[ntp:questions] Leap second functional question

David L. Mills mills at udel.edu
Fri Feb 22 20:26:53 UTC 2008


I stand corrected; it was the CCIR, not the CCITT. This is because the 
ITU recommendations are specifically for standard time and frequency 
dissemination by, for example, WWV/B/H and their international counterparts.

My reference for leap second introduction was CCIR Recommendation 517, 
which permits leaps only June/December. However, I just dug up the most 
recent ITU-R Proposed Recommendation TF.460-6 (2007) 
www.fcc.gov/ib/sand/irb/weritacrnc/archives/nc1893wp7a/1.doc, which says 
first preference is June/December, second preference is March/September 
and that standard time will continue in UTC with DUT1 and leap seconds.

I hope this is the end of it, but I bet it's not.


sla29970 at gmail.com wrote:

> On Feb 21, 3:15 pm, "David L. Mills" <mi... at udel.edu> wrote:
>>The current
>>code here can leap at the end of any month, which seems to be the
>>prevailing view of the standards folks. However, I can't find
>>confirmation at the IERS site.
> Images of the IAU proceedings from the General Assembly in 1973 are at
> http://www.ucolick.org/~sla/leapsecs/iau/proc1973p154.gif
> http://www.ucolick.org/~sla/leapsecs/iau/proc1973p155.gif
> This was the assembly immediately after leap seconds began (and the
> first one at which the IAU could make any response, given that the
> CCIR neglected to send them a letter in 1970 leaving them no standing
> upon which to comment on leap seconds before they began).  The changes
> recommended by the IAU in 1973 were incorporated into the first
> revision of what is now known as ITU-R TF.460, notably, that it was
> foreseeable that leap seconds would be needed more than twice a year.

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