[tz] New Yorker article on David Mills and NTP

[John Sauter]

On Tue, 2022-10-04 at 20:15 +0000, Michael H Deckers via tz wrote:
> 
>     On 2022-10-04 19:01, dpatte via tz wrote:
> 
> 
> > I follow numerous astronomy lists, and there is serious discussion
> > at the IAU (International Astronomical Union) to get rid of leap
> > seconds altogether, and possibly replace them by something else,
> > perhaps leap minutes (or even leap hours) - making them far less
> > common. I believe they expect to make a decision soon, though they
> > have been discussing it for years and had planned to make a
> > decision 2 or 3 years ago.
> 
> 
>     The BIPM is now in charge, and the CGPM on 2022-11-15..18
>     in Paris will vote on the proposal D on pages 7..8 and 23..24 in
> [
> https://www.bipm.org/documents/20126/66742098/Draft-Resolutions-2022.p
> df/2e8e53df-7a14-3fc8-8a04-42dd47df1a04]
> 
>     Michael Deckers.
> 

The essence of proposal D is:

   recognizing that the use of UTC as the unique reference time scale for
   all applications, including advanced digital networks and satellite
   systems, calls for its clear and unambiguous specification
   as a continuous time scale, with a well-understood traceability chain, 
   
   decides that the maximum value for the difference (UT1-UTC) will be
   increased in, or before, 2035,
   
   requests that the CIPM consult with the ITU, and other organizations
   that may be impacted by this decision in order to
      − propose a new maximum value for the difference (UT1-UTC) that will
      ensure the continuity of UTC for at least a century,
      − prepare a plan to implement by, or before, 2035 the proposed new
      maximum value for the difference (UT1-UTC),
      − propose a time period for the review by the CGPM of the new maximum
      value following its implementation, so that it can maintain control on
      the applicability and acceptability of the value implemented,
      − draft a resolution including these proposals for agreement at the
      28th meeting of the CGPM (2026),
      
   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

Considering that there has been about one leap second every 18 months,
the maximum value for abs(UT1-UTC) would have to be around 60, so this
proposal is contemplating leap minutes.  

Assuming agreement on that value is reached by 2026, there would then
be nine years to update everything that depends on abs(UT1-UTC) < 1. 
One example that comes quickly to mind is the time signals broadcast by
WWV, which include the value of UT1-UTC to the nearest 1/10 second, but
doesn't have enough space for abs(UT1-UTC) > 1.  See

https://www.nist.gov/time-distribution/radio-station-wwv/wwv-and-wwvh-digital-time-code-and-broadcast-format

I think it would take much longer than nine years to update the WWV
transmission format, since that requires updating all consumers of this
data.
    John Sauter (John_Sauter at systemeyescomputerstore.com)
-- 
get my PGP public key with gpg --locate-external-keys
John_Sauter at systemeyescomputerstore.com

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