Talk:Leap second/Archive 2

Archive 1

Archive 2

Screenshot

I like the screenshot (got one myself). I like that it's actually a UTC time, compared to the previous Central Time image (and my new Pacific Time image). However, it's odd that it reads "Right now, the official U.S. time is". I know why it does, but perhaps crop that image to exclude that line. (On the other hand, the source is from NIST in the U.S., so I suppose it could be considered the "official U.S. UTC time".) goodeye (talk) 01:28, 1 July 2012 (UTC)

Negative leap seconds

The article should mention that leap seconds can be either added or removed. The article currently gives the impression that they can only be added. Thue (talk) 19:34, 4 July 2012 (UTC)

The article states "A negative leap second would suppress second 23:59:59 of the last day of a chosen month, so that second 23:59:58 of that date would be followed immediately by second 00:00:00 of the following date. However, since the UTC standard was established, negative leap seconds have never been needed." Jc3s5h (talk) 20:26, 4 July 2012 (UTC)

It would probably help to insert explicit references to ITU-R TF.460 both here and on the UTC page. The ITU-R made the recent versions of this defining document openly available starting in December 2010.Steven L Allen (talk) 02:00, 12 July 2012 (UTC)

Although recent versions are useful for current practice, they are useless as historical documents. Only the 1970 and 1974 versions of CCIR Recommendation 460, or a reprint of them, or of their leap second sections would serve that purpose. — Joe Kress (talk) 08:36, 12 July 2012 (UTC)

US NBS reprinted the 1970 original Rec. 460 on page 31 of Monograph 140, Time and frequency: theory and fundamentals (Byron E. Blair, 1974). Prior to that it also reprints numerous other original defining documents about the SI second and TAI.Steven L Allen (talk) 18:31, 12 July 2012 (UTC)

Why can't the abolition movement just change to using TAI?

I am curious why the article makes no mention of the idea that those who wish to abolish the leap second might do better simply to use the existing TAI time system for their purposes rather than altering UTC to make it resemble TAI. We've had TAI since the 1950s, and it does what those who seek to abolish the leap second want a timescale to do. Why don't they just switch from using UTC to using TAI? If there are any interesting reasons why they would rather alter UTC than switch to using the existing TAI system, those reasons ought to be discussed in this article.

I'd edit the article to discuss these reasons myself, if I knew of any. But if there are no good reasons, that point ought to be addressed in the article as well, and I'm not enough of an expert in this subject to make assertions about the absence of good reasons.

In particular it's kind of crazy that we already have GPS time, which is a variant of TAI that differs from it by a constant offset. Abolishing the leap second would just leave us with a third such constant-offset-differing timescale when TAI is already adequate for all such purposes. Reasons for wanting to multiply the number of constant-offset atomic timescales should be discussed in this article, if such reasons exist.

--arkuat (talk) 23:41, 26 July 2012 (UTC)

Only arguments that have been reported in reliable noteworthy sources should go in the article. But I suspect the reason many of these sources have not adopted TAI is that it is not the legal civil time anywhere in the world. Many systems must keep legal time, and many other systems must interface with systems that are keeping legal time. Jc3s5h (talk) 03:08, 27 July 2012 (UTC)

What is "legal time"? -- Q Chris (talk) 07:23, 27 July 2012 (UTC)

In any country, civil time (rather than "legal time") is the timescale approved for official and commercial use.

In Switzerland for example civil time is defined as UTC+1 (+2 in the summer). So that's what you are required to use, by law, whether in a contract, a bus schedule, a police report or whatever. In the same way that you are required to sell, say, gasoline by the liter.

In practice the civil time of most (all?) countries is based on UTC. So for any system that interact with the outside world using anything else than UTC is not an option. Thus if you are not happy with UTC you can't just use something else, you need the whole word to switch.

TAI couldn't be used directly as we don't want clocks to suddenly jump backwards. Continuity with the current time has to be maintained. Whether you formally introduce a new timescale or change the definition of UTC is a detail.

So the real question, which IMO is not really addressed in the article at this time, is why would you want to abolish leap seconds ?

The main reason is that leap seconds are a huge pain in the butt for computers and networks

Bomazi (talk) 16:39, 17 January 2013 (UTC)

I think the pain in the butt is covered in the first paragraph of the Proposal to abolish leap seconds section. -—Kvng 15:07, 20 January 2013 (UTC)

Ok, I didn't read that part. Bomazi (talk) 21:56, 20 January 2013 (UTC)

One area where "traceable" time comes into play is in the financial markets where messages between traders and stock exchanges are time-stamped and people calculate transmission times between parties to the nearest millisecond and get excited once these take longer than 0.1 seconds. The only way that the times can be measured is for the transmitter to place a timestamp on their electgronic message and for the recipient to note the timestamp upon receipt. Martinvl (talk) 07:47, 21 January 2013 (UTC)

Incorrect edit

The following was added today:

Applications for which leap seconds cause problems can use one of the other existing time standards, such as TAI, which is the basis for UTC,[1] or GPS time, which may be calculated from satellite-broadcast signals.[2]

[Citations changed slightly to work in talk page.]

References

1. E. Felicitas Arias, Gianna Panfilo, and Gérard Petit (2011-09-11). "Status of UTC/TAI" (PDF). Retrieved 2013-08-20.{{cite web}}: CS1 maint: multiple names: authors list (link)

2. Geoffrey Blewitt (1997). "Basics of the GPS Technique: Observation Equations" (PDF). Retrieved 2013-08-20.

This is not correct. In the earlier part of the edit, it is claimed that TAI is the basis for UTC, which is partly true, but TAI is not broadcast or disseminated, so an application occurring outside a time laboratory does not have direct access to it. Furthermore, TAI is more than 30 seconds different from UTC, which is the defacto basis for civil time throughout the world. So for many applications TAI may not be used instead of UTC.

Which part of "TAI is the basis for UTC" is partly true. If you actually want to argue this further, it is probably best to do so at International Atomic Time or Coordinated Universal Time. ~KvnG 03:15, 25 August 2013 (UTC)

In the later part of the edit it is claimed that GPS time may be calculated from satellite-broadcast signals. This is backwards; GPS satellites broadcast GPS time. They also broadcast data that can be used to calculate UTC from GPS, but some applications cannot obtain the UTC calculation data in time to make use of it.

GPS time is based on TAI. A simple and completely accurate calculation (TAI – GPS = 19 seconds) converts between the two. No calculation data necessary. See Gps#Timekeeping. ~KvnG 03:15, 25 August 2013 (UTC)

Also, the second citation is unacceptable in that it fails to state what page in a 46 page paper supports the claim. Furthermore the strings "UTC" and "coordinated" (with no sensitivity to capitalization) cannot be found in the paper. Jc3s5h (talk) 16:34, 20 August 2013 (UTC)

I agree with this. ~KvnG 03:15, 25 August 2013 (UTC)

Dubious edit

user:Rightismight made this edit, with no citation provided. Rightismight asserts

In the event the ITU resolution passes and leap seconds are no longer inserted, special Network Time Protocol and other time servers could be set up that provide UT1 rather than UTC. Those astronomical observatories and other users that require UT1 could run off that time - although in many cases these users already downloaded UT1-UTC from the IERS, and apply corrections in software.

However, one of the concerns frequently raised is that no though analysis has been done to determine which systems will fail if leap seconds are eliminated. Not knowing which systems will be affected, there is no way to assess how effective a particular solution would be. Also, it is not known whether the systems will be accessible to make any software updates that may be required, or whether the documentation and skills that would be needed to update potentially old systems still exist.

Such a statement ought not to be made by a Wikipedia editor; it must come from a reliable source. Jc3s5h (talk) 02:23, 4 July 2014 (UTC)

I have added a reference, from a respected scientist, made at a well-known conference on this matter. Hope this is considered sufficient. — Preceding unsigned comment added by Rightismight (talk • contribs) 04:39, 4 July 2014 (UTC)

I support removing this apparently speculative and uncited contribution. ~KvnG 14:02, 22 July 2014 (UTC)

Citation clean-up

The citation format for this article is a mess. The usual practice is to follow the format that was first introduced, which appears to be the APA style. Comments? Jc3s5h (talk) 17:49, 15 July 2014 (UTC)

Manually formatting references is not fun. I prefer to use {{citation}} and friends. ~KvnG 14:02, 22 July 2014 (UTC)

Future of the leap second.

This source [1] seems to indicate to me that no decision was made at the 2015 conference WRC-15 to abolish the leap second although it was resolved to look at this possibility. Are there any secondary sources confirming this? What should we say about the subject in the article? Martin Hogbin (talk) 12:49, 14 November 2015 (UTC)

My impression is the conference is still in progress. The document cited by Martin Hogbin seems to me to just repeat the resolution from 2012 to consider the matter at this year's conference; it seems more like an agenda item than a decision. Jc3s5h (talk) 20:55, 14 November 2015 (UTC)

I have had another read and I think you are correct. Do we know when the decision is likely to be made? Martin Hogbin (talk) 13:29, 15 November 2015 (UTC)

I recall that the conference is to end near the end of November. Jc3s5h (talk) 18:16, 15 November 2015 (UTC)

This mailinglist thread states that the proposal to eliminate them is dead for now. —Steve Summit (talk) 17:22, 19 November 2015 (UTC)

Whoops! But now this mailinglist thread cites this reasonably definitive-looking press release. I'll update the article unless someone beats me to it. —Steve Summit (talk) 17:25, 19 November 2015 (UTC)

Negative Leap Seconds

I added a note about negative leap seconds which was quickly reverted by AstroLynx. The comment given was “discussing (negative) leap seconds before 1972 does appear to be useful here”. Where else but in an article on leap seconds would one discuss negative leap seconds? In order to avoid an edit war I am asking for a discussion. John Sauter (talk) 14:36, 18 May 2016 (UTC)

The practice of leap seconds was only introduced in 1972. What is the use of discussing leap seconds before 1972? AstroLynx (talk) 16:54, 18 May 2016 (UTC)

My intent is to correct this sentence: “However, negative leap seconds have never been needed since the UTC standard was established, and are highly unlikely to ever be.” First, the UTC standard was established earlier than 1972, but did not include leap seconds until 1972. Correcting this would result in “However, negative leap seconds have never been needed since leap seconds started in 1972, and are highly unlikely to ever be.” The second problem is that “are highly unlikely to ever be” is a judgment not supported by any reference. It would be adequate to simply remove it, but I tried to do better by mentioning that in the recent past (1885) the rotation rate of the Earth would have required a negative leap second if leap seconds had existed. John Sauter (talk) 17:14, 18 May 2016 (UTC)

Such a discussion could be useful further down in the article. The opening paragraph of this article is already rather long and should not be burdened with too much information. There might be a problem however with the source which you propose to add as it seems to be mainly based on WP:OR. AstroLynx (talk) 10:41, 19 May 2016 (UTC)

Would it be acceptable to delete the offending sentence, and add a section on negative leap seconds? Perhaps it would be better to move all but the first paragraph pf the lead into the body, change Insertion of Leap Seconds to Scheduling of Leap Seconds, and add subsections on positive and negative leap seconds. John Sauter (talk) 00:31, 20 May 2016 (UTC)

I support removing the sentence from the lead. The second paragraph of the lead is pretty thick if anyone wants to do some additional trimming. Scheduling of leap seconds seems like an improved title for the second section. The end of this section would be a good place to mention negative leap seconds because the next section is Slowing of the Earth. I don't think subsections are necessary to cover negative and positive. ~Kvng (talk) 14:02, 24 May 2016 (UTC)

Since the Earth is slowing down (and I do not think it would be too hard to find references for this), the unlikeliness of negative leap seconds is quite obvious. C.f. the graph in the article ΔT. — Edgar.bonet (talk) 19:06, 19 May 2016 (UTC)

As I read the graph of LOD in this article, the Earth was completing a rotation in less than 86,400 seconds as recently as 2005. Looking at the graph you mentioned, notice that to obtain a negative leap second doesn't require that the graph go back to 0, but only that it slopes downward for a while. I don't think it is unreasonable to imagine that the Earth might speed up again in the next few decades, and next time it might be enough to cause a negative leap second. John Sauter (talk) 00:39, 20 May 2016 (UTC)

You are right, a negative leap second is not completely unreasonable. But the secular deceleration only makes it less and less likely. This deceleration is not visible in the LOD graph of this article, as it covers too short a time span. It is more obvious in the ΔT graph. — Edgar.bonet (talk) 09:58, 20 May 2016 (UTC)

In the long run, the Earth is slowing down. 3000 years ago, a positive leap second would have been completely unreasonable, and 3000 years from now, a negative leap second will be completely unreasonable. Today, however, both are within the realm of possibility. John Sauter (talk) 01:10, 21 May 2016 (UTC)

Notwithstanding the discussion of negative leap seconds here on the talk page, which concluded that negative leap seconds are possible, though unlikely, an editor has modified the article to say that negative leap seconds are not possible. I deleted the sentence in the lead that characterizes the likelihood of negative leap seconds. John Sauter (talk) 20:41, 21 May 2016 (UTC)

Table of announced leap seconds to date

Recently there have been several suggested edits to the style of the "Announced leap seconds to date" table. This edit added to the table a new column titled "Offset" that apparently contains a running total of the leap seconds. A subsequent edit fixed the slightly misleading column title by renaming the column to make it clear it was a running total of leap seconds, not the offset from TAI. I'd like to suggest that the table be restored to it's original layout. I don't think the running total adds much value to the table, and given the height of the table I think it fits the page better in the narrower three column layout rather than the current four column layout. Thoughts? —RP88 ^(talk) 07:58, 1 January 2017 (UTC)

I'm inclined to save space. I don't think many people will need to know the running total of leap seconds; the few who do can add it up for themselves. I also liked the change which removed years in which no leap second occurred. Jc3s5h (talk) 16:18, 1 January 2017 (UTC)

Sounds good to me. The cumulative total, with or without the initial 10 second offset, might be better presented graphically. Having such a graph with its constant time scale might eliminate the need to include years with no leap seconds, or change it into a single column table of mm/dd/yyyy of all leap seconds, perhaps color-coded to distinguish June seconds from December ones. YBG (talk) 22:51, 1 January 2017 (UTC)

I mostly object to the recent addition of the running total of leap seconds, I don't think it is helpful, so I'm inclined to revert that change if no one objects. To be honest, I also kind of like the constant time scale of the current table and think it would be worse if the years without leap seconds were removed, but I'm open to the idea of finding an alternative presentation for that information. For that matter, the Deviation of day length from SI based day graph that is already in the article (in the "Slowing rotation of the Earth" section) has red dots that indicate leap seconds in a cumulative fashion on a constant time scale. —RP88 ^(talk) 23:41, 1 January 2017 (UTC)

I don't have a strong preference but have no objection to removing the total column. Fundamentally this is a 2-column table {date, adjustment amount}. Although it hasn't yet happened, leap seconds can be inserted any month, not just June and December. I like the idea of representing it graphically. That would likely be in addition to the table but would allow the table to list only non-zero adjustments. ~Kvng (talk) 15:20, 4 January 2017 (UTC)

OK, since there appear to be no objections, I've removed the "total" column. —RP88 ^(talk) 11:52, 6 January 2017 (UTC)

Fake screenshot

Showing 23:59:60 when there's still more than two hours to go! — Preceding unsigned comment added by 81.98.254.105 (talk) 21:57, 30 June 2015 (UTC)

Indeed not serious because people looking are misinformed about the time it happens. — Preceding unsigned comment added by 62.235.4.230 (talk) 22:16, 30 June 2015 (UTC)

The layout and colors at Time.gov match the look of the screenshot including the arrow buttons to change the time zone from a local United States time zone. The image is set at UTC which is when the second is inserted to display as 23:59:60. 22yearswothanks (talk) 07:00, 6 April 2017 (UTC)

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Hey, not so quick on the draw! That page still works - maybe check the URL twice, with some time between the tests, and if they both fail, then go to an archive. Guy Harris (talk) 01:44, 13 May 2017 (UTC)

Number of leap seconds is wrong, should change from 27 to 37

Hello

From the reference provided by Wikipedia: https://hpiers.obspm.fr/iers/bul/bulc/bulletinc.52 It says:

 from 2015 July 1, 0h UTC, to 2017 January 1 0h UTC   : UTC-TAI = - 36s
 from 2017 January 1, 0h UTC, until further notice    : UTC-TAI = - 37s 

But the wikipedia article says

"Since this system of correction was implemented in 1972, 27 leap seconds have been inserted, the most recent on December 31, 2016 at 23:59:60 UTC.[1]"

This should be changed to 37 as per reference

I am not allowed to edit this page, hence this post. Can someone with rights update that figure please?

Thanks. — Preceding unsigned comment added by Mrojakeo (talk • contribs) 04:30, 15 August 2017 (UTC)

The number of inserted leap seconds is not the same as the difference between TAI and UTC. TAI started out 10 seconds ahead of UTC; as the International Atomic Time page says, "TAI is exactly 37 seconds ahead of UTC. The 37 seconds results from the initial difference of 10 seconds at the start of 1972, plus 27 leap seconds in UTC since 1972." When the system of correction was implemented, there were 10 seconds difference between UTC and TAI; after that, 27 more seconds were inserted. The initial 10 seconds are separate from the 27 inserted sections. Guy Harris (talk) 04:49, 15 August 2017 (UTC)

I agree with Guy Harris, except for started out. UTC began around 1960, but initially was aligned with UT2 and later UT1 through the use of small changes in the length of a second, and small time steps (much less than one second). Similar methods were used to keep radio time signals that were referenced to atomic time in step with UT2 before those time signals were named UTC, since 1958. So the 10 second difference is the difference at the beginning of leap seconds, not the beginning of UTC. Jc3s5h (talk) 09:31, 15 August 2017 (UTC)

A proposal for the solution of leap second problem

Wikipedia talk pages are for discussing improvements to the Wikipedia article, not for making proposals about the underlying subject matter of the article. Since leap seconds are controlled by ITU, and the [International Telecommunications Union|ITU] is an agency of the United Nations. Proposals are dealt with at periodic conferences to which governments send representatives. So you should address your proposal to the appropriate representative from your country. Jc3s5h (talk) 15:17, 16 August 2017 (UTC)

Proposal has been posted at my talk page. Georges T. (talk) 13:21, 20 October 2017 (UTC)

Georges, we've already had dubious original research in another article. Please don't start on the leap second. What on earth makes you think that your proposed method will cope with unpredictable variations? Dbfirs 15:03, 20 October 2017 (UTC)

Mr Dbfirs, please let me express my sincere glad for you address me again after many months. In the article about equal temperament my contribution is general formulas, relating examples, and background theory. Indeed formulas express mathematically psycho-acoustical law known to ancient Egyptians. Before me, many others have published formulas about, but not in general form, and background theory is just my presentation of psycho-acoustical law.

Now, regarding leap second, I do not contribute to the article, because proposal is really original work of mine.

On your question my answer is that just because some of earth's rotational speed's variations are unpredictable (irregular, random) we have to use regularly adjusting second for abolish leap second keeping track earth's rotation, not cesium atom oscillation as Americans propose. British strongly oppose american proposal, then you, as British, should support my proposal.

Because Mr. Jc3s5h considers that we are not permitted to discuss this matter here, please put your comments at my talk page Questions and Answers on the proposal. Regards. The Straw Man Georges Theodosiou Georges T. (talk) 16:22, 20 October 2017 (UTC)

Personally, I would prefer to keep the second at a fixed length, as defined by the International Committee for Weights and Measures. No other unit varies in size. Dbfirs 08:23, 21 October 2017 (UTC)

Mr Dbfirs, please permit me say, we use conversion factor 60 for minute (1 minute = 60 sec), also 60 for hour (1 hour = 60 minutes) and 24 for day (1 day = 24 hours). Also 61 seconds for the minute including leap second, 60 minutes + 1 second for the hour including leap secont, 24 hours + 1 second for the day including leap second, 365 (for common year) or 366 (for leap year) days + 1 second for the year including leap second. That's real situation in measuring time for someone who loves exactness. Then why not use conversion factor ${\frac {9,192,631,875}{9,192,631,770}}$ or similar for yas? Please read my Proposal for the solution of leap second problem. With regards and friendship, Georges Theodosiou, the Straw Man. Georges T. (talk) 12:28, 21 October 2017 (UTC)

Because it is not, and never can be exact. Dbfirs 12:32, 21 October 2017 (UTC)

Mr Dbfirs, please permit following question: Factor's precision is 1 pcar. Does it not satisfy you? With regards and friendship, Georges Theodosiou, The Straw Man, Georges T. (talk) 12:48, 21 October 2017 (UTC)

That's for the calculation based on the past, not for the real current rotation. Dbfirs 15:44, 21 October 2017 (UTC)

Mr Dbfris, please let me answer: yes, my algorithm is based on the nearest past, but it's the only solution since we can not predict random jerks. However always offset |UT1-IST| be far less than 0.9 sec, the limit demanded by International Community. If you are interested for authoritative answer, ask Mr. Director of IERS/EOC. With regards and friendship, Georges Theodosiou, The Straw Man, Georges T. (talk) 13:56, 23 October 2017 (UTC)