Mills@UDEL.EDU (12/29/87)
Folk,
Q: What time is it DURING the impending leap second scheduled for Thursday?
A: The leap is considered the 61st second of the last minute of the day in which
scheduled. Thus, the time indicated midway in the leap would be 23:59:60.5.
I challenge anybody to write clean code that would do that trick and compare it
to the code that would produce 24:00:00.5 when given the number of milliseconds
past midnight and the number of milliseconds in any given day (including the
leap). Grumble. If you happen to tickle a fuzzy during the leap, you get the
latter. Life is too short.
Reference NBS Publication 432.
Davekwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (12/31/87)
I should think that if and when there are airborne routers or
orbital routers (fuzzballs in space!) that Dave Mills is the man to do
the relativistic corrections to the clocks and time-servers. He
certainly handled the leap-seconds crisis well, don't you think? :-)
--
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gross@GATEWAY.MITRE.ORG (Phill Gross) (12/31/87)
In case you leap-watchers out there missed it, the leap second will be celebrated as part of the midnight festivities in New York City. Although the leap second is to be officially inserted at 7pm EST, the New York revelers will celebrate it as the 61st second of the last minute of the year. According to a report on NPR this morning, the traditional countdown accompanying the falling ball will be changed for this occasion to `5..4.. 3..2..1..LEAP!..0..'. During the additional second, the falling ball will stop and some additional fireworks or light displays will happen. I guess this means that NYC will be one second off from 7pm EST to midnight. Dave, how will this startling development affect network time in NYSERnet for those 5 hours?! Phill
gross@GATEWAY.MITRE.ORG (Phill Gross) (12/31/87)
In case you leap-watchers out there missed it, the leap second will be celebrated as part of the midnight festivities tonight in New York City. Although the leap second is to be officially inserted at 7pm EST, the New York revelers will celebrate it as the 61st second of the last minute of the year. According to a report on NPR this morning, the traditional countdown accompanying the falling ball will be changed for this occasion to `5..4.. 3..2..1..LEAP!..0..'. During the additional second, the falling ball will stop and some additional fireworks or light displays will happen. I guess this means that NYC will be one second off from 7pm EST to midnight. Dave, how will this startling development affect network time in NYSERnet for those 5 hours?! Phill
schoff@NISC.NYSER.NET ("Marty Schoffstall") (01/01/88)
Dave, how will this startling development affect network time in NYSERnet
for those 5 hours?!
Actually only the three mobile packet radio gateways will be affected:
schoffstall's-red-chevy-S10-4x4.nyser.net
fedor's-tiny-blue-nissan.nyser.net
brim's-orange-junker-volvo.nyser.net
All other gateways are awaiting a new software load to be developed by the
vendor.
MartyMills@UDEL.EDU (01/01/88)
Phill, Well, I have good news and bad. The good news is that the umd1.umd.edu timeteller host will offer rigorous standard time pre-attack, trans-attack and post-attack the Leap. It is now squawking "danger: leap imminent" to its Network Time Protocol peers even now as per RFC-958. All fuzzballs on the U Delaware, U Maryland and Linkabit LANs will automatically follow the leap as required and relay the leap indicator to their pals. The bad news is that the wwvb.isi.edu timeteller got its clock punched, or something like that, since I can't reach out and touch its leap switch. It will miss the leap, at least until its radio clock notices, and thus keep NYT for probably about ten minutes while the radio clock resynchronizes. The remaining timetellers at Ford and NCAR have not had the software update required to leap correctly. Having said that, understand the radio clocks themselves have no provision to trach the leap, so will experience a period of befuddlement immediately following the Leap of from a few minutes to hours. Thus, my exquisitely crafted timewarp will come down at the leap, only to be yanked back maybe a minute later when the disagreement with the radio clock is noticed, then when the radio clock regains its marbles the unleaped leap will be releaped. Got that? Dave
LAWS@rsre.mod.UK (John Laws, on UK.MOD.RSRE) (01/01/88)
Phill, Meanwhile what happens over here in Europe? Since you officially leap at 7pm EST and UK is 5 hours advance on you - it sounds as if the UK (as the 'owner' of the long. 0 just east of the centre of London all associated with the high tech work on timekeeping done here over 200 years ago so as to sail the seas with better effect to found and hold the empire.....) is the point of origin for the world leaping. Prehaps Dave knows more detail. Happy new year from the time-centre of the universe - (and of course that is why we invented Dr. Who and the Time Lords...) John
LAWS@rsre.mod.UK (John Laws, on UK.MOD.RSRE) (01/02/88)
Dave, One hour after sending my 'Empire time' msg (Stars Wars is showing on the TV at this moment) I heard on the 'news' that Paris and not London pushed the leap button. I'll console myself with the knowledge that we are both part of the ECC. Years ago I worked at the National Physical Laboratory Teddington and I thought the atomic clock there had some national role. Missing has been the education of why we have leap seconds. I assume they are always positive and are because of either or both - the Earth does not rotate at a smooth constant rate year by year, the rotation is slowing down (and the Moon moving further away). John
karn@faline.bellcore.com (Phil R. Karn) (01/02/88)
Leap seconds are inserted once per year, on the average. They keep UTC (Coordinated Universal Time, as broadcast by WWV) within 0.7 seconds of another time scale, UT1. UT1 is the time as determined by astronomical observations of the rotation of the earth, corrected for an annual fluctuation of about +/- 30 milliseconds caused by seasonal movement of atmospheric mass and a slight annual distortion in the shape of the earth caused by solar tidal effects. Basically, the problem is that the second was defined to be too short with respect to the average rotation rate of the earth, so additional seconds have to be inserted periodically into UTC to allow the earth to "catch up". As you point out there is also a very long term trend having to do with the transfer of angular momentum from the earth's rotation to the moon. However, this amounts only to about 1 millisecond per century. References: Reference Data for Radio Engineers, Howard Sams & co. Phil
Mills@UDEL.EDU (01/03/88)
Phil, In that reference (Seventh Edition, 1985) it also points out that on 1 January 1972 the NBS reference was retarded ten seconds with respect to the International Atomic Time (TAI) scale maintained by the BIH. Since leap seconds have been syncronized since then, I conclude the whole thing is a plot to make sure the rest of the world is always ahead of us. Dave
perry@MCL.UNISYS.COM (Dennis Perry) (01/05/88)
Does that mean we get to put Dave in space? Gee, I think he is already high enough! :-) dennis
Mills@UDEL.EDU (01/05/88)
Dennis, Gee, I thought I presented my position to you when you were at DARPA, as well as your predecessor Barry Leiner and his predecessor Vint Cerf, not to mention assorted ears at DCEC and NOSC. I would be pleased to demonstrate things Internet, including fuzzballs, leaping clocks and other packet poppers, in orbit or other equally exotic place. How about the African bush using HF radio, or in a submarine under the Arctic using sonar, or on the Moon using laser or in China using OSCAR satellite? As for orbit, gotta fix the boosters first. Maybe the Russians would launch a fuzzsputnik. We could say it represented critical technology and set them back fifteen years. Dave