[LEAPSECS] Reliability

[Rob Seaman]

Adi Stav wrote:


> Rob Seaman wrote:

>>

>

>> Coordinate leap seconds with leap days.  Introduce an integral  

>> number of leap seconds each February 29th.  Discuss.

>

> February 29th does not start and end all over the world at the same  

> time.


This is no different than the end of December or June.  In fact, the  
current standard already permits leap seconds to be issued at the end  
of February, and that would sometimes mean February 29th.


> Some time zones will get the leap during the 28th, others in March  

> the 1st.


The leap occurs at midnight UTC on 30 June or 31 December.  These  
dates apply west of Greenwich, e.g., we saw the leap second in Tucson  
at 5 pm on New Years Eve.  East of Greenwich it is already the morning  
of 1 July or 1 January when the leap second occurs.

Confusion doesn't happen near the IDL since it is just before noon on  
the first day of the month on one side of the line or just after noon  
on the last day of the preceding month on the other side.

So just as with all the other months (and all are currently  
permissible), the leap second occurs in all localities on the last day  
of one month or the first day of the next.  It never occurs on day N-1.

I don't think any of this affects the interpretation of the word  
"coordinate".  It does, perhaps, emphasize that intercalary  
corrections to the calendar are made in coordination with our clocks  
(29 February begins at 0h local time).  And it should emphasize that  
intercalary corrections to our clocks have to be made in coordination  
with our calendar (1231T235960Z or 0630T235960Z).

The civil clock is a subdivision of the civil calendar.

Rob