On 6 Nov, 2014, at 20:16 , Sanjeev Gupta gha...@gmail.com wrote:
Anyone who wishes to believe 60 secs always to a minute can continue to do
so. Anyone who needs the extra accuracy (time-nuts, astronomers, pedants,
old men like me) will learn the fact that a minute is not always 60 secs.
Michael Deckers via LEAPSECS leapsecs@leapsecond.com wrote:
|On 2014-11-06 13:10, Steffen Nurpmeso wrote
|
|in defense of the description by the German metrology
|laboratory in [https://www.ptb.de/cms/en/fachabteilungen
|/abt4/fb-44/ag-441/coordinated-universal-time-utc.html]:
Sanjeev Gupta gha...@gmail.com wrote:
As a general rant, I still complain that (roughly) year 8 to year 12 of my
schooling required me to learn stuff in physics, and then the next year,
often the same teacher would tell me what I had learnt was wrong, and this
was the correct way.
On 6 Nov 2014, at 14:37, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message
CAHZk5WfKSLMy77HK1Vsvk9PQ5v=tpb0rzuri8j4kmcezooa...@mail.gmail.com
, Sanjeev Gupta writes:
Note that seconds are also a unit of angles, so UT1 seconds being a
measure of angle is not strange.
So when I was googling around for more information about what paper
timescales the BIPM publishes, I found this:
http://iag.dgfi.badw.de/fileadmin/IAG-docs/Travaux2013/08_BIPM.pdf
which says:
The algorithm used for the calculation of time scales is an iterative
process that starts by
Alex Currant via LEAPSECS leapsecs@leapsecond.com wrote:
Despite what the recommendations might say, I think the TA(k) reported
in the Circular T are not efforts by lab K to realize TAI, since it is
hard to imagine how a lab could get a different offset attempting to
realize TAI from
On 2014-11-05 15:30, Warner Losh wrote on the
determination of TAI - UT1:
Now, back to the SI second vs the UT1 second. The UT1 second is 1E-8 or 1E-9
different
from the SI second. Unless they are computing the results to 7 or more digits,
the answers
will be identical, no matter which
Alex Currant via LEAPSECS wrote:
Despite what the recommendations might say, I think the TA(k) reported
in the Circular T are not efforts by lab K to realize TAI,
Indeed. TA(k) are independent time scales, apparently not steered in
either phase or frequency. They in fact run at a variety of
michael.deckers via LEAPSECS wrote:
The IERS certainly won't fudge on their units.
I'm afraid they do. Everyone does in this area. Even the IAU resolutions
fudge the units.
However, Warner is *also* fudging units, in a different manner, and I
think that's causing you trouble. Warner has said
Michael Deckers via LEAPSECS wrote:
The symbol TAI(k) is defined in
RECOMMENDATION ITU-R TF.536-2: Time-scale notations
of 2003 with the text:
TAI(k): Time-scale realized by the institute k and defined
by the relation TAI(k) = UTC(k) + DTAI,
Oh cool, same as my definition.
Zefram zef...@fysh.org wrote:
Warner has said things like the UT1 second is 1e-9 different from the
SI second. That statement implies that the UT1 second is a physical
quantity, with dimensionality of proper time, which can thus be measured
using the SI second as a unit.
The UT1 second is
Warner Losh wrote:
On Nov 5, 2014, at 10:54 AM, Zefram zef...@fysh.org wrote:
TAI(k) = TAI + (UTC(k)-UTC) = UTC(k) + (TAI-UTC)
Except that's not how others define it.
Michael Deckers has now pointed at ITU Rec TF.536-2 which defines TAI(k)
in the same way as I do. What conflicting
Bonjour,
Michael Deckers via LEAPSECS leapsecs@leapsecond.com wrote:
|On 2014-11-05 11:28, Steffen Nurpmeso wrote:
| Oh, the German Physikalisch-Technische Bundesanstalt (PTB) also
| has a general -- at least -- overview of the set of problems.
| (English: [1] and all around that; oops,
On Thu, Nov 6, 2014 at 8:38 PM, Tony Finch d...@dotat.at wrote:
The UT1 second is 2pi/86400 times the reciprocal of the angular velocity
of the Earth. The units for this quantity are just seconds (because angles
are dimensionless), or if you want to be more explicit, seconds per
2pi/86400
In message CAHZk5WfKSLMy77HK1Vsvk9PQ5v=tpb0rzuri8j4kmcezooa...@mail.gmail.com
, Sanjeev Gupta writes:
Note that seconds are also a unit of angles, so UT1 seconds being a
measure of angle is not strange.
...and I'm sure any surveyor or ships navigator would be extremely suprised
if
@leapsecond.com
To: Leap Second Discussion List leapsecs@leapsecond.com
Sent: Wednesday, November 5, 2014 3:59 PM
Subject: Re: [LEAPSECS] the big artillery
On 2014-11-05 16:27, Zefram wrote:
... UTC is always
an integral number
On Nov 6, 2014, at 4:40 AM, michael.deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
On 2014-11-05 15:30, Warner Losh wrote on the
determination of TAI - UT1:
Now, back to the SI second vs the UT1 second. The UT1 second is 1E-8 or 1E-9
different
from the SI second. Unless they
On Nov 6, 2014, at 5:09 AM, Zefram zef...@fysh.org wrote:
My view is that the UT1 second is a unit, not a variable quantity.
It's a different unit from the SI second, and can't be described in
terms of the SI second. If anything it's a unit of angle, and so can be
described in radians or an
On Nov 6, 2014, at 5:55 AM, Zefram zef...@fysh.org wrote:
Warner Losh wrote:
On Nov 5, 2014, at 10:54 AM, Zefram zef...@fysh.org wrote:
TAI(k) = TAI + (UTC(k)-UTC) = UTC(k) + (TAI-UTC)
Except that's not how others define it.
Michael Deckers has now pointed at ITU Rec TF.536-2 which
Poul-Henning Kamp p...@phk.freebsd.dk wrote:
minutes and seconds are fractions of 60 and have been so since
babylonian times for minutes and since 13-mumble for seconds.
The etymology is actually helpful in this case rather than misleading as
etymologies so often are.
minute is short for pars
On Thu, Nov 6, 2014 at 10:37 PM, Poul-Henning Kamp p...@phk.freebsd.dk
wrote:
In message CAHZk5WfKSLMy77HK1Vsvk9PQ5v=
tpb0rzuri8j4kmcezooa...@mail.gmail.com
, Sanjeev Gupta writes:
Note that seconds are also a unit of angles, so UT1 seconds being a
measure of angle is not strange.
...and
Warner Losh wrote:
The conflicting definitions I've seen
have been from one of the time scientists that helped to setup TAI when he was
at NBS(later NIST) who strenuously instructed me that they weren't equivalent
and
was quite patient with my stupid
Tony Finch said:
minutes and seconds are fractions of 60 and have been so since
babylonian times for minutes and since 13-mumble for seconds.
The etymology is actually helpful in this case rather than misleading as
etymologies so often are.
minute is short for pars minuta prima, the first
...@leapsecond.com] On Behalf Of Clive
D.W. Feather
Sent: Thursday, November 6, 2014 11:20 AM
To: Leap Second Discussion List
Subject: Re: [LEAPSECS] the big artillery
Tony Finch said:
minutes and seconds are fractions of 60 and have been so since
babylonian times for minutes and since 13-mumble
On Nov 6, 2014, at 11:24 AM, Dennis Ferguson dennis.c.fergu...@gmail.com
wrote:
On Nov 6, 2014, at 11:19, Clive D.W. Feather cl...@davros.org wrote:
Tony Finch said:
minutes and seconds are fractions of 60 and have been so since
babylonian times for minutes and since 13-mumble for
On 2014-11-06 13:10, Steffen Nurpmeso wrote
in defense of the description by the German metrology
laboratory in [https://www.ptb.de/cms/en/fachabteilungen
/abt4/fb-44/ag-441/coordinated-universal-time-utc.html]:
Hm, indeed a sloppy translation of the original German text
Die
On 2014-11-04 22:26, Steve Allen quoted Bernard Guinot
about the unit for the difference TAI - UT1:
Guinot explained this using the term graduation second
in section 2.2 of 1995 Metrologia 31 431
http://iopscience.iop.org/0026-1394/31/6/002
He points out that the way the IAU has written
@leapsecond.com
Sent: Thursday, November 6, 2014 11:17 AM
Subject: Re: [LEAPSECS] the big artillery
On Thu, Nov 6, 2014 at 10:37 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message CAHZk5WfKSLMy77HK1Vsvk9PQ5v=tpb0rzuri8j4kmcezooa...@mail.gmail.com
, Sanjeev Gupta writes:
Note
On Fri, Nov 7, 2014 at 2:24 AM, Dennis Ferguson dennis.c.fergu...@gmail.com
wrote:
In some ways the UTC minute redefinition is even worse than that. A 6
year old
might not know how many seconds are in a hectosecond but would often be
expected to know there are 60 seconds in a minute.
Brooks Harris wrote:
On 2014-11-04 04:59 PM, Zefram wrote:
(Contrary to Brooks's earlier statement, the table does not
imply anything about pre-1972 UTC.)
I don't understand why you say that. Can you explain what you mean?
It seems to me the origins of both PTP and NTP are certainly
pre-1972 UTC.
Gerard Ashton ashto...@comcast.net wrote:
For example, the Standards of Fundamental Astronomy subroutine iauDat
provides the delta between TAI and UTC, and the source code comments say
UTC began at 1960 January 1.0 (JD 2436934.5) and it is improper to call
the function with an earlier date.
Michael Deckers via LEAPSECS leapsecs@leapsecond.com wrote:
| On 2014-11-04 19:45, Brooks Harris wrote on the history of UTC:
|
| For purposes of astronomy, and probably others, the rubber \
| band era may have
| relevance. To call it UTC seems a bit of a stretch to me, but there's no
|
On Wed 2014-11-05T11:11:38 +, Tony Finch hath writ:
Does anyone know where SOFA iauDat got its data for 1960 from? Because
that predates the USNO table.
By the way, which USNO table is that?
I'm wondering if it is actually a reprint of the BIH table.
--
Steve Allen
On Nov 4, 2014, at 2:52 PM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
On 2014-11-04 12:34, Zefram wrote:
UT1 always ticks a second for that ERA increase, but Warner's point
is that the second of UT1 isn't an *SI* second.
It is not, and cannot be a SI second, except
On Nov 4, 2014, at 6:07 AM, Zefram zef...@fysh.org wrote:
Warner Losh wrote:
Users can only get UTC(foo) or a signal derived from UTC(foo) (e.g.,
traceable to NIST) and never UTC itself. Of course they can get to a
putative TAI(foo) trivially (I say putative, because as far as I know, no
Steve Allen s...@ucolick.org wrote:
By the way, which USNO table is that?
http://maia.usno.navy.mil/ser7/tai-utc.dat
Tony.
--
f.anthony.n.finch d...@dotat.at http://dotat.at/
Southwest Forties, Cromarty, Forth, Tyne, Dogger: Northerly 4 or 5, becoming
variable 3 or 4, then southerly 5 to 7
Warner Losh wrote:
The markers aren't the same.
I was referring to the PPS marks in a time signal, and because TAI and UTC
tick the same seconds the marks work equally well for both. Taking MSF
as a specific example, the onset of each per-second carrier-suppressed
interval (specifically, the
On Wed 2014-11-05T15:49:05 +, Tony Finch hath writ:
Steve Allen s...@ucolick.org wrote:
By the way, which USNO table is that?
http://maia.usno.navy.mil/ser7/tai-utc.dat
Yes, that is the table from the BIH, who were given responsibility
for the coordination as of the beginning of 1961.
On Wed, Nov 05, 2014 at 04:27:19PM +, Zefram wrote:
UTC is always
an integral number of seconds offset from TAI, and so by construction
UTC(NPL) is always an integral number of seconds offset from TAI(NPL).
I don't see how the first follows from the second here, particularly
if you
David Malone wrote:
if you transmit a second boundary at what you later identify to be
the wrong time, you can correct for that in your paper estimate of
TAI(X) so that it does may not align with UTC(X).
That's not what I mean by TAI(k). You're describing having two distinct
time scale
On 2014-11-04 22:26, Steve Allen wrote:
Guinot explained this using the term graduation second
in section 2.2 of 1995 Metrologia 31 431
http://iopscience.iop.org/0026-1394/31/6/002
He points out that the way the IAU has written the definitions of the
time scales uses a subtly ambiguous
On 2014-11-05 11:28, Steffen Nurpmeso wrote:
Oh, the German Physikalisch-Technische Bundesanstalt (PTB) also
has a general -- at least -- overview of the set of problems.
(English: [1] and all around that; oops, not everything is
translated, what a shame! I hope it's not due to lack of
On 2014-11-05 16:27, Zefram wrote:
... UTC is always
an integral number of seconds offset from TAI, and so by construction
UTC(NPL) is always an integral number of seconds offset from TAI(NPL).
Hence each of the marks also occurs at the
On Nov 5, 2014, at 10:54 AM, Zefram zef...@fysh.org wrote:
David Malone wrote:
if you transmit a second boundary at what you later identify to be
the wrong time, you can correct for that in your paper estimate of
TAI(X) so that it does may not align with UTC(X).
That's not what I mean by
On Nov 5, 2014, at 1:59 PM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
On 2014-11-05 16:27, Zefram wrote:
... UTC is always
an integral number of seconds offset from TAI, and so by construction
UTC(NPL) is always an
On Wed 2014-11-05T14:50:06 -0700, Warner Losh hath writ:
On Nov 5, 2014, at 1:59 PM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
The symbol TAI(k) is defined in
RECOMMENDATION ITU-R TF.536-2: Time-scale notations
of 2003 with the text:
At the time, I couldn't find
@leapsecond.com
To: Leap Second Discussion List leapsecs@leapsecond.com
Sent: Wednesday, November 5, 2014 3:59 PM
Subject: Re: [LEAPSECS] the big artillery
On 2014-11-05 16:27, Zefram wrote:
... UTC is always
an integral number
.
From: Michael Deckers via LEAPSECS leapsecs@leapsecond.com
To: Leap Second Discussion List leapsecs@leapsecond.com
Sent: Wednesday, November 5, 2014 3:59 PM
Subject: Re: [LEAPSECS] the big artillery
On 2014-11-05 16:27, Zefram wrote
michael.deckers via LEAPSECS wrote:
UT1 is a timescale that ticks 1 SI second when the Earth Rotation Angle
increases by exactly (2 rad)/86 636.546 949 141 027 072,
Which it rarely does for any length of time.
On the contrary, the fixed angular speed d(ERA)/d(UT1) is a
defining
Warner Losh wrote:
Users can only get UTC(foo) or a signal derived from UTC(foo) (e.g.,
traceable to NIST) and never UTC itself. Of course they can get to a
putative TAI(foo) trivially (I say putative, because as far as I know, no
lab generates TAI synchronized signals for reasons you go into).
Brooks Harris wrote:
The discussion attempts to resolve the question about what the
TAI/UTC relationship was *before* 1972-01-01T00:00:00Z and how this
is related to POSIX and represented by 8601.
The actual historical relationship between TAI and UTC prior to 1972
is defined by the well-known
Of course Brooks Harris is free to define proleptic UTC any way he pleases
within the confines of a document he has control over, including a post to
this mailing list. But I think the term proleptic UTC, outside the
confines of a document that gives it a proprietary definition, could mean a
Brooks Harris wrote:
On 2014-11-04 09:04 AM, Zefram wrote:
POSIX is irrelevant to this,
I don't think so. 1588/PTP references POSIX and (POSIX) algorithms
many times, first in the main definition of the PTP Epoch -
The note 1 that you quote doesn't make POSIX relevant to the definition
of the PTP
On 2014-11-04 11:53 AM, Gerard Ashton wrote:
Of course Brooks Harris is free to define proleptic UTC any way he pleases
within the confines of a document he has control over, including a post to
this mailing list. But I think the term proleptic UTC, outside the
confines of a document that gives
Brooks Harris wrote:
To call it UTC seems a bit of a stretch to me,
but there's no generally accepted name for what Zefram calls
rubber-seconds era of UTC. Everybody has seized the name, and
attempted to give it some meaning other than what I, at least,
consider to be its
On Tue 2014-11-04T20:27:53 +, Zefram hath writ:
The name Coordinated Universal Time and initialism UTC are used
in the IAU 1967 resolutions, referring to the rubber-seconds system.
And that resolution explicitly refers to the content of the new CCIR
Recommendation 374-1 which uses the
On 2014-11-04 12:34, Zefram wrote:
UT1 always ticks a second for that ERA increase, but Warner's point
is that the second of UT1 isn't an *SI* second. The time taken for
that ERA increase, and hence the duration of a UT1 second, very rarely
exactly matches an SI second. The second of UT1
On 2014-11-04 03:35 PM, Steve Allen wrote:
On Tue 2014-11-04T20:27:53 +, Zefram hath writ:
The name Coordinated Universal Time and initialism UTC are used
in the IAU 1967 resolutions, referring to the rubber-seconds system.
And that resolution explicitly refers to the content of the new
I wrote:
It sounds as though Annex B may contain actual errors, in such things
as the interpretation of POSIX time_t. Good job it's not normative.
I've now seen the actual text of Annex B (thanks to an unattributable
benefactor). Here is my review of it. Overall it's mostly correct,
but poorly
LEAPSECS leapsecs-boun...@leapsecond.com wrote on 11/04/2014 02:45:09
PM:
From: Brooks Harris bro...@edlmax.com
To: leapsecs@leapsecond.com
Date: 11/04/2014 02:45 PM
Subject: Re: [LEAPSECS] the big artillery
Sent by: LEAPSECS leapsecs-boun...@leapsecond.com
On 2014-11-04 11:53 AM
On Tue 2014-11-04T21:52:05 +, Michael Deckers via LEAPSECS hath writ:
Then which unit would that be? When the IERS compute a difference
TAI - UT1, how do they do it? Do they convert the UT1 reading in
any way before they subtract? Or, if they don't, what is the unit
of the
On 2014-11-04 03:27 PM, Zefram wrote:
Brooks Harris wrote:
To call it UTC seems a bit of a stretch to me,
but there's no generally accepted name for what Zefram calls
rubber-seconds era of UTC. Everybody has seized the name, and
attempted to give it some meaning other than
On 2014-11-04 04:59 PM, Zefram wrote:
I wrote:
It sounds as though Annex B may contain actual errors, in such things
as the interpretation of POSIX time_t. Good job it's not normative.
I've now seen the actual text of Annex B (thanks to an unattributable
benefactor). Here is my review of it.
Warner Losh wrote:
TAI and UTC have a fixed offset relationship, it is true. However, UTC is
computed in real time (with several varieties to choose from if you care
about the nano-seconds), but TAI is a retrospective timescale that's not
computed until after the fact.
These two notions conflict:
On Nov 3, 2014, at 3:35 AM, Zefram zef...@fysh.org wrote:
Warner Losh wrote:
TAI and UTC have a fixed offset relationship, it is true. However, UTC is
computed in real time (with several varieties to choose from if you care
about the nano-seconds), but TAI is a retrospective timescale that's
On 11/03/2014 10:13 AM, Warner Losh wrote:
UTC realized from the labs of NIST will have a
small offset from the UTC realized from NRAO.
Did you mean USNO where you typed NRAO?
___
LEAPSECS mailing list
LEAPSECS@leapsecond.com
On Nov 3, 2014, at 8:19 AM, Greg Hennessy greg.henne...@cox.net wrote:
On 11/03/2014 10:13 AM, Warner Losh wrote:
UTC realized from the labs of NIST will have a
small offset from the UTC realized from NRAO.
Did you mean USNO where you typed NRAO?
Yes. My bad.
Warner
signature.asc
Hi Micheal,
On 2014-11-03 02:43 AM, michael.deckers via LEAPSECS wrote:
On 2014-10-31 17:39, Brooks Harris wrote:
Yes. Its primary timescale, sometimes called PTP Time, more
properly the PTP
Timescale, is a TAI-like counter (uninterrupted incrementing count of
seconds). Note its origin, or
On Nov 3, 2014, at 11:11 AM, Brooks Harris bro...@edlmax.com wrote:
CAUTION about the PTP Epoch. Its not just nitpicking”.
...
We've been advised by PTP experts that A) yes, its confusing, and B) most
implementations use a integral-second interpretation, as in Table B.1. I
understand the
On 2014-11-03 02:19 PM, Warner Losh wrote:
On Nov 3, 2014, at 11:11 AM, Brooks Harris bro...@edlmax.com wrote:
CAUTION about the PTP Epoch. Its not just nitpicking.
...
We've been advised by PTP experts that A) yes, its confusing, and B) most implementations use a integral-second
On Nov 3, 2014, at 12:53 PM, Brooks Harris bro...@edlmax.com wrote:
On 2014-11-03 02:19 PM, Warner Losh wrote:
On Nov 3, 2014, at 11:11 AM, Brooks Harris bro...@edlmax.com
wrote:
CAUTION about the PTP Epoch. Its not just nitpicking”.
...
We've been advised by PTP experts that A)
On 2014-11-03 03:04 PM, Warner Losh wrote:
On Nov 3, 2014, at 12:53 PM, Brooks Harris bro...@edlmax.com wrote:
On 2014-11-03 02:19 PM, Warner Losh wrote:
On Nov 3, 2014, at 11:11 AM, Brooks Harris bro...@edlmax.com
wrote:
CAUTION about the PTP Epoch. Its not just nitpicking.
...
On Nov 3, 2014, at 1:37 PM, Brooks Harris bro...@edlmax.com wrote:
On 2014-11-03 03:04 PM, Warner Losh wrote:
On Nov 3, 2014, at 12:53 PM, Brooks Harris bro...@edlmax.com
wrote:
On 2014-11-03 02:19 PM, Warner Losh wrote:
On Nov 3, 2014, at 11:11 AM, Brooks Harris
On 3 Nov, 2014, at 07:13 , Warner Losh i...@bsdimp.com wrote:
TAI is a paper clock. You can convert your time stamps you get today from
your atomic clock to TAI time stamps once the offsets (phase and frequency)
have been determined for your clock by comparing it to all the others in
the data
On Nov 3, 2014, at 3:03 PM, Dennis Ferguson dennis.c.fergu...@gmail.com wrote:
On 3 Nov, 2014, at 07:13 , Warner Losh i...@bsdimp.com wrote:
TAI is a paper clock. You can convert your time stamps you get today from
your atomic clock to TAI time stamps once the offsets (phase and frequency)
On 2014-11-03 04:50 PM, Warner Losh wrote:
On Nov 3, 2014, at 1:37 PM, Brooks Harris bro...@edlmax.com wrote:
On 2014-11-03 03:04 PM, Warner Losh wrote:
On Nov 3, 2014, at 12:53 PM, Brooks Harris bro...@edlmax.com
wrote:
On 2014-11-03 02:19 PM, Warner Losh wrote:
On Nov 3, 2014, at
On 2014-11-03 01:58, Warner Losh wrote:
A common grid is an artificial construct that measurements from
different clocks can be interpolated to. The top of second (or other
phase) measurements place place the top of second in time. Interpolating
to a grid places the time of each time scale
On 2014-11-01 23:31, Steve Allen wrote:
In the appropriate contexts there are days of Terrestrial Time,
International Atomic Time, Barycentric Coordinate Time, Geocentric
Coordinate time, GPS system time, BeiDou system time, etc. Each of
those days is 86400 SI seconds in its own reference
On Nov 2, 2014, at 11:21 AM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
On 2014-11-01 23:31, Steve Allen wrote:
In the appropriate contexts there are days of Terrestrial Time,
International Atomic Time, Barycentric Coordinate Time, Geocentric
Coordinate time, GPS
Warner,
Warner Losh wrote:
On Oct 31, 2014, at 4:17 AM, Martin Burnicki martin.burni...@meinberg.de
wrote:
Magnus Danielson wrote:
On 10/31/2014 02:49 AM, Sanjeev Gupta wrote:
Give it a new name, please. Independent of what the fundamental
unit is.
TAI and UTC already exists, but the
On 2014-11-02 19:04, Warner Losh wrote:
On Nov 2, 2014, at 11:21 AM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
For instance, the differential rate d(TAI - UT1)/d(UT1) is
published as LOD by the IERS as a dimensionless number
with unit ms/d. To compute this, one
On Nov 2, 2014, at 2:42 PM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
On 2014-11-02 19:04, Warner Losh wrote:
On Nov 2, 2014, at 11:21 AM, Michael Deckers via LEAPSECS
leapsecs@leapsecond.com wrote:
For instance, the differential rate d(TAI - UT1)/d(UT1) is
On 2014-10-31 17:39, Brooks Harris wrote:
Yes. Its primary timescale, sometimes called PTP Time, more properly the PTP
Timescale, is a TAI-like counter (uninterrupted incrementing count of
seconds). Note its origin, or epoch, is 1969-12-31T23:59:50Z, ten seconds before
the POSIX the Epoch
On 30 Oct, 2014, at 12:12 , Richard Clark rcl...@noao.edu wrote:
Well, for historical and archival purposes Julian date nearly always means
traditional days, as in solar days. But for astronomical uses a fixed
unit, the apocryphal atomic day is implied. This means needing to know
delta T if
So days may come and go, but UTC with or without leap seconds meets
its definition just fine - for those who just think of it as a
universally agreed-upon time reference that's coordinated by timing
labs. It is not amibuguous if this universal reference coincides
with UT1 to .9 seconds until
On Sat 2014-11-01T16:50:57 -0400, Athena Madeleina hath writ:
So days may come and go, but UTC with or without leap seconds meets
its definition just fine - for those who just think of it as a
universally agreed-upon time reference that's coordinated by timing
labs. It is not amibuguous if
On 2014-10-30 23:57, Clive D.W. Feather wrote:
The problem is that some people use UTC to mean TAI plus adjustments to
keep it less than a second from UT1 while other people use UTC to mean
the basis of legal time here. For the second set, using a new name for a
different concept
On Oct 31, 2014, at 4:17 AM, Martin Burnicki martin.burni...@meinberg.de
wrote:
Magnus Danielson wrote:
On 10/31/2014 02:49 AM, Sanjeev Gupta wrote:
Give it a new name, please. Independent of what the fundamental
unit is.
TAI and UTC already exists, but the use of TAI has been actively
On 2014-10-31 11:40 AM, Warner Losh wrote:
On Oct 31, 2014, at 4:17 AM, Martin Burnicki martin.burni...@meinberg.de
wrote:
Magnus Danielson wrote:
On 10/31/2014 02:49 AM, Sanjeev Gupta wrote:
Give it a new name, please. Independent of what the fundamental
unit is.
TAI and UTC already
In message 20141030143121.ga20...@ucolick.org, Steve Allen writes:
I wonder if the ITU-R process can go to its completion without
introducing any document which points out that to omit leap seconds
from a time scale called UTC is to redefine the word day.
You mean the same way
Day is a fundamental physical fact about a planet or moon. Minute is an
artificial concept. Its intuitive role as a fraction of a day takes precedence
over serving as a round number of equally artificial SI seconds. There are two
kinds of time that must be accommodated.
Rob Seaman
NOAO
--
I see Terrestrial Time being expressed as a Julian Date quite
a lot. What is the unit of that number if not Day?
Dennis Ferguson
On 30 Oct, 2014, at 09:16 , Rob Seaman sea...@noao.edu wrote:
Day is a fundamental physical fact about a planet or moon. Minute is an
artificial concept. Its
Well, for historical and archival purposes Julian date nearly always means
traditional days, as in solar days. But for astronomical uses a fixed
unit, the apocryphal atomic day is implied. This means needing to know
delta T if you need to relate it back to a civil date or time.
The term 'day'
Poul-Henning Kamp writes:
In message 20141030143121.ga20...@ucolick.org, Steve Allen writes:
I wonder if the ITU-R process can go to its completion without
introducing any document which points out that to omit leap seconds
from a time scale called UTC is to redefine the word day.
Harlan Stenn said:
I'm still thinking the answer is leave existing 'names' alone - if you
want TAI use TAI. If you want UTC, use UTC. If you want something new,
call it something new.
If people are using a defined name for a defined purpose and it works
for them, leave it alone. If people
Clive D.W. Feather writes:
Harlan Stenn said:
I'm still thinking the answer is leave existing 'names' alone - if
you want TAI use TAI. If you want UTC, use UTC. If you want
something new, call it something new.
If people are using a defined name for a defined purpose and it works
for
On Fri, Oct 31, 2014 at 7:01 AM, Harlan Stenn st...@ntp.org wrote:
I'm still thinking the answer is leave existing 'names' alone - if you
want TAI use TAI. If you want UTC, use UTC. If you want something new,
call it something new.
If people are using a defined name for a defined purpose
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