Re: Leap Second planned for 2016
On Sun 2016-07-10T11:27:33 +0300, Saku Ytti hath writ: > So how can we solve the problem? Immediately and long term? The ITU-R had the question of leap seconds on their agenda for 14 years and did not come up with an answer. Their 2015 decision was to drop the question and ask an alphabet soup of international acronym agencies to come up with something better by 2023. The problem remains that simply abandoning leap seconds has the effect of redefining the calendar, and Pope Gregory's last attempt to do that took 300 years to consolidate. For time scales there are three desirable goals, but it is only possible to pick two http://www.ucolick.org/~sla/leapsecs/picktwo.html -- Steve Allen<s...@ucolick.org> 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 http://www.ucolick.org/~sla/ Hgt +250 m
Re: REMINDER: LEAP SECOND
On Sat 2015-06-20T10:48:17 +0300, Saku Ytti hath writ: You're right. Hopefully POSIX will become monotonic next year, by removal of leaps from UTC. Probably not. The ITU-R has outlined four methods for this issue, see http://www.acma.gov.au/Industry/Spectrum/Spectrum-planning/International-planning-ITU-and-other-international-planning-bodies/wrc-15-agenda-item-114 where of method A1, A2, B, C1, C2, and D not all of them remove the leap second from UTC. In any case, previous draft proposals have all specified a 5 year interval from deciding to change until the change happens, so we should plan for 5 more years of leap seconds no matter what. -- Steve Allen s...@ucolick.org WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High StreetVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/Hgt +250 m
Re: Leap Second
On Tue 2013-07-02T10:23:58 -0400, Todd S hath writ: Anyone else run in to this, or have any further intel about servers that advertised the leap second? David Malone has been monitoring the NTP pool for years. See his plots http://www.maths.tcd.ie/~dwmalone/time/leaps/ This time pool was much better than it has been. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165Lat +36.99855 1156 High StreetVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
Re: F-ckin Leap Seconds, how do they work?
On Thu 2012-07-05T10:26:22 -0700, Roy hath writ: Lets see. There have been nine leap seconds in 20 years. So at the start of the next century the difference will probably be less than a minute There is no predicting how large the decadal variations in LOD will be, but the difference should be somewhere between 1 minute and 3 minutes. Please see these charts and tables for how unpredictable it is. http://www.ucolick.org/~sla/leapsecs/dutc.html Remember OpenTime is only for people who want their system clocks to ignore leap seconds. I don't include myself among the possible users of OpenTime. Anyone who needs that can already do that using existing, deployed, and tested code and hardware and the GPS system time scale. Please see this worked example. Please do not invent yet another private time scale. http://www.ucolick.org/~sla/leapsecs/right+gps.html -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165Lat +36.99855 1156 High StreetVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
Re: F-ckin Leap Seconds, how do they work?
On 2012 Jul 4, at 08:50, Jimmy Hess wrote: So accept the inaccuracy and correct the clock in the normal way that NTP corrects clocks that have drifted. This is basically the leap smear that google instituted after the issues in 2005. It works nicely in cloud applications where real-time is not an issue. It does not work so well when precision calculations of real-time physics are important, nor in heterogeneous environments where not all devices pay attention to NTP or some handle the leap differently than others. Those are places where a kernel should never be asked to do what the combination of POSIX and leap seconds demand. -- Steve Allen s...@ucolick.org WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855 University of California Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
Re: F-ckin Leap Seconds, how do they work?
Tony Finch dot at dotat.at wrote No that is not correct, or at least it's nowhere near as simple as that. The atomic second was matched to the second of ephemeris time, and that was based on Newcomb's tables of the sun, which in effect used the average length of the second from the 1800s. http://ucolick.org/~sla/leapsecs/dutc.html Last fall we held a meeting to consider how UTC might be changed and what the implications of leaps seconds were. The proceedings fill 400 pages of a book. For the sound bite version (only 3 pictures) of leap seconds http://www.ucolick.org/~sla/leapsecs/amsci.html For a view of the international legal mess caused by leap seconds http://www.ucolick.org/~sla/leapsecs/epochtime.html For a blow-by-blow review of the international bureaucratic regulatory situation for leap seconds see http://www.ucolick.org/~sla/leapsecs/onlinebib.html For a worked example that could alleviate the disagreement between POSIX and leap seconds, and which might break the international stalemate http://www.ucolick.org/~sla/leapsecs/right+gps.html In there are also links to those 400 pages of the book, but I suggest that this forum is not the best place to rehash this information. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165Lat +36.99855 1156 High StreetVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m
Re: F-ckin Leap Seconds, how do they work?
On 2012 Jul 3, at 18:13, Vadim Antonov wrote: PS. I would vote for using TAI instead of UTC as the non-relativistic time base in computer systems. A problem with the use of TAI is that the BIPM and CCTF (who make TAI) expressed strongly that they do not want it used as a system time in document CCTF09-27 http://www.bipm.org/cc/CCTF/Allowed/18/CCTF_09-27_note_on_UTC-ITU-R.pdf so strongly that they end by contemplating the discontinuation of TAI. Unless there is international agreement that a time scale should be used, and support of the agency making that time scale, there will be trouble. The only way out of those constraints is to have the wherewithal of the US DoD or the Chinese government who simply asserted that the GPS system time and Beidou system time would be something other than those international standards. -- Steve Allen s...@ucolick.org WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855 University of California Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
Re: F-ckin Leap Seconds, how do they work?
On 2012 Jul 3, at 21:29, Paul Graydon wrote: http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat Which is simply reiterating an older version of the regulatory document that specifies how UTC shall be done http://www.itu.int/rec/R-REC-TF.460/en On paper it is a scheme that will work for 1000 years, but the original regulation contained no implementation details, no interoperability studies, no agency responsible for describing how implementations might communicate requirements, and that paper was locked behind a paywall for the first 40 years of its existence. All of that is too late to fix now. The events in January showed that the notion of simply abandoning leap seconds could not achieve consensus required for change. We are in Disney's Haunted Mansion with the spirit taunting us to find a way out. -- Steve Allen s...@ucolick.org WGS-84 (GPS) UCO/Lick Observatory Natural Sciences II, Room 165 Lat +36.99855 University of California Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m
