leapsecs  

Re: What problems do leap seconds *really* create?

Markus Kuhn
Wed, 29 Jan 2003 11:04:44 -0800

John Cowan wrote on 2003-01-29 17:56 UTC:
> The problem is that they are not announced much in advance, and one needs
> to keep a list of them back to 1972 which grows quadratically in size.

Is this a real problem?

Who really needs to maintain a full list of leap seconds and for what
application exactly?

Who needs to know about a leap second more than half a year in advance
but has no access to a time signal broadcasting service (the better ones
of which all carry leap second announcement information today)?

For pretty much any leapsecond-aware time-critical application that I
can think of, it seems more than sufficient to know:

  - the nearest leap second to now
  - TAI-UTC now
  - UT1-UTC now

This information is trivial to broadcast in a fixed-width data format.
(For the nitpicker: The number of bits to represent TAI-UTC admittendly
grows logarithmically as be move away from 1950. We know we can live
with that, as O(log(t)) is equivalent to O(1) for engineering purposes.)

Markus

--
Markus Kuhn, Computer Lab, Univ of Cambridge, GB
http://www.cl.cam.ac.uk/~mgk25/ | __oo_O..O_oo__