Re: UT1 confidence

2007-01-18 Thread Rob Seaman
Steve Allen wrote: The plots by Arias indicate how well UT1 could have been predicted over two and three year intervals for the 40 year interval starting around 1960. It is based on those plots that I have voiced no concerns for the pointing of our telescopes if leap seconds were published

The Martian Chronicles

2007-01-15 Thread Rob Seaman
defining a perceived problem out of existence, one could actually find that a real problem has been defined into existence. Or perhaps I'm wrong. Demonstrate why. Rob Seaman NOAO

Re: The Martian Chronicles

2007-01-15 Thread Rob Seaman
I said: I also wonder whether it might be productive to consider closing the NTP servo loop in velocity (frequency) in this case, rather than position (phase). Before somebody else calls me on it, I should point out that NTP actually uses both: The clock discipline algorithm functions

Re: Introduction of long term scheduling

2007-01-07 Thread Rob Seaman
Warner Losh wrote: Actually, every IP does not have a 1's complement checksum. Sure, there is a trivial one that covers the 20 bytes of header, but that's it. Most hardware these days off loads checksumming to the hardware anyway to increase the throughput. Maybe you are thinking of TCP or

Re: Introduction of long term scheduling

2007-01-06 Thread Rob Seaman
Warner Losh wrote: leap seconds break that rule if one does things in UTC such that the naive math just works All civil timekeeping, and most precision timekeeping, requires only pretty naive math. Whatever the problem is - or is not - with leap seconds, it isn't the arithmetic involved.

Re: Introduction of long term scheduling

2007-01-06 Thread Rob Seaman
Warner Losh wrote: Anything that makes the math harder (more computationally expensive) can have huge effects on performance in these areas. That's because the math is done so often that any little change causes big headaches. Every IP packet has a 1's complement checksum. (That not all

Re: Introduction of long term scheduling

2007-01-05 Thread Rob Seaman
, but rather transmogrified into a similar requirement to maintain and convey a table of DUT1 values. Rob Seaman NOAO

Re: Introduction of long term scheduling

2007-01-05 Thread Rob Seaman
Ashley Yakeley wrote: As the author of a library that consumes leap-second tables, my ideal format would look something like this: a text file with first line for MJD of expiration date, and each subsequent line with the MJD of the start of the offset period, a tab, and then the UTC-TAI seconds

Re: how to reset a clock

2007-01-04 Thread Rob Seaman
Peter Bunclark wrote: Indeed isn't this Rob's ship's chronometer? Actually, I think it was Mr. Harrison's. (And Steve Allen has been basing his arguments more recently on this distinction.) This healthy debate between astronomical time and clock time has happened before. The answer is the

Re: Introduction of long term scheduling

2007-01-02 Thread Rob Seaman
permitting liquid water. Without the Moon, the Earth could nod through large angles, lying on its side or perhaps even rotating retrograde every few million years. Try making sense of timekeeping under such circumstances. Rob Seaman NOAO

Re: A lurker surfaces

2007-01-02 Thread Rob Seaman
to be approximated while using SI seconds. Rob Seaman NOAO

Re: Introduction of long term scheduling

2007-01-02 Thread Rob Seaman
Poul-Henning Kamp wrote: That's an interesting piece of data in our endless discussions about how important DUT1 really is... The point is that by allowing it to grow without reasonable bound, DUT1 would gain an importance it never had before.

Happy New Year!

2007-01-01 Thread Rob Seaman
different than 36,000 tenths. Rob Seaman NOAO --

Re: A lurker surfaces

2006-12-31 Thread Rob Seaman
Poul-Henning Kamp wrote: Rob, If you feel uncomfortable with calling leapseconds discontinuities, then we can use the term arrhythmia instead. Which raises the question of why projects requiring an interval time scale lacking in such arrhythmias would have selected UTC in the first place.

Re: A lurker surfaces

2006-12-30 Thread Rob Seaman
Jim Palfreyman wrote: With my time hat on, having time that is discontinuous pains me. It doesn't make sense in my heart. But at least these discontinuities are in whole seconds. Any discontinuities must be regularly done. So they are part of all computer systems and are tested and used all

Re: Mechanism to provide tai-utc.dat locally

2006-12-29 Thread Rob Seaman
Tony Finch wrote: You need to do so in order to implement an accurate clock, since the clock produces interval time and you need a way to convert its output to time of day. As Steve Allen has pointed out, it is in the nature of a clock to be reset on occasion. What is NTP but a mechanism for

Design - a Tufte decision

2006-12-28 Thread Rob Seaman
in civil timekeeping. In short: 6) Where should the lines of elegant design and rational compromise be drawn? Rob Seaman NOAO

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
Poul-Henning Kamp wrote: I seriously don't belive you do equality comparisons at the 1msec level in real world software. Please provide examples. You know you're in trouble when PHK and I agree. One would think a (double precision) floating point epsilon test might be what you want. In

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
John Cowan wrote: I assume you mean 23-hour or 25-hour LCT days? True. It does work against UCT days, though, since they are uniformly 1440 minutes long. Not should leap hours replace leap seconds.

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
I am talking about time intervals; you are talking about periodic events. Two different things. Amen!

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
M. Warner Losh wrote: And avoiding the ugly 61 or 59 second minutes to define away the problem... It was the time lords who decreed that rubber minutes were prettier than rubber seconds. We're now to skip right over rubber hours to rubber days? Their aesthetic sense seems strangely

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
fending off an absurd non-solution, perhaps it would be better to design from clearly stated use cases, responsive requirements, coherent risk analyses, a reasonable deployment schedule, a fair-minded budget. We're not going to successfully define the real world out of existence. Rob Seaman NOAO

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
M. Warner Losh wrote: Let's turn the question around. What would the harm be if |DUT1| were 1.1s? 1.5s? 2.0s? Contrast this with the harm and difficulty that the current 6 month scheduling window affords. Indeed. Go for it. I look forward to reading your report. Who and what interests

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
John Cowan wrote: It can't possibly be. Nobody can know what a change is going to cost except those who are going to have to pay for it (or not pay for it). Are you really suggesting that the planning of technical projects is impossible? One might expect some investment of time and money in

Re: Mechanism to provide tai-utc.dat locally

2006-12-28 Thread Rob Seaman
? Excellent questions. Might I suggest that they be appropriately answered before UTC is removed from life support? Rob Seaman NOAO

Re: Mechanism to provide tai-utc.dat locally

2006-12-27 Thread Rob Seaman
understand that better than I. Rob Seaman NOAO

Re: Mechanism to provide tai-utc.dat locally

2006-12-25 Thread Rob Seaman
interlocking cycles of the solar system provide a unique check on any clock. Rob Seaman NOAO

Re: Equitable estoppel

2006-12-19 Thread Rob Seaman
On Dec 17, 2006, at 11:48 AM, Poul-Henning Kamp wrote: Regarding an intenational treaty as a contract is not only pointless, it is downright silly. Regarding me as an expert on international law is what would be silly :–) The point was to elaborate, in the context of UTC, on some issues

Equitable estoppel

2006-12-17 Thread Rob Seaman
to this provision of it now. Rob Seaman NOAO A type of estoppel that bars a person from adopting a position in court that contradicts his or her past statements or actions when that contradictory stance would be unfair to another person who relied on the original position.

Re: what time is it, legally?

2006-12-13 Thread Rob Seaman
On Dec 12, 2006, at 5:56 PM, [EMAIL PROTECTED] wrote: To avoid such failures in the future, Tom Van Baak has agreed to take over its management and he is now working on the technical issues involving the migration. Thanks for looking into that. Thanks to Tom for accepting another (nearly)

Re: what time is it, legally?

2006-12-12 Thread Rob Seaman
are simply one possible mechanism for achieving this. The notion of a leap hour fails to preserve mean solar time in any practical fashion. Rob Seaman NOAO

Re: what time is it, legally?

2006-12-12 Thread Rob Seaman
(http://en.wikipedia.org/wiki/Precautionary_principle). Rob Seaman NOAO

Re: how posterity will measure time

2006-12-04 Thread Rob Seaman
, and maybe, just maybe – to a few politicians. I'd vote, myself, for using a subduction zone for this purpose, although having a goal of launching our waste into the Sun might serve to invigorate the space program for a few decades. Rob Seaman NOAO

Re: how posterity will measure time

2006-12-04 Thread Rob Seaman
On Dec 4, 2006, at 9:41 AM, Rob Seaman wrote: Any group of hunter-gatherers who stumble on WIPP and think to raid it as they will likely have been raiding landfills and other fin de millénaire treasure troves, will first have to pass the threshold of being capable of gaining physical entry

Re: how posterity will measure time

2006-12-04 Thread Rob Seaman
On Dec 4, 2006, at 4:27 PM, Ed Davies wrote: Do you really mean UTC here? Well, I mean any of the various approximations of Universal Time as a synonym for Greenwich Mean Time. As continental drift becomes important, the job gets harder. (But then, to return to the original topic, PHK

The fine print

2006-11-29 Thread Rob Seaman
, declare time-of-day to be distinct from time interval, who are we to disagree? As the New York State Supreme Court rules in the play: Since the United States government... declares this man to be Santa Claus... this court will not dispute it. Case dismissed! Rob Seaman NOAO

Re: Titan Time

2006-10-26 Thread Rob Seaman
Zefram wrote: the radian is not a very practical unit. There's nothing at all wrong with the radian - but there is a reason calculators let you switch between degrees and radians. Each is best for particular purposes, just as interval time and time-of-day are best for different uses. See

Re: trading amplitude for scheduling

2006-08-04 Thread Rob Seaman
Hi Tom,Careful not to confuse rate with acceleration andpropagate a common misconception that leapseconds are due to an acceleration/decelerationeffect (as in "leap seconds are due to the earthslowing down").In fact, leap seconds are simply due to the earthbeing slow. How it got to be "slow" and

Re: trading amplitude for scheduling

2006-08-04 Thread Rob Seaman
John Cowan wrote: 1) We have leap seconds because the Earth rotates more slowly than once every 86,400 SI seconds. 2) Leap seconds will become more frequent in the future because the Earth is decelerating. 3) Leap seconds occur irregularly because the Earth's deceleration is not constant and

Re: trading amplitude for scheduling

2006-08-04 Thread Rob Seaman
John Cowan accepts the blame: 1) We have leap seconds because the SI second is shorter than 1/86,400 of a mean solar day. Post in haste, repent at leisure (I've been going with too little sleep lately, for reasons unknown...) I actually do know that the earth rotates in less than 1 mean

Re: trading amplitude for scheduling

2006-08-04 Thread Rob Seaman
John Cowan wrote: I accidentally specified sidereal rather than mean solar days by using the wording the Earth rotates. Rotate is as perfectly good a word to use relative to our nearby star as to the distant ones :-) The solar system is chock full of nifty synodic periodicities and

trading amplitude for scheduling (was Re: [LEAPSECS] leap seconds in video art)

2006-08-03 Thread Rob Seaman
Brian Garrett wrote: the mini-lectures did imply that leap seconds compensate for secular deceleration of the earth rather than seasonally accumulated differences between UTC and UT1. To the extent that I understand the point you are aiming for, this statement conflates two issues: 1) that

the case for created time

2006-07-18 Thread Rob Seaman
We have all been so utterly wrong!  The scales dropfrom my eyes (http://www.creation-answers.com):A theory of evolution for the creation of the solar systemseems less than satisfactory in regard that the Earth andMoon appear to generate interrelated time cycles.A prize (well, a beer when next we

Re: PT Barnum was right

2006-07-06 Thread Rob Seaman
Steve Allen wrote:In the news.google this week is a press release for a clock thatautomatically tracks leap seconds.Anybody volunteering to tell these guys that their product is about to be orphaned?  Sounds like a lawsuit in the making.  Would think the ITU lawyers would be interested in their

Re: PT Barnum was right

2006-07-06 Thread Rob Seaman
On Jul 6, 2006, at 12:46 PM, Brian Garrett wrote: I was told that the station delays their broadcast in order to enable on-the-spot editing of objectionable material. Surely the requirement is to permit review of *potentially* objectionable material. A time signal is no such thing and need

Re: independence day

2006-07-05 Thread Rob Seaman
John Cowan wrote: I regret to state that this remark appears to me no more than scaremongering. Merely hyperbole intended to make a point about the art of crafting fundamental standards. Obviously I failed to make that point :-) Why precisely, however, do you regret your inference? If my

Re: building consensus

2006-06-08 Thread Rob Seaman
Clive D.W. Feather wrote: March was the first month of the year; look at the derivation of September, for example. Makes the zero vs. one indexing question of C and FORTRAN programmers look sane. I've pointed people to the whole 7, 8, 9, 10 sequence from September to December on those

Re: building consensus

2006-06-08 Thread Rob Seaman
John Cowan wrote: In the cover story, it was used as a final defense against the Invaders and destroyed by them. In the true story, it was destroyed because it constituted a hazard, but I forget exactly how. Thanks! But not sure true story is the opposite of cover story, here :-) Both

Re: building consensus

2006-06-08 Thread Rob Seaman
On Jun 8, 2006, at 8:08 AM, Clive D.W. Feather wrote: Rob Seaman said: Thanks! But not sure true story is the opposite of cover story, here :-) I don't think John's referring to Against the Fall of Night versus The City and the Stars. Rather, at least in the latter, the official (cover

Re: building consensus

2006-06-07 Thread Rob Seaman
On Jun 7, 2006, at 2:01 AM, Clive D.W. Feather wrote: Actually, the evidence from experiments is that the natural sleep- wake cycle is about 27 hours long, but force-locked to the day-night cycle (it's easier to synchronise a longer free-running timer to a shorter external signal than

Re: building consensus

2006-06-07 Thread Rob Seaman
On Jun 7, 2006, at 2:03 AM, Clive D.W. Feather wrote: In the UK in 1750, there were two different Julian calendars in use: the day and month enumeration matched, but year numbers changed at different dates (1st January in Scotland, 25th March in England and Wales). I've heard this said, but

Re: building consensus

2006-06-07 Thread Rob Seaman
Tim Shepard replies: Also hard to imagine how one gracefully transitions from one to two sleep cycles a day. It is already the norm in some places: http://en.wikipedia.org/wiki/Siesta Thanks for the chuckle. One is then left wondering whether our far future, Clarkeian Against the Fall

Re: building consensus

2006-06-06 Thread Rob Seaman
Ed Davies quoted:The Gregorian calendar provides a reference system consisting of a,potentially infinite, series of contiguous calendar years. Consecutivecalendar years are identified by sequentially assigned year numbers.A reference point is used which assigns the year  number 1875 to thecalendar

Re: building consensus

2006-06-05 Thread Rob Seaman
On Jun 4, 2006, at 9:57 PM, M. Warner Losh wrote: leap days have a rule, while leap seconds are scheduled. A schedule and a rule are the same thing, just regarded from different historical perspectives. The leap day rule will most certainly have to accommodate scheduling changes over the

Re: building consensus

2006-06-05 Thread Rob Seaman
On Jun 5, 2006, at 8:45 AM, Warner Losh wrote:Leap days have an iron-clad rule that generates the schedule on whichthey happen.  Leap seconds have a committee that generates theschedule on which they happen.Further discussion in this thread calls into question the characterization of "iron-clad

Re: building consensus

2006-06-05 Thread Rob Seaman
On Jun 5, 2006, at 1:05 PM, John Cowan wrote: (ObOddity: It seems that in Israel, which is on UTC+3, the legal day begins at 1800 local time the day before. This simplifies the accommodation of Israeli and traditional Jewish law.) I wouldn't call this an oddity, but rather an interesting

Re: building consensus

2006-06-05 Thread Rob Seaman
On Jun 5, 2006, at 1:38 PM, John Cowan wrote: I found another spectacular illustration of how massive the difference between solar and legal time can be. Before 1845, the time in Manila, the Philippines, was the same as Acapulco, Mexico, a discrepancy of 9h16m from Manila solar time. This was

Re: building consensus

2006-06-05 Thread Rob Seaman
On Jun 5, 2006, at 2:47 PM, John Cowan wrote: I'm not sure what you mean by civil time in this context. I meant whatever we've meant in this forum for the past five years. For some people, civil time is synonymous with standard time; for others, it means the time shown by accurate clocks in

Re: building consensus

2006-06-05 Thread Rob Seaman
On Jun 5, 2006, at 4:05 PM, Rob Seaman wrote: On the other hand, all I've ever meant by the term civil time is that time that a well educated civilian sets her clock in order to agree with other civilians for civilian purposes. I should clarify this to mean the underlying internationalized

Re: building consensus

2006-06-01 Thread Rob Seaman
Warner Losh objects:There are several doughty people here who happen to have that opinion, but they abide with us mortals outside the time lords' hushed inner sanctum.I have spent much time explaining why leap seconds cause real problems in real applications, only to be insulted like this.Sincere

Re: extracting leap second schedule

2006-05-30 Thread Rob Seaman
-utc.dat will always be in the future. Non-amusingly, in the alternate no-time-of-day universe, this never becomes a non-issue for recovering the orientation of Earth-2. Rob Seaman National Optical Astronomy Observatory

Re: Precision vs. resolution

2006-05-30 Thread Rob Seaman
On May 24, 2006, at 7:25 AM, John Cowan wrote: Can someone lay out for me exactly what the difference is between clock precision and clock resolution? Interesting question. Perhaps it is the distinction between addressability and physical pixels that one encounters on image displays and

Re: ideas for new UTC rules

2006-04-15 Thread Rob Seaman
Only hours ago did I learn of the recent problems with D-Link routers. Remarkable! Just imagine the logical disconnect at the product development meetings. The marketing folks emphasizing the highly desirable feature of NTP compliance and the tech folks tossing a list of 50 servers into the

Re: ideas for new UTC rules

2006-04-14 Thread Rob Seaman
On Apr 13, 2006, at 10:41 PM, Steve Allen wrote:Today is one of the four days in the year when Newcomb's_expression_ for the equation of time has a value of zeroand it was Samuel Beckett's hundredth birthday.  Leap second as Godot: ESTRAGON: And if he doesn't come?

Re: 24:00 versus 00:00

2006-02-27 Thread Rob Seaman
On Feb 17, 2006, at 12:30 PM, Markus Kuhn wrote: Clive D.W. Feather wrote on 2006-02-17 05:58 UTC: However, London Underground does print 24:00 on a ticket issued at midnight, and in fact continues up to 27:30 (such tickets count as being issued on the previous day for validity purposes, and

Re: 1884 IMC online

2006-02-20 Thread Rob Seaman
On Feb 19, 2006, at 1:35 PM, Steve Allen wrote:A few years ago Joseph S. Myers of Cambridge University went through the trouble of scanning a copy of the proceedings of the 1884 International Meridian Conference, and I put the TIFFs online http://www.ucolick.org/~sla/leapsecs/scans-meridian.htmlI

Re: 24:00 versus 00:00

2006-02-17 Thread Rob Seaman
window around midnight - say, 23:59-00:01, or 2 out of 1440 minutes per day. It should be even easier for NTP and other UTC transport mechanisms to avoid 2 minutes out of 365+ days. This isn't the solution to every challenge facing civil time - but it sure simplifies the search space. Rob Seaman

Re: Ambiguous NTP timestamps near leap second

2006-02-16 Thread Rob Seaman
On Feb 16, 2006, at 2:06 PM, Markus Kuhn wrote: While there is a 24:00:00, there is certainly *no* 24:00:00.0001. That would be 00:00:00.0001 instead. Says who? Didn't we just burn a lot of calories discussing whether UTC was a real number or a continuous function? Time does

Re: Ambiguous NTP timestamps near leap second

2006-02-16 Thread Rob Seaman
On Feb 16, 2006, at 4:46 PM, Warner Losh wrote:UTC rules state that the time sequence should be23:59:59.7523:59:60.023:59:60.2523:59:60.5023:59:60.7500:00:00.:00:00.25Well, no.  ITU-R-TF.460-4 says nothing whatsoever about the representation of time using sexigesimal notation: "2.2 A

Re: An immodest proposal

2006-02-14 Thread Rob Seaman
On Feb 14, 2006, at 12:50 PM, Markus Kuhn wrote: You can, of course, define, publish, implement, and promote a new version (4?) of NTP that can also diseminate TAI, EOPs, leap-second tables, and other good things. I'm all for it. But why are you for it? Before investing large amounts of time

Re: An immodest proposal

2006-02-14 Thread Rob Seaman
On Feb 14, 2006, at 2:28 PM, M. Warner Losh wrote:UTC time stamps in NTP are ambiguous.  TAI ones are not.Requirements should be kept separate from implementation.  Whatever the underlying timescale, certain external global requirements apply.  Whether NTP or some other implementation properly

Re: Comparing Time Scales

2006-02-04 Thread Rob Seaman
/4800) aren't even denumerable with the length of our week. Why then is a requirement that one minute out of 800,000 accommodate one extra (or one fewer) second seen to be such an imposition? Especially when anybody who does find it so can simply choose to use TAI instead? Eppur si muove! Rob

The nature of risk

2006-01-25 Thread Rob Seaman
are asserted to be a risk. Does their lack present fewer risks? Prove it. Rob Seaman NOAO

Re: The nature of risk

2006-01-25 Thread Rob Seaman
Leap seconds are asserted to be a risk. Does their lack present fewer risks? Prove it. No, you prove it. Such rhetorical devices are designed to divide and separate, No, my rhetoric really isn't designed for that purpose. And even if it were so - how does that possibly undermine the idea

Re: the tail wags the dog

2006-01-24 Thread Rob Seaman
On Jan 24, 2006, at 12:50 AM, Peter Bunclark wrote: I don't think Rob meant the above to be a complete course on navigation! ...although as a fan of Patrick O'Brian I am qualified not only to teach navigation, but also the violin and Catalan. You should see me in a Bear costume. Good

Re: the tail wags the dog

2006-01-24 Thread Rob Seaman
On Jan 24, 2006, at 8:06 AM, Ed Davies wrote: James Maynard wrote: The problem is not that the SI second is not based on a natural phenonemon (it is), but that the periods of the various natural phenonema (rotations of the earth about its axis revolutions of the earth about the sun,

Re: the tail wags the dog

2006-01-24 Thread Rob Seaman
On Jan 24, 2006, at 7:21 AM, Poul-Henning Kamp wrote:I think the crucial insight here is that geophysics makes (comparatively) lousy clocksThe crucial insight is that the Earth is not a clock at all, but rather the thing being timed.and we should stop using rotating bodies of geophysics for 

worthy challenges

2006-01-24 Thread Rob Seaman
Ed Davies wrote:By "rubber seconds" you, presumably, mean non-SI seconds.  What do you mean by "rubber days"?  I'd guess you mean days which are divided into SI seconds but not necessarily 86 400 of them.Yes.  See for instance:

Re: the tail wags the dog

2006-01-23 Thread Rob Seaman
On Jan 23, 2006, at 9:33 AM, M. Warner Losh wrote: The legal time in the US is the mean solar time at a given meridian, as determined by the secretary of commerce ...and many may have seen Mr. Gutierrez shooting the sun with his sextant out on the Mall in front of the AS Museum :-) With all

Re: Approach to leap second discussion

2006-01-22 Thread Rob Seaman
I hope we can all continue this discussion in a more positive manner. I'm of the opinion that messages on this list (no matter how tricky :-) are always positive. Timekeeping is a fundamental issue. It would be remarkable if there weren't diverse opinions. Any negative aspects of this

Re: Risks of change to UTC

2006-01-21 Thread Rob Seaman
to convert shipboard apparent time to local mean time. Subtraction does the rest. Rob Seaman NOAO

Re: Risks of change to UTC

2006-01-21 Thread Rob Seaman
is the Russian Global Navigation Satelllite System :-) In any event, one suspects that the Russians (or the FSU, even more so) would object to its being characterized as a GPS backup. Rob Seaman NOAO

Re: Risks of change to UTC

2006-01-21 Thread Rob Seaman
for either scientists or sailors. Whether we're also selfish is immaterial. Rob Seaman NOAO

Re: Internet-Draft on UTC-SLS

2006-01-19 Thread Rob Seaman
-SLS is intended to serve all needs. Rather, we've heard the opposite. Suspect I'm not alone in being suspicious of any overreaching solution proffered for all timekeeping situations - sounds like the definition of a kludge. Rob Seaman NOAO

Re: Internet-Draft on UTC-SLS

2006-01-19 Thread Rob Seaman
On Jan 19, 2006, at 10:02 AM, Rob Seaman wrote: How delightful! A discussion about the design merits of actual competing technical proposals! Apologies for failing to credit the quotes from Poul-Henning Kamp.

Re: Internet-Draft on UTC-SLS

2006-01-19 Thread Rob Seaman
be tempted to suggest that we don't even try, but rather look for separate solutions to various pragmatic classes of timekeeping needs. Glad to see the list moving in that direction. Rob Seaman NOAO

Risks of change to UTC

2006-01-16 Thread Rob Seaman
that many deployed systems (of whatever nature) are naively configured. Is this likely to change overnight? Rob Seaman NOAO

Re: Problems with GLONASS Raw Receiver Data at Start of New Year

2006-01-15 Thread Rob Seaman
choices should be made adds a little spice to the discussion :-) UNB1 Web page is here: http://gge.unb.ca/Resources/UNB1.html. IGS Central Bureau Web page is here: http://igscb.jpl.nasa.gov/ Thanks for the pointers. Rob Seaman NOAO

Re: Monsters from the id

2006-01-14 Thread Rob Seaman
On Jan 13, 2006, at 12:46 AM, John Cowan wrote: In the end, it will be impossible to maintain the notion that a solarday is 24h of 60m of 60s each: we wind up, IIRC, with the solar dayand lunar month both at about 47 current solar days. There's a lot of difference between what happens over a

Re: Report of Leap Second Problem with GPS Data

2006-01-14 Thread Rob Seaman
that some other data products were unaffected? So, the issue has been resolved - would likely have been resolved sooner if a leap second had occurred earlier - and is no longer directly pertinent to a discussion of future leap seconds? Well done, Geoscience Australia! Rob Seaman NOAO

Re: Problems with GLONASS Raw Receiver Data at Start of New Year

2006-01-14 Thread Rob Seaman
-round and the media circus would have moved on. Rob Seaman NOAO

Re: Report of Leap Second Problem with GPS Data

2006-01-14 Thread Rob Seaman
This goes counter to my claims so it is of no importance. and This time, there were no reports of death with the leap second, therefore they can't be too bad... :-) I invite derision with my flights of rhetoric. But this is an internet forum and a little leeway may be warranted. We all

Re: Problems with GLONASS Raw Receiver Data at Start of New Year

2006-01-14 Thread Rob Seaman
days - or alternately, to convert Universal Time into a count of seconds - that creates confusion between the two. Rob Seaman NOAO

Re: The real problem with leap seconds

2006-01-13 Thread Rob Seaman
I'm glad to see such active traffic on the list - particularly discussions such as this that are wrestling with fundamental concepts. On 2006-01-13, Mark Calabretta wrote: The point is that UTC is simply a representation of TAI. On Jan 13, 2006, at 4:17 AM, Michael Deckers wrote: I

Re: The real problem with leap seconds

2006-01-13 Thread Rob Seaman
On Jan 13, 2006, at 8:05 AM, Ed Davies wrote: MJD 27123.5 means 12:00:00 on day 27123 if it's not a leap second day, but what does it mean on a day with a positive leap second? 12:00:00.5? And we're back to the point in question. The precise issue is the definition of the concept of a day.

Re: Monsters from the id

2006-01-12 Thread Rob Seaman
On Jan 12, 2006, at 12:36 AM, John Cowan wrote:No one, at least not on this list, is arguing for an alignment of theabsurd leap hour proposal (henceforth ALHP) with DST changes.I went rummaging through the ITU proposal and back as far as Torino.  Found this comment from a LEAPSECS thread on 28

War of the Worlds

2006-01-11 Thread Rob Seaman
I see Steve Allen has already supplied a thorough answer. Interested individuals might also scrounge through the list archives (http:// rom.usno.navy.mil/archives/leapsecs.html) since the topic has come up before. In fact, Demetrios Matsakis speculated on solar system wide timescales even

Monsters from the id

2006-01-11 Thread Rob Seaman
What now, Dr. Moebius?                      Prepare your minds for a new scale...                    of physical scientific values, gentlemen.Mark Calabretta takes the lazy man's way out and appeals to facts: Here in a topology-free way is what the axis labels of my graph looklike during

Re: MJD and leap seconds

2006-01-10 Thread Rob Seaman
On Jan 10, 2006, at 9:17 AM, Peter Bunclark wrote:On Tue, 10 Jan 2006, Poul-Henning Kamp wrote:In message [EMAIL PROTECTED], Peter Bunclark writes: Good grief.  MJD is used widely in astronomy, for example in variablility studies where you want a real number to represent time rather than deal with

Re: MJD and leap seconds

2006-01-10 Thread Rob Seaman
On Jan 10, 2006, at 11:06 AM, Poul-Henning Kamp wrote: Let me see if understood that right: In order to avoid computing problems and to get precise time, astronomers rely on a timescale without leapseconds, because the Earths rotation is too unstable a clock for their purposes. Just like

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