Re: [LEAPSECS] leap seconds in POSIX
On Sat 2020-02-01T00:01:22-0800 Hal Murray hath writ: > I was hoping that there would be a good white paper or blog that discussed all > the possibilities that have been considered and explained why they were > rejected. That cannot happen because of the other factor that has been in the politics of time since the 1950s: fear The surviving scientific and technical discussions indicate that two time scales were considered a plausible option. It was the regulatory context of the CCIR where two time scales were deemed unacceptable. The memoirs of the participants indicate that those discussions happened at conferences where the principals gathered but which were not actually part of the bodies who actually exercised authority. The discussions where the decisions were made are not recorded, and the discussion of those discussions at IAU 1970 was redacted. The fear comes from the fact that the broadcasts of time were funded by national governments. The urgency to adopt leap seconds came from the German law that which disenfranchised the German Hydrological Institute that had been providing old rubber second UTC and declared that only the PTB with its cesium seconds was able to provide legal time. If bureaucrats and lawmakers in other countries had access to documents which described the dichotomy between SI seconds and calendar days they might have legislated differently, and that would destroy decades of efforts to get all radio broadcast time signals to supply the same time scale. The fear seen in the redaction of the 1970 IAU proceedings is still clear early in 1972 just after the inception of leap seconds where G.M.R. Winkler of USNO (who was in charge of the 1970 IAU redaction) explicitly cautioned against open discussion of legal issues. By 1974 there had been enough recommendations and acceptance of UTC with leaps that Winkler openly remarked "The C.C.I.R. may have overstepped its remit in defining UTC" and then paraphrased Spock "The process that led to UTC may have been illogical, but it was effective." The problem for POSIX and any technical implementations follows from the carefully worded recommendations that were handed to bureaucrats to get their approval. The wording allowed the insiders to implement what they understood to be the only politically acceptable compromise. Anyone outside the process was thereafter condemned to conform to specifications for a political compromise that gave no clues about its underlying technical barrenness. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap seconds have a larger context than POSIX
On Sun 2020-02-02T00:33:08+0100 Warner Losh hath writ: > It's the fact that things like filesystems > specify an elapsed time since an epoch in a time scale without leap > seconds. Every FAT or NTFS disk around has a time like this. Beginning 2018-06-01 the value of Microsoft Windows FILETIME ceases to be seconds of UT since 1600 and begins to be (TAI - 37 s). Microsoft has decided to become the authoritative point of distribution for the leap second information that no international agency has ever been tasked to be. > Replacing steering systems > for telescopes is likely somewhat less than that. I have already written up how it is not an insurmountable problem for telescope systems, but digging deep into the literature from around 1970 even further invalidates any notion that leap seconds are for astronomers. In the many meetings and recommendations there were several instances where the participants and wording recognized the requests from astronomers to preserve UT. In every instance where a document specified a maximum deviation that agreement was later violated. In one case it was broken specifically because a high official at CCIR conceded to a high official from USSR and directed the BIH to violate the wording of the existing agreement. The leap seconds were included in the CCIR recommendation not because of anything any astronomer said, but because a few of the participants in the CCIR process understood that they did not have the legal authority to cause all nations to change calendar days from mean solar days to atomic days. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Leap seconds have a larger context than POSIX
On Sun 2020-02-02T17:59:20+ Michael Deckers hath writ: > The maximum deviation |UTC - UT1| <= 0.9 s as stipulated in > 1974 by CCIR Rec. 460-1 has never been violated until now. That violates the agreement that the difference between UTC and UT1 would be encoded as part of the time broadcasts. > > In one case it was broken specifically because a high official at CCIR > > conceded to a high official from USSR and directed the BIH to violate > > the wording of the existing agreement. > > Do you mean the only violation of applicable CCIR rules, the > introduction of a leap second into UTC at 1973-01-01? Right. Sadler covers this in his memoir and in several contemporary publications. Delving into this reveals more of the fear in the process. Several memoirs show that the principals involved with the creation of UTC with leaps were very concerned that the change of broadcast time signals might cause havoc with ships using celestial navigation. Reading through those shows palpable relief when they managed to evoke from the Maritime Safety Committee of the IMCO a statement that Rec. 460 would not cause difficulties with navigation predicated on the expectation that governments whose radio broadcasts used new UTC would issue notices about the change of their broadcasts. That meant that the Time Lords did not have their arses on the line if a ships might collide as a result of the new system. With the maximum difference of 0.7 s that could be encoded in the radio broadcasts not being able to handle the 0.9 s difference that put their arses back on the line. Other concern was expressed that exceeding the 0.7 limit might be blamed on the BIH and might trigger governmental review of the operation and funding of the BIH. At that time about 80% of the funds for BIH were coming from Observatoire de Paris as slush from their allotment from the French government. That was hardly an "international" arrangement, but BIH had only just been handed the responsibility for maintaining TAI specifically because any other arrangement would have required effectively duplicating the expertise and hardware of the BIH and finding a way to fund that. Prompting governments or journalists to open an investigation into the process of writing an international "technical" specification that was violated in less than two years was not a welcome notion. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] leap seconds in POSIX
On Mon 2020-01-27T10:15:56-0500 Steve Summit hath writ: > Remarkably, though, *Microsoft* of all people seized the bull by > the horns and announced more-or-less proper leapsecond support in > Windows a little while back; it might be instructive to study > that effort for lessons. I think Microsoft was able to achieve this because Windows 10 is designed to be continuously updated, including leap second information, with new code from corporate headquarters. This would not have been possible with an earlier version of Windows, nor with most any other system. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Bulletin C number 60
On Tue 2020-07-07T22:38:59+0100 Tony Finch hath writ: > The LOD is hovering around 0 and the UT1-UTC chart is looking remarkably > flat. > > https://datacenter.iers.org/singlePlot.php?plotname=FinalsAllIAU2000A-UT1-UTC-BULA=9 > > https://datacenter.iers.org/singlePlot.php?plotname=FinalsAllIAU2000A-LOD-BULA=9 The earth has accelerated so that it is spinning as fast as it was during World War 2, and before that, the 1890s. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] leap seconds, newspapers, earth rotation
On Wed 2021-01-06T10:36:10-0800 Tom Van Baak hath writ: > Does anyone know who started it? Is there a way to track it down? I am pretty sure that it started when some reporter meandered over to timeanddate.com and then started writing a followup. They have had a running dashboard showing just how long each day has been according to the IERS bureau predictions and keeping a sports statistics page on how the earth is doing. They ran a year end article looking over the stats https://www.timeanddate.com/time/earth-faster-rotation.html -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] Judah Levine of NIST
Judah Levine has begun a multi-part essay Everyday Time and Atomic Time https://nist.medium.com/everyday-time-and-atomic-time-part-one-9107b60fd9d0 -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Judah Levine of NIST
On Wed 2021-03-31T20:55:05-0700 Steve Allen hath writ: > Judah Levine has begun a multi-part essay > Everyday Time and Atomic Time > https://nist.medium.com/everyday-time-and-atomic-time-part-one-9107b60fd9d0 Part 2 on music and frequency https://nist.medium.com/everyday-time-and-atomic-time-part-2-65bb74d04f50 Part 3 the slippery slope of mean solar time https://nist.medium.com/everyday-time-and-atomic-time-part-3-24421c7a8c0f -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] Unsung Science with David Pogue
Leap Seconds, Smear Seconds, and the Slowing of the Earth as seen at https://unsungscience.com/the-podcast/ with the half-hour podcast available through many of the places that host podcasts. Comes to a near end just past halfway through after the assertion of what IAU and CGPM said, that leap seconds are the perfect solution, then abruptly continues about how that did not turn out to be true. Near the end are sound snips from the 2015 ITU WRC delegates deciding not to decide. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] 256-week / leap seconds / in the news
On Sat 2021-07-24T18:50:50-0700 Tom Van Baak hath writ: > First, there really isn't a thing called a "0 leap second", but if you've > read the GPS ICD wrt leap seconds, you can see why it was posted. Second, it > happened once before, in 2003. "Modulo arithmetic class is tough" -- Barbie -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] 256-week / leap seconds / in the news
On Sat 2021-07-24T18:50:50-0700 Tom Van Baak hath writ: > In the news: > > "GPS will broadcast a 0 second leap second in 128 days" > https://news.ycombinator.com/item?id=27944776 A tweet from Leo Bodnar electronics about their NTP device https://twitter.com/LeoBodnar/status/1419239590532206597 which famously includes highlighted text from the section of the GPS ICD that describes the need to do modulo arithmetic along with the URL to the new version of the firmware. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] 256-week / leap seconds / in the news
On Sun 2021-07-25T09:47:24-0700 Tom Van Baak hath writ: > Per the GPS ICD, when dt_LS == dt_LSF there is no leap second to speak of; > not in recent past; not in near future. The 8-bit WN and DN fields are not > applicable to a non event. I see this as one example of the problem of handling NULL in an API and all the layers of software that use that API. POSIX (and many other interfaces, not just about time) supposes that it is always possible for the system to give a value for the time now. On social media recently I saw a weather app showing a temperature of 0 degF for a place that is not freezing. In the observatory control software that runs telescopes and instruments at Keck and Lick the overall system allows the concept of NULL, but not all of the underlying layers of code can handle NULL. Software in general, and programmers, should be prepared to handle the (hopefully) exceptional events when the answer to "What time is it?" is "I do not know" or "Here is a value but I cannot confirm that it is valid." For time in particular it has always been the case that the answer is "Here is a value that you can use for now, but if you want to compare it with the value deemed as correct by other systems and required by regulations you will have to check back later using another interface." -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
On Mon 2022-03-07T06:57:02+ Poul-Henning Kamp hath writ: > I'm not talking about the two spikes, I'm talking about the oscillation > disappearing, > and that seems to be in all the data sources ? ah, yes. I think we need another nutation cycle worth of high precision data, but I suspect nothing unusual is happening. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] problems with early TAI
Becker had a lot of opinions about atomic time, and he laid out the pictures of just how bad things were. Note figures 4 and 5 https://onlinelibrary.wiley.com/doi/epdf/10.1002/phbl.19830390302 Those show how the rate of TA(BIH) was way off as of the 1969 rearrangement that did not attempt to constrain the frequency of the new scale, and they show just how much the lack of air conditioning in the USNO clock house was messing up the HP units. Those artifacts of rate problems affect TAI forever inasmuch as they mean that the supposed 1958 origin and the actual 1961 origin do not correspond to the number of elapsed SI seconds in the value of TAI. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
On Mon 2022-03-07T06:33:31+ Poul-Henning Kamp hath writ: > I looked at the Bulletin A plots this morning to see how DUT1 is > developing, but then I noticed the 'dX' term plot: > > > https://datacenter.iers.org/singlePlot.php?plotname=BulletinA_All-DX=6 > > What happened in late 2019 ? 2019 October is when USNO had to take their machines offline due to new security requirements. Those artifacts do not show at the ObsPM site https://hpiers.obspm.fr/eop-pc/index.php?index=analysis=en -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Never mind DUT1, what happened to dX ?
On Tue 2022-03-08T15:30:37+ Tony Finch hath writ: > (note that the coefficient is seconds _shorter_ than 24*60*60µss, > so +0.00021 means the long-term average LoD is 24h-210µs) Ah, that points out what may be a cool correlation. Looking back at dX and dY over their relatively short history it may be the case that the celestial pole position wobble around the predictable position is smaller when the rotation is accelerating. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] URSI speaks
URSI resolved about leap seconds https://www.ursi.org/Publications/RadioScienceLetters/Volume3/RSL21-0047-final.pdf It includes yet another passive voice redacted history of why they were implemented. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] IGS 2022 leap second statement
On Wed 2022-07-06T15:09:42-0400 John Sauter via LEAPSECS hath writ: > I hope everyone noticed that the IERS issued Bulletin D 142 today, > which raises DUT1 from -0.1 to 0 as of July 28. In a less public forum on May 22 the International GNSS Service recommended that no more leap seconds be added to UTC https://files.igs.org/pub/resource/IGS_LeapSecond_Statement_Final.pdf -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] fb/meta join the leap second haters
Anyone with a twitter stream can see that Meta/Facebook have blogged that they want leap seconds to stop https://engineering.fb.com/2022/07/25/production-engineering/its-time-to-leave-the-leap-second-in-the-past/ This is referenced in more and more tech publications like CNET https://www.cnet.com/tech/computing/tech-giants-try-banishing-the-leap-second-to-stop-internet-crashes/ The CNET article includes a quote from correspondence which repeats a trick that has been performed since the 1960s, that being to produce a significant underestimate of the difference between solar and atomic time by saying that the absence of leap seconds will not be noticed for 2000 years. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] fb/meta join the leap second haters
On Tue 2022-07-26T23:33:15+ Poul-Henning Kamp hath writ: > So looking at the IERS LOD plot going all the way back it seems to > me that we have been missing the big signal for about five decades: > > > https://datacenter.iers.org/singlePlot.php?plotname=EOPC04_14_62-NOW_IAU2000A-LOD=224 > > How did we not notice that earlier ? even better is the view from the Paris bureau at https://hpiers.obspm.fr/eop-pc/index.php which at the moment is showing a Vondrak filtering of the data with the predictable tidal terms removed. Even better would be to remove the UT2 semi/annual variation. caveat is that plot may change before you all look at it. The rotation of the earth's crust started accelerating right when the CCIR decided that we should start using leap seconds. karma -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] fb/meta join the leap second haters
On Tue 2022-07-26T20:42:03-0400 Brooks Harris hath writ: > Can anyone elaborate on what these 'decadal variations' may be? What they are is power in the spectrum of LOD at periods of decades that has been visible in the relatively good data from the past two centuries and which contributed to the inclusion of "non-gravitational" terms in the planetary theories of Newcomb and the lunar theories of Hill and Brown. Why they happen is harder to say since they probably originate in the weather of the core of the earth, but maybe not. See this Journees 2019 paper saying it may be crustal motion and ice https://syrte.obspm.fr/astro/journees2019/journees_pdf/SessionIV_2/SIDORENKOV_Nikolay.pdf Also in there that the earth had been getting less oblate, more spherical, through around year 2000 but maybe now is getting more oblate https://syrte.obspm.fr/astro/journees2019/journees_pdf/SessionIV_1/LIU_JiaCheng.pdf -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] podcast from Orolia
Orolia has a 17 minute podcast about leap seconds https://www.orolia.com/place-and-time-episode-3-the-leap-second-on-trial/ -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] article for Metrologia
On Fri 2022-10-28T22:55:54-0400 Demetrios Matsakis via LEAPSECS hath writ: > You might be interested in this presentation I gave at the CGSIC > last month, entitled “Will we have a negative leap second”: > https://www.gps.gov/cgsic/meetings/2022/matsakis.pdf compare https://www.ucolick.org/~sla/leapsecs/seasonal.html Is it not the case that references to the 19 year Metonic cycle should be references to the 18.6 year Draconic cycle? -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] article for Metrologia
On Sat 2022-10-29T13:48:19-0400 Joseph Gwinn hath writ: > So, those faulty designers of yore had insufficient clairvoyance > skills. Not the fault of the designers. The Time Lords who incepted leap seconds were caught between conflicting legal requirements. They had no choice, or rather, no choice other than to risk becoming part of another another Ides of March scenario in international timekeeping. Their lack of choice included preventing their dilemma from appearing in official documents. They knew that leap seconds were technically barren and that no other legal option was possible to implement at that time. This is why Winkler limited himself to paraphrasing Mr. Spock while directing that the USNO navigational broadcast systems would shift from old UTC to TAI-10. The need for purely atomic time was evident more than 50 years ago, but the ability to implement it correctly was not yet technically possible. So the principals guarded their speech into their retirement and death rather than advocate that the leap second scheme was necessarily temporary and would need to be replaced by something better. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] article for Metrologia
Levine, Tavella, and Milton have an upcoming article for Metrologia on the issue of leap seconds in UTC https://iopscience.iop.org/article/10.1088/1681-7575/ac9da5b -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] article for Metrologia
On Thu 2022-10-27T19:25:01-0700 Steve Allen hath writ: > Levine, Tavella, and Milton have an upcoming article for Metrologia > on the issue of leap seconds in UTC > > https://iopscience.iop.org/article/10.1088/1681-7575/ac9da5b sorry, stray character appended to my cut and paste https://iopscience.iop.org/article/10.1088/1681-7575/ac9da5 -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] The Variable Earth’s Rotation in the 4th–7th Centuries: New ΔT Constraints,from Byzantine Eclipse Records
On Sun 2022-09-18T23:43:59-0400 Brooks Harris hath writ: > The Variable Earth’s Rotation in the 4th–7th Centuries: New ΔT Constraints > from Byzantine Eclipse Records > https://iopscience.iop.org/article/10.1088/1538-3873/ac6b56/pdf Very nice. The old eclipse observations are very scarce and the decadal fluctuations can take the value of Delta T far askew. It takes a lot of work to recognize the useful descriptions. The authors clearly also wanted to typset Amharic. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] leap seconds in the not so news
today in leap second clickbait https://supplycloset.supplies/2022/12/04/scientists-killed-the-leap-second-your-birthday-could-be-next/ Scientists Killed The Leap Second. Your Birthday Could Be Next. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] King Charles
On Sun 2022-12-04T16:30:01+ Tony Finch hath writ: > So if you agree with Donald Sadler, has already GMT concluded. I do agree, and I also disagree, for Sadler and was in large part responsible for another tacit change to GMT. Like others engaged in the present redefinitions, given his job Sadler could not have dared to describe the consequences of that in plain language. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Global timekeepers vote to scrap leap second by 2035
On Sun 2022-11-20T13:23:32+ Kevin Birth hath writ: > As far as I can tell, they were never successful, but it did keep them busy. As Rod Serling wrote in The Big Tall Wish You got to believe, Bolie. But worse, because in this arena infidels will not be tolerated. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] King Charles
It was King Charles II who oversaw the inception of GMT. If King Charles III lives as long as his mother then he will oversee the conclusion of GMT. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] King Charles
On Fri 2022-11-25T00:20:11+ Robert Jones hath writ: > GMT will probably be redefined yet again as it was in 1925 when noon was no > longer the start of the day and when leap seconds were introduced. 'When I use a word,' Humpty Dumpty said in rather a scornful tone, 'it means just what I choose it to mean--neither more nor less.' 'The question is,' said Alice, 'whether you CAN make words mean so many different things.' 'The question is,' said Humpty Dumpty, 'which is to be master-- that's all.' -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] Alanna Mitchell in NYT
Starting tomorrow the CGPM meets in Paris. Resolution D says leap seconds must die. CGPM will almost certainly approve that resolution. https://www.nytimes.com/2022/11/14/science/time-leap-second.html -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Alanna Mitchell in NYT
On Mon 2022-11-14T23:44:54+ Michael Deckers via LEAPSECS hath writ: > The reason why the CIPM (for now) sticks to the requirement that > |UTC - UT1| be bounded is most probably the argument brought forward > by some people from ISO who say that, without explicit bound on > |UTC - UT1|, UTC had to change its name so that "polysemy" is avoided. The funny part there is that UT1 does not mean what they think it means. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Alanna Mitchell in NYT
On Mon 2022-11-14T18:27:25+ Poul-Henning Kamp hath writ: > And with a 2035 deadline we might just get to see if our implementations > of negative leap-seconds work before it is too late. > > Yes, it should have happened 20 years ago. I believe I recently saw PHK ruminating that forward compatibility in computing is at least as important as backward compatibility because the next 30 years of software need to know where they are going. The NYT article ends with Arias ruminating about how someday there will have to be a leap minute or leap hour. To have systems which will handle that eventuality we need to be openly considering the goals and implementation for that already. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] leap minute or hour
On Mon 2022-11-14T21:22:27+ Poul-Henning Kamp hath writ: > I doubt the will manage to convince the other 99+% to do something > as deranged as a leap-minute. > Thanks to timezones and DST, less than 1% of the worlds population > live where mean solar time is correct to a minute. The reason we got leap seconds in the first place is that one country changed its law so that the rubber/elastic seconds of original UTC became illegal. Even though they were advised of serious technical problems the other countries capitulated to leap seconds as the "parfaitement recommandable" solution to the political problem. We do not have Hari Seldon theory to guage the psychohistory of international alliances and how they will align with each other about answering "What time is it?" -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] USNO predictions of UT1-UTC
On Mon 2023-03-20T00:55:26+ Seaman, Robert Lewis - (rseaman) hath writ: > Much consternation will be feigned. I will be making much use of the Michael Jackson eating popcorn gif -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] USNO predictions of UT1-UTC
On Sun 2023-03-19T19:24:56-0400 Demetrios Matsakis via LEAPSECS hath writ: > https://insidegnss.com/will-we-have-a-negative-leap-second/ > Will We Have a Negative Leap Second? The USNO predictions in IERS Bulletin A have been pretty good... https://www.ucolick.org/~sla/leapsecs/bulla52w.html It will be interesting to see what kind of consternation arises if the predictions start saying the negative leap is impending. Somewhere in USNO/UKHO somebody has been making longer term predictions for use in the navigational almanacs, but as far as I know those have never been published. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] smear
On Mon 2023-03-20T19:36:51+ Michael Deckers via LEAPSECS hath writ: > � This seems to be lenient enough to allow for not scheduling > � a negative leap second even in the case that the difference > � (UT1 - UTC) should go a bit below -1 s before 2035. And today in the NTP working group mail list we see that the big guns expect to force the issue because > From: Doug Arnold > Subject: Re: [Ntp] draft-ntp-ntpv5-requirements update for IETF 116 > > Re leap smearing: > > Operators from multiple data centers tell me that they intend to > smear leap seconds. When I pointed out the pitfalls they were > undeterred. I have come to understand that leap smearing is viewed as > less problematic than trying to fix leap second handing in distributed > database software. they have taken the stance that if leap seconds do not go away then they will smear. This is like Eucla Australia setting their clocks the way they please and daring the state government to do something about it. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] speeding up again?
On Mon 2023-05-22T16:44:30+0200 Tony Finch hath writ: > The prospect of a negative leap second is receding. The longer-term > projected length of day from Bulletin A has been increasing towards 24h > in recent months. We can probably put a lot of the blame onto El Niño -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] UT1 offset
On Thu 2023-12-28T09:23:30+ Poul-Henning Kamp hath writ: > Also: When celestial navigation is possible, most vessels > travel a lot further than 50 meters during the time it takes to make > a measurement of the necessary precision. As noted by ION https://www.ion.org/Museum/item_view.cfm?cid=6=5=29 "Modern sextants can read the angle to a 0.1 minute level of accuracy" and older sextants to more like 0.5 arcminute. The best navigator under the best circumstances might get to within 0.1 nautical mile. More typical accuracy in actual use was several arcminutes or several nautical miles. When a sextant was used to shoot the moon to determine time half an arcminute accuracy means one time minute accuracy which is 15 arcminutes of longitude, so longitudes in mid-ocean could be off by many nautical miles. Frank Reed teaches the old techniques and if the opportunity presents itself I highly recommend taking his classes. https://reednavigation.com Few living astronomers have held a sextant in hand to shoot stars and the moon. I have, but during my lifetime has grown as disconnect between theory and practice. Some who are responsible for the tabulations in the almanacs are not facile with those techniques. Frank Reed taught me that the reason navigators did not like changes to the almanacs was because the reduction of a lunar was basically a ritual. Navigators did not know the nitty gritty of the celestial mechanics, but they did know a sequence of operations with the almancs which would produce a valid position. The instructional manuals for navigators still teach the equator and equinox and Greenwich meridian, but the equinox was abolished entirely by the IAU in 2003. The values tabulated in the almanacs had ceased to represent those original concepts a century before that, but a navigator who used the tabulations in the almanacs in the classical fashion would still compute a correct result. Gary Miller recently noted that navigators do not know about the existence of DUT1. I suspect that may be because the calculations are no longer being performed according to the ritual found in the old log books of ships. If the calculations are now performed by machines that are connected to telecom systems then all of the nitty gritty details like DUT1 are probably in the computer. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] UT1 offset
On Mon 2023-12-25T00:25:07-0800 Hal Murray hath writ: > Who uses DUT1 via radio? Who will be using it 50 years from now? > > Is it needed for anything other than navigation and astronomy? UT1 is not needed for navigation if the almanacs switch their tabulations to use the time scale that is available. This was true 70 years ago. Navigators hate changes to the almanacs. 70 years ago the astronomers who made the almanacs preferred to maintain a Ptolemaic world view in part to avoid presenting a change to the navigators, in part to avoid having to prove that a different scheme of tabulation would be reliably correct and do all the new calculations still largely by hand, but most of all because their other job was to provide legal time, and legal time was based on mean solar time. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] prep for WRC 23
This week began the meeting of ITU-R WRC 23. One preparation for this meeting was a document issued early this year The future of Coordinated Universal Time https://www.itu.int/en/itunews/Documents/2023/2023-02/2023_ITUNews02-en.pdf This looks at the use of time in several arenas, many of which would like UTC to stop having leap seconds. Many also allow that keeping agreement with the earth in the long run is necessary, and that they have no idea how to do that. -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] negative leap second in 2029?
On Sat 2024-03-30T16:03:30-0700 Paul Hirose hath writ: > "Even a few years ago, the expectation was that leap seconds would always be > positive, and happen more and more often," Duncan Agnew, a geophysicist at The paper in Nature takes a very narrow view of history. Agnew looks only at data in IERS C04. That started in 1962 because 1) There were no available atomic time scales until the middle of year 1961, so earlier earth rotation data were less precise https://www.ucolick.org/~sla/leapsecs/taiepoch.html 2) The IAU had resolved that 1962-01-01 would be the date to change from using the FK3 star catalog to using the FK4 star catalog, and as noted in my TAI web page above that caused a discontinuity in the value of time. 3) Although coordinated time existed before, it was 1962-01-01 when BIH Paris was put in charge of what they would later name UTC. 4) The early atomic time scales from BIH were computed entirely by hand. The published values show arithmetic errors which were never corrected. With BIH perennially understaffed going back farther in time would incorporate more such errors into C04. With C04 there is only one point at which the core of the earth made one of its huge shifts in angular momentum, and that was coincidentally right around 1972. Agnew further restricts his analysis to only the earth rotation after 1972. Agnew is certainly correct that melting ice caps are slowing the rotation of the surface of the earth. With the acceleration being caused by whatever the core has been doing for the past 50 year Agnew is also correct that the meltwater is delaying the need for a negative leap second. But the analysis by Agnew is blind to the long history of big changes in the core. I think that is why Matsakis is quoted in one of the news articles about not betting on predictions of earth rotation. Also do not forget McCarthy and Matsakis previously looking at the trend https://insidegnss.com/will-we-have-a-negative-leap-second/ -- Steve Allen WGS-84 (GPS) UCO/Lick Observatory--ISB 260 Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 https://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
