[time-nuts] June 30 2015 leap second

Didier Juges shalimr9 at gmail.com
Mon Jan 12 10:34:36 EST 2015

Hi Tom,

You are correct, but it does not really matter because it will not be instantaneous, and for a period of time that is well within the range of human perception, the clock will be off by more than you would normally expect.

We have been talking about NTP being able to keep the time to within uS or better and this is a system that deliberately introduces an error a million times bigger. I am just surprised Time-Nuts would not go nuts about it :)

Didier KO4BB

On January 11, 2015 8:31:12 AM CST, Tom Van Baak <tvb at LeapSecond.com> wrote:
>> Keep in mind that this system drives you to having pretty bad time
>for the
>> better part of a whole day, on purpose... I realize that when the
>Hi Didier,
>The google article never claims the smear spans an entire day. I think
>you may be confusing references to the leap smear with a DIY digital
>clock someone on the list wanted to build (and they proposed using a
>slow 86400 second slew).
>The google code is "lie(t) = (1.0 - cos(pi * t / w)) / 2.0" and they
>are wise not to publish the actual window value, w. If it were me I'd
>make it somewhere between a couple of seconds or couple of minutes but
>I too would not make it a published or hardcoded constant.
>Here's the link again:
>Again, I don't know what value they use, or even if they use the same
>value from one leap second to the next. If any of you have inside
>contacts with google and can find out let me know, off-list.
>Regardless, it should be possible to experimentally determine the smear
>duration by repeatedly using some google service that returns
>time-stamps during the day, hours, minutes, or seconds before and after
>June 30. It would make a nice posting for a time nut, or a research
>paper for a high school student or undergrad: Experimental Confirmation
>of Google's Leap Smear Algorithm.
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