[time-nuts] What time is it anyway?

[Magnus Danielson]

Steve Rooke wrote:
> So there are 250 clocks, presumably, spread around the World and owned
> by the member countries of the BIPM.
There is a fair spread geographically, yes. See map:

http://www.bipm.org/en/scientific/tai/tai.html
> Their time is somehow compared centrally and an "absolute" time is determined from them.
They are compared by various methods in a network style of operation. 
The sites are compared against each other and the clocks of each site is 
compared against the clock driving the network comparison. Hence, 
through these steps phase differences can be cranked out.

http://www.bipm.org/en/scientific/tai/clock_comparisons.html

Equipment calibrations:
http://www.bipm.org/jsp/en/TimeCalibrations.jsp
> Each clock will then have a delta to apply to it's own time to provide the BIPM
> "absolute" time which then allows each member country to use its own
> clock for timing.
>   
Yes, out comes the delta of each individual clock as well as the 
individual labs. These are reported upon regularly to be found in BIPM 
circular T:

http://www.bipm.org/jsp/en/kcdb_data.jsp
ftp://ftp2.bipm.org/pub/tai/publication/cirt.266

Useful resource:
http://www.bipm.org/jsp/en/TimeFtp.jsp?TypePub=publication
> This sounds like a logistic and bureaucratic nightmare,  I will have
> to look further as to how this is achieved. Any pointers gratefully
> accepted.
I hope the above pointers get you started.

They have spent some time cooking this up, yes.

Toss into that, we have not really spoken too much about how they 
process things. I can't tell you too much about it, except that I know 
that their tool is called ALGOS. If someone could give me the 
appropriate articles I would be greatful.

Cheers,
Magnus