Another leap-second, December 31st.

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Another leap-second, December 31st.

Postby Steve Anderson » Fri Dec 19, 2008 9:20 pm

Now this might not seem a time-dilating event but those interested in time I would like to remind them there's another leap second at the end of this year. In the last second of 2008 your clocks should read 23:59:60 before going to 00:00:00 in 2009.

For those interested here's a site worth visiting:-

http://www.leapsecond.com/

And this:-

http://www.leapsecond.com/java/nixie.htm

There's also this:-

http://www.leaphour.com/

Steve A.

But then again perhaps some just don't have time for this.
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Postby Klaas Robers » Fri Dec 19, 2008 10:13 pm

Then I ask myself: Is this leap second still part of 2008, is it already part of 2009, or is it a non-year-dependent second?

In the first case I fear that many people are wishing "Happy new Year" one second too early. You can pronounce this just within a second, so you can be too fast.

Anyway I am going to look at the second pulses of my DCF-77 clock at that moment, to see the missing second coming at the transition of 59 to 00 instead of 58 to 59. And the seeing how fast my software recovers.

Oh, I have even two clocks, one my home brew Nixie clock, the other a mechanical clock, both running at DCF-77 (77,5 kHz time signal stations).
I think that my Nixie clock needs several minutes to resynchronise the minutes flywheel loop. I made no provisions to foresee the leap seconds, although DCF sends an extra bit to inform me about it.
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Just a sec...

Postby Steve Anderson » Fri Dec 19, 2008 10:26 pm

Klaas Robers wrote:Then I ask myself: Is this leap second still part of 2008, is it already part of 2009, or is it a non-year-dependent second?


The additional second is added to the current year. So the last second of 2008 will be 31/12/2008 23:59:60. i.e. the last minute of 2008 will have 61 seconds. The first second of 2009 will be 01/01/2009 00:00:00. This can also happen on the last day of June, I'm not sure when the next leap-second will be, it's announced only months before the event. e.g (an example, not for real) 30/06/2010 23:59:60.

If you have a GPS receiver with NMEA data output you can record the event on a PC while you party. It happens at midnight UTC so with the time difference here it will happen at 0700 local on the 1st of January for me. Those in Australia somewhat later.

Steve A.
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Re: Just a sec...

Postby Dave Moll » Sun Dec 21, 2008 12:14 am

Steve Anderson wrote:I'm not sure when the next leap-second will be, it's announced only months before the event.

I assume that the need for leap seconds is not entirely predictable as the earth's orbital period is altered slightly by the gravitational interplay beween it and other celestial bodies.
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Postby Klaas Robers » Sun Dec 21, 2008 8:31 am

Oh, that is a relief. Then it happens here in NL at 00:59:59 as we are one hour in advance of GMT. Then there is no danger for us to say "Happy New Year" too early. But it also gives me a more quiet chance to see the time shifting.
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Re: Just a sec...

Postby Steve Anderson » Sun Dec 21, 2008 2:35 pm

Dave Moll wrote:I assume that the need for leap seconds is not entirely predictable as the earth's orbital period is altered slightly by the gravitational interplay beween it and other celestial bodies.


Yes, that's part of the reason which explains the rather random nature of when leap-seconds are inserted into a year. But the main reason for them is the Earth's rotational speed is slowing down, but there's no cause for alarm, it won't make any noticeable difference for a long while yet.

Steve A.

Added later...I found this which shows the Earth's rotation slowing down.
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It happened....

Postby Steve Anderson » Thu Jan 01, 2009 11:18 am

Well guys, it happened...

Note the PC clock (bottom right-hand corner) was unaware of the leap second...

The top line is my local time, the second line is UTC...

The decoded NMEA data from the GPS system showed this:-

2008 December 31, 23h 59m 59s
2008 December 31, 23h 59m 60s
2009 January 1, 0h 0m 0s

Steve A.
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Very Important!

Postby Steve Anderson » Mon Jun 29, 2009 10:26 pm

AT 5 MINUTES AND 6 SECONDS AFTER 4 A.M., ON THE 7TH OF AUGUST, THIS YEAR, THE TIME AND DATE WILL BE:

04:05:06 07-08-09

THIS WILL NOT HAPPEN AGAIN UNTIL THE YEAR 3009!!!
I had a deep feeling that you just needed to know this.

Steve A.

Except:-

05:06:07 08-09-10

...and so on...
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Postby Steve Anderson » Wed Feb 22, 2012 10:09 pm

OK chaps, I've just been made aware of another leap-second to be inserted into 2012, at the end of June 30 your clocks should read 23:59:60 UTC...or whatever your local time-zone offset is.

Another momentous event not to be missed!!!

I wonder how you'd adjust a sundial to take account of that?

Steve A.
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Postby Dave Moll » Thu Feb 23, 2012 2:14 am

Steve Anderson wrote:I wonder how you'd adjust a sundial to take account of that?

Actually, the adjustment probably keeps us in synch with the sundials!
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Another leap-second, June 30 2015.

Postby Steve Anderson » Sat Apr 11, 2015 2:52 pm

If you're not already aware there'll be another leap-second at the end of June 2015...though not Dec 31 this year.

The last minute of June 30 this year will contain 61 seconds so as before your digital clocks should display 23:59:60.

If you have Java installed this site is worth a quick look...

http://www.leapsecond.com/java/nixie.htm

Steve A.

Added later, the leap-second is inserted after 23:59:59 to become 23:59:60, this is UTC time. If you're on a time-zone that's not UTC you'll have to work out when this happens locally to you. For me it's the second before 7AM...assuming I'm in Thailand when this occurs.
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Re: Another leap-second, December 31st.

Postby Steve Anderson » Thu Jul 02, 2015 4:20 pm

Did you miss it? Due to the time-zone here it happens at 06:59:60 local time.

The site I got this screen-scrape from is...

http://time.is/

Steve A.
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Re: Another leap-second, December 31st.

Postby Steve Anderson » Sun Jan 01, 2017 12:00 pm

If you missed it, another one happened 31/12/2016 during which the last minute had 61 seconds.

Photo of Internet site dealing with this attached, as well as NMEA data from GPS receiver, Lat/Long data replaced with 'X's for security reasons...other irrelevant sentences edited out.

The GPS system simply repeats 23:59:59 to add the inserted second. Digital clocks should show 23:59:60 as per screen-shot.

http://leapsecond.com/java/nixie.htm

Steve A.
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Re: Another leap-second, December 31st.

Postby kd2bd » Sat Jan 14, 2017 5:14 am

The 2016 leap second was also reported by my homebrew WWVB Frequency Standard:

2016_Leap_Second.jpg
2016 Leap Second
(164.51 KiB) Not downloaded yet


Video of the event is available here: https://www.youtube.com/watch?v=zBS1ZTWMBVw. Associated audio is from CHU in Canada (since reception of CHU at my QTH was better than WWV at the time).

73 de John, KD2BD
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