[tz] leap_second.list not updated after latest IERS Bulletin C

Martin Burnicki martin.burnicki at meinberg.de
Mon Dec 18 11:35:16 UTC 2023

Brian Inglis via tz wrote:
> On 2023-12-15 02:31, Martin Burnicki via tz wrote:
>> Has anyone ever suggested a formulation that meets the requirement of 
>> the TZDB project, and told them why this was a requirement? I have no 
>> doubt that the folks at IERS would pick it up and integrate it.
> I was in touch with them when they initially provided the files, about 
> their often inconsistent validity and expiry dates and timestamps, often 
> expiring before the next Bulletin C would be issued, until they 
> standardized on 0Z on the Bulletin C issue date and the 28th of the last 
> month of the half year following the expected date the next Bulletin C 
> is issued.

Yes, I remember the first publications had some 'glitches', and I had 
several discussions with the guys.

The hardest part was to explain why it is best practice (under the given 
conditions) to set the expiration date almost 12 months in the future.

The problem was that they didn't know how the NTP leap second file is 
being used. They were assuming that it would be better to let the 
currently installed file expire, then generate some alarm that the file 
needed to be updated and then update the file. However, this would mean 
that the NTP daemon runs for some time without leap second information.

BTW, the leap second file is also a good way to provide a device with 
the TAI/UTC offset, which is important if you run for example a PTP 

Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
Email: martin.burnicki at meinberg.de
Phone: +49 5281 9309-414
Linkedin: https://www.linkedin.com/in/martinburnicki/

Lange Wand 9, 31812 Bad Pyrmont, Germany
Amtsgericht Hannover 17HRA 100322
Geschäftsführer/Managing Directors: Günter Meinberg, Werner Meinberg, 
Andre Hartmann, Heiko Gerstung
Websites: https://www.meinberg.de  https://www.meinbergglobal.com
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