[ale] OT ntp - leap second - how many knew what this was 3 weeks ago

[Michael H. Warfield]

On Wed, 2012-07-04 at 10:39 -0400, Ron Frazier (ALE) wrote:
> Hi all,

> Around the beginning of this year, I was doing quite a bit of research
> into ntp and gps and eventually set up my own gps based ntp time
> server in both Linux and Windows. At the end of June, a leap second
> was inserted into the time sequences of the clocks on Earth. For those
> that may not know what that is, the atomic clocks are coordinated with
> the earth's rotation, so, for example, when the clock says noon, the
> sun is always roughly overhead. However, the earth's rotation speeds
> up and slows down at times. So,sometimes, we have to tweak the clocks
> to match the earth again. At the end of June, an extra second was
> inserted. Normally, the seconds go 58 ... 59 ... 00. This time, they
> went 58 ... 59 ... 60 ... 00. As it turns out, this crashed a number
> of servers.

It crashed (really just interfered with) a few someone high profile
servers.  The vast majority were unaffected.

> I find this very interesting, and somewhat scary as a potential
> programmer. Since I'm thinking of learning programming again, and
> since I have an interest in timekeeping, I have considered writing a
> world clock program etc., to show the time in different parts of the
> world. However, prior to my NTP research, I never knew about the leap
> second. So, there would have been a good possibility, had I written
> the program prior to this year, that my program would have crashed as
> well.

> So, my question is, how many of you knew about leap seconds prior to
> this incidence of it and prior to my describing it. If you were
> writing a clock program, would you have known to account for this?

Known about it for decades.  Just about anyone involved with time and
timezones and such, particularly if they have a strong interest in
astronomy, should know about them and the difference between UTC and UT1
(astronomical time).  Normally, though, it's on the 1st of the year they
make that adjustment.  I was surprised they were doing it when they did
this year.  They must have had been too close to their critical boundary
and realized they wouldn't make it to Dec 31 before it was too far out.
Astronomers tend to be a pissy lot.

I think the first time I remember about "leap seconds" I actually
listened to WWV out of Boulder, probably on 10MHz which generally gave
me the best reception up in Michigan on a long-wire antenna, for it.
One December 31 night I listened and counted down the seconds as they
ticked through 60 and ticked 61 before the top of the minute chime.
This was lllooonnnggg before GPS and the Internet.  This would have been
back in the 70's.

Interesting thing about the time signals from WWV (Boulder) and WWVH
(Hawaii) is that they also indicate the .1 seconds offset between UCT
and UT1 as well.  It will tick off the 1/10 second lead or lag by
"double ticks" on the seconds before and after the minute mark.  Up to a
second or so lead could be heard with the double ticks after the minute
and up to a second or so lag could be heard by ticks before the minute.
Obviously, you could tick off up to several seconds plus or minus using
that method but they don't.  When it approaches around one half second
to one full second is when they would have to kick in or,
(theoretically) pull out a second.  When they throw in that leap second
you can hear them go from +.5 to -.5 from one minute to the next as
well.  I don't know that I recall them pulling a second, though it is
possible.  The drift is not linear and varies subtly over the years as
the earth's axis wobbles slightly.

There were some proposals put out recently (again) to do away with "leap
seconds" entirely and shift back to astronomical time as the standard
and compensate in "atomic time" by just letting it drift, but that
discussion pops up every couple of years and then goes nowhere.  When I
heard about it again, yearly this year, they sounded seriously in
earnest about changing our time standard but then it dropped out of the
news yet again.

> Sincerely,

> Ron

Regards,
Mike

> --
> 
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> (To whom it may concern. My email address has changed. Replying to former
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> (PS - If you email me and don't get a quick response, you might want to
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> 
> Ron Frazier
> 770-205-9422 (O) Leave a message.
> linuxdude AT techstarship.com
> 
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-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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