Leap Second At The End of 2005 269
Ruff_ilb writes "Because of the discrepency between an ephemeris second (the fraction 1/31,556,925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time) and the second of atomic time (the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom), we're left with more than leap years. In order to ensure that the the atomic time and civil stay coordinated, "Civil time is occasionally adjusted by one second increments to ensure that the difference between a uniform time scale defined by atomic clocks does not differ from the Earth's rotational time by more than 0.9 seconds."" And Happy New Years everyone ;)
How did you use yours? (Score:4, Funny)
Re:How did you use yours? (Score:5, Interesting)
Re:How did you use yours? (Score:5, Informative)
http://hpiers.obspm.fr/iers/bul/bulc/bulletinc.da
Re:How did you use yours? (Score:4, Informative)
(By "solar" I don't just mean sundials. I mean clocks that are set by pointing the hour hand straight up at noon, which is how all clocks were set before time zones were invented.)
I think what you were trying to say is, "most NTP servers are corrected against official UTC time signals."
Re:How did you use yours? (Score:3, Insightful)
How do they know its noon then?
(Its overcast here)
Re:How did you use yours? (Score:4, Funny)
They used 747s to fly the clocks above the clouds.
Re:How did you use yours? (Score:5, Insightful)
Yes, that's the point of serving the Network Time Protocol...
Re:How did you use yours? (Score:2, Funny)
Re:How did you use yours? (Score:3, Funny)
A cool thing to do (Score:5, Funny)
Re:A cool thing to do (Score:2)
Re:A cool thing to do (Score:4, Funny)
Re:A cool thing to do (Score:2)
The hard way (Score:5, Funny)
Real engineering solution would involve changing earth's rotation speed to match the clock. Any takers?
Re:The hard way (Score:5, Funny)
Oh yeah? It took me about ten minutes to adjust all the clocks in my house due to the damn leap second. Multiply this by the 100 million households in the nation, and we have a very serious issue here.
I demand that George Bush pull us out of whatever God forsaken U.N. treaty that got us into this mess.
Re:The hard way (Score:2, Funny)
Re:The hard way (Score:3, Funny)
If you have ten second-exact clocks in your house, someone has a very serious issue. If you believe 99,999,999 other households have ten second-exact clocks in their home, someone definately has a very serious issue. Besides the geeky solution is to have all of them synchronized automagically, what are you doing on slashdot?
Re:The hard way (Score:3, Interesting)
I wish I were making this up.
Re:The hard way (Score:2, Offtopic)
Re:The hard way (Score:3, Funny)
Re:The hard way (Score:4, Funny)
This is Slashdot. Quit spamming us with stuff we already know.
Re:The hard way (Score:2, Funny)
Re:The hard way (Score:2)
You can try this on yourself: sit on a swivel chair and start spinning with your hands held apart, then quickly pull your hands close to your body - you should start rotate faster.
I think if we level all mountain ranges and melt both ice caps it should be enough to make Earth spin faster enough to compensate for this leap second.
Re:The hard way (Score:3, Insightful)
Um, if you melt the ice caps, won't the water spread itself out through the oceans? This will, on the average, make the molecules move away from the axis, thus slowing the planet's rotation.
What you want to do is pile mass up close to the axis, i.e., at the poles. With water, you'd need to precipitate it out at the poles. This isn't what we're doing, though.
For mountains, you don't want to just level them; you want to move the mass closer to the axis. So you want to pile the rubble on the poleward side of where the mountain used to be (north in the northern hemisphere, etc.).
Re:The hard way (Score:2)
Re:The hard way (Score:2)
countdown (Score:3, Funny)
-Sj53
Re:countdown (Score:2, Funny)
And those with computers... (Score:2, Insightful)
Re:And those with computers... (Score:3, Informative)
Re:And those with computers... (Score:2)
I don't have a computer!"
I suppose it is a sign of the times that I had to stop and linger on this for a second (no pun intended)...
Mostly because of the fact that I can now read, and post to
What an amazing speed at which things are changing.
So, yes.. some could very well now answer to something "But I don't *own* (or have access to) a computer!
It is not likely, but certainly possible now!
oh great (Score:2, Funny)
Damn! (Score:4, Funny)
Thank goodness I didn't bother setting the VCR clock after the last thunderstorm.
Obligatory Three Dead Trolls in a Baggy joke... (Score:2)
Re:Damn! (Score:2)
Highlights problem with ntp... (Score:5, Informative)
So, as of today, any time stamp you have made using NTP, ever, has been retroactively displaced by one second. Intervals that included midnight (UTC) last night are all too short by one second.
This may not be a problem for handling your calendar appointments, but it can muck up all kinds of scientific applications that require high precision.
Re:Highlights problem with ntp... (Score:5, Insightful)
Just because everybody agrees to change their clocks doesn't mean time actually slows down or speeds up.
Re:Highlights problem with ntp... (Score:2)
Re:Highlights problem with ntp... (Score:2)
Re:Highlights problem with ntp... (Score:5, Interesting)
he error is carried by the fact that NTP stays synchronized to UTC in the present, but the past is "free floating". If, today, I convert my previous NTP timestamp back to UTC I will find that it occurred at 11:00:01pm yesterday rather than 11:00:00, the time that I actually made it. That's because NTP counts offsets from the present moment, assuming that UTC behaves like TAI.
Re:Highlights problem with ntp... (Score:2, Interesting)
Further down there is a discussion of how leap seconds are handled. I was curious so I checked my computer clock (which is synced using NTP) against my alarm clock (which uses the radio signal from the MSF [npl.co.uk] service and they are the same. So it seems that NTP must have observed leap seconds contrary to your original post.
Re:Highlights problem with ntp... (Score:3, Informative)
NTP is intended for synchronising computers together (useful for servers). It is not intended to provide a highly accurate time signal for scientific applications. If you need that kind of precision, then you use a direct time source such as a GPS signal - a common secondary use of the atomic clocks onboard the satellites. The only way to get better precision than that is to get your own atomic clock
Re:Highlights problem with ntp... (Score:2)
That leads to an interesting question: the satellites are in reduced gravity, which increases the rate at which time passes, and moving faster than we do here on the ground which lowers it. I doubt that the two effects cancel out completely, as they're not moving that fast. Is there a correction for this included in their software, or is GPS time really a little fast compared to what we have on the ground? Anybody out there know?
Re:Highlights problem with ntp... (Score:2)
How the operating system deals with a leap second is, for me, a different issue. Again, perhaps the OS should work in TAI and then convert everything to UTC (or more properly local time) for display to humans. Problem with that is the OS doesn't know when the leap second happen, since the aren't predictable - but nowadays that information could be distributed as an OS update.
Re:Highlights problem with ntp... (Score:4, Interesting)
You are confusing transport with content. NTP, by itself, has no inherent concept of leap-seconds, leap-years or any other sort of temporal leapage; it simply provides a way to statistically analyze time sources, account for latency, jitter and dispersion and keep a local clock as closely synced as possible to one or more remote clocks. When making adjustments to the local clock, it is careful to not introduce large amounts of skew which might wreak havoc on time sensitive running processes Iinstead it will slowly "bump" the clock towards what it currently thinks is the most accurate time.
To make NTP useful, of course, it must be provided with one or more ultimately trusted authoritative time source (these can be stratified [stratums] in terms of network closeness to the original time reference). As you noted, major reference clocks on the net use a UTC time source, which makes more sense for common applications than TAI, as non-scientific-clocks world-wide are based on UTC.
When the leap second was added at the beginning of this year (this morning -- or perhaps the very end of last year), the UTC was simply adjusted by one second. stratum 1 NTP servers which are directly hardwired to reference clocks (ultimately, that means atomic clocks), adjusted by the UTC-TAI offset, trust their reference clocks above all else; thus when they saw the UTC adjustment they simply assumed that their local cpu clock was off and began adjusting it accordingly (from the reference frame of the NTP timescale, time "stood still" for one second). Simultanously, any new broadcasts or query-responses sent out on a network interface used the newly offset time. Downstream NTP daemons would make a similar conclusion; that their local clock had drifted one second off and should be slowly adjusted towards the correct time.
The net effect is that if you were to view NTP as a continous set of incrementing ticks beginning on 0h Jan 1, 1900 GMT (UTC origin is TAI -10s 0h Jan 1, 1972, and thus technically is meaningless for timescales that originate prior to the epoch), historical timecodes are effectively lost on each update where a leap second has been inserted, however the current timecode is in sync with UTC.
Sensitive scientific applications will likely simply avoid the UTC offset completely and use a direct TAI reference clock.
Re:Highlights problem with ntp... (Score:2)
WOOHOO! (Score:2)
time.gov (Score:5, Informative)
It was Amazing! This was the first time for me... *remebers where I was at that moment
Re:time.gov (Score:4, Informative)
WWV (Score:3, Interesting)
I listened to it on WWV. They drop the 29th and 59th tick of each minute, and at 2359 UTC it sounded like (I counted the seconds myself):
...and so on. The UT1 time correction went from -0.6 to +0.3 seconds. It's encoded in the double ticks.
Yes, I got a recording. Lame or what?
...laura
How did you spend the extra second? (Score:2, Funny)
Re:How did you spend the extra second? (Score:2)
old news (Score:5, Funny)
Nope, this year. (Score:2)
oh, shit. (Score:2, Funny)
It's not the 'ephemeris second' that's the problem (Score:5, Informative)
it's the fact that the Earth, like all of us, is getting older and slowing down, so that
the 2005 "Earth rotation" second (i.e. 1/86400 of one spin of the Earth) is longer than
the 1900 equivalent and longer than the atomic time (SI) second. Instead of changing
the length of the second, it is currently deemed less painful to keep using the old
length and stick in an extra second every now and again.
Since this depends on the slop of the Earth's interior, it's not a fully regular and predictable thing - we might even have to remove a second one year.
Re:It's not the 'ephemeris second' that's the prob (Score:2)
http://www.leapsecond.com/java/gpsclock.htm [leapsecond.com]
Re:It's not the 'ephemeris second' that's the prob (Score:2, Insightful)
Re:It's not the 'ephemeris second' that's the prob (Score:2)
Re:It's not the 'ephemeris second' that's the prob (Score:2)
To within about one part in 1.E12 the ephemeris second is identical to the SI second defined by the cesium resonance. In 1977 the length of the second of TAI was changed [ucolick.org] so as to conform better with the preferred definition of the SI second. Before 1977 TAI and UTC ticked faster than they do now. Astronomers did not object to the change in rate of TAI because it was within the uncertainty of the original definition of the ephemeris second.
Great (Score:5, Funny)
January 0 (Score:2)
- Thomas;
Re:January 0 (Score:2)
The clock problems (Score:4, Interesting)
Re:The clock problems (Score:2, Informative)
Re:The clock problems (Score:2)
Re:The clock problems (Score:2)
I also flipped back and forth between like ABC and NBC, Pacific Time, and notice they were like 3 seconds or so different in their countdown clocks. What is up with that?
I was watching CNN and they had a couple seconds difference between their on screen countdown and the Times Square Coke-sign countdown. It kind of scrapped the fun of counting down to 2006, CNN was allready at 0 when Times Square had 4 seconds left.
Yeah, I'm a dork, having my new year's fun scrapped by a 4 seconds discrepancy.
Re:The clock problems (Score:2, Informative)
Re:The clock problems (Score:4, Informative)
Last year during the Superbowl it was noticeable at my house, I had 3 TVs tuned to the game, 2 via DirecTV and another using rabbit ears, the over the air broadcast was easily 2-3 seconds ahead of the DTV broadcast. This is one of the reasons that the Sport Betting Houses that allow betting up until play completion don't allow cellphones, because you could have someone watching via a faster source or at the game itself, feeding you what's going to happen.
Re:The clock problems (Score:3, Informative)
It wasn't far off the pips on radio 4 analog (ignore big ben etc) in the gallery.
After leaving the gallery, it travels down to one CTA, then another, then another, then gets split, and is sent via seperate routes to the main transmitter in Crystal Palace. Other regions outside London recieve their feeds via various routes.
DTT is sent seperatly, and the signal is encoded (with major delay) as a low bitrate (to the local transmitter), and a high bitrate (to nations/regions) which can be opted out of (I'm a little hazy on this bit).
Additonally DSat is encoded then uplinked to a satelite.
As a consumer, if you recieve digital there will be an additional delay in decoding.
The point is that the time might be fine in the studio, however it goes through a lot of equipment that adds a lot of delay, and different networks will have different delays, different equipment etc.
Now how do you line your studio up? Based on the studio output, the analog reception from a nearby transmitter, the analog reception from a 2nd or 3rd level slave, the digital reception from one of many different transmitters (each with different equipment encoding with a different delay), from satelite (with the 3/4 second bounce plus digital encoding), and how do you account for various decoders?
That's the problem for a normal new year broadcast. Add in a leap second (99% of equipment out there will not accept 23:59:60 as a valid time) and you've got even more problems.
In the UK the most accurate broadcast signal you'll get is the pips on Radio 4 LW.
If you want to know the real time, get a GPS system.
Re:The clock problems (Score:2)
Differing amounts of broadcast time delay?
That's So, Like, 2005, eh (Score:2)
Rob, we all saw that coming a few days ago. But
Leap Second Lovers Are Traitors Says Bill O'Reilly (Score:5, Funny)
I remember liberals at a party saying, 'let's add a second to the year' and I was the only one who spoke up against it. Why would they want to add a second to the year? Because it gives them a second longer to hate Bush.
"Look, look, look, look. A leap second is a denial of everything American, of everything good, of everything moral. They're saying we need this second because the earth rotates on its axis and revolves around the earth, well this is the no spin zone. So we don't need a leap second. Though I would rather have a leap second than some of these hate-mongers who go around hating even their own ideas! They need to hate their own ideas so much that you have many liberals proposing the leap second, which is an idea that they hate, yet, they propose.
"I am so so so so upset with these people, who actually believe their ideas, yet, I have no hate in my heart. I am a simple guy, who only has my own true beliefs and a few products that are my cornerstone to fight against the leap second poobah. Let me say it aloud: Leap Second, leap second, leap second. Doesn't it sound ugly?
"Please, don't let these Darwinian leap-seconders, who believe that the planets revolve around the sun, who believe that rocks are sedimentary, igneous and stalactites, who are innocent dim-wit believers in a faith bordering on hating everything religious like trees and fruitcake, yet, who don't believe in John 7:12:45:67:89, have their say.
"But you know what I love? Dialogue. Rational dialogue which allows me to say that aliens from a Iraqi loving planet want to abolish Christmas by adding a leap second to the Darwinian anti-God year. Dialogue is what keeps the American system God-loving and anti non-God. It also keeps the anti-God loving non-Iraqi loving insurgent deniers able to voice their hideous so-called opinions over the American loving tolerant airways. And now let's take some calls."
Steve Martin [huffingtonpost.com]
Re:Leap Second Lovers Are Traitors Says Bill O'Rei (Score:2)
tsunami caused rotation change (Score:2, Interesting)
http://www.pbs.org/wgbh/nova/tsunami/ask-050331.h
(scroll down to the sixth question)
Log of Atomic GPS Clock adjustment (Score:5, Interesting)
2005.12.31 18:33:49 00032 GPS Status - Tracking: 3D
2005.12.31 18:43:27 00020 Offset: 000.016 Buffer: 13
2005.12.31 18:43:27 00032 GPS Status - Tracking: 3D
2005.12.31 18:43:49 00020 Offset: -000.031 Buffer: 13
2005.12.31 18:43:49 00032 GPS Status - Tracking: 3D
2005.12.31 18:45:15 00033 GPS Status - Tracking: No
2005.12.31 18:45:34 00032 GPS Status - Tracking: 1D
2005.12.31 18:46:48 00033 GPS Status - Tracking: No
2005.12.31 18:46:52 00032 GPS Status - Tracking: 3D
2005.12.31 19:01:43 00033 GPS Status - Tracking: No
2005.12.31 19:01:55 00032 GPS Status - Tracking: 1D
2005.12.31 19:03:45 00020 Offset: 001.016 Buffer: 13
2005.12.31 19:03:45 00032 GPS Status - Tracking: 2D
2005.12.31 19:13:45 00020 Offset: -000.016 Buffer: 13
2005.12.31 19:13:45 00032 GPS Status - Tracking: 3D
2005.12.31 19:23:43 00020 Offset: 000.000 Buffer: 13
2005.12.31 19:23:43 00032 GPS Status - Tracking: 3D
2005.12.31 19:33:43 00020 Offset: 000.000 Buffer: 13
2005.12.31 19:33:43 00032 GPS Status - Tracking: 3D
2005.12.31 19:43:30 00033 GPS Status - Tracking: No
2005.12.31 19:43:40 00032 GPS Status - Tracking: 1D
2005.12.31 19:53:41 00020 Offset: -000.031 Buffer: 13
2005.12.31 19:53:41 00032 GPS Status - Tracking: 3D
2005.12.31 20:03:39 00020 Offset: 000.000 Buffer: 13
2005.12.31 20:03:39 00032 GPS Status - Tracking: 3D
times square crowd 1 sec off tv time (Score:2)
of course, they printed "live" on the screen which was bs -- but did anyone else notice that the digital time on the screen and the seconds that the crowd were chanting down were 1 second off? obviously, I had way too little to drink this year to notice this, and no girl nearby to kiss.
I'm wondering if maybe this was due to some clocks on 2005 time and some with more accurate accounting?
last year the US proposed to cancel this update (Score:3, Interesting)
She added that because of this among many other updates, there have been a formal proposal by the US, some months ago, to change the rules and abandon any updating before there is a full day (!) of delay, but the proposal was refused.
FYI, this 1-s correction is the first in 5 years, but there were 4 others in the previous 5 years.
Waiting for one day would basically mean renouncing for some thousand years, or more probably, waiting for the next civilization to come
Hervé
Woohoo! An extra second of sleep! (Score:2)
Typo (Score:2)
In order to ensure that the the atomic time
Re:Typo (Score:5, Funny)
In order to ensure that the the atomic time
No, that's a leap the.
Newspapers couldn't resist the hype (Score:2)
http://www.suntimes.com/output/news/cst-nws-sec01
Quote: "If you don't get all the clocks synchronized when the leap second occurs -- you could have potentially interesting effects," Chester said. "The Internet could stop working, cell phones could go out."
YEA. SURE!
Re:Newspapers couldn't resist the hype (Score:2)
Re:Newspapers couldn't resist the hype (Score:2)
When you take complete date with seconds, minutes, days etc. etc. instead of just a timestamp, you have to implement much better logic that implements rolling of seconds into minutes, minutes into hours etc. then months into years, also account for leap years and so on.
If the programmer got lazy and implemented logic up to months, you'll experience odd behaviour each new year's eve.
But nothing is odd on new years eve, if you take the timestamp (timestamp is usually a flat number of milliseconds that have passed since specific point of time, say 1980) there's no even such thing as new year in it, everything flows smoothly.
And as for the leap second, well all devices that work in networks have to account for latency, drop outs and so on which means they the Internet doesn't have One Global Super Accurate Clock which if desyched can break.
So I just call BS on that quote in my previous post (plus it's Jan2 and noone reported something big weird happen).
Re:happy new year (Score:4, Funny)
Re:Happy New Year (Score:4, Informative)
Re:Happy New Year (Score:2)
I think it's a contraction of "Happy New Year's Day" with incorrect punctuation. This being Slashdot, incorrect punctuation shouldn't surprise you.
Either that, or it's a conflation of "New Year's Eve" and "Happy New Year." Or, Taco's drunk, dictating articles, and he's slurring his speech. There's a veritable menagerie of possibilities; a smorgasbord of likely explanations, if you will.
Re:Happy New Year (Score:2)
What, after 2006 the calendar just ends? Of course there'll be many more New Years, and the original poster just wanted to pro-actively wish that all of them are Happy.
Re:Happy New Year (Score:2, Informative)
If you care to know, someone decided, it would seem, to make up a word in order to create "de facto regulation" of an industry--that is, anyone can call themselves real estate agents, but only those who get trademark license (possibly by passing a test on how well they understand real estate agency or REALTY) can legally call themselves REALTORs. And people are "supposed" to prefer a REALTOR over a real estate agent (at least that's the hope of the company owning the name REALTOR--I don't know whether it works or not).
Re:Happy New Year (Score:2)
Re:BBC TV yesterday (Score:2, Informative)
Re:Missed it? (Score:2, Informative)
Re:GPS not synchronized? (Score:3, Informative)
Re:GPS not synchronized? (Score:4, Informative)
As of yesterday, the difference between UTC and GPS time is 14 seconds.
http://maia.usno.navy.mil/ser7/series14.txt [navy.mil]
Re:Expected Result (Score:2)
Pretty much the same on my Mac:
> osascript -e 'date "Jan 1, 2006 11:58:59 am" - date "Dec 31, 2005 11:58:59 am"'
86400
Re:Why bother? (Score:2)
Anyone who is doing navigation based on the current time (UTC) and the positions of the Sun and other celestial bodies. You get the longitude from the difference between local time and UTC.
Re:Why bother? (Score:2, Informative)
The big argument about leap seconds is that the computer folks want to eliminate them, but the astronomers are upset because the useful bit of information that tells how many seconds TAI is off from UTC is transmitted in a field that can only hold a number up to +/- one second in some time transmission protocols. So after a missed leap second, asatronomical time wil lbe off from UTC by an unspecified amount, which could be bad for anyone who uses UTC time to do astronomy. (Since UTC is the time that's transmitted around the world, this is important.)
expanding earth? (Score:2)
Re:Working (Score:2)
Re:Leap Seconds are Unamerican! (Score:2)