Goodbye leap seconds, hello leap hour?

General
1

At a recent global standards meeting the subject of “leap seconds” came up.

The final decision was that starting on 20 May 2027, there will be no more leap second corrections, and instead the difference between UT0 and UT1 must be (I presume) more than 30 minutes’ off before a “leap hour” adjustment is made.

https://www.newscientist.com/article/2594285-scientists-have-just-voted-to-abolish-leap-seconds/ has more information.

How should the NTP codebase handle this change?

2

Don’t you mean “UTC and UT1” Harlan?

The presenters of Resolution 5 at the CGPM implied that there will be nothing to do. At least before 20 may 2027. We have no indication of how a future 3600 second leap would be handled and I a wonder whether there will be any humans around to make it.

I was disappointment that the working party and CGPM have to my mind, diluted the CGPM 2022 Resolution 4 with relation to the dissemination of UTC-UT1.

In Resolution 4, we have:

encourages the BIPM to work with relevant organizations to identify the need for updates in the different services that disseminate the value of the difference (UT1-UTC) and to ensure the correct understanding and use of the new maximum value.

In Resolution 5 we have:

further recognizing that

  • users of UT1 can find information on the value of the difference UT1-UTC in the Global Navigation Satellite Services (GNSS) navigation messages, and internet services provided by the International Earth Rotation and Reference Systems Service (IERS), National Metrology Institutes (NMIs), and other services,
3

Someone replied to your post.

[al_zheimer49] al_zheimer49 https://community.nwtime.org/u/al_zheimer49
October 17

Don’t you mean “UTC and UT1” Harlan?

Yes, thanks for the correction!

H
==> The presenters of Resolution 5 at the CGPM implied that there will be

4

Harlan,

While I still believe that there will be nothing necessary to do in the short term. NTP in a broad sense will need to be reviewed. One of the issues that will need review and possible modification are the radio clock drivers. For instance with respect to DUT1, WWVB has only the two sign bits and four fractional bits , giving it a maximal -0,7 - +0, sec magnitude in current use but could be pushed to 15 x 0.1 secs. While this was enough for pre-continuous UTC it will not be sufficient from now on. The current DUT1 is increasing at a rate of 0,5 ms per day and so should that rate continue, the current use limits will be hit in 4 years. That rate is of course not fixed.

This is important as WP-7A, under IUT-R will have to decide on the format’s future, if any and in consequence the NTP driver code will need to be updated.

This same process will have to be done for all supported radio time services when the changes become known.

Another point, though not urgent is that I think that a UT1 driver should be developed for NTP. As you are probably aware there is a UT1 NTP server available at NIST Colorado, developed by Dr. Judah Levine and now administered by Dr. Jeff A. Sherman. This is only one clock and we know what that means.

Regards,

Mike