[LEAPSECS] Leapsecs Listserve Moving.

[James Maynard]

M. Warner Losh wrote:

> In message: <7623093C-60C6-43CE-A6CE-D73557F18482 at noao.edu>

>             Rob Seaman <seaman at noao.edu> writes:

> : On Jan 31, 2007, at 8:52 PM, M. Warner Losh wrote:

> : 

> : > and 13 times when a leap second could have been inserted, but wasn't

> : > :-)

> : 

> : Make that 1 out of 84 opportunities by the standard as written.

> 

> Well, bulletin C says:

> 

>  Leap seconds can be introduced in UTC at the end of the months of December 

>  or June,  depending on the evolution of UT1-TAI. Bulletin C is mailed every  

>  six months, either to announce a time step in UTC, or to confirm that there 

>  will be no time step at the next possible date.

> 

> which is what I based my statement on.  The standard says that June

> and December are primary, and March and October are secondary times

> for a leap second.  Much of the gear in the field handles Jun/Dec OK.

> Some handles Mar/Oct.  But much of it won't handle Mar/Oct or other

> months.  ntpd handles only June/December.  This whole monthly thing,

> while technically allowed in the UTC standard, as a practical matter

> won't happen for a long, long time.  Even when the quadratic nature of

> leapseconds causes their frequency to be more often, I suspect a

> different mechanism will need to be in place.

> 

> Warner

> 

> 


The "standard," however, is not Bulletin C, but ITU-R Recommendation 
TF.460-4, which reads (Annex I, section D.2.1): "A positive or negative 
leap-second should be the last second of a UTC month, but first 
preference should be given to the end of December and June, and second 
preference to the end of March and September."

-- 
James Maynard
Salem, Oregon, USA