From sla at ucolick.org Tue Sep 8 21:39:31 2009 From: sla at ucolick.org (Steve Allen) Date: Tue, 8 Sep 2009 18:39:31 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva Message-ID: <20090909013931.GA14174@ucolick.org> The WP7A is meeting in Geneva this week. There are two documents about UTC on their table as seen here http://www.itu.int/md/R07-WP7A-C/en one from People's Republic of China, and another from BIPM (which, curiously, is not about question 236/7) This should be interesting. -- Steve Allen 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 From gwinn at Raytheon.com Wed Sep 9 11:10:56 2009 From: gwinn at Raytheon.com (Joseph M Gwinn) Date: Wed, 9 Sep 2009 11:10:56 -0400 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <20090909013931.GA14174@ucolick.org> References: <20090909013931.GA14174@ucolick.org> Message-ID: Steve, It's hidden behind a username and password wall, making it unavailable. Joe leapsecs-bounces at leapsecond.com wrote on 09/08/2009 09:39:31 PM: > From: > > Steve Allen > > To: > > Leap Second Discussion List > > Date: > > 09/08/2009 10:46 PM > > Subject: > > [LEAPSECS] it's WP7A week in Geneva > > Sent by: > > leapsecs-bounces at leapsecond.com > > The WP7A is meeting in Geneva this week. > > There are two documents about UTC on their table as seen here > http://www.itu.int/md/R07-WP7A-C/en > one from People's Republic of China, > and another from BIPM (which, curiously, is not about question 236/7) > > This should be interesting. > > -- > Steve Allen 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 > _______________________________________________ > LEAPSECS mailing list > LEAPSECS at leapsecond.com > http://six.pairlist.net/mailman/listinfo/leapsecs > > The following line is added for your protection and will be > used for analysis if this message is reported as > spam: (Raytheon Analysis: IP=199.46.199.195; e- > from=leapsecs-bounces at leapsecond.com; from=sla at ucolick.org; > date=Sep 9, 2009 2:46:11 AM; subject=[LEAPSECS] it's WP7A week in Geneva) From sla at ucolick.org Wed Sep 9 13:20:25 2009 From: sla at ucolick.org (Steve Allen) Date: Wed, 9 Sep 2009 10:20:25 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <20090909013931.GA14174@ucolick.org> References: <20090909013931.GA14174@ucolick.org> Message-ID: <20090909172025.GM21922@ucolick.org> On Tue 2009-09-08T18:39:31 -0700, Steve Allen hath writ: > The WP7A is meeting in Geneva this week. > > There are two documents about UTC on their table as seen here > http://www.itu.int/md/R07-WP7A-C/en > one from People's Republic of China, > and another from BIPM (which, curiously, is not about question 236/7) In response to several notes, yes, these are protected, so the only broadly visible aspects are the authors and titles. It seems to me that the ITU-R operates in a sort of 19th century diplomatic mode. I do find this annoying by comparison to the internet IETF/IESG/RFC model of standards development (in particular because the resulting recommendations are also under lock and key even though that interferes with the expectation that they will be broadly and correctly implemented in software and hardware systems) but I understand that it is their perogative to operate in this mode. In the US any draft contributions must be reviewed publicly, so those drafts can be openly seen, but even to find out about their availability for review means tracking a byzantine system. I suppose that other countries also require review that might make the drafts visible, but following the ever-evolving bureaucratic structures is beyond me. -- Steve Allen 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 From imp at bsdimp.com Wed Sep 9 13:37:31 2009 From: imp at bsdimp.com (M. Warner Losh) Date: Wed, 09 Sep 2009 11:37:31 -0600 (MDT) Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <20090909172025.GM21922@ucolick.org> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> Message-ID: <20090909.113731.1119102511.imp@bsdimp.com> In message: <20090909172025.GM21922 at ucolick.org> Steve Allen writes: : On Tue 2009-09-08T18:39:31 -0700, Steve Allen hath writ: : > The WP7A is meeting in Geneva this week. : > : > There are two documents about UTC on their table as seen here : > http://www.itu.int/md/R07-WP7A-C/en : > one from People's Republic of China, : > and another from BIPM (which, curiously, is not about question 236/7) : : In response to several notes, yes, these are protected, so the only : broadly visible aspects are the authors and titles. It seems to me : that the ITU-R operates in a sort of 19th century diplomatic mode. Any chance the docs will leak out after the meeting? There's been several leaks in the past of similar docs... Do we know, broadly, what the docs say? Warner From lang at unb.ca Wed Sep 9 16:39:49 2009 From: lang at unb.ca (Richard B. Langley) Date: Wed, 9 Sep 2009 17:39:49 -0300 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <20090909.113731.1119102511.imp@bsdimp.com> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> Message-ID: <1252528789.4aa81295689c6@webmail.unb.ca> There will likely be a report on anything significant at the CGSIC meeting in Savannah the week after next . -- Richard Langley Quoting "M. Warner Losh" : > In message: <20090909172025.GM21922 at ucolick.org> > Steve Allen writes: > : On Tue 2009-09-08T18:39:31 -0700, Steve Allen hath writ: > : > The WP7A is meeting in Geneva this week. > : > > : > There are two documents about UTC on their table as seen here > : > http://www.itu.int/md/R07-WP7A-C/en > : > one from People's Republic of China, > : > and another from BIPM (which, curiously, is not about question 236/7) > : > : In response to several notes, yes, these are protected, so the only > : broadly visible aspects are the authors and titles. It seems to me > : that the ITU-R operates in a sort of 19th century diplomatic mode. > > Any chance the docs will leak out after the meeting? There's been > several leaks in the past of similar docs... > > Do we know, broadly, what the docs say? > > Warner > _______________________________________________ > LEAPSECS mailing list > LEAPSECS at leapsecond.com > http://six.pairlist.net/mailman/listinfo/leapsecs > =============================================================================== Richard B. Langley E-mail: lang at unb.ca Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ =============================================================================== From seaman at noao.edu Wed Sep 9 18:14:01 2009 From: seaman at noao.edu (Rob Seaman) Date: Wed, 9 Sep 2009 15:14:01 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <1252528789.4aa81295689c6@webmail.unb.ca> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> Message-ID: > There will likely be a report on anything significant at the CGSIC > meeting in Savannah the week after next > >. > -- Richard Langley It's impressive that civil GPS discussions reach back through so many meetings. Any idea when the 1st CGSIC meeting was held? The last five such meetings have been annual, but I'm not having much luck clicking through the site for earlier info. GPS as a project dates back to the mid-70's, right? With completion in the early 90's? Presumably they met more frequently early on, but that still seems like a lot of meetings (for just the civil sub-community) to squeeze in. I'm sensitive (really) to the concerns expressed in the title of this talk: Why leap seconds are difficult to get right for an equipment vendor ? Sam Stein, Symmetricom, Inc. but the system engineering question here is backwards. First, discover the requirements. Second, figure out how to meet them. That said, I hope the presentations will be posted online. Rob -------------- next part -------------- An HTML attachment was scrubbed... URL: From sla at ucolick.org Wed Sep 9 19:27:17 2009 From: sla at ucolick.org (Steve Allen) Date: Wed, 9 Sep 2009 16:27:17 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> Message-ID: <20090909232717.GT21922@ucolick.org> On Wed 2009-09-09T15:14:01 -0700, Rob Seaman hath writ: > Why leap seconds are difficult to get right for an equipment vendor > Sam Stein, Symmetricom, Inc. I'd like to see what the folks from Meinberg have to say about that. ... because POSIX does not admit that leap seconds exist. ... because there is no implementation which is right in all jurisdictions http://www.ucolick.org/~sla/leapsecs/epochtime.html -- Steve Allen 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 From phk at phk.freebsd.dk Wed Sep 9 19:49:42 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Wed, 09 Sep 2009 23:49:42 +0000 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: Your message of "Wed, 09 Sep 2009 15:14:01 MST." Message-ID: <76878.1252540182@critter.freebsd.dk> In message , Rob Seaman writes: > Why leap seconds are difficult to get right for an equipment vendor >Sam Stein, Symmetricom, Inc. > >but the system engineering question here is backwards. First, >discover the requirements. Second, figure out how to meet them. That >said, I hope the presentations will be posted online. Ask him ? Sam has been very friendly & responsive in the past. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. From imp at bsdimp.com Wed Sep 9 20:41:38 2009 From: imp at bsdimp.com (M. Warner Losh) Date: Wed, 09 Sep 2009 18:41:38 -0600 (MDT) Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> Message-ID: <20090909.184138.1728818297.imp@bsdimp.com> In message: Rob Seaman writes: : I'm sensitive (really) to the concerns expressed in the title of this : talk: : Why leap seconds are difficult to get right for an equipment vendor ? : Sam Stein, Symmetricom, Inc. : : but the system engineering question here is backwards. First, : discover the requirements. Second, figure out how to meet them. That : said, I hope the presentations will be posted online. Sam is very much aware of the practical difficulties in getting leap seconds right. He was my boss, and as you all know, I've enumerated the problems here many times. While the requirements are "known" up front, the problems in meeting them are much more non-trivial than people like Rob have said they should be. I've been there, done that. They are hard when you have to cover the edge cases that vender gear has to cover. Especially when you have "fast start" requirements coupled with "deep, cold spares" that have to know what UTC time is faster than the gps almanac can deliver it. Eg, if you have to start up in < 5 minutes at the right UTC time how do you do that when your GPS receiver has been off for 2 years sitting on a shelf waiting to be put into serive? Anyway, Sam will present a fair and balanced view of things. He's a good guy who is sensitive to both the benefits of leap seconds, as well as to their costs. He's in a position to know exactly what the costs are as he's been there and done that for a lot longer than I have... Plus, he's a good speaker, so it should be an entertaining talk... Warner From seaman at noao.edu Thu Sep 10 04:45:23 2009 From: seaman at noao.edu (Rob Seaman) Date: Thu, 10 Sep 2009 01:45:23 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <8194EAD9-4EA6-4B9B-B32B-960992D4FD3E@noao.edu> References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <20090909.184138.1728818297.imp@bsdimp.com> <8194EAD9-4EA6-4B9B-B32B-960992D4FD3E@noao.edu> Message-ID: M. Warner Losh wrote: > Rob Seaman writes: > >> First, discover the requirements. Second, figure out how to meet >> them. > > While the requirements are "known" up front, the problems in meeting > them are much more non-trivial than people like Rob have said they > should be. As Gertrude Stein said, "a requirement is a requirement is a requirement". Either UTC is required to remain tied to the sun or it isn't. How much effort is necessary to make this work is separate from the question of whether the requirement must be met. I have (tediously, bombastically, endlessly) asserted that civil time IS solar time. This is a statement of requirements. Requirements describe the problem space. On the other hand, focusing on leap second issues - whether features or bugs - is to grapple with solution space. One can certainly entertain trading off one solution in favor of another. One cannot, however, simply decommission a solution unless the requirements that demanded the solution in the first place are somehow removed. Per Fatboy Slim: "You can go with this XOR you can go with that". Rob From phk at phk.freebsd.dk Thu Sep 10 05:33:13 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Thu, 10 Sep 2009 09:33:13 +0000 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: Your message of "Thu, 10 Sep 2009 01:45:23 MST." Message-ID: <78639.1252575193@critter.freebsd.dk> In message , Rob Seaman writes: >I have (tediously, bombastically, endlessly) asserted that civil time >IS solar time. This is a statement of requirements. Requirements >describe the problem space. And you have repeatedly tried to ignore the question of how large the civil-solar tolerance is, can or should be. I would estimate that the majority of the worlds population are not within one hour of solar time at any point in the year. China, for instance, is one single timezone. But maybe part of that problem is in the moniker "civil time", which we have never fully agreed what means ? How about we operate with _three_ kinds of time and one kind of geophysics: "Timekeeping Time": What timekeeping scientists work with, for keeping time. Mind you: "Time", not 'Earth Orientation". Today this would be TAI, TAL etc. "Earth Orientation": A set of physical parameters describing the motion of this planet, including its rotation. Today this would be UT, UT1, UT2, and half of UTC. "Scientific/Technical Time": What computers and scientific experiments use internally, in order to be able to communicate temporal relationships unambiguously. Today this is UTC + Leap-second table + Leap-second announcement. "Human time": What people see on their clock. Today that is usually UTC, fuzzed by political concepts such as DST. Obviously, Neither ITU nor BIPM has any control over what "Human Time" is or how it works. National and federal lawmakers decide that, often illadvisedly, and occationally very stupidly. China, as I recall, is one single timezone, and some places countries have 30 minute offsets from UTC I belive. If any national government wants to do something stupid to human time in their country, nobody can prevent them from doing so. Timekeeping Time and Earth Orientation should be left to the scientists, and should obviously be established and maintained as precise as funding will allow. UN and ITU has no mandate in this area, so the relevant organizations (IAU etc) are free to do as they please. What is left then, is the Scientific and Technical time. Which is exactly what UTC was intended to be originally, and why the definition and possible redefinition of UTC happens in an obscure technical corner, of a UN organ most people have not heard about. Now, please make your argument, that Scientific and Technical time should be polluted by earth orientation parameters ? Yes, it would be convenient for astronomers pointing their telescopes, but do you have any other argument than that ? Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. From nimh at pipe.nl Thu Sep 10 05:55:01 2009 From: nimh at pipe.nl (Nero Imhard) Date: Thu, 10 Sep 2009 11:55:01 +0200 (CEST) Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <20090909.184138.1728818297.imp@bsdimp.com> References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <20090909.184138.1728818297.imp@bsdimp.com> Message-ID: <4726c660355d1b90529896c10c7cc9fa.squirrel@mx.pipe.nl> M. Warner Losh wrote: > Sam is very much aware of the practical difficulties in getting leap > seconds right. He was my boss, and as you all know, I've enumerated > the problems here many times. Valid points are being raised about leap seconds being royal PITAs for the purposes of the ITU, and it is only reasonable that they want to get rid of them. But I'm quite disappointed that the question on the table continues to be "should UTC abandon leap seconds?", while the relevant question is "should the ITU stop using/broadcasting a time scale that is causing trouble?". I'm worried that this hasn't even been considered by WP7A. Decoupling UTC and UT isn't wrong in a way related to ITU's actual problem (which makes the whole thing so disturbing); it's wrong in itself. N From dot at dotat.at Thu Sep 10 07:33:10 2009 From: dot at dotat.at (Tony Finch) Date: Thu, 10 Sep 2009 12:33:10 +0100 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <78639.1252575193@critter.freebsd.dk> References: <78639.1252575193@critter.freebsd.dk> Message-ID: On Thu, 10 Sep 2009, Poul-Henning Kamp wrote: > > Obviously, Neither ITU nor BIPM has any control over what "Human > Time" is or how it works. National and federal lawmakers decide > that, often illadvisedly, and occationally very stupidly. China, > as I recall, is one single timezone, and some places countries have > 30 minute offsets from UTC I belive. China's single time zone causes some interesting problems that highlight the political nature of "human time" (as if it needed any further highlighting). In Xinjiang it's common for Uighurs to use UTC+6 whereas Han Chinese observe UTC+8 China Standard Time. So your choice of time zone doesn't depend on just your location, but also what you are trying to do and who you are communicating with. India is a prominent example of a half hour timezone offset. (Sorry for straying off topic.) Tony. -- f.anthony.n.finch http://dotat.at/ GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS. MODERATE OR GOOD. From lang at unb.ca Thu Sep 10 09:11:37 2009 From: lang at unb.ca (Richard B. Langley) Date: Thu, 10 Sep 2009 10:11:37 -0300 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> Message-ID: <1252588297.4aa8fb0960f48@webmail.unb.ca> Quoting Rob Seaman : > > There will likely be a report on anything significant at the CGSIC > > meeting in Savannah the week after next > > > > > >. > > -- Richard Langley > > > It's impressive that civil GPS discussions reach back through so many > meetings. Any idea when the 1st CGSIC meeting was held? Probably 1986: Title: Civil GPS Service Interface Committee (CGSIC) Author: Heywood O. Shirer Meeting: Proceedings of the 1991 National Technical Meeting of the Institute of Navigation January 22 - 24, 1991 Sheraton San Marcos Hotel Phoenix, AZ Page(s): 183 - 185 Abstract: The Civil GPS Service Interface Committee (CGSIC) was established to identify civil GPS user technical information needs in support of the Civil GPS (CGS) program. To effectively identify information needs that relate to the civil use of GPS, the CGSIC interfaces between civil GPS users, the Civil GPS Program Office, and the GPS operators (Department of Defense). The current CGSIC evolved from DOD preliminary planning for a GPS civil user interface function in 1986. As part of the effort, an oversight committee led by the USAF Joint Program Office, with representatives from government, industry and the user community, was established to provide a GPS Information and Data System for the civil community. This committee became known as the Civil GPS Service Steering Committee and became jointly chaired by DOD and DOT after DOT accepted responsibility for the civil interface in 1987. In 1988 DOT assumed the sole Chairmanship of the CGSSC, but with continued DOD representation on the committee. In early 1991 the Committee's named was changed to the Civil GPS Service Interface Committee (CGSIC) and its charter revised to more accurately reflect its mission of establishing a forum for technical information exchange. The current CGSIC is jointly chaired by the U.S. Coast Guard and the Research and Special Programs Administration and consists of a general committee and five subcommittees that meet about every four months. Until recently the CGSIC consisted of a general committee open to all and an executive committee restricted to government representatives. The executive committee was dropped in an interest to open up the meetings to all interested groups. Membership in the Committee is intended to represent the widest possible coverage of the civil community. About 100 participants from relevant private, government, and industry user groups, both U.S. and international, attend each meeting. > The last > five such meetings have been annual, but I'm not having much luck > clicking through the site for earlier info. GPS as a project dates > back to the mid-70's, right? Started in 1973. > With completion in the early 90's? How do you define "completion"? Reaching FOC (full operational capability)? Then, July 17, 1995. > Presumably they met more frequently early on, but that still seems > like a lot of meetings (for just the civil sub-community) to squeeze in. Go to the "Wayback Machine" aka Internet Archives to find more. Use www.navcen.uscg.gov as well as www.navcen.uscg.mil (previous URL). You should be able to get back to at least the 22nd meeting (1993). -- Richard > I'm sensitive (really) to the concerns expressed in the title of this > talk: > > Why leap seconds are difficult to get right for an equipment vendor ? > Sam Stein, Symmetricom, Inc. > > but the system engineering question here is backwards. First, > discover the requirements. Second, figure out how to meet them. That > said, I hope the presentations will be posted online. > > Rob > > =============================================================================== Richard B. Langley E-mail: lang at unb.ca Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ =============================================================================== From sla at ucolick.org Thu Sep 10 09:36:20 2009 From: sla at ucolick.org (Steve Allen) Date: Thu, 10 Sep 2009 06:36:20 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <4726c660355d1b90529896c10c7cc9fa.squirrel@mx.pipe.nl> References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <20090909.184138.1728818297.imp@bsdimp.com> <4726c660355d1b90529896c10c7cc9fa.squirrel@mx.pipe.nl> Message-ID: On 2009 Sep 10, at 02:55, Nero Imhard wrote: > But I'm quite disappointed that the question on the table continues > to be > "should UTC abandon leap seconds?", while the relevant question is > "should > the ITU stop using/broadcasting a time scale that is causing > trouble?". > > I'm worried that this hasn't even been considered by WP7A. I believe that this can only happen if one of the member delegations submits a document detailing such a proposal. It would seem most likely for it to come from a nation where mean solar time is the current legal standard (Denmark? UK?). But I think the proposal has to come along with significant support from the technical communities in the form of agreement that such a change is preferable to the stalemate of the past few years. It has to overcome whatever objection has prevented the adoption of the result of the WP7A's 2003 colloquium in Torino. -- Steve Allen 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 From imp at bsdimp.com Thu Sep 10 09:44:29 2009 From: imp at bsdimp.com (M. Warner Losh) Date: Thu, 10 Sep 2009 07:44:29 -0600 (MDT) Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090909.184138.1728818297.imp@bsdimp.com> <8194EAD9-4EA6-4B9B-B32B-960992D4FD3E@noao.edu> Message-ID: <20090910.074429.-1308039306.imp@bsdimp.com> In message: Rob Seaman writes: : M. Warner Losh wrote: : : > Rob Seaman writes: : > : >> First, discover the requirements. Second, figure out how to meet : >> them. : > : > While the requirements are "known" up front, the problems in meeting : > them are much more non-trivial than people like Rob have said they : > should be. : : As Gertrude Stein said, "a requirement is a requirement is a : requirement". Either UTC is required to remain tied to the sun or it : isn't. How much effort is necessary to make this work is separate : from the question of whether the requirement must be met. : : I have (tediously, bombastically, endlessly) asserted that civil time : IS solar time. This is a statement of requirements. Requirements : describe the problem space. : : On the other hand, focusing on leap second issues - whether features : or bugs - is to grapple with solution space. One can certainly : entertain trading off one solution in favor of another. One cannot, : however, simply decommission a solution unless the requirements that : demanded the solution in the first place are somehow removed. Yes. And I'll point out that many of the systems that have UTC specified for them aren't because the folks using them need to have a time scale that's tied to the sun. UTC is specified because it is what everybody else uses, and these folks need to be on the same time as everybody else. There are a number of solutions to the current leap-seconds problems that don't completely decouple UTC from the sun. There's some that do in the recognition that UTC really is going to be viable at most a few hundred to a few thousand years anyway due to the quadratic acceleration of leap second timing. There's some that don't keep UTC coupled to the sun. There's some that live in multiple of these spaces. Life would be a lot simpler, for example, if GPS were to broadcast every second or 10 an extra 40ish bits of data: last leap second, next leap second. Right now it does this every 1200ish seconds, which is too slow. As satellite acquisition times have improved, the engineering balances that dictated a 20ish minute almanac download need to change as well... [[ Life would also be simpler if there were some way to assume devices were connected to the Internet for this data too, but many trust scenarios and mobile applications make that difficult. GPS has good, strong authentication available and deployed (SAASM), while there's no equivalent for ntp that's widely deployed and reliable today. And even if it was, there's many places where you can't get internet, or the costs are prohibitively expensive. ]] Anyway, as with all engineering issues, the practical problems should be discussed as widely as possible, and the real requirements for the system should be continually reevaluated to ensure that the system is meeting the real needs of its users. Warner From seaman at noao.edu Thu Sep 10 09:55:31 2009 From: seaman at noao.edu (Rob Seaman) Date: Thu, 10 Sep 2009 06:55:31 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <78639.1252575193@critter.freebsd.dk> References: <78639.1252575193@critter.freebsd.dk> Message-ID: <6A9FA5E8-CE02-4642-BB2B-48602B7D65BA@noao.edu> Poul-Henning Kamp wrote: > And you have repeatedly tried to ignore the question of how large > the civil-solar tolerance is, can or should be. I don't think a fair and impartial witness would say given my plethora of messages over the years that I've ever successfully ignored anything :-) That said, a one-hour tolerance is many orders of magnitude too large, see previous threads. > But maybe part of that problem is in the moniker "civil time", which > we have never fully agreed what means ? What I mean is "the common international timescale that underlies local time worldwide for everyday purposes". > How about we operate with _three_ kinds of time and one kind of > geophysics: Certainly one geophysics - that's the point of tying the standard to physical reality rather than to racks of equipment demanding constant attention and robust interconnects forever. There are many more than three kinds of time, but I believe previous discussions have uncovered no reason for layering the civil timekeeping standard and infrastructure on more than the two that UTC already references. There are plenty of degrees of freedom to find alternate solutions that actually address the requirements. > If any national government wants to do something stupid to human > time in their country, nobody can prevent them from doing so. Which is why underlying physical reality has to fill that role. Also, what exactly would an isolated "human time in their country" actually mean? Every day for everyone, our activities are connected to those of humans and systems in other time zones. There is one international community and there must be one common timescale. > astronomers pointing their telescopes, but do you have any other > argument than that ? As stated many times, astronomers are power users for more kinds of time (in more bizarre places) than anybody else. We certainly use both atomic and mean solar timescales. This discussion is about civil timekeeping. Rob From dot at dotat.at Thu Sep 10 10:11:59 2009 From: dot at dotat.at (Tony Finch) Date: Thu, 10 Sep 2009 15:11:59 +0100 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <20090909.184138.1728818297.imp@bsdimp.com> <4726c660355d1b90529896c10c7cc9fa.squirrel@mx.pipe.nl> Message-ID: On Thu, 10 Sep 2009, Steve Allen wrote: > > I believe that this can only happen if one of the member delegations > submits a document detailing such a proposal. It would seem most > likely for it to come from a nation where mean solar time is the > current legal standard (Denmark? UK?). The UK doesn't acknowledge any difference between GMT and UTC. Tony. -- f.anthony.n.finch http://dotat.at/ GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS. MODERATE OR GOOD. From seaman at noao.edu Thu Sep 10 10:14:42 2009 From: seaman at noao.edu (Rob Seaman) Date: Thu, 10 Sep 2009 07:14:42 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <78639.1252575193@critter.freebsd.dk> Message-ID: <4C17FD48-24BE-461D-A7A9-36AF7D81D3B2@noao.edu> Tony Finch wrote: > India is a prominent example of a half hour timezone offset. > > (Sorry for straying off topic.) Indeed. I reset the second clock on my phone to the timezone of New Delhi when my daughter had a semester in Dharamsala. It's been a couple of years and I've never set it back. It is precisely the fact of a international civil timescale that makes the timezone system work. In return, the many timezones and numerous special cases represent constraints on the common underlying standard to better track mean solar time. (Not off topic at all.) Rob From seaman at noao.edu Thu Sep 10 10:24:01 2009 From: seaman at noao.edu (Rob Seaman) Date: Thu, 10 Sep 2009 07:24:01 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <1252588297.4aa8fb0960f48@webmail.unb.ca> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <1252588297.4aa8fb0960f48@webmail.unb.ca> Message-ID: <46D8CFBD-40E7-41FE-94D7-34661A474BD4@noao.edu> Richard B. Langley wrote: > Quoting Rob Seaman : > >> It's impressive that civil GPS discussions reach back through so >> many meetings. Any idea when the 1st CGSIC meeting was held? > > Probably 1986: Cool. Thanks! > Proceedings of the 1991 National Technical Meeting of the Institute > of Navigation > January 22 - 24, 1991 Sheraton San Marcos Hotel Phoenix, AZ Argh! Another meeting I could have attended easily if I only knew it existed. >> GPS as a project dates back to the mid-70's, right? > > Started in 1973. > >> With completion in the early 90's? > > How do you define "completion"? Reaching FOC (full operational > capability)? Then, July 17, 1995. Even a bit longer than I thought. So it took GPS 22 years and they're still talking about it 14 years after that. We've only been talking since 1999. We have 26 years to go! Rob From dot at dotat.at Thu Sep 10 10:41:17 2009 From: dot at dotat.at (Tony Finch) Date: Thu, 10 Sep 2009 15:41:17 +0100 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <4C17FD48-24BE-461D-A7A9-36AF7D81D3B2@noao.edu> References: <78639.1252575193@critter.freebsd.dk> <4C17FD48-24BE-461D-A7A9-36AF7D81D3B2@noao.edu> Message-ID: On Thu, 10 Sep 2009, Rob Seaman wrote: > > It is precisely the fact of a international civil timescale that makes the > timezone system work. Yes. > In return, the many timezones and numerous special cases represent > constraints on the common underlying standard to better track mean solar > time. The constraints from timezones aren't tight enough to make any diffence to leapseconds. For civil time the key requirement is that everyone agrees, which is why timezones are wider than a second. The situation in Xinjiang is a good example, because the argument over how to set the clocks is entirely political and makes little practical difference to things like business opening hours. Tony. -- f.anthony.n.finch http://dotat.at/ GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS. MODERATE OR GOOD. From seaman at noao.edu Thu Sep 10 10:46:16 2009 From: seaman at noao.edu (Rob Seaman) Date: Thu, 10 Sep 2009 07:46:16 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <20090910.074429.-1308039306.imp@bsdimp.com> References: <20090909.184138.1728818297.imp@bsdimp.com> <8194EAD9-4EA6-4B9B-B32B-960992D4FD3E@noao.edu> <20090910.074429.-1308039306.imp@bsdimp.com> Message-ID: M. Warner Losh wrote: > There are a number of solutions to the current leap-seconds problems > that don't completely decouple UTC from the sun. As well as non-solutions like leap-hours that don't actually eliminate leap-seconds, but rather accumulate them for later release in one colossally indigestible lump. > There's some that do in the recognition that UTC really is going to > be viable at most a few hundred to a few thousand years anyway due > to the quadratic acceleration of leap second timing. The quadratic acceleration will apply to any proposed solution relative to atomic timescales where the second is of a fixed length. This issue is not specific to the current UTC. In particular, it is not addressed at all by the proposal to embargo leap-seconds. > Anyway, as with all engineering issues, the practical problems > should be discussed as widely as possible, and the real requirements > for the system should be continually reevaluated to ensure that the > system is meeting the real needs of its users. Amen! And with engineering best practices, no single power bloc should seek to force adoption of their preferred option. We would have gotten much more done (and I would have written many fewer messages to everyone's benefit :-) over the past 10 years if there weren't a need for constant vigilance to fend off incessant attempts to hurry a decision. Rob From imp at bsdimp.com Thu Sep 10 11:21:40 2009 From: imp at bsdimp.com (M. Warner Losh) Date: Thu, 10 Sep 2009 09:21:40 -0600 (MDT) Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090910.074429.-1308039306.imp@bsdimp.com> Message-ID: <20090910.092140.-1612177427.imp@bsdimp.com> In message: Rob Seaman writes: : M. Warner Losh wrote: : : > There are a number of solutions to the current leap-seconds problems : > that don't completely decouple UTC from the sun. : : As well as non-solutions like leap-hours that don't actually eliminate : leap-seconds, but rather accumulate them for later release in one : colossally indigestible lump. Actually, that solution does keep UTC coupled to the sun. I tend to agree that large adjustments like that would never happen. But any insertion of time into the time scale would : > There's some that do in the recognition that UTC really is going to : > be viable at most a few hundred to a few thousand years anyway due : > to the quadratic acceleration of leap second timing. : : The quadratic acceleration will apply to any proposed solution : relative to atomic timescales where the second is of a fixed length. : This issue is not specific to the current UTC. In particular, it is : not addressed at all by the proposal to embargo leap-seconds. Actually, it *IS* addressed by the embargo on leap seconds. The idea there would be to publish the UT1 and not worry that it grows without bound. Then you don't have to coordinate the insertion of leap seconds, just publish a measurement that says what the delta is. What isn't addressed is keeping them in sync. They are two different things, and we shouldn't lose sight of that fact. And embargo on leap seconds forever is exactly the same thing as saying UTC is no longer tied to the sun. That's a change that should be considered, even if it ultimately proves to be not a viable change. This is a proposed solution, and one that may have merit. However, only if the users of time for which it actually matters that DUT1 is < 1s can get the larger corrections from somewhere else, retool, etc. These costs may be smaller than continued insertions of leap seconds (they could very well be larger too: nobody has done a public, comprehensive study here). : > Anyway, as with all engineering issues, the practical problems : > should be discussed as widely as possible, and the real requirements : > for the system should be continually reevaluated to ensure that the : > system is meeting the real needs of its users. : : Amen! : : And with engineering best practices, no single power bloc should seek : to force adoption of their preferred option. We would have gotten : much more done (and I would have written many fewer messages to : everyone's benefit :-) over the past 10 years if there weren't a need : for constant vigilance to fend off incessant attempts to hurry a : decision. Correct. Unfortunately, the power block that was in control in the late 60's and early 70's has shifted now so that the relative importance of each of the factions has changed. The importance for various factors going into the leap-second decision has changed. The biggest one is now almost all terrestrial navigation is done with GPS and the DUT1 error correction no longer matters since people don't do things by hand anymore. Yet the fundamental solution hasn't. If there had been no action, no leap seconds, etc invented to harmonize the atomic and civil time scales (this would go back into the late 50's), then we'd come up with a different solution today because the playing field is so radically different. Some say different enough to pay the penalty of disturbing the status quo, others are not so sure so there's friction between the different groups. This tends to lead to preservation of the status quo. The current stalemate likely won't change until a plane crash can be tied to leap seconds... Warner From seaman at noao.edu Thu Sep 10 15:54:53 2009 From: seaman at noao.edu (Rob Seaman) Date: Thu, 10 Sep 2009 12:54:53 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <80E73B36-2AB8-4B25-B198-05C425E2F59E@noao.edu> References: <20090910.074429.-1308039306.imp@bsdimp.com> <20090910.092140.-1612177427.imp@bsdimp.com> <80E73B36-2AB8-4B25-B198-05C425E2F59E@noao.edu> Message-ID: M. Warner Losh wrote: > Actually, that solution does keep UTC coupled to the sun. I tend to > agree that large adjustments like that would never happen. Timezones are an hour wide. Any such adjustment would only occur after the entire error budget propagated all the way across. This is equivalent to no solution at all. I wasn't addressing the issue of "coupling", but rather the more basic issue of "solving the problem". > The idea there would be to publish the UT1 and not worry that it > grows without bound. Then you don't have to coordinate the > insertion of leap seconds, just publish a measurement that says what > the delta is. I won't critique this notion now, but if this is part of the solution shouldn't it be addressed in the proposal? > What isn't addressed is keeping them in sync. They are two > different things, and we shouldn't lose sight of that fact. Ok - that's two rather obvious things that are missing from the proposal. > And embargo on leap seconds forever is exactly the same thing as > saying UTC is no longer tied to the sun. That's a change that > should be considered, even if it ultimately proves to be not a > viable change. And the status quo should also be considered in any trade-off study. As well as entertaining the Torino consensus of leaving UTC alone by defining a new timescale unencumbered by annoying astronomers. And the numerous interesting variations of the zoneinfo concept. Or simply distributing GPS time instead of UTC. > This is a proposed solution, and one that may have merit. However, > only if the users of time for which it actually matters that DUT1 is > < 1s can get the larger corrections from somewhere else, retool, > etc. These costs may be smaller than continued insertions of leap > seconds (they could very well be larger too: nobody has done a > public, comprehensive study here). I'm all for coherently studying the issues. The heart of my argument, however, is distinct from the need to constrain DUT1. Rather, civil time is obviously a flavor of mean solar time (sidereal time plus the offset for lapping the Sun every year) - see list archive for discussion(s). In fact, the small cadence of leap seconds at the current epoch is the only reason an embargo can even be entertained as an option. We can productively debate non-UTC options or different scheduling strategies or different transport infrastructure or different tolerances, but night divides the day and the leap-second is ultimately a mechanism to keep the definition of the day stationary. Embargoing leap seconds is an unworkable strategy because the rate also matters, not just local offsets. Rob From sla at ucolick.org Fri Sep 11 01:34:04 2009 From: sla at ucolick.org (Steve Allen) Date: Thu, 10 Sep 2009 22:34:04 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <76878.1252540182@critter.freebsd.dk> References: <76878.1252540182@critter.freebsd.dk> Message-ID: <20090911053404.GA4432@ucolick.org> On Wed 2009-09-09T23:49:42 +0000, Poul-Henning Kamp hath writ: > In message , Rob Seaman writes: > > Why leap seconds are difficult to get right for an equipment vendor > >Sam Stein, Symmetricom, Inc. > > I hope the presentations will be posted online. > > Ask him ? Sam has been very friendly & responsive in the past. The CGSIC presentations are often posted to the web. I welcome the presentation by Sam Stein and look forward to seeing it. It has the possiblility of addressing one of the big lacunae in the whole story of UTC and abandoning leaps: Who are the stakeholders and what problems are they having? The atomic chronometer keepers have been insisting that there is some urgent need to avoid leap seconds, and to avoid more time scales, but they do not name names, they do not give examples, they simply repeat that assertion, sometimes along with the spectre of planes crashing which was first aired 40 years ago. As they say on the USENET (or is that blogosphere now?) cite or shite. Without the cite it is clear that the BIPM temporal hegemony is threatened, but it is not clear how much the rest of the world should care. What the CCIR did demonstrate by their action in 1970, and the IAU (by redefining UT1 twice in the past 30 years), and the UK Admiralty (changing GMT by twelve hours) is that a time scale defined by somebody else can be changed at their whim to have characteristics which are no longer compatible with previous uses. So the natural response from everyone whose new operational system needs an operational time scale is to say "If we use their scheme we're just SOL, for they may change it at any time in a way that breaks our system, so why not define a new time scale that suits us?" The only thing in the favor of the current ITU-R structure is that this time it has been so diplomatically circumspect that there may be no organization which could hold the current UTC definition in a condition safer against any kind of change. This has become an "Us vs. Them" situation instead of a "We the people" situation -- all of the people, not just the physicists, not just the astronomers, not just the navigators, and not just us here now, but looking forward to secure things for "our posterity". I have to suppose some leadership of that sort was present, privately, while Klepczynski acted for US DoS as he got the Galileo folks to agree to change the specified time scale for the EU navigation satellites from the original TAI to GPS time. That sort of leadership and diplomacy is not evident openly in the ITU-R process. But having typed this I seem to have echoed a Canadian actor playing a 23rd century starship captain reciting an 18th century US document on a devastated planet. This is way too Kirk-like for me, where's Spock? -- Steve Allen 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 From sla at ucolick.org Fri Sep 11 09:53:51 2009 From: sla at ucolick.org (Steve Allen) Date: Fri, 11 Sep 2009 06:53:51 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <20090909.184138.1728818297.imp@bsdimp.com> <4726c660355d1b90529896c10c7cc9fa.squirrel@mx.pipe.nl>

Message-ID: <3A39FF73-275F-4941-A92D-BA9C81FF2A45@ucolick.org> On 2009 Sep 10, at 07:11, Tony Finch wrote: > The UK doesn't acknowledge any difference between GMT and UTC. But they are aware of it, and for those in London, moreso Oct 28 http://ilreports.blogspot.com/2009/09/ucl-laws-and-ila-british- branch.html October 28, 2009 - Richard Gardiner (UCL), From Greenwich Mean Time to Leap Seconds: International Agreement on Uniform Regimes -- Steve Allen 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 From dot at dotat.at Fri Sep 11 10:14:17 2009 From: dot at dotat.at (Tony Finch) Date: Fri, 11 Sep 2009 15:14:17 +0100 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <3A39FF73-275F-4941-A92D-BA9C81FF2A45@ucolick.org> References: <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <20090909.184138.1728818297.imp@bsdimp.com> <4726c660355d1b90529896c10c7cc9fa.squirrel@mx.pipe.nl>

<3A39FF73-275F-4941-A92D-BA9C81FF2A45@ucolick.org> Message-ID: On Fri, 11 Sep 2009, Steve Allen wrote: > On 2009 Sep 10, at 07:11, Tony Finch wrote: > > The UK doesn't acknowledge any difference between GMT and UTC. > > But they are aware of it I meant the UK government. See for example the millennial fuss about putting some atomic clocks in a data centre across the river from Greenwich. http://news.bbc.co.uk/1/hi/sci/tech/580334.stm Tony. -- f.anthony.n.finch http://dotat.at/ GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS. MODERATE OR GOOD. From sla at ucolick.org Wed Sep 16 14:17:46 2009 From: sla at ucolick.org (Steve Allen) Date: Wed, 16 Sep 2009 11:17:46 -0700 Subject: [LEAPSECS] it was ITU-R SG7 week in Geneva Message-ID: <20090916181746.GE13711@ucolick.org> WP7A produced a new draft TF.460 and elevated it to SG7. http://www.itu.int/md/meetingdoc.asp?lang=en&parent=R07-SG07-C&question=102/7 SG7 met yesterday. -- Steve Allen 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 From nimh at pipe.nl Wed Sep 16 15:10:38 2009 From: nimh at pipe.nl (Nero Imhard) Date: Wed, 16 Sep 2009 21:10:38 +0200 (CEST) Subject: [LEAPSECS] it was ITU-R SG7 week in Geneva In-Reply-To: <20090916181746.GE13711@ucolick.org> References: <20090916181746.GE13711@ucolick.org> Message-ID: Steve Allen wrote: > WP7A produced a new draft TF.460 and elevated it to SG7. > > http://www.itu.int/md/meetingdoc.asp?lang=en&parent=R07-SG07-C&question=102/7 Any idea what's in it? That link is hardly useful to anyone without a TIES account (i.e. almost everyone). N From imp at bsdimp.com Wed Sep 16 15:27:43 2009 From: imp at bsdimp.com (M. Warner Losh) Date: Wed, 16 Sep 2009 13:27:43 -0600 (MDT) Subject: [LEAPSECS] it was ITU-R SG7 week in Geneva In-Reply-To: References: <20090916181746.GE13711@ucolick.org> Message-ID: <20090916.132743.1572274698.imp@bsdimp.com> In message: "Nero Imhard" writes: : Steve Allen wrote: : > WP7A produced a new draft TF.460 and elevated it to SG7. : > : > http://www.itu.int/md/meetingdoc.asp?lang=en&parent=R07-SG07-C&question=102/7 : : Any idea what's in it? That link is hardly useful to anyone without a TIES : account (i.e. almost everyone). Is there a summary available? If not, can someone make a summary and post it here? Warner From lang at UNB.ca Fri Sep 25 08:55:29 2009 From: lang at UNB.ca (Richard B. Langley) Date: Fri, 25 Sep 2009 09:55:29 -0300 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <1252528789.4aa81295689c6@webmail.unb.ca> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> Message-ID: <1253883329.4abcbdc1826e4@webmail.unb.ca> -- Richard Langley Quoting "Richard B. Langley" : > There will likely be a report on anything significant at the CGSIC meeting in > Savannah > the week after next > . > -- Richard Langley > > Quoting "M. Warner Losh" : > > > In message: <20090909172025.GM21922 at ucolick.org> > > Steve Allen writes: > > : On Tue 2009-09-08T18:39:31 -0700, Steve Allen hath writ: > > : > The WP7A is meeting in Geneva this week. > > : > > > : > There are two documents about UTC on their table as seen here > > : > http://www.itu.int/md/R07-WP7A-C/en > > : > one from People's Republic of China, > > : > and another from BIPM (which, curiously, is not about question 236/7) > > : > > : In response to several notes, yes, these are protected, so the only > > : broadly visible aspects are the authors and titles. It seems to me > > : that the ITU-R operates in a sort of 19th century diplomatic mode. > > > > Any chance the docs will leak out after the meeting? There's been > > several leaks in the past of similar docs... > > > > Do we know, broadly, what the docs say? > > > > Warner > > _______________________________________________ > > LEAPSECS mailing list > > LEAPSECS at leapsecond.com > > http://six.pairlist.net/mailman/listinfo/leapsecs > > > > > =============================================================================== > Richard B. Langley E-mail: lang at unb.ca > Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ > Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 > University of New Brunswick Fax: +1 506 453-4943 > Fredericton, N.B., Canada E3B 5A3 > Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ > =============================================================================== > > > _______________________________________________ > LEAPSECS mailing list > LEAPSECS at leapsecond.com > http://six.pairlist.net/mailman/listinfo/leapsecs > =============================================================================== Richard B. Langley E-mail: lang at unb.ca Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ =============================================================================== From seaman at noao.edu Fri Sep 25 12:19:25 2009 From: seaman at noao.edu (Rob Seaman) Date: Fri, 25 Sep 2009 09:19:25 -0700 Subject: [LEAPSECS] Violins and sunspots In-Reply-To: <1253883329.4abcbdc1826e4@webmail.unb.ca> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <1253883329.4abcbdc1826e4@webmail.unb.ca> Message-ID: <157CA2BD-4006-4C28-94BC-AFAB63E6F4D6@noao.edu> > > > > -- Richard Langley Thanks! Very interesting. I especially like the connection drawn between sunspots and Stradivarius :-) Beard's quote that the ?astronomical community, at large, has moved [away from UTC] to dynamic relativistic time scales based on TT(1980)" is rather misleading. First, astronomers "at large" continue to use UTC widely for almost every conceivable purpose - it is precisely that UTC remains a flavor of Universal Time that permits this. Second, astronomers have always been at the forefront of defining and using new timescales - we're not naively looking for a single standard, but value each timescale as with the bouquet of a fine wine. Third, there will always be a role for UT in steering and scheduling Earth-based telescopes - the role is simply evolving in response to new IAU standards. And fourth, this gives the impression that astronomers are lonely luddites. Rather, UTC planning should focus on the requirements (whatever they are) for aligning civil timekeeping with mean solar time, and the range of possible mechanisms for satisfying those requirements. I wonder whether it really took them the entire 10 years to realize that WP7A failing to act was the same as WP7A recommending the elimination of leap seconds. Rob Seaman NOAO From sla at ucolick.org Fri Sep 25 13:36:43 2009 From: sla at ucolick.org (Steve Allen) Date: Fri, 25 Sep 2009 10:36:43 -0700 Subject: [LEAPSECS] Violins and sunspots In-Reply-To: <157CA2BD-4006-4C28-94BC-AFAB63E6F4D6@noao.edu> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <1253883329.4abcbdc1826e4@webmail.unb.ca> <157CA2BD-4006-4C28-94BC-AFAB63E6F4D6@noao.edu> Message-ID: <20090925173643.GY22483@ucolick.org> On Fri 2009-09-25T09:19:25 -0700, Rob Seaman hath writ: > First, astronomers "at large" continue to use > UTC widely for almost every conceivable purpose - it is precisely that > UTC remains a flavor of Universal Time that permits this. It's much simpler than that. Since the epoch when central authorities took over time distribution from the individual observatories (at first by telegraph, later by radio, now also by internet) everyone has used a broadcast time scale. The only other option is to buy an atomic chronometer and eschew the rest of the world, which is basically what interferometers and pulsar timing do. We use UTC because that is the internationally approved name for the broadcast time scale -- the scale which all the broadcasters of sovereign time scales have agreed to use as a result of their conformance to ITU-R recommendations. (In this I gloss over the fact that fear of FCC fines for blue language caused many US broadcasters to delay their analog transmissions of hourly time signals even when the only human voices were their own staff, and this was before the widespread deployment of digital radio and its inherent buffering delays. So there is still no option but to use a broadcast time scale, it's just a matter of how many seconds off one can expect to be.) The LIDAR community and some geophysics folks have chosen GPS because that is another broadcast time scale which can be expected to be available to every measurement system with above-ground components. -- Steve Allen 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 From seaman at noao.edu Fri Sep 25 14:41:45 2009 From: seaman at noao.edu (Rob Seaman) Date: Fri, 25 Sep 2009 11:41:45 -0700 Subject: [LEAPSECS] Violins and sunspots In-Reply-To: <20090925173643.GY22483@ucolick.org> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <1253883329.4abcbdc1826e4@webmail.unb.ca> <157CA2BD-4006-4C28-94BC-AFAB63E6F4D6@noao.edu> <20090925173643.GY22483@ucolick.org> Message-ID: <89F18508-CA34-4E63-AE54-075E9624C43E@noao.edu> I said: >> First, astronomers "at large" continue to use UTC widely for almost >> every conceivable purpose - it is precisely that UTC remains a >> flavor of Universal Time that permits this. Steve Allen wrote: > It's much simpler than that. [...] We use UTC because that is the > internationally approved name for the broadcast time scale Really, both the logistics of delivery, as well as UTC's definition as a flavor of mean solar time matter here, for instance: > The LIDAR community and some geophysics folks have chosen GPS > because that is another broadcast time scale which can be expected > to be available to every measurement system with above-ground > components. And many telescopes rely on GPS receivers as standard references (independent of NTP strata) because of the logistical convenience. New telescopes such as LSST (http://www.lsst.org) may even consider making this an explicit requirement. (I was in the meeting.) UT remains an intermediate time product, however, independent of how the time signals arrive. The need to sync systems slaved to GPS with systems slaved to NTP likely *also* places UTC related requirements, but lots of astronomical code (independent of recent IAU standards) remains dependent on Universal Time (mean solar time) itself. Why shouldn't a one word proposal, "GPS", be sufficient for ITU-R TF. 460 (v2.0)? Release Universal Time into the wild to compete on its own. Rob From lang at UNB.ca Mon Sep 28 13:33:43 2009 From: lang at UNB.ca (Richard B. Langley) Date: Mon, 28 Sep 2009 14:33:43 -0300 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <1253883329.4abcbdc1826e4@webmail.unb.ca> References: <20090909013931.GA14174@ucolick.org> <20090909172025.GM21922@ucolick.org> <20090909.113731.1119102511.imp@bsdimp.com> <1252528789.4aa81295689c6@webmail.unb.ca> <1253883329.4abcbdc1826e4@webmail.unb.ca> Message-ID: <1254159223.4ac0f377278f5@webmail.unb.ca> Tried sending a copy of Ron Beard's viewgraphs as it might be some time before they show up on the Coast Guard web site but the message is held up awaiting moderator approval. Here is a link to them instead . -- Richard Langley Quoting "Richard B. Langley" : > > > -- Richard Langley > > Quoting "Richard B. Langley" : > > > There will likely be a report on anything significant at the CGSIC meeting in > > Savannah > > the week after next > > > . > > -- Richard Langley > > > > Quoting "M. Warner Losh" : > > > > > In message: <20090909172025.GM21922 at ucolick.org> > > > Steve Allen writes: > > > : On Tue 2009-09-08T18:39:31 -0700, Steve Allen hath writ: > > > : > The WP7A is meeting in Geneva this week. > > > : > > > > : > There are two documents about UTC on their table as seen here > > > : > http://www.itu.int/md/R07-WP7A-C/en > > > : > one from People's Republic of China, > > > : > and another from BIPM (which, curiously, is not about question 236/7) > > > : > > > : In response to several notes, yes, these are protected, so the only > > > : broadly visible aspects are the authors and titles. It seems to me > > > : that the ITU-R operates in a sort of 19th century diplomatic mode. > > > > > > Any chance the docs will leak out after the meeting? There's been > > > several leaks in the past of similar docs... > > > > > > Do we know, broadly, what the docs say? > > > > > > Warner > > > _______________________________________________ > > > LEAPSECS mailing list > > > LEAPSECS at leapsecond.com > > > http://six.pairlist.net/mailman/listinfo/leapsecs > > > > > > > > > =============================================================================== > > Richard B. Langley E-mail: lang at unb.ca > > Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ > > Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 > > University of New Brunswick Fax: +1 506 453-4943 > > Fredericton, N.B., Canada E3B 5A3 > > Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ > > =============================================================================== > > > > > > _______________________________________________ > > LEAPSECS mailing list > > LEAPSECS at leapsecond.com > > http://six.pairlist.net/mailman/listinfo/leapsecs > > > > > =============================================================================== > Richard B. Langley E-mail: lang at unb.ca > Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ > Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 > University of New Brunswick Fax: +1 506 453-4943 > Fredericton, N.B., Canada E3B 5A3 > Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ > =============================================================================== > > > _______________________________________________ > LEAPSECS mailing list > LEAPSECS at leapsecond.com > http://six.pairlist.net/mailman/listinfo/leapsecs > =============================================================================== Richard B. Langley E-mail: lang at unb.ca Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ =============================================================================== From phk at phk.freebsd.dk Mon Sep 28 14:42:13 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Mon, 28 Sep 2009 18:42:13 +0000 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: Your message of "Mon, 28 Sep 2009 14:33:43 -0300." <1254159223.4ac0f377278f5@webmail.unb.ca> Message-ID: <21080.1254163333@critter.freebsd.dk> In message <1254159223.4ac0f377278f5 at webmail.unb.ca>, "Richard B. Langley" writ es: >Tried sending a copy of Ron Beard's viewgraphs as it might be some time before they show >up on the Coast Guard web site but the message is held up awaiting moderator approval. >Here is a link to them instead Any chance you could make a .pdf version of them for people not in the thrall of Microsoft ? Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. From lang at unb.ca Mon Sep 28 15:01:04 2009 From: lang at unb.ca (Richard B. Langley) Date: Mon, 28 Sep 2009 16:01:04 -0300 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <21080.1254163333@critter.freebsd.dk> References: <21080.1254163333@critter.freebsd.dk> Message-ID: <1254164464.4ac107f0211cd@webmail.unb.ca> Quoting Poul-Henning Kamp : > In message <1254159223.4ac0f377278f5 at webmail.unb.ca>, "Richard B. Langley" writ > es: > >Tried sending a copy of Ron Beard's viewgraphs as it might be some time before they > show > >up on the Coast Guard web site but the message is held up awaiting moderator > approval. > >Here is a link to them instead > > Any chance you could make a .pdf version of them for people not in the > thrall of Microsoft ? > > Poul-Henning > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > phk at FreeBSD.ORG | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > LEAPSECS mailing list > LEAPSECS at leapsecond.com > http://six.pairlist.net/mailman/listinfo/leapsecs > =============================================================================== Richard B. Langley E-mail: lang at unb.ca Geodetic Research Laboratory Web: http://www.unb.ca/GGE/ Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142 University of New Brunswick Fax: +1 506 453-4943 Fredericton, N.B., Canada E3B 5A3 Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/ =============================================================================== From phk at phk.freebsd.dk Mon Sep 28 15:19:39 2009 From: phk at phk.freebsd.dk (Poul-Henning Kamp) Date: Mon, 28 Sep 2009 19:19:39 +0000 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: Your message of "Mon, 28 Sep 2009 16:01:04 -0300." <1254164464.4ac107f0211cd@webmail.unb.ca> Message-ID: <21326.1254165579@critter.freebsd.dk> In message <1254164464.4ac107f0211cd at webmail.unb.ca>, "Richard B. Langley" writ es: > Thanks. Although I do appreciate what the context conveys, I did smile when I noticed that the last slide mentions "GPS time" but ends with "Only UTC can be disseminated". I don't know if GPS or POSIX time is the most diseeminated timescale, but I suspect they both beat UTC by an order of magnitude when it comes to number of receivers... Anyway, it sounds to me like the message is "We'll just thread water until some more old astronomers retire/die"... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. From sla at ucolick.org Mon Sep 28 15:01:51 2009 From: sla at ucolick.org (Steve Allen) Date: Mon, 28 Sep 2009 12:01:51 -0700 Subject: [LEAPSECS] it's WP7A week in Geneva In-Reply-To: <21080.1254163333@critter.freebsd.dk> References: <1254159223.4ac0f377278f5@webmail.unb.ca> <21080.1254163333@critter.freebsd.dk> Message-ID: <20090928190151.GD22483@ucolick.org> On Mon 2009-09-28T18:42:13 +0000, Poul-Henning Kamp hath writ: > Any chance you could make a .pdf version of them for people not in the > thrall of Microsoft ? via openoffice I had to reduce font size on one page http://www.ucolick.org/~sla/beard.pdf -- Steve Allen 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