to the UTC standard. If there is an actual
proposal to go with this no new leap second notion, let's hear
it - hopefully it will be better conceived than the surveys that
have been so narrowly worded and disseminated.
Folks, this isn't just some obscure technical question.
Rob Seaman
National Optical
are discussed very prominently in a very short document.
Rob Seaman
National Optical Astronomy Observatory
potentially incur huge
costs for remediation of, as yet, completely unquantified risks.
Rob Seaman
National Optical Astronomy Observatory
a
conclusion that Leap seconds must die! that was already formed
prior to Y2K.
Rob Seaman
National Optical Astronomy Observatory
about leap seconds.
Many will - and the number of users and their applications (meaning
people, their jobs and what they do in their private lives) who do
care will grow as civil time and UT1/GMT diverge.
Y2K had a razor sharp deadline. L2K (or L3K?) is a timebomb with a
slow burning fuse.
Rob
- and definitely should not be avoided due to
the potential for worldwide Y2K-like disasters.
Go ahead, cut the Gordian knot.
Rob Seaman
National Optical Astronomy Observatory
discussions among biased insiders.
It ain't your clock - it's *our* clock.
Rob Seaman
National Optical Astronomy Observatory
changes are needed
is no surprise (see http://iraf.noao.edu/~seaman/leap for my analysis
of the situation), but what the hell is the hurry?
Rob Seaman
National Optical Astronomy Observatory
Time (of whatever flavor).
Universal Time was to be reserved for timescales synchronized to the
rotation of the Earth. One might wonder at the reluctance of
proponents to follow through on this easily comprehended consensus.
Rob Seaman
National Optical Astronomy Observatory
there be for truncating the
discovery process for uncovering similar requirements placed on civil
time by the great religions of the world before making a large change
in the definition of civil time?
Rob Seaman
National Optical Astronomy Observatory
this was
the case or not, the wording of the quoted article makes it clear that
UTC is being sold to everyday Australians in its original sense of
being a continuing approximation to GMT:
UTC is adjusted to remain consistent with GMT using leap seconds
every 18 months.
Rob Seaman
National Optical
: Call the new system of time resulting from the
leap hour proposal International Time, TI for short. Walk through
the front door of the world's parliaments and legislatures and attempt
to sell TI as a high priority proposal. What would be the likely
response?
Rob Seaman
National Optical Astronomy
of Universal Time. UTC is a useful
approximation to GMT. Keep it that way and call any new system of
civil time that might win the day something else. It is the height of
intellectual dishonesty to do otherwise.
Rob Seaman
National Optical Astronomy Observatory
be disregarded - I will.
Rob Seaman
National Optical Astronomy Observatory
unilaterally changing a 120 year-old
international standard.
Duck and cover!
Rob Seaman
National Optical Astronomy Observatory
discussions) simply regroup, withdraw the
current silly proposal and define a process to patiently and
prudently reach a consensus.
It will take time to make time - better.
Rob Seaman
National Optical Astronomy Observatory
[presumably manned by Pee Wee
Herman's robot from Star Tours] a real horror show. And as you
surely now see, little Sally, all of these robotical slaughterhouse
shenanigans are like totally the fault of those dastardly leap
seconds...
Rob Seaman
National Optical Astronomy Observatory
- it
is infrastructure that we must include in our planning.
Rob Seaman
National Optical Astronomy Observatory
are in this situation. Any civil time
proposal that does not include an analysis of instrumentalities is
void of meaning.
Rob Seaman
National Optical Astronomy Observatory
evident. Please help
me to remove these and to avoid adding any of your own. The
structure is also too flat - categories might benefit from
hierarchical nesting.
Rob Seaman
National Optical Astronomy Observatory
to convince the politicians to vote against it?
We'd have more luck legislating against the transfer of angular
momentum from the Earth to the Moon...
Rob Seaman
National Optical Astronomy Observatory
to the mean solar
day length. (And I'm doubtful that any of us would want to live on a
planet or in a society for which this assertion was false :-)
With no sense of irony - thanks for the excellent discussion.
Rob Seaman
National Optical Astronomy Observatory
in the previous message.
Rob Seaman
National Optical Astronomy Observatory
.
It isn't sufficient for any of us simply to claim that our own pet
proposal has no negative ramifications and to leave it at that.
Rob Seaman
National Optical Astronomy Observatory
and Calcutta, wish to be consulted and advised?
Rob Seaman
National Optical Astronomy Observatory
and hide the effect for most purposes (ignoring the
gawdawful expense to astronomy), but is cheating really what the
precision timing community wants to do?
It may be annoying that Mother Earth spins irregularly, but spin she
most certainly does.
Rob Seaman
National Optical Astronomy Observatory
would reject the current proposal if anybody had thought to
ask them about it.
Rob Seaman
National Optical Astronomy Observatory
On Sep 26, 2005, at 11:56 AM, Poul-Henning Kamp wrote:Again: merely trying to point out that the "only one timescale" argument Rob pushes doesn't work.This misrepresents my position. There are clearly many time scales for many purposes. One of those purposes is something that might be referred
Perhaps I might expand on some of Bill Thompson's statements in the context of the great convenience factor of using the current UTC standard.The accuracy requirement for the delivery of UTC to the instruments is +/- 0.410 seconds.High quality, cutting edge science doesn't always require
of astronomy professor, Fr. Edward Jenkins, was fond of
the fourth Astronomer Royal, Nathaniel Bliss. He recalled (often)
having seen a beer mug with the gent's face on it and the motto,
This is Bliss, if bliss on Earth there be.
Rob Seaman
National Optical Astronomy Observatory
On Dec 6, 2005, at 3:27 PM, Steve Allen wrote:Finally we begin to see folks stand up and identify their systems as having abysmally failed to implement the UTC standard. http://www.acrelectronics.com/alerts/leap.htmEven more remarkably, they proudly proclaim: "The quality systems of this
.
Rob Seaman
National Optical Astronomy Observatory
solid state
physics or the airframe designer, fluid dynamics?
The Earth rotates. For some purposes, some people can ignore this.
For other purposes, other people can't. Deciding the implications
requires actual thought and planning. Is this really a radical notion?
Rob Seaman
National Optical
and oranges,
we're talking about apples and the rate of change of qumquats. In
fact, it is remarkable that the existence of a significant
acceleration (second derivative or quadratic effect) in the need for
leap seconds is being asserted as a bogus justification for not
issuing leap seconds at all.
Rob
On Dec 20, 2005, at 1:30 AM, Poul-Henning Kamp wrote:There is an interesting PowerPoint (sigh...) at Schriever AFB's GPS support center:https://www.schriever.af.mil/GpsSupportCenter/archive/advisory/Leap_Second_Event.pptAgreed. Very interesting.They clearly know what the problem with leap seconds
, but this occurs only something like
36% of the time. Would greatly appreciate knowledgeable comments
from list members in Japan or Australia.
This scheduling was a conscious design choice. I'm asserting it may
not have been the right choice.
Rob Seaman
National Optical Astronomy Observatory
problem (and lack thereof)
reports to me. Will comment further when these are available.
Rob Seaman
National Optical Astronomy Observatory
.
Rob Seaman
National Optical Astronomy Observatory
be some interesting
hay to be made by generalizing our definition of a clock to include
quasi-periodic phenomena more complicated than a once-per-second
delta function. Would give us some reason to explore the Fourier
domain if nothing else.
Rob Seaman
National Optical Astronomy Observatory
(for once). (Some might consider me a software professional
as well - am not particularly annoyed if you do not.)
Would be delighted to hear more about your leap second infrastructure.
Rob Seaman
National Optical Astronomy Observatory
it is permitted to drift before action is taken - and
what kind of action is appropriate - and who gets to make these
decisions.
Rob Seaman
National Optical Astronomy Observatory
Hi Ed,
Poul-Henning Kamp wrote:
What a weird concept...
Why not go the full distance and define a timescale for each
particular kind of time-piece:
and give each of them their own unique way of coping with
leapseconds ?
Ignoring the ridiculous parody - no, it's not a weird
On Jan 7, 2006, at 11:37 AM, John Cowan wrote:Whether we choose to bleed off the daily accumulating milliseconds one second or 3600 at a time, bleed them we must...and even people who loathe the very notion of leap seconds admit this. NO, I DON'T ADMIT THAT. On the contrary, I deny it, flatly,
On Jan 7, 2006, at 11:01 PM, M. Warner Losh wrote:
This would phase in the predictive timeline for leap second
insertions, and would also give the IERS control to end the
experiment if the time horizons exceeded their ability to predict
with confidence.
it would also be completely within the
On Jan 8, 2006, at 4:41 AM, Poul-Henning Kamp wrote:
It sounds to me like BIPM ought to make an Internet service
available which will deliver UT1 to astronomers in a timely fashion ?
Not sure BIPM is necessarily the appropriate agent, but otherwise
agree 100%. Perhaps we should seek other
On Jan 8, 2006, at 5:38 AM, Poul-Henning Kamp wrote:
As I understood it, it was mainly that TAI is a post-factum
postal timescale.
One is left pondering the fact that UTC is now (and would remain
under any changes I've heard suggested) a time scale based on TAI.
What magic makes one
.
Time zones (and the prime meridian?) would race more-and-more rapidly
around the globe.
Perhaps I've misunderstood, but this line of reasoning doesn't appear
to resolve anything.
Rob Seaman
National Optical Astronomy Observatory
On Jan 8, 2006, at 4:04 PM, Tom Van Baak wrote:
You cannot divide timekeeping, time dissemination, into neat stages.
Again. My point is strengthened. This being the case, a requirement
on one flavor of time transfers to others. We will not solve the
problem of creeping complexity and
On Jan 9, 2006, at 12:03 AM, John Cowan wrote:
Each locality decides when and how to adjust both its offset from
TAI and its seasonal transition function (if any), just as it does
today.
Not just as today, see intervening messages.
What we abandon is a universal time tightly synchronized to
On Jan 9, 2006, at 12:06 AM, Poul-Henning Kamp wrote:
You yourself defined stage one as TAI with some constant offset
yourself, you can't change definition in the middle of the discussion.
I was attempting to describe your position. In point of fact, I
agree with Tom Van Baak:
You cannot
On Jan 9, 2006, at 12:23 AM, John Cowan wrote:
This is like the day is light and night is dark statement: there
is, at any given location, one and only one sunrise per (solar)
day, no matter what clocks say.
Communication prospers when people's clear meaning is not subjugated
to petty
On Jan 9, 2006, at 1:01 AM, Clive D.W. Feather wrote:
We go through such discontinuities twice a year in most years.
Only the uninteresting daylight saving jumps. UTC remains without
discontinuities above the level of a leap second. If UTC weren't
equivalent to what I call civil time, the
On Jan 9, 2006, at 1:22 AM, Clive D.W. Feather wrote:
At some point, probably around the time that we're seeing an hourly
shift every year, people are going to have to divorce second from
day, or at least re-negotiate the terms of engagement.
By what magic do we believe the issues involved
On Jan 10, 2006, at 9:17 AM, Peter Bunclark wrote:On Tue, 10 Jan 2006, Poul-Henning Kamp wrote:In message [EMAIL PROTECTED], Peter Bunclark writes: Good grief. MJD is used widely in astronomy, for example in variablility studies where you want a real number to represent time rather than deal with
I see Steve Allen has already supplied a thorough answer. Interested
individuals might also scrounge through the list archives (http://
rom.usno.navy.mil/archives/leapsecs.html) since the topic has come up
before. In fact, Demetrios Matsakis speculated on solar system wide
timescales even
What now, Dr. Moebius? Prepare your minds for a new scale... of physical scientific values, gentlemen.Mark Calabretta takes the lazy man's way out and appeals to facts: Here in a topology-free way is what the axis labels of my graph looklike during
On Jan 12, 2006, at 12:36 AM, John Cowan wrote:No one, at least not on this list, is arguing for an alignment of theabsurd leap hour proposal (henceforth ALHP) with DST changes.I went rummaging through the ITU proposal and back as far as Torino. Found this comment from a LEAPSECS thread on 28
I'm glad to see such active traffic on the list - particularly
discussions such as this that are wrestling with fundamental concepts.
On 2006-01-13, Mark Calabretta wrote:
The point is that UTC is simply a representation of TAI.
On Jan 13, 2006, at 4:17 AM, Michael Deckers wrote:
I
On Jan 13, 2006, at 8:05 AM, Ed Davies wrote:
MJD 27123.5 means 12:00:00 on day 27123 if it's not a leap second
day, but what does it mean on a day with a positive leap second?
12:00:00.5?
And we're back to the point in question. The precise issue is the
definition of the concept of a day.
On Jan 13, 2006, at 12:46 AM, John Cowan wrote: In the end, it will be impossible to maintain the notion that a solarday is 24h of 60m of 60s each: we wind up, IIRC, with the solar dayand lunar month both at about 47 current solar days. There's a lot of difference between what happens over a
that some other data products were unaffected?
So, the issue has been resolved - would likely have been resolved
sooner if a leap second had occurred earlier - and is no longer
directly pertinent to a discussion of future leap seconds?
Well done, Geoscience Australia!
Rob Seaman
NOAO
-round and the media circus
would have moved on.
Rob Seaman
NOAO
This goes counter to my claims so it is of no importance.
and
This time, there were no reports of death with the leap second,
therefore they can't be too bad... :-)
I invite derision with my flights of rhetoric. But this is an
internet forum and a little leeway may be warranted. We all
days - or alternately,
to convert Universal Time into a count of seconds - that creates
confusion between the two.
Rob Seaman
NOAO
choices should be made adds
a little spice to the discussion :-)
UNB1 Web page is here: http://gge.unb.ca/Resources/UNB1.html.
IGS Central Bureau Web page is here: http://igscb.jpl.nasa.gov/
Thanks for the pointers.
Rob Seaman
NOAO
that many deployed systems (of whatever
nature) are naively configured. Is this likely to change overnight?
Rob Seaman
NOAO
-SLS is
intended to serve all needs. Rather, we've heard the opposite.
Suspect I'm not alone in being suspicious of any overreaching
solution proffered for all timekeeping situations - sounds like the
definition of a kludge.
Rob Seaman
NOAO
On Jan 19, 2006, at 10:02 AM, Rob Seaman wrote:
How delightful! A discussion about the design merits of actual
competing technical proposals!
Apologies for failing to credit the quotes from Poul-Henning Kamp.
to convert shipboard
apparent time to local mean time. Subtraction does the rest.
Rob Seaman
NOAO
is the Russian Global
Navigation Satelllite System :-) In any event, one suspects that the
Russians (or the FSU, even more so) would object to its being
characterized as a GPS backup.
Rob Seaman
NOAO
for
either scientists or sailors. Whether we're also selfish is immaterial.
Rob Seaman
NOAO
On Jan 24, 2006, at 12:50 AM, Peter Bunclark wrote:
I don't think Rob meant the above to be a complete course on
navigation!
...although as a fan of Patrick O'Brian I am qualified not only to
teach navigation, but also the violin and Catalan. You should see me
in a Bear costume.
Good
On Jan 24, 2006, at 8:06 AM, Ed Davies wrote:
James Maynard wrote:
The problem is not that the SI second is not based on a natural
phenonemon (it is), but that the periods of the various natural
phenonema (rotations of the earth about its axis revolutions of the
earth about the sun,
On Jan 24, 2006, at 7:21 AM, Poul-Henning Kamp wrote:I think the crucial insight here is that geophysics makes (comparatively) lousy clocksThe crucial insight is that the Earth is not a clock at all, but rather the thing being timed.and we should stop using rotating bodies of geophysics for
Ed Davies wrote:By "rubber seconds" you, presumably, mean non-SI seconds. What do you mean by "rubber days"? I'd guess you mean days which are divided into SI seconds but not necessarily 86 400 of them.Yes. See for instance:
are asserted to be a risk. Does their lack present
fewer risks? Prove it.
Rob Seaman
NOAO
Leap seconds are asserted to be a risk. Does their lack present
fewer risks? Prove it.
No, you prove it. Such rhetorical devices are designed to divide
and separate,
No, my rhetoric really isn't designed for that purpose. And even if
it were so - how does that possibly undermine the idea
/4800) aren't even denumerable with
the length of our week. Why then is a requirement that one minute
out of 800,000 accommodate one extra (or one fewer) second seen to be
such an imposition? Especially when anybody who does find it so can
simply choose to use TAI instead?
Eppur si muove!
Rob
On Feb 14, 2006, at 12:50 PM, Markus Kuhn wrote:
You can, of course, define, publish, implement, and promote a new
version (4?) of NTP that can also diseminate TAI, EOPs, leap-second
tables, and other good things. I'm all for it.
But why are you for it? Before investing large amounts of time
On Feb 14, 2006, at 2:28 PM, M. Warner Losh wrote:UTC time stamps in NTP are ambiguous. TAI ones are not.Requirements should be kept separate from implementation. Whatever the underlying timescale, certain external global requirements apply. Whether NTP or some other implementation properly
On Feb 16, 2006, at 2:06 PM, Markus Kuhn wrote:
While there is a 24:00:00, there is certainly *no*
24:00:00.0001.
That would be 00:00:00.0001 instead.
Says who? Didn't we just burn a lot of calories discussing whether
UTC was a real number or a continuous function? Time does
On Feb 16, 2006, at 4:46 PM, Warner Losh wrote:UTC rules state that the time sequence should be23:59:59.7523:59:60.023:59:60.2523:59:60.5023:59:60.7500:00:00.:00:00.25Well, no. ITU-R-TF.460-4 says nothing whatsoever about the representation of time using sexigesimal notation: "2.2 A
window around midnight - say,
23:59-00:01, or 2 out of 1440 minutes per day. It should be even
easier for NTP and other UTC transport mechanisms to avoid 2 minutes
out of 365+ days.
This isn't the solution to every challenge facing civil time - but it
sure simplifies the search space.
Rob Seaman
On Feb 19, 2006, at 1:35 PM, Steve Allen wrote: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.htmlI
On Feb 17, 2006, at 12:30 PM, Markus Kuhn wrote:
Clive D.W. Feather wrote on 2006-02-17 05:58 UTC:
However, London Underground does print 24:00 on a ticket issued at
midnight, and in fact continues up to 27:30 (such tickets count as
being
issued on the previous day for validity purposes, and
On Apr 13, 2006, at 10:41 PM, Steve Allen wrote:Today is one of the four days in the year when Newcomb's_expression_ for the equation of time has a value of zeroand it was Samuel Beckett's hundredth birthday. Leap second as Godot: ESTRAGON: And if he doesn't come?
Only hours ago did I learn of the recent problems with D-Link routers.
Remarkable! Just imagine the logical disconnect at the product
development meetings. The marketing folks emphasizing the highly
desirable feature of NTP compliance and the tech folks tossing a list
of 50 servers into the
-utc.dat will always be in the future.
Non-amusingly, in the alternate no-time-of-day universe, this never
becomes a non-issue for recovering the orientation of Earth-2.
Rob Seaman
National Optical Astronomy Observatory
On May 24, 2006, at 7:25 AM, John Cowan wrote:
Can someone lay out for me exactly what the difference is between
clock precision and clock resolution?
Interesting question. Perhaps it is the distinction between
addressability
and physical pixels that one encounters on image displays and
Warner Losh objects:There are several doughty people here who happen to have that opinion, but they abide with us mortals outside the time lords' hushed inner sanctum.I have spent much time explaining why leap seconds cause real problems in real applications, only to be insulted like this.Sincere
On Jun 4, 2006, at 9:57 PM, M. Warner Losh wrote:
leap days have a rule, while leap seconds are scheduled.
A schedule and a rule are the same thing, just regarded from
different historical perspectives. The leap day rule will most
certainly have to accommodate scheduling changes over the
On Jun 5, 2006, at 8:45 AM, Warner Losh wrote:Leap days have an iron-clad rule that generates the schedule on whichthey happen. Leap seconds have a committee that generates theschedule on which they happen.Further discussion in this thread calls into question the characterization of "iron-clad
On Jun 5, 2006, at 1:05 PM, John Cowan wrote:
(ObOddity: It seems that in Israel, which is on UTC+3, the legal
day begins at 1800 local time the day before. This simplifies
the accommodation of Israeli and traditional Jewish law.)
I wouldn't call this an oddity, but rather an interesting
On Jun 5, 2006, at 1:38 PM, John Cowan wrote:
I found another spectacular illustration of how massive the difference
between solar and legal time can be. Before 1845, the time in Manila,
the Philippines, was the same as Acapulco, Mexico, a discrepancy of
9h16m from Manila solar time. This was
On Jun 5, 2006, at 2:47 PM, John Cowan wrote:
I'm not sure what you mean by civil time in this context.
I meant whatever we've meant in this forum for the past five years.
For some people, civil time is synonymous with standard time; for
others, it means the time shown by accurate clocks in
On Jun 5, 2006, at 4:05 PM, Rob Seaman wrote:
On the other hand, all I've ever meant by the term civil time is
that time that a well educated civilian sets her clock in order to
agree with other civilians for civilian purposes.
I should clarify this to mean the underlying internationalized
Ed Davies quoted:The Gregorian calendar provides a reference system consisting of a,potentially infinite, series of contiguous calendar years. Consecutivecalendar years are identified by sequentially assigned year numbers.A reference point is used which assigns the year number 1875 to thecalendar
On Jun 7, 2006, at 2:01 AM, Clive D.W. Feather wrote:
Actually, the evidence from experiments is that the natural sleep-
wake
cycle is about 27 hours long, but force-locked to the day-night
cycle (it's
easier to synchronise a longer free-running timer to a shorter
external
signal than
Tim Shepard replies:
Also hard to imagine how one gracefully transitions
from one to two sleep cycles a day.
It is already the norm in some places:
http://en.wikipedia.org/wiki/Siesta
Thanks for the chuckle. One is then left wondering whether our far
future, Clarkeian Against the Fall
Clive D.W. Feather wrote:
March was the first month of the year; look at the derivation of
September, for example.
Makes the zero vs. one indexing question of C and FORTRAN programmers
look sane. I've pointed people to the whole 7, 8, 9, 10 sequence
from September to December on those
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