Warner Losh wrote:
> I'm asking for either of the plots, rescaled with a second based on the
> average second of 1900 rather than on the average second of 1820ish that
> newcomb's second (which is what the SI second wound up being based on) wound
> up being based on…
The y-axis is length-of-da
We can speculate contrary to fact on all sorts of things (those are the "straw men" of the subject line), but rather I
think this talking point is fairly neutral, or cuts both ways.
Rob
Right. Isn't it refreshing to have neutral points every now and then? Not everything about leap seconds is p
Tom Van Baak wrote:
> The longer-term plot (http://ucolick.org/~sla/leapsecs/lod.pdf) makes it
> clear there are no guarantees, but if this trend were to continue we will
> have negative leap seconds 15 or 20 years from now. That would be good news
> for the eliminate-leap-second-proposal since
On Jan 11, 2012, at 10:20 AM, Rob Seaman wrote:
> Warner Losh wrote:
>
>> For the purposes of my question "better" means "lower rate of leap second
>> introduction for the next few decades"
>
> Then we're good right now.
But would we be "better" or "worse" by that metric if we adopted an SI s
Another way of asking the question is 'what would the rate of leap seconds (or slope of TAI - UT or TT-UT)' if the
definition of a second gave is an average LOD - 86400s of more like 1ms or 100us. And would we have had to have
negative leap seconds...
Warner,
I'll track that down. I made plot
Warner Losh wrote:
> For the purposes of my question "better" means "lower rate of leap second
> introduction for the next few decades"
Then we're good right now.
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On Jan 11, 2012, at 9:53 AM, Rob Seaman wrote:
> Warner Losh wrote:
>
>> Tom Van Baak wrote:
>>
>>> Although on average LOD is more than 86400 s by a few milliseconds, in the
>>> past fifty years about 3% of the days have been shorter than 86400 s. In
>>> the past decade alone the figure is 1
On Jan 11, 2012, at 9:53 AM, Rob Seaman wrote:
> Warner Losh wrote:
>
>> Tom Van Baak wrote:
>>
>>> Although on average LOD is more than 86400 s by a few milliseconds, in the
>>> past fifty years about 3% of the days have been shorter than 86400 s. In
>>> the past decade alone the figure is 1
Warner Losh wrote:
> Tom Van Baak wrote:
>
>> Although on average LOD is more than 86400 s by a few milliseconds, in the
>> past fifty years about 3% of the days have been shorter than 86400 s. In the
>> past decade alone the figure is 14% (the earth has sped up quite a bit the
>> past decade)
On Jan 11, 2012, at 4:59 AM, Tom Van Baak wrote:
> > When was the _rate_ of UTC such that 86400s == 1 mean solar day?
> >
> > ian
> Ian,
>
> Although on average LOD is more than 86400 s by a few milliseconds, in the
> past fifty years about 3% of the days have been shorter than 86400 s. In the
> When was the _rate_ of UTC such that 86400s == 1 mean solar day?
>
> ian
Ian,
Although on average LOD is more than 86400 s by a few milliseconds, in the past
fifty years about 3% of the days have been shorter than 86400 s. In the past
decade alone the figure is 14% (the earth has sped up quit
On 10 Jan 2012, at 1959, Clive D.W. Feather wrote:
> Ian Batten said:
>> You cannot set up a bijection between successive 1s timestamps of UTC and
>> successive valid 1s timestamps of UK Civil Time, because the civil
>> timestamps between 01:00:00 and 02:00:00 on the fourth Sunday in October
>
Ian Batten said:
> You cannot set up a bijection between successive 1s timestamps of UTC and
> successive valid 1s timestamps of UK Civil Time, because the civil timestamps
> between 01:00:00 and 02:00:00 on the fourth Sunday in October each map to two
> distinct UTC timestamps, as they are repe
Rob Seaman wrote:
> Tony Finch wrote:
>
> > It used to be local apparent solar time. Then local mean solar time.
> > Then standard mean solar time. Then standard time with daylight
> > saving. The definition of civil time is evidently not fixed.
>
> One notes that TAI is not on the list.
Not yet,
On 1/10/2012 12:06 PM, Ian Batten wrote:
But unfortunately, UK civil time does not include a DST indicator
Is there a law or rule that specifies how UK civil time ought to be written?
Where can we examine the law or rule to see if there is a DST indicator
or not?
If there is no rule, how is th
On 10 Jan 2012, at 1528, Tony Finch wrote:
> Rob Seaman wrote:
>> Warner Losh wrote:
>>
>>> It is only one possible definition, not the only one. That makes it a
>>> belief, not a mathematical identity.
>>
>> Alternate definition?
>
> It used to be local apparent solar time. Then local mean
Tony Finch wrote:
> It used to be local apparent solar time. Then local mean solar time. Then
> standard mean solar time. Then standard time with daylight saving. The
> definition of civil time is evidently not fixed.
One notes that TAI is not on the list. If it were, it would be preferable to
Rob Seaman wrote:
> Warner Losh wrote:
>
> > It is only one possible definition, not the only one. That makes it a
> > belief, not a mathematical identity.
>
> Alternate definition?
It used to be local apparent solar time. Then local mean solar time. Then
standard mean solar time. Then standard
Clive D.W. Feather wrote:
>
> If you said that people prefer that the middle of the solar night be within
> a couple of hours of 00:00 local civil time, I might be more ready to agree.
Actually it's more like people prefer sunrise to be near 7am. They don't
much care about noon or midnight, and a
On Jan 9, 2012, at 11:31 PM, Rob Seaman wrote:
> As you point out, this is an approximation not a definition of a fundamental
> concept. The synodic day is good from now until the Earth melts. It is the
> difference between the rotational period of a planet and its day. See, for
> instance:
On Jan 9, 2012, at 11:22 PM, Rob Seaman wrote:
> See the Simpson, Storz and Malys contributions at
> http://futureofutc.org/preprints/
>
> "Several years to update" is not a plan.
It is not my job to make their plans for them, nor is it ITUs. If things
change, you need to adapt.
Warner
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Pot. Kettle.
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Le 10/01/2012 08:18, Poul-Henning Kamp a écrit :
Rob,
To say that your unconvincing statement of conjecture as fact is getting
a bit tiresome may be to understate the situation somewhat.
If you start with the name, the word that sets UTC apart from all
the other UTs is the word "coordinated".
Ian Batten said:
>> A more accurate statement is: ?Civil time is mean solar time?, because this
>> is really just a definition of terms (p.7)
>
> I know you really, fervently believe that to be not only true currently but
> inevitably and essentially true, but it just isn't.
Indeed, and Rob nee
Whoops. Never mind the "calling several things" part. I'm a Mac user
and some things require Adobe software to read correctly. The rest of
the sentence still seems correct, though.
Dennis Ferguson
On 10 Jan, 2012, at 15:10 , Dennis Ferguson wrote:
>
> On 10 Jan, 2012, at 14:39 , Rob Seaman w
Ian Batten said:
> Y2K? You do realise that "The astronomical community started preparing for
> Y2K in 1996 and barely had enough time" isn't something to be proud of, don't
> you? We'd _finished_ by 1996, having started the programme in about 1989.
Indeed.
In 1985 I was sitting in meetings
On 10 Jan 2012, at 0541, Rob Seaman wrote:
>
> And yet many arguments here have proceeded from the observation that
> civilians rely on complex modern infrastructure.
That's a geek argument, if I might make so bold. Just because A relies on B
doesn't mean that the consumers of A have any n
Rob,
To say that your unconvincing statement of conjecture as fact is getting
a bit tiresome may be to understate the situation somewhat.
If you start with the name, the word that sets UTC apart from all
the other UTs is the word "coordinated".
That word refers to the coordination between the n
On 10 Jan, 2012, at 14:39 , Rob Seaman wrote:
> Gotta love this equation:
>
> UT1 = UTC + UT1 + UT1 (t – tEOP)
You do have to love it, because beyond calling several different things
UT1 (and unless I'm missing something, which is always possible) it seems
to imply either that they expec
Gotta love this equation: UT1 = UTC + UT1 + UT1 (t – tEOP)--On Jan 9, 2012, at 11:31 PM, Dennis Ferguson wrote:On 10 Jan, 2012, at 14:02 , Rob Seaman wrote:Dennis Ferguson wrote:By the time leap seconds stop you should be able to get UT1 directly, with high precision, from your satellite navigatio
As you point out, this is an approximation not a definition of a fundamental
concept. The synodic day is good from now until the Earth melts. It is the
difference between the rotational period of a planet and its day. See, for
instance: http://cseligman.com/text/sky/rotationvsday.htm
I also
On 10 Jan, 2012, at 14:02 , Rob Seaman wrote:
> Dennis Ferguson wrote:
>
>> By the time leap seconds stop you should be able to get UT1 directly, with
>> high precision, from your satellite navigation receiver
>
> I'll borrow one of these from Ian:
>
> [Citation Needed]
For GPS fetch this
See the Simpson, Storz and Malys contributions at
http://futureofutc.org/preprints/
"Several years to update" is not a plan.
--
On Jan 9, 2012, at 11:12 PM, Warner Losh wrote:
>
> On Jan 9, 2012, at 10:41 PM, Rob Seaman wrote:
>> And yet many arguments here have proceeded from the observation
On Jan 9, 2012, at 11:02 PM, Rob Seaman wrote:
> Warner Losh wrote:
>> It is only one possible definition, not the only one. That makes it a
>> belief, not a mathematical identity.
>
> Alternate definition?
A SI second is defined by BIPM.
Everybody knows that minutes have 60 seconds, hours ha
On Jan 9, 2012, at 10:41 PM, Rob Seaman wrote:
> And yet many arguments here have proceeded from the observation that
> civilians rely on complex modern infrastructure. For instance, a lot of
> telecommunications depends on satellite technology, hence the sponsorship of
> the Future of UTC mee
Dennis Ferguson wrote:
> By the time leap seconds stop you should be able to get UT1 directly, with
> high precision, from your satellite navigation receiver
I'll borrow one of these from Ian:
[Citation Needed]
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Warner Losh wrote:
> It is only one possible definition, not the only one. That makes it a
> belief, not a mathematical identity.
Alternate definition?
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On Jan 9, 2012, at 5:23 PM, Rob Seaman wrote:
> Ian Batten wrote:
>
>> I know you really, fervently believe that to be not only true currently but
>> inevitably and essentially true, but it just isn't.
>
> No, rather I assert it as a definition of terms. A mathematical identity if
> you like
Ian Batten wrote:
> Clearly a day which consists of 86400 SI seconds isn't a mean solar day over
> any extended period of time.
Indeed.
> One of "86400" or "SI" or "a day runs from mean noon to mean noon" has to go
> at some point many thousands of years out.
A good place to start, although t
On 10 Jan, 2012, at 05:38 , Michael Sokolov wrote:
> Clive D.W. Feather wrote:
>
>> I don't need Universal Time,
>
> But I do. By what right are you seeking to take it away from me?
>
> MS
If the requirement is for UT I don't think anyone is taking it away
from you, in fact it seems like th
Daniel R. Tobias wrote:
> I can recall, as early as 1981, making a point of using 4-digit years in any
> programs I wrote (at that time they were in BASIC for the Apple II).
Then there's: http://blog.longnow.org/2007/10/12/y10k-compliance/
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On 9 Jan 2012 at 21:08, Michael Sokolov wrote:
> The most recent code change I've made in connection with Y2K was just
> a few months ago in 2011-07: I have finally changed SCCS to use
> 4-digit years instead of just the last two digits.
I can recall, as early as 1981, making a point of using 4-
On 9 Jan 2012 at 15:55, Ian Batten wrote:
> And that in the end, society at large's response may well be a
> great big "meh", in that removing leap seconds solves problems for
> 99% of the population, while the remaining 1% need to just sort out
> their own house. Sorry.
My guess is that about
On 10 Jan 2012, at 0023, Rob Seaman wrote:
> A day for civil timekeeping purposes is a mean solar day.
Clearly a day which consists of 86400 SI seconds isn't a mean solar day over
any extended period of time.One of "86400" or "SI" or "a day runs from mean
noon to mean noon" has to go at so
Ian Batten wrote:
> your watch is set to civil time;
Because the word "you" and "your" when posted on a public mailing list
effectively imply "everyone on the list", I can easy prove that your
statement is false: *my* watch is set to whatever time *I* choose,
which is *not* necessarily the same
Ian Batten wrote:
> I know you really, fervently believe that to be not only true currently but
> inevitably and essentially true, but it just isn't.
No, rather I assert it as a definition of terms. A mathematical identity if
you like.
> For a start off, as the examples of Penzance,
On 9 Jan 2012, at 2129, Rob Seaman wrote:
>>
>> Pages 7 and 8 appear to be assertions that it's true, rather than any solid
>> reasons why it's true.
>
> I'll try harder next time.
The problem is
> A more accurate statement is: “Civil time is mean solar time”, because this
> is really just
In message <7422cd7e-2405-4c94-99d6-b9da1f1bc...@pipe.nl>, Nero Imhard writes:
>On 2012-01-09, at 20:42, Poul-Henning Kamp wrote:
>
>> It can easily be argued that if you need UT to better than 1s, you
>> should use one of IERS's UT products and you will have five years to
>> make the fix.
>
>This
Clive D.W. Feather wrote:
> I don't need Universal Time,
But I do. By what right are you seeking to take it away from me?
MS
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You know, I only picked the subject line "straw men" because the "China"
subject was being reused for topics completely unrelated. As I think I've said
before, I'd be delighted to buy any of you guys a beer should our paths ever
cross. I will be in Amsterdam the week following the leap second
Ian Batten wrote:
> Why would UTC be different between localities?
Because different countries will react differently to the morally
despicable and reprehensible actions of the ITU. Some countries will
gleefully accept the redefined UTC as legitimate, while others will
reject it as fraudulent.
On 9 Jan 2012, at 2025, Rob Seaman wrote:
> Absence of handy examples has no implications for the preceding statement.
"Just because I can't find examples doesn't mean it isn't happening" is hardly
persuasive. Gathered on this list is a pretty solid cross-section of people
who've worked in c
Tony Finch wrote:
> There should be no fragmentation of the underlying
> timescale, and there will continue to be a consensus realization of it.
How sure are you of the last part? How sure are you that some
countries won't consider the ITU's UTC redefinition act to be
fraudulent and illegitimat
Ian Batten wrote:
> > There are, for instance, ongoing Y2K-related issues.
> [Citation Needed]
I am continuing to deal with Y2K fallout issues in 4.3BSD-Quasijarus
to the present day, as it becomes apparent to me that my initial fixes
made just before the Y2K moment aren't good enough in the lon
On 2012-01-09, at 20:42, Poul-Henning Kamp wrote:
> It can easily be argued that if you need UT to better than 1s, you
> should use one of IERS's UT products and you will have five years to
> make the fix.
This is the arrogance I mentioned earlier. What good is a definition (that of
UTC being a
Rob Seaman said:
>> You keep trying to cook the process so that it only winds up with your
>> solution.
> I am not trying to "cook the process". The assertion of the notion that
> timezones will magically fix "the problem" is rather a confirmation of my
> point. There would be no problem, no
On 1/9/2012 3:14 PM, Ian Batten wrote:
And you do this not by looking up sunset in an almanac, a newspaper, a website,
but by performing a calculation that relies on UTC-plus-leapseconds? Could you
give me more detail of this?
> ...
No one has yet provided even the beginnings of the suggesti
Ian Batten wrote:
> On 9 Jan 2012, at 1845, Rob Seaman wrote:
>
>> Yes, I expect issues to continue to arise decades hence in currently
>> deployed systems and processes. There are, for instance, ongoing
>> Y2K-related issues.
>
> [Citation Needed]
I was thinking of this: http://catless.ncl.
On Jan 9, 2012, at 12:40 PM, Ian Batten wrote:
> So a little less of the "the astronomical community are the only competent
> engineers, the rest of you are just charlatans" would be nice.
My point exactly!
Warner
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On 9 Jan 2012, at 2004, Gerard Ashton wrote:
> On 1/9/2012 2:40 PM, Ian Batten wrote:
>> So long as those all tick the same thing, its relationship to the rotation
>> of the earth is, +/- several hours, irrelevant. No-one cares what the
>> relationship between their watch/clock/computer and th
>
> 3) There is an assumption - without benefit of any documentation whatsoever -
> that timezone adjustments can indeed serve this stated purpose. If this is
> obvious (I don't find it such), then it should be easy to write a description
> of how this would work.
>
> a) Please address
On 1/9/2012 2:40 PM, Ian Batten wrote:
So long as those all tick the same thing, its relationship to the rotation of
the earth is, +/- several hours, irrelevant. No-one cares what the
relationship between their watch/clock/computer and the sun is at anything
other than the grossest scale
Th
In message <85fc73d9-2bfa-4b7d-816f-45e2ea73e...@noao.edu>, Rob Seaman writes:
>Ian Batten wrote:
>
>It breaks applications that relied on something called "Coordinated
>Universal Time" to actually remain a type of Universal Time.
No, it only breaks those that relies on the DUT1 being <1s.
There
Rob Seaman wrote:
>
> Currently the zone system is tied worldwide to an underlying mean solar
> time standard. The notion is to fragment this such that different
> localities will separately realize whatever synchronization they deem
> necessary. That is, a single common civil timescale is being
On 9 Jan 2012, at 1845, Rob Seaman wrote:
> Ian Batten wrote:
>
>> And you accuse others of erecting straw men? Are you saying that if UTC
>> were redefined tomorrow, in a hundred years time there would still be
>> equipment in use that would be mis-behaving?
>
> Convenient way to forget the
Rob Seaman wrote:
>
> Apparent solar time is derived from mean solar time, not the other way
> around.
That is how it has been calculated for the last century or two, but
historically it was the other way around. The word "derived" is unhelpful
because it sounds too much like historical developme
Warner Losh wrote:
> On Jan 9, 2012, at 11:17 AM, Rob Seaman wrote:
>
>> Warner Losh wrote:
>>
>>> Actually it is a fair engineering question: Why pay the cost of leap
>>> seconds when we can keep civil time aligned to the sun with time zones once
>>> every N generations.
>>
>> First off - wh
Ian Batten wrote:
> And you accuse others of erecting straw men? Are you saying that if UTC were
> redefined tomorrow, in a hundred years time there would still be equipment in
> use that would be mis-behaving?
Convenient way to forget the word "decades". Yes, I expect issues to continue
to
On Jan 9, 2012, at 11:17 AM, Rob Seaman wrote:
> Warner Losh wrote:
>
>> Actually it is a fair engineering question: Why pay the cost of leap seconds
>> when we can keep civil time aligned to the sun with time zones once every N
>> generations.
>
> First off - what is that cost? There is an
Ian Batten wrote:
> More specifically, it breaks a subset of earth-facing applications which rely
> on UTC, by name, and have no means to apply any offset other than DUT1 in the
> range |DUT1|<1, but do have the ability to apply those small DUT1s, which in
> turn tends to imply that these are a
Warner Losh wrote:
> Actually it is a fair engineering question: Why pay the cost of leap seconds
> when we can keep civil time aligned to the sun with time zones once every N
> generations.
First off - what is that cost? There is an absence of costing efforts for
either leap seconds as they
On 9 Jan 2012, at 16:21, Warner Losh wrote:
>
> It breaks earth-facing applications and nothing else. No examples have been
> given of what it breaks apart from that.
>
More specifically, it breaks a subset of earth-facing applications which rely
on UTC, by name, and have no means to apply
On Jan 9, 2012, at 10:17 AM, Ian Batten wrote:
> That'll give you a century's protection from the problem.
You'd think in a century somebody would update the tables...
Warner
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On 9 Jan 2012, at 16:32, Gerard Ashton wrote:
> On 1/9/2012 10:55 AM, Ian Batten wrote:
>> pace all the bizarre claims about bear hunting
>
> There are a number of laws and rules related to sunset and sunrise, including
> hunting, turning headlights on
> in automobiles, and being present in par
On 1/9/2012 10:55 AM, Ian Batten wrote:
pace all the bizarre claims about bear hunting
There are a number of laws and rules related to sunset and sunrise,
including hunting, turning headlights on
in automobiles, and being present in parks. No reliable evidence has
been presented as to whether
On Jan 9, 2012, at 6:24 AM, Rob Seaman wrote:
> Ian Batten wrote:
>
>> The invocation of "won't somebody think our of great^8 grand children's
>> watches!" is disingenuous.
>
> And it's a straw man erected by the folks who want to redefine UTC.
Actually it is a fair engineering question: Why
On 9 Jan 2012, at 13:24, Rob Seaman wrote:
> I
> Redefining UTC will break things immediately in astronomy and aerospace and
> related applications. And it will break things at unpredictable intervals
> over the decades and centuries to come.
And you accuse others of erecting straw men? Are
What a great and thorough catalogue of the various time systems!
-- Richard Langley
For the true complexity of the situation, see:
http://ucolick.org/~sla/leapsecs/timescales.html
Rob Seaman
National Optical Astronomy Observatory
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Clive D.W. Feather wrote:
> Rob Seaman said:
>> Redefining UTC will break things immediately in astronomy and aerospace and
>> related applications.
>
> False.
>
> It might break them at the point that |DUT| > 0.9s. Or it might not. But it
> won't break them until then, which could easily be so
On Jan 9, 2012, at 6:36 AM, Ian Batten wrote:
> UTC has been redefined within living memory.One might suggest that good
> engineering would avoid assuming that a timescale which has been repeatedly
> redefined in both rate and phase won't be redefined again.
More straw. UTC has always mean
Clive D.W. Feather wrote:
> we've moved from local mean solar time to GMT to summer time to double summer
> time to back again to BST to summer time again
And another straw man. Only proponents of redefining UTC have ever suggested
this superficial view of a connection to apparent solar time.
Rob Seaman said:
> Redefining UTC will break things immediately in astronomy and aerospace and
> related applications.
False.
It might break them at the point that |DUT| > 0.9s. Or it might not. But it
won't break them until then, which could easily be some years away.
> And it will leave any p
On 9 Jan 2012, at 13:24, Rob Seaman wrote:
>
> Redefining UTC will break things immediately in astronomy and aerospace and
> related applications.
UTC has been redefined within living memory.One might suggest that good
engineering would avoid assuming that a timescale which has been repea
In message <43660828-da25-44ed-9c97-8afc511c0...@noao.edu>, Rob Seaman writes:
>And it will leave any purely atomic timescale many minutes or hours
>in error at a future epoch with no plan for mitigation.
Try to be precise: " no plan *OR DESIRE* for mitigation."
--
Poul-Henning Kamp
Ian Batten wrote:
> The invocation of "won't somebody think our of great^8 grand children's
> watches!" is disingenuous.
And it's a straw man erected by the folks who want to redefine UTC.
> It is a hell of a stretch to claim that re-aligning time zones once every ten
> generation is unreasona
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