UTC is the time scale maintained by the BIPM, with assistance
from the IERS
which makes for a very fuzzy division of responsibility.  I think all
responsibility for UTC should be delivered to IERS.  I would change
ITU-R TF.460 such that it had no annexes at all and basically ended
with the words
UTC is the time scale maintained by the IERS in conjunction
with the BIPM.
And with that in place I don't really care whether the ITU-R decides
that it is better to broadcast UTC or (TAI - n).  If the ITU-R
later deems that the external agencies maintaining those time scales
are not following rules suitable for broadcasts then they can change
the document to name yet another time scale.

In one sense this would put a great deal of responsibility onto the
IERS, but for practical purposes that is already the case.  Maybe it's
not workable for the IERS to have full responsibility; it's purely
scientific and there's no direct democratic structure.  The BIPM is
constrained by the resolutions of the CGPM and its international
structure.

But really, when it comes down to it, people are probably in general
agreement that it shouldn't be necessary to rely on either scientists
or international diplomacy to tell them when the sun is up.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


RFC 2445 and unplanned pregnancies

2006-12-29 Thread Steve Allen
On Fri 2006-12-29T09:25:33 +, Clive D.W. Feather hath writ:
 Why is this challenging? It's whichever of 23 to 29 November (inclusive) is
 a Friday.

Yes, and without bothering to patch a version of the old Tcl/Tk ical
well enough to run on what I have here, I believe that is pretty much
the way its user interface presented one option for repeating that
date annually.

Try the same thing with anything that proclaims conformance with
RFC 2445 and see if it can reproduce that Friday correctly --
a Palm Pilot, Microsoft LookOut, Novell's clone Evolution, etc.

Then produce an ical (= RFC 2445) output from one such and try
feeding it to another such.

Then read RFC 2445 and try to interpret from its rules and examples
what the correct ical snippet for that repeating date should be,
and compare it with any of the output from the above programs.

I don't think it works (and I think that is in part due to one vendor
providing a suboptimal implementation that everyone else has felt
obliged to emulate), and in that is validation of the fears of folks
who worry about the handling of leap seconds.  If something as obvious
as describing the annual repetitions of the day after US Thanksgiving
can't be implemented correctly in a non-real-time application, what
sorts of havoc might be wrought by a real-time application that is
supposed to interact with other real-time systems while handling a
leap second.

In the old days when Mr.  Astronomer was boinking Miss Quartz clock
she just wasn't able to carry a kid to term.  There were repeated
little miscarriages as the terrestrial clocks were reset, but those
left no obvious evidence.  Then Miss Quartz was replaced by Ms.
Cesium who was robustly fecund.  After an interval of fits and starts
that union started producing almost annual progeny -- a scandal, for
now the relationship was out in the open and every offspring had to be
named.  As the word got around some folks found this unacceptable.
What we're pondering is whether Mr.  Astronomer is simply going to
stop fooling around with the clocks at the BIPM, or if maybe they can
agree to use some sort protection in order to provide a less
scandalous schedule of planned parenthood.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Steve Allen
On Thu 2006-12-28T22:07:08 -0700, M. Warner Losh hath writ:
 I know the benefits, but nobody has yet produced a study on why 0.9s
 was chosen.

That's pretty easy.  In 1969 the CCIR subcommittee was preparing its
unilateral decision to switch from rubber seconds and 200 ms steps
to leap seconds.  They were disregarding the other international
scientific organizations who had called for a multi-lateral meeting
on how to deal with time and frequency broadcasts.

When the CCIR plenipotentiary voted in early 1970 their resolution
said the limit was 0.7 seconds.  When the IAU met in the middle of
that year they had no correspondence from the CCIR, so they could take
no action and provide no response to give input before the 1972 deadline.

The limit of 0.7 was somebody's idea of how well the astronomers
could do on a six month schedule given the observing techniques and
telecomm and computational means available in 1970.  Unfortunately at
that time the earth rotation was almost as slow as it has ever been,
so it seemed likely that there would have to be a lot of leap seconds,
and whoever was in charge tended to jump the gun on inserting them such
that the DUT1 value was often very close to the 0.7 s limit.
In 1973 the IAU did have standing to respond to the CCIR and recommended
0.9 s, which the CCIR then implemented despite the fact that the WWV
coding for DUT1 could not go past 0.7 s.

So the indications are that 0.7, and then 0.9 was as close as
anyone believed was possible in the early 1970s on a semi-annual
schedule.  It was a compromise then, and a few people were very,
very upset about the situation, but so far as I know no ships
ran aground as a result.  The subject of leap seconds causing
planes to crash was raised then, too, and that didn't happen
either.

This story may not be exactly right, but the existing public documents
make it seem pretty close to the truth.
Who exactly the principals were in these cases is still obscure;
some of them have died, and others have not.  Maybe the future will
have access to existing memoirs of some of the dead folks, and maybe
some of those living can be exhorted to leave their views behind.

So we don't really need a study of the history of why 0.9 because
the record of what happened and who did what when is pretty good
and that's all kindof moot for solving the dissatisfaction now.

The point of keeping DUT1 small was mainly for consistency
with existing navigation practices, and also for ease of
broadcasting that difference.  I don't think that either of
these constraints is relevant anymore.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Mechanism to provide tai-utc.dat locally

2006-12-26 Thread Steve Allen
On Tue 2006-12-26T17:10:34 +, Tony Finch hath writ:
 You should treat this kind of conversion in the same way that you treat
 local time zone conversions, which are also unpredictable.

This past year was fun in the state of Indiana as daylight time
happened for the first time ever in many counties.  I hope someone
is writing a book about that.

This next year will be fun across the US as devices which have no idea
what congress did to the daylight time dates start giving incorrect
readings from their clocks.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Hippocratic humours

2006-12-26 Thread Steve Allen
What time is it?

Given that there are basically two substantive answers to the question
and the current scheme is a compromise I'm afraid that the answers are
always going to split along lines of temperament.
http://en.wikipedia.org/wiki/Four_humours
I'll offer a crude paraphrase of the viewpoints on the issue of
knowing the interval to a date a year in the future:

It's not practically useful to predict the future to one part in 1e7.
I absolutely must know exactly how many seconds there will be until then.
I would like to be sure we have a method of agreeing when we get there.
Who cares how long it takes, the point is to enjoy the journey.

In this discussion list we never hear from the last group.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


calendrical precedent

2006-12-26 Thread Steve Allen
On Tue 2006-12-26T17:55:43 +, Michael Sokolov hath writ:
 You would have a much easier time (pun) predicting the interval in SI
 seconds to a calendar date a year in the future if you use the Republic
 of Terra Calendar instead of the Gregorian one:

I keeping with the historical precedent set 122 years ago on
http://www.gutenberg.org/files/17759/17759-h/17759-h.htm#Page_152
and the following four pages I suppose that this is separate from
the problem the LEAPSECS list was created to ponder.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Equitable estoppel

2006-12-17 Thread Steve Allen
On Sun 2006-12-17T18:48:16 +, Poul-Henning Kamp hath writ:
 But you could conceiveably argue the point, that ITU-R only controls
 time, as far as it pertains to telecommunication and radio transmission
 of time signals, and that each country is free to use another
 timescale for civilian time.

 Unfortunately, the Metre-Convention and the Longitude Conference
 has nailed your left and right feet to the floor [1], so in practice
 ITU-R gets to decide all time.

If only it were evidently that simple.  ITU-R TF.460 says the IERS
announces leap seconds, and the head of the bureau who makes such
decisions has indicated a desire to continue to do so, and the IERS
http://www.iers.org/MainDisp.csl?pid=36-25787prodid=16
says  UTC is defined by the CCIR Recommendation 460-4 (1986)
which the ITU-R has already superseded twice with no indication
that the IERS intends to heed any updated version.

The BIPM says
http://www1.bipm.org/jsp/en/ViewCGPMResolution.jsp?CGPM=15RES=5
that UTC gives an indication of mean solar time, which it can only do
using leap seconds.  The Metre Convention authorizes the BIPM as one
of the three agencies who have a say in these matters.

I don't see those feet nailed down.  I see a gauzy web of
insubstantial constraints being held self-consistent only by the fact
that there once was consensus about how everything worked and there is
not yet consensus to overturn that.

To mix metaphors (and risk adopting Rob's tone), too many cooks spoil
the broth, possibly by pissing into it.  In this case the cook who is
recognized as the holder of UTC does have his feet nailed down by the
ITU rules which say their documents must be sold, not given away.  All
the other agencies contributing to this broth are allowed to work
openly and publish freely.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: what time is it, legally?

2006-12-13 Thread Steve Allen
On Tue 2006-12-12T09:18:57 -0400, Richard B. Langley hath writ:
 For an overview of some of the legal issues of time see GPS and the Legal
 Traceability of Time by Judah Levine in my GPS World Innovation column,
 January 2001.
 -- Richard Langley
Professor of Geodesy and Precision Navigation
and Contributing Editor, GPS World Magazine

viz
http://gauss.gge.unb.ca/papers.pdf/gpsworld.january01.pdf

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


what time is it, legally?

2006-12-11 Thread Steve Allen
Longtime readers of LEAPSECS will remember that in the wake of the
Torino colloquium we started joking about legal implications of civil
time in the absence of leap seconds.  This was before the Internet
Mail Archive started recording the content of the list, and due to
issues at USNO it was among the correspondence lost to the official
archive as well.  I have had it online at
http://www.ucolick.org/~sla/leapsecs/reductio.html

I ran across a rather lengthy article by Jenni Parrish of UC Hastings
College of Law in the Akron Law Review.
http://www.uakron.edu/law/docs/parrish36.1.pdf
It is 47 pages of legal history regarding litigation in the US (and
also a seminal case in the UK) during the advent of standard time.
It is copiously footnoted with source references.

I have not counted whether the majority of cases were about
the time of liquor sales (an issue which had been resonating
throughout the US for all of the same interval of time) or
about contractual obligations of insurers.
The bottom line is that the discussion in LEAPSECS was no joke, for
people really did engage in court cases about the time on the clock.

This history is apparently not lost to folks at NIST, for the US
senate continues to consider legislation which would explicitly
rewrite US legal time to be based on UTC (as locally interpreted)
rather than Greenwich mean solar time.  The most recent incarnation of
the bill appeared in September as S3936, and section 1406 contains the
text to make the change.  See at
http://thomas.loc.gov/cgi-bin/query/z?c109:S.3936.PCS:
(and note the trailing colon in the URL).

The bill has a lot of cosponsors as seen in the links on Thomas.
Clearly the passage of this bill would short circuit a litigation
process which the Jenni Parrish document shows to have lasted for most
of a lifetime.

To end with some fun, here's a Flash clock application
http://home.tiscali.nl/annejan/swf/timeline.swf

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


ADASS poster on UTC

2006-10-28 Thread Steve Allen
Last year at the Astronomical Data Analysis Software  Systems (ADASS)
conference a Birds of a Feather (BoF) session resulted in an
extemporaneous group formed to focus on the subjects of leap seconds
and UTC.  This year the group continued to raise awareness at ADASS
with a poster presentation.

The poster is at
http://www.ucolick.org/~sla/adass/UTCposter.pdf
It is 36 inches by 46 inches, and with the exquisite background
artwork by Pete Marenfeld it consumes 2496378 bytes.

For brevity's sake of bandwidth the 6609 bytes of text are attached.

In an attempt to harmonize with all co-authors I adopted a viewpoint
which I'll summarize as:

Yes, the sky is falling, but it has been falling for 170 years.
You should be used to it by now.  Consider it as job security.

The first reaction to the poster was Get a life.
(Got one, thanks, next?)

Subsequent reactions went so far as to demonstrate that the IAU (and
other international agencies relevant to timekeeping) have produced
resolutions and decisions which are so obscure that lead scientists
for major flight project software are unaware enough of their
implications to provide self-inconsistent directives and Interface
Control Documents to their software teams.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
Astronomical timekeeping strategies to
accommodate possible changes to UTC

Steve Allen (UCO/Lick Observatory)
Rob Seaman (National Optical Astronomy Observatory)
Peter Bunclark (University of Cambridge/Institute of Astronomy)
Mark Calabretta (ATNF/CSIRO)
Jonathan McDowell (Smithsonian Astrophysical Observatory)
Clive Page (University of Leicester)
Arnold Rots (CfA/Harvard)
Christian Veillet (CFHT)

UTC may be redefined without leap seconds.  This would significantly
affect many astronomical software systems.

No time scale has been immune to change

MNRAS vol 2, # 1, pp 11-12 (1831)

The most prominent subject of public interest, (and one that has
engaged much of the attention of your Council during the past
year,) was the proposing an amended form of the _Nautical
Almanac_.  The Lords Commissioners of the Admiralty, being
desirous that the National Ephemeris should be remodelled, so as
to meet the increasing wants and intelligence of the navy, and
also the demands of astronomers, referred the consideration of the
subject to the Council of the Astronomical Society.  A Committee
was formed, with the co-operation of the most distinguished
navigators and astronomers of the empire, and an elaborate Report
drawn up, recommending various alterations and additions.  This
has been approved of by the proper authorities; and the _Nautical
Almanac_ of 1834 will appear in strict conformity with the plan
advised.

The most important _alteration_ is the substitution of _mean_ for
apparent solar time in all the data of the Ephemeris.  It was with
considerable reluctance, and after viewing the subject in every
light, that the Committee resolved upon this material departure
from the mode adopted by Maskelyne, and rendered familiar by the
practice of more than half a century; but, as chronometers are to
be found in perhaps every ship which relies upon astronomical
means for her guidance, and as mean time must necessarily be
obtained where chronometers are used, it was deemed safer to
dismiss apparent solar time altogether as unnecessary, and as
being a source of confusion.  The advantages, as to simplicity, of
exchanging a varying for a constant measure of duration, and of
assimilating the computations of the navigator and of the
astronomer, are too obvious to be dwelt upon; and, in the opinion
of all the naval officers present, no serious or lasting
inconvenience from the change is likely to be felt.

The Admiralty of 1831 understood the different time scales.  They
recognized a distinction between a rarely-if-ever-reset private ship's
chronometer, measuring time intervals with its log of offsets and
rates, and a public clock, continually reset by astronomy to record an
epoch.  They deemed that most navigators already had the requisite
tools for a change in time scale.

Despite objection by the IAU, the Admiralty redefined GMT by 12 hours
in 1925.

The BIH and BIPM have made adjustments to TAI since its inception,
including major changes as of 1977 and 1995.

The IAU has redefined UT (UT1) as of 1956, 1984, 1997, and 2003; TT
(TDT) in 1991 and 2000; and TDB in 1991 and 2006.

Using the language of the 1831 Admiralty, the monthly issue of BIPM
Circular T demonstrates that the best chronometers in the world are
only clocks after they compare how different they are and reset
themselves, and TT(BIPMnn

Re: 2006 WP-7A meeting summary

2006-10-26 Thread Steve Allen
On Thu 2006-10-26T16:01:55 -0400, [EMAIL PROTECTED] hath
forwarded:

After the introduction of the document the WP-7A counsellor
informed WP-7A that a preliminary document i.e.  the PDRR, could
not be circulated beyond WP-7A according to ITU-R resolutions nor
could the currently in effect Recommendation ITU-R TF.460-6, be
attached to the SRG report with an explanation of proposed changes
since all ITU-R Recommendations are only sold by the ITU-R.

Anyone care to join in an accolade to Shakespeare's Dick?
Henry VI, Part 2, Act 4, scene 2, line 76
http://en.wikiquote.org/wiki/Henry_VI%2C_part_2

Alternatively just to mope like Cassius to Brutus?
Julius Caesar, Act 1, scene 2

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: catching up, AAS and US Senate

2006-09-13 Thread Steve Allen
On Tue 2006-09-12T23:18:05 -0700, Steve Allen hath writ:
 It appears that the version as reported in the senate in July
 struck out all of section 508.  I could be wrong.

I receive word that the UTC text still appears to be in Title V, and
at the moment the link in the document seems to be named Section 2.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: leap seconds in video art

2006-08-02 Thread Steve Allen
On Tue 2006-08-01T14:05:13 -0700, Brian Garrett hath writ:
 Interesting video, though most of the mini-lectures did imply that leap
 seconds compensate for secular deceleration of the earth rather than
 seasonally accumulated differences between UTC and UT1.  Then again, anyone
 likely to watch this video will probably already understand the difference.

Having seen the way Daniel Gambis ended his presentation by donning
his hat, I can only wish that I had ended mine by donning some very
dark sunglasses.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


leap seconds in video art

2006-07-31 Thread Steve Allen
Earlier this year Felicity Hickson produced a work of art comprised of
23 seconds of statements by 23 people on the 23 leap seconds since 1972.

http://youtube.com/watch?v=GtYvSjS1jUI

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


PT Barnum was right

2006-07-06 Thread Steve Allen
In the news.google this week is a press release for a clock that
automatically tracks leap seconds.  The PR glowingly touts how the
clock traceable to NIST, so it is useful for timekeeping in all sorts
of processes that need ISO 9000 certification.
http://news.thomasnet.com/fullstory/488673
It goes on to say that the clock is always accurate to 1/1 s.

The manufacturer has more to say
http://www.control3.com/5125p.htm
For less than $20 this battery powered clock is certified by an
ISO 17025 calibration laboratory accredited by A2LA.

But the only output is a liquid crystal display, and liquid crystals
have response times around 10 ms.  That's 1/100 s, not 1/1 s.

This seems akin to all the complaints about GPS receivers which
display a time that is off by about 2 seconds.  I've never bothered
to dig on that, but my impression is that they probably also display
a position of where they were 2 seconds ago.

Finally, I've been spending a lot of time in the LA region lately.
The CBS radio affiliate in the SF Bay area broadcasts the hourly
national news spot on, and the time tone is useful for setting a
watch.  The CBS radio affiliate in the LA area very plainly is using a
time compressing/FFT pitch shifting device on the live national feed.
The time tone in LA always happens around 10 to 15 seconds after the
hour.

Sometimes system delay is unintentional, sometimes it is intentional.
Even before PT Barnum latin had a two word phrase for such products.

Somebody tell me again -- why is it thta broadcast civil time signals
need atomic accuracy?

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


independence day

2006-07-04 Thread Steve Allen
Mostly for the US residents, but in the first case for some beyond
the national borders, I relay two links of interest.

In response to a document created by its Division of Dynamical
Astronomy the American Astronomical Society has formed a committee to
make recommendation to the ITU-R.
http://www.aas.org/policy/LeapSecondCommittee.html
They solicit input before making their recommendation to the AAS council.
Input is requested prior to 2006-09-15.

In the middle of May some text about legal time in the US was
introduced into a US Senate bill regarding funding for NSF and NIST.
See section 508 of S.2802 introduced 2006-05-15, e.g.
http://thomas.loc.gov/cgi-bin/query/z?c109:S.2802:
(note that the final colon in the URL is relevant)
This bill is currently awaiting amendments as seen in
http://thomas.loc.gov/cgi-bin/bdquery/z?d109:s.02802:

The language seeks to redefine the national time standard from GMT to UTC.
Language like this was introduced in 2002, but the bill was killed.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


leap seconds in art

2006-06-23 Thread Steve Allen
Artist Felicity Hickson created a documentary of 23 people speaking
for 23 seconds each.  Its show debuts today in London, um, Kensington.

http://www.communication2006.com/content/au/35.php

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: building consensus

2006-06-01 Thread Steve Allen
On Thu 2006-06-01T08:09:22 -0400, John Cowan hath writ:
 Some do, some don't, some couldn't care less.

It deserves to be noted that last year at the GA in India URSI
Commission J decided that it couldn't care, and discontinued its
working group on the leap second.

http://www.ursi.org/J_BusRepGA05.doc

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: building consensus

2006-06-01 Thread Steve Allen
On Thu 2006-06-01T06:25:39 -0700, Tom Van Baak hath writ:
  UT1 et al are not really measures of time, but of angle (of Terran
  rotation).

 To some degree yes, but don't they also include minor
 corrections (polar motion, longitude, etc.) and so at one
 level they already depart from raw angle measurement
 and instead are trying to act like clocks?

Yes.  It is ironic that UT1 and UT2 were introduced in hopes of
getting timeservices worldwide to finally start broadcasting time
signals that agreed, but that because the observatories feeding the
data to the broadcasters would not abandon the self-inconsistent
values for their conventional longitudes (c.f.  Janssen and Newcomb
at the 1884 IMC) the signals did not start to agree until coordinated
cesium clocks were in use.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


dysfunction or dereliction?

2006-04-28 Thread Steve Allen
On March 21 the branch of the IERS at l'Observatoire de Paris
issued Bulletin D 93, visible at
http://hpiers.obspm.fr/iers/bul/buld/bulletind.dat
which says, in brief, that starting 27 April 2006, 0h UTC
the value of DUT1 = +0.2 s.

The US broadcasts on WWV and WWVH now have two double ticks.
That's good for NIST.

Things are not so good at the US Naval Observatory.

The usual Thursday copy of IERS Bulletin A, Vol. XIX No. 017,
came out on April 27
http://maia.usno.navy.mil/ser7/ser7.dat
and it says
 DUT1= (UT1-UTC) transmitted with time signals
 =  +0.3 seconds beginning 01 January  2006 at  UTC
Which is to say, USNO did not assimilate Bulletin D.

Look for it quickly, for they may rewrite web history.

This is not the first time something like this has happened.
After IERS Paris issued Bulletin C 30 on Monday 2005-07-04 there was
a disagreement between two files issued by the USNO on July 7.
ser7/ser7.dathad the leap second.
ser7/finals.data did not have the leap second.
This was quietly fixed before the end of Friday July 8.

I've used this word before, and I'll use it again,
the IERS is dysfunctional.

There are international agreements which are apparently being
implemented with techniques that have not changed since someone had to
punch a new Hollerith card, hand insert it into the deck, and
re-submit the batch job.  This is not a system of the 21st century.

In this case I suppose it would take a judge advocate to tell whether
this lapse by the USNO reaches to the level of dereliction of duty,
but I don't think that failure to follow prescribed procedures on the
part of the USNO justifies the abandonment of leap seconds.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: ideas for new UTC rules

2006-04-14 Thread Steve Allen
On Fri 2006-04-14T09:43:45 +0200, Poul-Henning Kamp hath writ:
 If you put a provisional table of leapseconds into your products and
 reality turns out differently, who is liable for the discrepancies ?

It's a good question.  My immediate response is that my notions are
also part of the
Full Time-Scale-Aware Lawyer Employment act of {YA}

 If you add 10 more leapsecond opportunities per year you will
 decrease reliability of the provisional table, compared to if
 there is only two opportunities per year.

The motivation is that allowing ten more per year requires action on
the part of all systems to upgrade anything which now believes only
June and December (and they get ten years of notice to do so).  More
importantly, it allows the IERS to react better to any surprises in
decadal fluctuations of LOD.

I should add one more culturally-derived defense of a possible problem.
The DUT1 signals which only allow as much as 0.7 or 0.8 s of
magnitude.  What sorts of applications will be affected by that?

Paraphrasing Westly in the fireswamps of The Princess Bride
DUT1 signals?  I don't think they exist.
Well, I don't think anyone uses them.  If there are still many
applications for DUT1 signals, most likely they are for sextant-style
navigation.  If the leap seconds are being predicted five years in
advance then the annually published navigation almnacs can incorporate
projections which are as good as the broadcast signals.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: ideas for new UTC rules

2006-04-14 Thread Steve Allen
On Fri 2006-04-14T19:39:31 +0200, Poul-Henning Kamp hath writ:
 In message [EMAIL PROTECTED], Steve Allen writes:
 It's a good question.  My immediate response is that my notions are
 also part of the
 Full Time-Scale-Aware Lawyer Employment act of {YA}

 I don't want us to adopt anything that makes that necessary.

My apologies for unfortunate timing on my joke.
Only hours ago did I learn of the recent problems with D-Link routers.

http://people.freebsd.org/~phk/dlink/

and the media coverage at

http://yro.slashdot.org/article.pl?sid=06/04/07/130209
http://news.bbc.co.uk/1/hi/technology/4906138.stm

which hearks back to the older similar problem with NetGear

http://www.cs.wisc.edu/~plonka/netgear-sntp/

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


1884 IMC online

2006-02-19 Thread Steve Allen
A few years ago Joseph S. Myers of Cambridge University went through
the trouble of scanning a copy of the proceedings of the 1884
International Meridian Conference, and I put the TIFFs online
http://www.ucolick.org/~sla/leapsecs/scans-meridian.html

I have just been alerted that Project Gutenberg has just finished
checking its transcription of the document into fully machine readable
and searchable form.
http://www.gutenberg.org/etext/17759

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Ambiguous NTP timestamps near leap second

2006-02-16 Thread Steve Allen
On Thu 2006-02-16T19:12:30 +, Markus Kuhn hath writ:
   No reply from an NTP server shall ever represent any point in time
   between 23:59:60 and 24:00:00 of a UTC day. If a client requests an
   NTP timestamp and the response would represent a point in time during
   an inserted leap second, then this request shall be ignored.

Minor point, I think it has to read more like this

between 23:59:60 of a UTC day that ends with a positive leap
second and 00:00:00 of the subsequent UTC day.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Risks of change to UTC

2006-01-23 Thread Steve Allen
On Mon 2006-01-23T11:08:29 +, David Malone hath writ:
 As far as I can see from my 1992 edition of the Explanatory Supplement
 to the Astronomical Almanac, UT1 and GMST were (defined?)

 the relationship seems to have been changed to ones documented in
 (Capitaine et al., 2000, Capitaine et al., 2003, McCarthy and Petit,
 2004). They say that that This relationship was developed to
 maintain consistency with the previous defining relationship, but
 I think this probably means that they were stitched together in a
 smooth way, not that they are identical.

The explanatory supplment is a place for revealed truth.
The underlying process is only evident in the literature and reading
between the lines of the reports of the triennial IAU General
Assemblies.  May I not so humbly suggest looking at

http://www.ucolick.org/~sla/leapsecs/timescales.html

for a slightly explained version with links to most of the
papers and dates of changes.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: the tail wags the dog

2006-01-23 Thread Steve Allen
On Mon 2006-01-23T14:02:01 +, Clive D.W. Feather hath writ:
 Steve Allen said:
  The official time of the US for commerce and legal purposes is UTC(NIST).
  The official time of the US DOD is UTC(USNO).

 The official time of the UK is GMT.

Please distinguish between official and legal.

The legal time of the US is (in many more words) GMT.
The officials who are charged by congress with the task of providing
time provide UTC.

The situation is exactly the same in the UK.
http://www.npl.co.uk/time/truetime.html
http://www.npl.co.uk/time/msf.html

I reiterate that the tail wags the dog.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: the tail wags the dog

2006-01-23 Thread Steve Allen
On Mon 2006-01-23T09:33:10 -0700, M. Warner Losh hath writ:
 (the term mean
 solar time isn't legally defined, but does have an accepted scientific
 meaning).

Would that it were so, but I don't believe it because I've read the
proceedings of the IAU general assemblies and related papers.  I've
seen the arguments which arose when it became clear that Newcomb's
constant of aberration was distinctly wrong, and about the Fictitious
Mean Sun and whether that concept needed to be revised to distinguish
it from the Fictitious Mean Apparent Sun.

The concept of using a single expression for calulation of mean solar
time worldwide was meant to solve the telecommunications problem of
scheduling telegraphic communications across the trans-oceanic cables
which were first laid in the 1860s and 1870s.  To that end, one second
was plenty good.  It was still plenty good in the manually-keyed radio
age of 1918 when the US Calder act originally specified mean
astronomical time as the legal time.

Science is a process, as are technology and law.
The processes are not perfect; they do not have good foresight.
The accumulated oh wow, look at that, how about this?,
let's just do that has resulted in the kludge on a hack set of
time distribution schemes upon which we ruminate.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Fixing POSIX time

2006-01-19 Thread Steve Allen
On Thu 2006-01-19T19:00:27 +, Markus Kuhn hath writ:
 Please remember that the TAI second differed noticeably from the SI
 second until about 1998, because black-body radiation shift was not
 taken into account in the definition of TAI before then. Also caesium
 fountains have improved quite a lot shortly before 2000.

True, but not really relevant.

What is important for society at large is to have a time scale upon
which we can all agree, and to have it available in as near to real
time as possible.  The fact that there have been deficiencies in the
rate of TAI is only relevant to radio observatories observing pulsars
and comparing those pulse timings with their own atomic clocks.
In that sense there will always be a need for retrospective revision
of the true meaning of the time scale which was conventionally available.

If you want to have a time scale which extends far into the past, you
only have a choice of UT and TT.  UT is that which people knew from
looking at the shadow of sticks in the ground.  TT is that which
historians and astronomers can deduce from records of eclipses.

Starting with the IMC in 1884, UT was the time scale upon which
everyone could agree (although it did not achieve agreement on that
name until half a century later).  Starting with the almanacs in 1901,
Newcomb's expression for UT was the one on which everyone could agree.
Within a few years of that, radio broadcasts became the best way to
disseminate the agreeable time.  As such, it became admissable to
have only one entity which could be called the agreeable time.

As the BIH intercompared radio broadcasts it became evident that
different sources of UT disagreed because of factors both constant and
variable.  Thus in 1955 came the agreement to name UT0, UT1, and UT2
and to use the most uniform one as the basis of civil time.  But
agreement only existed ex post facto (by at least months) in the
publications of the BIH.

At the same time came the cesium resonator which quickly proved that
it was a better way to achieve agreement on what time it was.  Adding
in the transistor and telecom revolutions made intercomparisons much
easier, and so for technical purposes the BIH's TAI became a time
upon which everyone could agree.  Handing the control of UTC over to
BIH let them resolve the conventional longitude problem and finally
coordinate agreement at the sub-millisecond level.  But the manner in
which TAI is agreeable is as much political as technical, for it is
maintained by a club of those who pay their dues to the BIPM and
follow the BIPM rules by buying the right equipment.

The question that the ITU-R is asking is what is the character of the
one agreeable time which will be broadcast.  That is undeniably an
important concept for navigation and commerce, but it is based on a
specific notion of coordinate time.  As the ability increases to
notice that my proper time progresses at a different rate than your
proper time, it becomes possible to question whether it is relevant to
admit that different applications may want to agree on different kinds
of time.

No matter whether leap seconds persist or cease, the nature of the
agreeable time scale which is most conventionally available is going
to change.  The best that a computer representation can do is to be
flexible enough to admit as much in the footnotes of its
documentation.  Aside from that it seems important not to over-specify
the interpretation of the underlying time scale.

To that end, examine GPS itself.  The only thing its time scale
acknowledges is week number and second-of-week.  The signal itself
does not presume anything about the conventional calendar scheme
to which that time will be converted, not even to the point of
pre-supposing the Gregorian calendar.  Yes, there is a field
for counting leap seconds, so the signal does acknowledge that
the earth rotates and that people are interested in knowing how
far it has rotated.  Until this point in history, that has been
fundamental in the notion of what we mean by the agreeable time.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Problems with GLONASS Raw Receiver Data at Start of New Year

2006-01-17 Thread Steve Allen
On Tue 2006-01-17T18:26:49 +0100, Poul-Henning Kamp hath writ:
 As far as I recall GLONASS was messed up for hours on the previous
 leapsecond, so there is a good chance it is because of the leap
 seconds that it fell out this time.

Not according to the Russians:

http://www.glonass-center.ru/1999_1e.html

There was a NAGU at the time of the mid 1997 leap second

http://www.glonass-center.ru/1997_7e.html

but the text clearly indicates it was not because of the leap second.

Of course the Russian GLONASS operators could be in denial about leap
second issues.  They wouldn't be the only ones with that condition.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: The real problem with leap seconds

2006-01-11 Thread Steve Allen
On Wed 2006-01-11T09:01:07 -0500, Daniel R. Tobias hath writ:
 If, however, this Martian second is actually defined as a particular
 multiple of the SI second, then the use of leap seconds on Mars would
 ultimately be necessary to account for any future changes in the
 length of the Martian day.

The martian second in their case is defined purely for the sake of the
local solar time of the solar powered rovers which are effectively
stationary on the planet.  Something akin to the long-used Newcomb
expression for mean solar time is more than sufficient.  In that
respect the rovers are sundials.

The mission clock on the lander has a more uniform time scale used for
the sake of such things as the cool photos of the martian moons
transiting the sun.

Leap seconds for Mars seem irrelevant until there are VLBI antennae on
Mars performing routine observations.  The atomic clocks used by such
VLBI antennae will not, however, keep synchronized with earth using
anything less than a fully general relativistic expression for the
intercomparisons.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: interoperability

2006-01-09 Thread Steve Allen
On Mon 2006-01-09T08:20:40 +0100, Poul-Henning Kamp hath writ:
 beginning (SI seconds are constant length).

Yes, SI seconds are constant length, but the ghost of my general
relativity teacher prompts me to assert that my SI seconds are not
equal to your SI seconds because we are in different reference
frames.

The rate at which TAI ticks has been modified several times to meet
improved notions of whose SI second it should really try to match.
The current notion is that of a coordinate time scale at a depth in
the geopotential field which is close to mean sea level.

Such a coordinate time scale cannot be extended very far from the
surface of the earth without requiring some fascinating corrections
to the rates measured by different observers.

Tom Van Baak can show you how measuring this is now child's play.

Why should my lab use TAI when the proper time experienced by my
real-time control processes runs at a different, and continually
varying, rate?

The answer is the same as for UT defined by Newcomb's expression used
from 1901 through 1983 and implemented via astronomy: it is the most
practical uniform time scale that we all can agree upon.

For current purposes with stationary clocks the varying terms in the
rate differences are immeasurable.  In the limit of very precise lab
timekeeping eventually the question arises as to whether TAI really is
the most suitable scale for some applications.

(This has nothing to do with leap seconds, but does raise the question
of the limits at which it becomes much more difficult to agree on time.)

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: The opportunity of leap seconds

2006-01-08 Thread Steve Allen
On Sun 2006-01-08T12:41:21 +0100, Poul-Henning Kamp hath writ:
 It sounds to me like BIPM ought to make an Internet service available
 which will deliver UT1 to astronomers in a timely fashion ?

That would have to be the IERS.

 Something as simple as

 finger [EMAIL PROTECTED]

 Or even just a more stringent formatting of the bulletins on the ftp
 site could do it as well.

I do not believe that any of the IERS bureaus have internet
connections and servers which are anywhere near robust and redundant
enough to make that a reliable service.

There is a lot that could and should be done.

The USNO branch of the IERS issues two files with predictions about
earth orientation every Thursday.
It is not widely known that last July on the Thursday following the
Daniel Gambis announcement one of those files acknowledged the leap
second we just experienced, and the other did not.
This was fixed with a new release which happened by Friday.

(Despite some NTP servers which reportedly still have not acknowledged
the leap second, I think the overall indications are that the NTP
network did better than 50 %.)

The existing IERS system is dysfunctional.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: The real problem with leap seconds

2006-01-08 Thread Steve Allen
On Sun 2006-01-08T11:44:04 -0700, M. Warner Losh hath writ:
 How is it that UTC can be realized in realtime, but TAI isn't.  I
 thought the difference between the two was an integral number of
 seconds, by definition.  Is that understanding flawed?

I believe the claim would be that UTC(insert your national time
service here) is realized in real time.  UTC(USNO) is the official
time of the US, and I suspect that there would be loss of face if
any agency charged with keeping a national time did not, in some
sense, proclaim autonomy.  UTC(pick one) is, of course, directly
related to TAI(pick one).

TAI(anywhere) has no official status anywhere, except in the ex post
facto statistical sense that it contributes to TAI (unmodified, the
real thing from the BIPM).

In an official sense of operational time scales, it is not clear that
there really is anything such as UTC (plain old, unmodified) which
differs from TAI by an integral number of seconds.  As an identifiable
entity, UTC (unmodified) may only exist within the text of ITU-R
TF.460

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: The real problem with leap seconds

2006-01-07 Thread Steve Allen
On Sat 2006-01-07T07:39:58 +, Michael Sokolov hath writ:

 http://ivan.Harhan.ORG/~msokolov/articles/leapsecs.txt

If I read it right you have reinvented Markus Kuhn's UTS as seen in

http://www.cl.cam.ac.uk/~mgk25/uts.txt
http://www.cl.cam.ac.uk/~mgk25/time/leap/
http://www.cl.cam.ac.uk/~mgk25/time/leap/utc-torino-slides.pdf

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: The real problem with leap seconds

2006-01-07 Thread Steve Allen
On Sat 2006-01-07T21:20:33 +0100, Poul-Henning Kamp hath writ:
 You can find locate your countrys ITU-R representative and contact
 them with your input, just as well as I can for mine.

You can try that, and you may succeed, but it is deceptive to assert
that is easy to do.

In the US the process is Byzantine.  Whereas it is apparently required
that draft contributions to the ITU be publicly available, it is
apparently not required that their availability be published outside
of predefined special interest groups.  I would describe more of what
I know, but given that my knowledge is assembled from little bits
gleaned from unrelated documents I'm not convinced I am right.

If anyone else cared to challenge me to post the rules of some other
nation I'll gladly rise to the challenge and post the US rules.

 There is nothing hidden, undemocratic or revolutionary about it.
 The ITU _process_ does actually work.

Agreed, you just have to be prepared to play the Byzantine games.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Defining our terms (was Re: [LEAPSECS] Longer leap second notice)

2006-01-06 Thread Steve Allen
On Sat 2006-01-07T00:32:44 +0100, Poul-Henning Kamp hath writ:
 TAI
 Owned by BIPM / Metre Convention

This is indisputably agreed to be true since the demise of the BIH.
I know of no endorsement for the use of TAI outside of metrological
circumstances.

 UTC
 UTC(time) = TAI(time) + Leap(time)

 Owned by ITU.
 IERS evaluates Leap(time) according ITU definition

Not quite.  The endorsement for the usage of UTC comes from CGPM,
and that is predicated on the existence of leap seconds.

But in the original agreement, UTC and TAI were defined solely by the
BIH according to the rules of the CCIR.  Both the BIH and the CCIR are
defunct.  TAI was transferred from BIH to the BIPM.  Determination of
the UTC offset was transferred from BIH to IERS.  But IERS is not
a single entity, it is an ensemble of entities.

The branch of the IERS responsible for the UTC offset currently
asserts that it is still following the UTC rules from the CCIR before
there was an IERS.

At the beginning of 1984 and at the beginning of 2003 the branches of
the IERS responsible for UT1 followed new IAU recommendations and
changed the rules by which UT1 is calculated.  The current version
of UT1 has a notably different flavor and long-term purpose than
the version of UT1 which was in place when UTC with leap seconds
was originally defined by the CCIR.

The whole scheme works now because there is still consensus about
the way in which the original agreements are to be interpreted.
It remains to be seen whether the gentleman's agreements which hold
this whole scheme together will tolerate a non-consensual arrangement.

 Now tell me why you think Leap seconds are so important again.

In a word, I offer psychology.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: civil time = solar time

2006-01-05 Thread Steve Allen
On Thu 2006-01-05T08:18:11 +0100, Poul-Henning Kamp hath echoed Rob:
 Which is why the longitude conference decided on a 1 hour quantum.

No, they did not.

The delegates gratuitously offered existing schemes (the US railroads
being one touted long and hard by some guy named Allen) along with
proposed schemes (one for Europe had zones on meridians spaced 10
time-minutes apart).

All of those schemes were withdrawn after being entered into the
official record.  The reasoning was that their conference could not
pretend to assert any authority over local civil time in any
jurisdiction.

Only the local civil authorities can decide what passes for local
civil time.  In the US the result of this will be seen this year as
many embedded devices start making daylight time transitions on the
wrong dates.

I remain in awe of McCarthy's indication that predicting leap seconds
might be acceptable over decade timescales.

I remain in dismay that said point is moot for embedded devices, for
the local civil authorities are more whimsical than the earth with
larger amplitude deviations at less predictable intervals.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


NTP behavior in Australia

2006-01-01 Thread Steve Allen
Here is one indication of NTP response to the presence of low stratum
servers which did not behave well.

http://members.iinet.net.au/~nathanael/ntpd/leap-second.html

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: went pretty dang smoothly at this end

2005-12-31 Thread Steve Allen
On Sat 2005-12-31T20:51:03 -0500, Keith Winstein hath writ:

 (b) Am I mistaken, or did WWV fail to correctly beep in the new year?

We had two shortwave radios going, one on  10 MHz, one on 15 MHz,
and with the two the ionosphere was pretty much tamed.
To my memory they did it all right, including the change in the DUT1
clicks, but I can check later.
At some point I will be able to put up a .wav file with WWV, WWVB, me,
and my kids.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


the principals speak

2005-12-25 Thread Steve Allen
Congrats are due to Guy Gugliotta of the Washington Post for managing to hunt
down the principals and get some words during the holiday rush.

http://www.washingtonpost.com/wp-dyn/content/article/2005/12/25/AR2005122500496.html

It is worth mentioning that in November the WP7A invited everyone to
send them reports of problems with the upcoming leap second.
They also deserve to be informed of systems which had no problems.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


I hope the Onion does even better

2005-12-25 Thread Steve Allen
Satire!

http://www.thespoof.com/news/spoof.cfm?headline=s3i9970

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: a system that fails spectacularly

2005-12-07 Thread Steve Allen
On Wed 2005-12-07T06:59:39 -0700, Rob Seaman hath writ:
 it seems that one of two things must be true.  Either the fact that
 the letter is dated December 5, 2005 indicates that they just now got
 around to acting on the July, 2005 announcement of the upcoming leap
 second - or, they acted upon this in a more timely fashion and
 decided to embargo the announcement until the latest plausible moment
 at which it would be possible for their lawyers to later argue timely
 notification of their customers.

ACR is not alone, see Saab, who announced much earlier

http://www.transpondertech.se/node1924.asp?intContentID=3197

also reported by Canada
http://www.ican.nf.net/R4update.htm

also reported by USCG
http://www.uscg.mil/hq/g-m/moa/docs/Saab505.pdf
http://www.uscg.mil/d14/units/feact/images/safety%20alert.pdf

Google is your friend.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: a system that fails spectacularly

2005-12-07 Thread Steve Allen
On Wed 2005-12-07T14:56:35 +, Markus Kuhn hath writ:
 As a general-purpose management standard, ISO 9001 obviously says
 nothing about how you have to handle leap seconds. ISO 9001 does not
 even specify any particular level of quality. All it does is tell you
 how you must document what level of quality you are producing and what
 you do to make sure it remains the same for all instances of the same
 product.

This became a long-running joke in the morris dance community.  A few
years back some English town councils decided to become ISO 9000
compliant.  That required them to ascertain that all of their
sub-contractors were also compliant.  This extended to morris sides
who were to be remunerated for dancing their traditional dances
outside pubs at town festivals.  Despite having done such for
uncounted decades, the morris side leaders suddenly had to fill out
forms describing their own quality control processes.

Most of those forms came back to the town council stained with beer
and chips.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Google news alerts condemn the ITU

2005-11-17 Thread Steve Allen
Dr. Matsakis has revealed something much more deep about the ITU
and leap seconds than he realized.

On Fri 2005-11-11T02:55:22 -0500, [EMAIL PROTECTED] hath writ:
 There is a nifty google feature that will scour the internet for news
 articles on any subject, and send you weeky, daily, or immediate
 notifications.

 Browse on http://www.google.com/alerts

 Beware- If you ask for 'leap second' you will get more than you want!

 Ask for leap second, and you will get emails like what is below.

As I mentioned, I've been scanning for news in other languages.
Until yesterday I was a bit mystified to find that searches on
the Spanish term segundo intercalar produced nothing.  Then a hint from
a Spanish weblog prompted me to try something different.

See what you get if you try this link today
http://news.google.com/news?hl=esie=UTF-8oe=UTF-8scoring=dbtnG=Search+Newsq=%22segundo+intercalar%22

However, if you try the following link today you get much more
http://news.google.com/news?hl=esie=UTF-8oe=UTF-8scoring=dq=%22segundo+adicional%22btnG=Search+News
It is evident that the Spanish language press picked up the press release from
Nothnagel at U Bonn.

It is also evident that when they translated the press release from German to
Spanish they had no idea what the canonical name of a leap second was.
They used the words segundo adicional instead of segundo intercalar.

The text of ITU-R TF.460-6 is available from the ITU in three languages:
English, French, and Spanish.  The Spanish text plainly indicates that the
name for a leap second is segungo intercalar, plural segundos intercalares.

But nobody knows this.
Why?
Because for practical purposes ITU-R TF.460-6 is a secret.

Everyone in the world is supposed to implement it in their operational
and legal systems, but it is not openly available for them to see it.

If there is blame to be had for improper implementation and use of
leap seconds it is pretty clear where that blame lies.
The same analysis probably applies to the reason why POSIX had double
leap seconds in its specification for a decade.

I agree with Andreas Bauch of the German PTB when he was quoted
recently in Die Welt
http://www.welt.de/data/2005/10/28/794936.html?s=2
but the blame for the ignorance which has contributed to sloppy software
does not belong on the programmers.

Last week the WP7A reported that they lacked consensus.
I know I am not alone in thinking that one of the first things that
WP7A needs to do is to publish ITU-R TF.460 with no access restriction.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: ABC leapsec article

2005-11-13 Thread Steve Allen
On Sat 2005-11-12T14:53:29 -0800, Tom Van Baak hath writ:
 The other 3 alerts that occasionally give interesting
 results are leapsecond, leap hour, and leaphour.

It deserves mention that scanning news for the corresponding words in
seven other languages picks up more articles, but it turns out that
aside from English it's the German speakers who seem most fascinated
by the subject.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Be thankful for John Flamstead

2005-11-10 Thread Steve Allen
On Thu 2005-11-10T10:48:29 +, Ed Davies hath writ:
 BBC article, Leap second proposal sparks row:

   http://news.bbc.co.uk/1/hi/sci/tech/4420084.stm

It should be noted that, as is typical of the BBC, the spelling error
has been corrected and there is now a biographical link to the first
astronomer royal.  The BBC are really good about correcting factual
errors on their website.  That's both archivally scary (Orwell
anyone?)  and very nice.

But in full context they also have more today:
Europe names Galileo trailblazer
http://news.bbc.co.uk/1/hi/sci/tech/4417290.stm

I think the BBC does not realize how the stories are connected.

The relevance between that and the LEAPSECS list becomes evident if
you take a really close reading of the following document.
http://tycho.usno.navy.mil/ptti/ptti2004/panel.pdf

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: US proposal to abolish leap seconds - Not Found

2005-11-08 Thread Steve Allen
On Tue 2005-11-08T10:52:21 -0700, Neal McBurnett hath writ:
 If anyone knows of a new place to find the latest proposal, please
 post it.  And does anyone know where to find an archive of the
 comments made in response to the proposal?

 In the meantime, I highly recommend Steve's excellent web page at

  http://www.ucolick.org/~sla/leapsecs/nc1985wp7a.html

 which summarizes the cogent arguments of  who disagrees with
 the proposal.

When the FCC pulled it after its expiration date I put it up as the
first link on that page.  I remain surprised that the FCC does not
have the 2005 draft contribution in its archives.

It makes sense that the comments really do belong to the USWP7A
members and the Department of State, but I can cite a reference which
says the rules are that anyone can apply to become a member of USWP7A.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


The Truth is Out There

2005-11-08 Thread Steve Allen
 and labor.  If
UTC is changed then that's part of ongoing operation and maintenance
of a system.  You just have to keep it in perspective.

After all, it's not like the world is going to come to an end.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


POSIX in the crosshairs?

2005-10-30 Thread Steve Allen
This past week both Die Welt and Die Zeit ran articles on leap seconds.
In one Andreas Bauch of PTB has an unprecedented quote

Schlampig programmierte Software ist das Problem, nicht die Schaltsekunde

( translation
Sloppily programmed software is the problem, not the leap second
although one reference offers slutty as an alternative to sloppy.
Upon reflection, I'd probably be a lot richer if I wrote slutty software.)

Of course I have already said that the root of the problem lies not so
much with POSIX itself, but with the proprietary nature of ITU-R
TF.460 which so obscured what POSIX needed to do that it contained the
concept of double leap seconds for a decade before it was corrected.

Also, this morning at 06:28 PST when I looked at my CDMA cell phone it
was telling me that it was 07:28.  It was not until I cycled the power
that it bothered to note that daylight time had ended.

Next year there should be even more chaos as a batch of consumer
products in the US with embedded code that just knows the dates of
the US daylight time transitions will fail because congress decided to
save something like 0.3% of the annual US energy budget by increasing
the calendar interval during which daylight time will be in use.
Could it be that the public awareness generated by that will interfere
with any further attempts to modify the public perception of time?

--
Steve Allen [EMAIL PROTECTED]   WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165   Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046  Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m


Mary Baker Eddy joins in

2005-10-12 Thread Steve Allen
There is now a story in the Christian Science Monitor

http://www.csmonitor.com/2005/1013/p15s01-stgn.html

Their wireservice is already spreading it elsewhere.

--
Steve Allen [EMAIL PROTECTED]   WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165   Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046  Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m


curiouser and curiouser

2005-10-05 Thread Steve Allen
Do the folks in Roanoke really wonder about leap seconds?
http://www.roanoke.com/editorials/wb/wb/xp-34869

Will things get even stranger in the eight and a half days left for
comment on the USWP7A proposal?

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


was it because of Asimov?

2005-10-02 Thread Steve Allen
The Times has a piece on the ITU process.
http://www.timesonline.co.uk/article/0,,20909-1808771,00.html

Somehow the facts got twisted.  It will not take hundreds of thousands
of years for day to become night without leap seconds.  None of that
sort of thing is news.  But more curiously, where did it become
supposed that cesium is a radioactive element and that the decay of a
radioactive element can be used in a precision timing device?

I am supposing that I will wake up to find further news that Asimov's
Mule from Foundation and Empire really is exerting telepathic control
over world leaders.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


response from Germany

2005-09-28 Thread Steve Allen
On Wed 2005-09-28T10:03:08 +0100, Ed Davies hath writ:
 The BBC web site has an article about the leap second debate:

   http://news.bbc.co.uk/1/hi/sci/tech/4271810.stm

At the end it indicates that UK DTI is creating a response.

I have no idea what branch of government creates it, but contribution
23 on the ITU website indicates Germany also has a response.
http://www.itu.int/md/meetingdoc.asp?lang=etype=sfoldersparent=R03-WP7A-C
Alas, only ITU cognoscenti get to read it for now.

The draft US document which is under consideration for submission is
available for review and still open for comment

http://www.fcc.gov/ib/sand/irb/weritacrnc/review/nc1985wp7a/01.doc

The significant difference from last year seems to be that leap seconds
would stop not in 2007 but rather five years after the ITU general
assembly approves the change.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: RAS hits the news

2005-09-27 Thread Steve Allen
On Mon 2005-09-26T10:27:11 -0400, John.Cowan hath writ:
 In addition, since GPS time is TAI - 19s, the GPS-UTC difference will
 eventually overflow any fixed-sized transmission packet (if transmitted
 as a delta or as a table, it makes no difference in the end).

Yes, but (as already mentioned) that does not preclude getting the
difference between GPS and UTC right for the immediate future (by
which I mean the expected useful life of most GPS receivers) with the
addition of a little bit of heuristic algorithm that predicts the
magnitude of the 8-bit signed Delta-t_LS as compared with the 10-bit
unsigned

Today is a big day for GPS, for the launch of the first of the next
generation of SVs just happened.
http://www.cnn.com/2005/TECH/space/09/26/rocket.launch.ap/index.html

The new GPS L2 ICD that describes the Block IIF SVs
is available via this web page
http://www.navcen.uscg.gov/gps/modernization/default.htm
under the link that reads ICD-GPS-200 Rev. C

There are two significant additions in the Block IIF signals.

6.2.5 and 20.3.3.5.1.13 indicate that bits 7 through 22 of word ten in
page 25 of subframe 5 will be a 16-bit integer giving the calendar
year (curiously it does not specify whether this is signed or
unsigned, but the Control Segment has around 14000 years to clarify
that point).

30.3.3.1.1.1 indicate that bits 39 through 51 of L2 CNAV message type
1 will be a 13-bit unsigned integer which extends the range of the
existing Transmission Week Number from 1024 weeks to 8192 weeks.
This extends the ability of a GPS receiver to tell when it is from not
quite 20 years to over 150 years, which should be longer than any GPS
receiver is likely to last.  Unfortunately, 30.3.2 indicates that
message types 1 and 2 are temporary and will be replaced by the as yet
undefined messages 7 through 9.  This no doubt will reduce the
likelihood that a GPS receiver will bother to use them.

The inclusion of calendar year is an interesting addition to the
original week-based scheme.  The week-based scheme was perhaps chosen
while noting that the week remained intact when Pope Gregory (and
then, eventually, all the protestants) switched calendars.  Thus the
GPS scheme is probably robust against anything short of adoption of
the doomed-to-fail World Calendar schemes which proposed the
intercalation of weekday-free days, but which had little hope of ever
being adopted.  As such the inclusion of calendar year does not
prohibit the adoption of new calendars with new year schemes so long
as the change is adopted with sufficient lead time to permit the
firmware in GPS receivers to be updated.

With the calendar year available, the fact is that the signed 8-bit
quantity Delta-t_LS is no longer a limitation.  It will be something
like 3 years before the combination of calendar year and
Delta-t_LS values is incapable of producing an unambiguous result.

On Mon 2005-09-26T11:26:00 -0700, Tom Van Baak hath writ:
 The other point I was trying to make is that there are
 web pages that still claim that GPS WILL FAIL on
 such and such a date because of the 8-bit leap second
 field. This sort of hyperbole is uncalled for.

Mea culpa.  I have more homework to do on my web pages to incorporate
these very details.  It remains the fact that most existing GPS
receivers will fail by around 2070 or so, but that really should not
be much of a surprise or inconvenience to their owners.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Consensus rather than compromise

2005-08-31 Thread Steve Allen
On Wed 2005-08-31T22:57:42 -0400, John.Cowan hath writ:
 Fortunately, it's not that bad.  All 365 current zones define
 their LCTs using a list of offsets from a common reference time.

The current effort to abolish leap seconds completely violates the
subject line of this thread.  There is no consensus or compromise,
there is only fiat.  We see at least the UK government unwilling to
support the change, and the official at the IERS who is accorded the
responsibility to call for leaps unwilling to support the change.

I ponder whether the current effort to redefine UTC might create a
fragmentation of practice which would violate offsets from a common
reference time and make the situation much uglier.  It is not clear
whether the pressures of economics and trade can override tradition
and national pride.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


most recent news

2005-08-29 Thread Steve Allen
For those who were not on the recipient list (I was not) the most
recent leap seconds news is the public release of a letter from P.K.
Seidelmann which was sent in July.  It was posted here:

http://igscb.jpl.nasa.gov/mail/igsmail/2005/msg00114.html

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


vive le BIH!

2005-08-26 Thread Steve Allen
Australia's change to UTC is about to happen.

http://www.guardian.co.uk/australia/story/0,12070,1556764,00.html

The most curious note is that Dr. Catchpole seems to think the BIH
still exists.  The BIH was vivisected at the end of 1987 so that the
IERS could be created and assimilate its astronomical portion.

Will the leap second misinformation never cease?

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Civil Time decision tree v0.5

2005-08-17 Thread Steve Allen
On Wed 2005-08-17T16:45:51 -0700, Rob Seaman hath writ:
 I suspect that we are all agreed that a single civil time standard
 should exist.  The question of multiplicity is one of drawing narrow
 distinctions.  Many people use devices and systems that rely on non-
 UTC time scales, for instance, GPS receivers.  Is GPS a second civil
 time standard already?

To answer other than one for a civil time standard in the vicinity of
earth would be to set the clock back to where it was before the 1884
International Meridian Conference.  Some of the point of that
conference was to produce a convention for syncronizing human activity
on the (then relatively new) trans-oceanic telegraphic cables.

 III) Locale
 A) restricted to Earth [projects or users, not necessarily
 hardware]
 B) other than Earth [e.g., Martian rovers]
 B) Solar system scope
 C) truly Universal

 Personally, I think each planet is likely to require a separate
 standard.

The spacetime metric adopted by the IAU does not have enough terms in
it to generalize to a solar-system wide coordinate system with full
precision of current atomic clocks in the vicinity of rotating,
gravitating bodies.  In a rough sense the metric was designed to
permit the definition of a self-consistent coordinate frame out to
around twice the geostationary radius.

In the broader sense, even a solar-system barycentric coordinate frame
is suspect at the level measurable by current atomic clocks, and that
is part of the motivation for the various international scientific
unions recommending the establishement of a pulsar-based time scale.

In a still broader sense, there is no meaning for a universal
coordinate time scale.  Every observer experiences a proper time
peculiar to the local environment.

For the foreseeable future, each planet will have its own coordinate
time scale.

--
Steve Allen [EMAIL PROTECTED]WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046   Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m


Re: Precise time over time

2005-08-11 Thread Steve Allen
On Thu 2005-08-11T14:40:10 +0200, Poul-Henning Kamp hath writ:
 Because the food industry is required to provide trackability for
 food and the requirement is UTC time.

Not over here it isn't.  I'm pretty sure the time stamps on the milk
cartons are local time, and I don't think I care much whether the
clock on the dairy was accurate to a minute.

It seems to me that this one would be pretty simple to fix.
If every factory started using TAI (or, horrors, GPS time)
and a few lobbyists went to the government to have TAI declared
as a legal time scale (just as the metric system was declared legal
here well over a century ago, and it, in truth, the actual standard
by which things operate) then there could hardly be as much objection
as the dairies are having right now to the new Daylight Saving Time
legislation.

--
Steve Allen [EMAIL PROTECTED]   WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165   Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046  Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m


Re: new beginning

2005-08-04 Thread Steve Allen
On Thu 2005-08-04T09:27:20 +0200, Poul-Henning Kamp hath writ:
 So one feasible option is to predetermine all leapseconds (or
 leap minutes ?) for the next 50 years in advance.

 That means an UT1-UTC difference that could go as high as 20-30
 seconds but it is still locked and bounded (by our knowledge of
 geophysics, admittedly, but bounded nontheless).

This was one of the options presented by McCarthy around 1999 during
the early ruminations about changing UTC.  It was quickly excluded
from the list of possible options, even before the Torino conference
when Arias further discussed the predictive capabilities.

It would be interesting to know why this option was excluded, but then
it would be interesting to really know why any of this is happening.

--
Steve Allen [EMAIL PROTECTED]   WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165   Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046  Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m


Re: new beginning

2005-08-04 Thread Steve Allen
On Thu 2005-08-04T15:44:17 +0100, Ed Davies hath writ:
 Perhaps it would be a mistake for the relationship between
 civil and SI seconds to be anything other than identity.

I would agree for planning purposes for the next century.

 On the other hand, the schedule for
 the day would be in civil seconds.  Of course, the schedule
 doesn't need to be held to the exact second (though it's
 often done pretty close to that) but somewhere in the chain
 there would have to be a switch over.  Where, exactly?

I don't know what things are like in the UK, but US viewers are all
too familiar with the fact that civil time does not correlate with TV
program start and stop time to within a minute.  Thursday night
viewers are well aware that CBS always runs CSI right up to, or
sometimes past 22:00 while NBC starts ER as much as two minutes before
22:00.  Undoubtedly there are other examples, but I have other things
to do.

The networks apparently believe that strategies aimed at shaming the
viewers for non-loyalty are more important than precise time.  I
suppose that the A.C.  Nielson company has already had to adjust its
ratings gathering processes in order to accommodate such things.

 Clearly, there's a use for a
 solar second but perhaps it's even more specialised than
 a sidereal second.

This is not directly on the topic of discontinuing leap seconds, but
the sidereal second became undefined as of 2003-01-01 when the Vernal
Equinox was abandoned in favor of the NRO/CEO/CIO.
Of course at the same instant the mean solar second of UT1 also lost
all connection with its original intent.
For most practical purposes the old FK5-based definitions will remain
adequate throughout the next century, or two, but after that...

--
Steve Allen [EMAIL PROTECTED]   WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165   Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046  Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m


Re: Who uses DUT1?

2005-07-31 Thread Steve Allen
On Sat 2005-07-30T10:18:42 -0700, Tom Van Baak hath writ:
 So my question is - is the actual value of DUT1,
 as broadcast with single digit precision, still
 used? And if so, from where do they get the
 value?

We do not use them for our telescopes at Lick, but our big telescope
is built out of battleship-era technology.  Pointing to within 15 arc
seconds is quite acceptable for a telescope which is controlled by a
human operator.

This will change for the new telescope we are having constructed this
year.  It is to operate entirely autonomously.  Its software system
expects to download the predictions from the USNO website on a regular
basis.  Given that we are not writing the software, we do not know
what sorts of alarm conditions it will set off if it cannot contact
the internet for an extended period.

The reports and proceedings of the IAU GAs in 1970 and 1973 make it
clear what the concerns regarding DUT1 were.  I suspect that the
reports and proceedings of the CCIR from those years reveal the same
thing, the differences being in who realized which things first.

Initially the plan was to broadcast the difference from UT2, because
it had been the practice since 1956 for the broadcasts to give UT2.
The astronomers at the IAU GA in 1970 pointed out that for purposes of
navigation it was UT1 which was relevant, because navigators already
had to back out the UT2 correction to make most precise use of the
broadcasts.  In practice that detail was moot for the broadcasts
because the value of |UT1 - UT2| never exceeds 0.35 seconds.

The broadcast values of DUT1 were instituted along with leap seconds
such that the radio broadcasts of time signals would remain just as
useful to the typical limits of human-sighted sextant readings as they
had been.  That is to say, a skilled navigator might get to 50 meter
accuracy under the best of circumstances.  My unpracticed star shots
were 20 times worse than that, so the DUT1 would never have benefitted
me.

--
Steve Allen [EMAIL PROTECTED]   WGS-84 (GPS)
UCO/Lick ObservatoryNatural Sciences II, Room 165   Lat  +36.99858
University of CaliforniaVoice: +1 831 459 3046  Lng -122.06014
Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m


Re: Wall Street Journal Article

2005-07-31 Thread Steve Allen
On Sun 2005-07-31T08:23:30 +0200, Poul-Henning Kamp hath writ:
 No, they had everything to do with computers don't liking time to
 jump around.

But the reality is that no computer system (or any system, for even
NIST and USNO don't know what the value of TAI and UTC is until next
month) can guarantee that it always knows what time it is.  If the
system does not know what time it is (at boot time, or if the system
does not have radio or network connectivity) then the system clock can
be wrong.  If the system clock can be wrong then the system either has
to admit that it does not care that it is wrong or the system has to
have procedures for correcting that wrongness.  The system can correct
the wrongness either by changing the length of seconds or by resetting
(leaping) the system clock.

 When you start out on a long march, you don't put a stone in your
 boot deliberately, and if one is there already, you take it out.

 Leapseconds is such a stone for real-world IT installations.

In this sense leap seconds give the system designer the opportunity
and incentive to face reality instead of ignoring it.  Taking away
leap seconds will not fix this.

 I'm pointing out that UTC with leap seconds is unsafe at any speed.

Presuming that the system clock is always right is delusional.

 It would have been much smarter to use TAI, wouldn't it ?  I thought
 I heard some astronomer say in this discussion that all applications
 which need proper timekeeping should use TAI ?

If proper timekeeping means time as defined by physics then:
All applications which need proper timekeeping in the reference frame
of the solar system should use TCB.
All applications which need proper timekeeping in the terrestrial
environment should use TCG.
All applications which need proper timekeeping on the surface of the
earth should use TT.
These are the recommendations from astronomers to everyone.

But these are not practical time scales.  They are Platonic ideals.
Some sort of conversion needs to be applied in order to compare them
with practical time scales.  The algorithms for that conversion are
not trivial -- they involve complex numeric calculations.
This is a fact of life that cannot be defined away.

 And if anything, if astronomers switched to TAI on 2008-01-01 they
 would not run into this problem in the future.

TAI is a practical time scale, but its seconds are not of constant
length.  Even if TAI were the result of perfect atomic clocks, TAI
currently ignores the diurnal GR effects of changing depth in the
gravitational potentials of solar system objects.  Someday TAI will
have to incorporate those currently-too-subtle effects of the passage
of proper time for every given clock.  TAI is unarguably the best time
scale for use in telecommunications, but that does not make it
perfect.  And even if TAI were perfect that does not make it the best
time scale for civil time.

 I think the sneakage happened in 1972 and we're trying to evict it.

Leap seconds were proposed and instituted by the physicists who ran
the atomic clocks.  They were opposed by many astronomers, but after
the shouting stopped (and in the proceedings of the IAU GAs it is
evident that there was shouting) the astronomers agreed that UTC as SI
seconds with leap seconds was the best option.

--
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Re: Wall Street Journal Article

2005-07-31 Thread Steve Allen
On Sun 2005-07-31T09:19:40 +0200, Poul-Henning Kamp hath writ:
 I don't hear the counter proposal from the astronomers to fix leap
 seconds.

They're not broken.

All the surveys which were taken in the past six years indicate that
the majority of time users believe this to be the case.  They also
indicate that there is no consensus about whether there needs to be a
change, let alone about what that change might be.

 Is this discussion really just about astronomers trying to make
 sure this doesn't happen in their lifetime, and if not, why are
 there no counter proposals for a better solution ?

When the Wall Street Journal reporter called them why did the
proponents of abolition either provide the same old and unjustified
explanations or avoid talking altogether?  The content of that front
page story was vetted for over two weeks, and the words secret and
secrecy survived the WSJ editorial process.  Why would the
proponents risk such a public result?

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it's all humor

2005-07-17 Thread Steve Allen
The difference between this leap second and all the previous ones is that
even the humorists seem to understand why it is happening:

http://www.startribune.com/stories/404/5508732.html

I suppose this means we can all thank the Time Lords for triggering a
significant increase in the level of discourse.

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Philippine opinion piece

2005-07-14 Thread Steve Allen
Here's a good op-ed piece from Manila about the leap second.

http://www.manilatimes.net/national/2005/jul/14/yehey/opinion/20050714opi1.html

It ends thus

Why worry?  Or, more to the point, what's the point?
[...]
It's good to know that there are people who take these things
seriously.  But for most of us, a second more or a second less is
more or less a question of taste.

and happy Bastille Day, albeit a bit late.

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so sorry, Markus

2005-07-08 Thread Steve Allen
Nature interviewed Markus Kuhn about the leap second and did a good job.

UPI has turned the Nature story into an abomination; e.g.,

http://washingtontimes.com/upi/20050707-090936-2878r.htm

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Re: About UTC / a disaster for classical astronomy

2005-07-08 Thread Steve Allen
On Fri 2005-07-08T18:23:01 +0200, Christian Steyaert hath writ:

 With permission from the author. (Jean is not subscribed to [leapsecs] ).

For any parties concerned by the letter from Daniel Gambis I point out
these links with their abundance of resource information.

http://www.ucolick.org/~sla/leapsecs/onlinebib.html#Event2005-07-05
http://www.ucolick.org/~sla/leapsecs/gambis.html

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time-nuts

2005-07-06 Thread Steve Allen
Given that LEAPSECS seems to have gone aphasic, I point out this

http://www.febo.com/pipermail/time-nuts/2005-July/

wherein there is an ongoing thread about
IERS Bulletin C number 30

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interesting thing of the day

2005-04-29 Thread Steve Allen
A new web article on leap seconds and timekeeping

http://itotd.com/index.alt?ArticleID=534

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two media links and an inference

2005-03-25 Thread Steve Allen
In the March newsletter of the American Astronomical Society is
a letter from McCarthy, Fliegel, and Nelson promoting UTC without
leap seconds.

In the March issue of The Compendium, the quarterly journal of
the North American Sundial Society, is a note about leap seconds.

Dare any inferences be drawn from the letter in the AAS newsletter?

McCarthy works at the USNO branch of the IERS which produces the
near-real-time bulletin A.  Leap seconds are announced (currently by
Daniel Gambis) by l'Observatoire de Paris branch of the IERS in the
semi-annual bulletin C.

Dare this be taken as an indication that, for those who care about
earth rotation, the USNO believes the contribution of l'OBSPM as seen
in Bulletin C could just as well be replaced by a suitably damped
filtering of the Bulletin A data?  And that, for those who do not care
about earth rotation (presumably the majority of the population of the
planet), the USNO believes the role of l'OBSPM for controlling civil
time is irrelevant?

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Re: GMT - UTC in Australia

2005-02-24 Thread Steve Allen
On Wed 2005-02-23T23:02:14 -0800, Steve Allen hath writ:
 [ the New South Wales bill ]
 defines UTC as being determined by the BIPM.

 So it remains unclear who ultimately controls the fate of civil time
 in New South Wales.

There is sociology behind this statement.

W. Lewandowski is Principal Physiscist at the BIPM time lab.  He
often chairs sessions at the various precise time conferences, and he
did so at CGSIC last September.  His introductory Powerpoint
presentation is online as presentation number 60 at
http://www.navcen.uscg.gov/cgsic/meetings/summaryrpts/44thmeeting/44th_CGSIC_agenda.htm

In his slides 6 and 7 he indicates that the transition to uniform time
would follow the recommendations of the Torino conference; i.e., a
uniform time scale gets a new name.  It is not clear that this dare be
interpreted as a position statement by the BIPM, nor whether it
represents a stance in opposition to the draft documents that the
ITU-R has been circulating regarding its preferred re-definition of
UTC.

I suppose that there are individuals on both sides of the leaps-in-UTC
issue at the BIPM, the IERS, and the ITU-R.  That was the case at the
BIH where the Stoykos championed earth rotation time while Guinot
championed atomic time.  The Stoykos died first, and with the demise
of the BIH they have largely been omitted from the history of time
keeping.  That recalls the tag line in the posting on POSIX time:

http://www.opengroup.org/platform/single_unix_specification/show_mail.tpl?source=Llistname=austin-group-lid=
Time folk take their time, they do.  Bet they have their time
wars too, but they bury their dead in private.

In the end the resolution of the leap second issue for civil time may
also become a game of who dies first.

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Re: GMT - UTC in Australia

2005-02-23 Thread Steve Allen
On Tue 2005-02-22T18:27:36 -0800, Steve Allen hath writ:
 Australia has decided to redefine its legal time scale.

The bill was introduced today.
Details of Bill 11 are found here.
http://www.parliament.nsw.gov.au/cgi-bin/isys/isyswebext.exe?op=geturi=/isysquery/irl66ce/1/doc/#hit1

The text of the bill is here
http://www.parliament.nsw.gov.au/prod/parlment/nswbills.nsf/0/de842061017f029eca256fb000169179/$FILE/b04-133-16-p01.pdf

It defines UTC as being determined by the BIPM.
Nowhere is the ITU-R mentioned.

The BIPM says UTC is based on TAI, which is acknowledged to be their
own responsibiliy, and leaps as determined by the IERS.

So it remains unclear who ultimately controls the fate of civil time
in New South Wales.  But the explicit mention of the CGPM endorsement
from 1975 could be interpreted to mean that NSW expects that UTC
should conform to mean solar time, and thus it should have leaps.

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GMT - UTC in Australia

2005-02-22 Thread Steve Allen
Australia has decided to redefine its legal time scale.

http://abc.net.au/science/news/space/SpaceRepublish_1307267.htm

The last line in the article implies other jurisdictions are doing the
same.  The exact text of the laws would be interesting in order to see
whether they intend that UTC be matched to mean solar days or not.

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leaps in jazz/rock fusion

2005-02-06 Thread Steve Allen
For a view of how leap seconds have entered popular culture,
there is a jazz/rock fusion album titled
Leap Second Neutral
which echoes the subject line of some net discussions leap seconds.

The publisher's web site is
http://cuneiformrecords.com/bandshtml/machine.html
with reviews from resellers at
http://www.ear-rational.com/detail.php?id=16603
http://www.squidco.com/miva/merchant.mv?Screen=PRODStore_Code=SProduct_Code=4501
http://www.fusion3.com/works/rune210/

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Re: two world clocks AND Time after Time

2005-01-25 Thread Steve Allen
On Tue 2005-01-25T09:57:46 +, Clive D.W. Feather hath writ:
 I think you're out by a factor of 10. Would the Man On The Clapham Omnibus
 be able to identify the solstice or equinox to within 14 days? Other than
 knowing the conventional dates?

 [That is, if the equinox was actually on March 9th, would anyone outside
 the astronomical community notice?]

The answer is in Duncan Steel's book Marking Time
http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471298271.html

The answer is yes, and it is evident in the orientation of churches
in England built before and after the English calendar reform in 1752.

Churches were built oriented to sunrise on their saint's day.
In 1752 the calendar shifted, and sunrise shifted.  Additions made to
pre-reform churches were oriented to sunrise on the new saint's day.
The result was crooked churches.  Steel counts 81 such churches
within Oxfordshire alone.

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Re: two world clocks AND Time after Time

2005-01-24 Thread Steve Allen
On Mon 2005-01-24T00:50:10 -0800, Tom Van Baak hath writ:
 Isn't knowing when noon is already a specialist operation?
 I mean, most people could tell you when noon is to within
 an hour or two or three, but finer than that requires a far
 amount of daily mental calculation, no?

Noon has long required a calendar, an almanac, a longitude, and the
ability to perform addition and subtraction.  This has long been
something that could be presumed within the abilities of any locality
big enough to call itself a town.  The tasks of business, payroll,
and banking demand that much.

Sunrise and sunset have required haversines.  That's why the
newspapers publish them.  Trigonometry was not required for simple
civil life.

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Re: two world clocks AND Time after Time

2005-01-23 Thread Steve Allen
 to accomplish this change.

Realistically, anything worth wearing to accomplish the function
of a wristwatch will soon have far more computational capability than
is required to tell when noon will really be, if anyone cares.

But the current strategy of retaining the name UTC creates one real
and unresolvable problem that will persist indefinitely.  It is very
bad policy to corrupt the historical meaning of anything called
Universal Time by redefining UTC to be something that has no
relation to the rotation of the earth.

This list has discussed mitigations for astronomers to use with legacy
systems which amount to re-creating UTC with leap seconds.  The effect
of that is to create old UTC and new UTC.  It also leaves
confusion over which form should be interpreted when reading
historical documents and comments in software systems.

We have already seen the chaos of such ambiguity when the British
Admiralty demanded that the term GMT continue to be used when
the beginning of the day was switched from noon to midnight.
The 2003 conference in Torino made it quite clear that a new name
should be used.

Yes, there is extreme cost required to change the name of the most
practically available civil time scale, but that cost is temporary.
As seen with GMT, the cost of not changing the name of a time scale is
also large.  That cost is eternal, and eventually ends up demanding a
name change anyway.

The belief that a precisely-defined time scale can have a basic
characteristic changed without eventually incurring the cost of also
changing the name is a fantasy.

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Re: ITU Meeting last year

2005-01-20 Thread Steve Allen
On Thu 2005-01-20T13:39:58 +, Markus Kuhn hath writ:
 That was certainly the idea of the BIPM proposal presented at the Torino
 meeting.

As seen on my online bibliography web page, the proposal probably was
a slightly evolved form of this document

http://www.fcc.gov/ib/sand/irb/weritacrnc/archives/nc1893wp7a/1.doc

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Re: ITU Meeting last year

2005-01-20 Thread Steve Allen
On Thu 2005-01-20T09:33:01 -0800, Tom Van Baak hath writ:
 So it's safe to say we're talking millennia rather
 than centuries, yes? I wonder where the notion
 that it's just a few centuries away came from.

If there is something not clear in the presentation on

http://www.ucolick.org/~sla/leapsecs/dutc.html

I would be obliged to know about it.


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Re: ITU Meeting last year

2005-01-20 Thread Steve Allen
On Thu 2005-01-20T12:34:09 +, Clive D.W. Feather hath writ:
 I may be wrong here, but I thought the leap hour idea did *not* insert a
 discontinuity into UTC. Rather, in 2600 (or whenever it is), all civil
 administrations would move their local-UTC offset forward by one hour,
 in many cases by failing to implement the summer-to-winter step back.

The text of the document from USWP 7A continues the trend that has
been displayed publicly for several years now, namely that UTC would
officially switch from leap seconds to leap hours.  This is clearly an
artifice, for there can be no expectation that people 5 centuries
hence will respect the content of any revision of ITU-R TF.460 made
today.  It is not even clear that the BIPM is ready to respect it now.

Looking at the players, however, a plausible reason for the artifice
becomes clear.  Many of the proposers are employees of agencies of the
US Federal government.  Under federal law the legal time of the United
States is specified as mean astronomical time, and in the parlance
of the era of that legislation that clearly must be interpreted as the
form of earth rotation time known as mean solar time.  The most recent
attempt to change the wording of the US Code failed.

To propose the complete abolition of leaps would be to propose a time
scale which demonstrably violates federal law.  To propose leap hours
is to propose an artifice which keeps the proposers from using their
positions to advocate a violation of federal law.  Legal fiction is
a well-tested means of effecting change.

It is hard to say what the actual intent is when so few documents have
made it out of the inner sanctum of the Time Lords.

In the hopes of enlightenment for this list, but without the ability
to authenticate these draft documents, I offer the following:

http://www.ucolick.org/~sla/leapsecs/SRG7Afinalreport.doc
http://www.ucolick.org/~sla/leapsecs/PropRevITU-RTF460-6.doc

It seems that atomic clock keepers have lost all interest in the
continued existence of mean solar time, sundials, or the analemma.

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leaps and C language standards

2004-06-14 Thread Steve Allen
For the past two weeks in the USENET newsgroup comp.std.c there has
been a discussion of the handling of the C language time_t type now
and in the future.  The hottest topic this past weekend has been the
handling of leap seconds, or lack thereof.

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precision time web search

2004-05-05 Thread Steve Allen
I monitor the traffic to the various web pages that I set up as a
result of the leap seconds discussions.  One of the more useful
aspects of the server logs is the HTTP referrer string that
often indicates what search query brought the web surfer to my page.

A recent referrer entry was

http://search.msn.com/results.aspx?srch=105FORM=AS5q=EAL+time+scale

which, as of this moment, shows that my page on time scales is the
best match for someone searching for the Echelle Atomique Libre.

I do not believe that my web page should be the principal authority on
the products of the BIPM.

I humbly request that members of the precision timekeeping community,
especially any at the BIPM, enhance their web pages.  It would be good
for the web surfing public to have a more authoritative (and hopefully
more accurate) website than my own detailing the inner workings of
atomic time.

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recent CCTF meeting

2004-04-14 Thread Steve Allen
The photograph at
http://www.bipm.org/jsp/en/CCPicture.jsp?cc=CCTF
strongly suggests that the CCTF met according to schedule at the
beginning of the month.

Is anyone able to reveal any actions related to leap seconds?

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CCTF and the future of UTC

2004-03-29 Thread Steve Allen
This week is the 16th meeting of the CCTF.
http://www.bipm.org/en/committees/cc/cctf/

Among the last words from the Torino conference was a note that
the ITU-R SRG 7A report could not be final until the CCTF had
responded, and that will presumably be forged this week.

The report from Torino is at odds with the sentiments expressed by the
1999 letter from the CCTF which was used as fuel for the ITU-R
process, but the few public comments from CCTF members have not made
it clear whether they agree or disagree.

Given the 1975 CGPM endorsement of UTC as a worldwide standard, I'm
supposing that the CCTF might opine that a 20-year life before the end
of UTC is too short.  I wonder if they would recommend to the CIPM the
following: If the ITU-R withdraws UTC as a standard, that the BIPM
should assume reponsibility for continuing it until there is consensus
on a superior alternative.

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Re: Unifying Atomic Time and the post-Gregorian calendar corrections

2004-03-09 Thread Steve Allen
Resurrecting a theme from long ago

On Thu 2003-07-03T19:54:11 +0100, Joseph S. Myers hath writ:
 On the effects of solar mass loss on orbital computations and definitions
 of units, and its (non-)detectability, see Solar Mass Loss, the
 Astronomical Unit, and the Scale of the Solar System by Peter D.
 Noerdlinger
 http://web.archive.org/web/20011104125211/http://home.netcom.com/~pdnoerd/SMassLoss.html
 (I can't now locate a good copy of this paper; that archived copy is
 missing images for many of the equations).

It now appears to be here
http://home.comcast.net/~pdnoerd/SMassLoss.html

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Re: ITU-R SRG7A Turin colloquium proceedings available online

2004-02-24 Thread Steve Allen
On Tue 2004-02-24T12:04:42 +, Markus Kuhn hath writ:
 The proceedings and final report of the ITU-R SRG7A Colloquium on the
 UTC Timescale, Turin, Italy, 28-29 May 2003, have now appeared online at
 the IEN web site:

   http://www.ien.it/luc/cesio/itu/ITU.shtml

It is somewhat ironic that they did not wait until tomorrow, for then
they would have been able to announce the release of the fate of the
leap second on the leap day.

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