[time-nuts] Time offset

phil fortime at bellsouth.net
Wed Mar 18 21:01:32 EDT 2009


----- Original Message ----- 
From: "Magnus Danielson" <magnus at rubidium.dyndns.org>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Wednesday, March 18, 2009 7:20 PM
Subject: Re: [time-nuts] Time offset


> Phil,
>
> phil skrev:
>> Magnus,
>>
>> The most comprehensive collection of time offset data and reference to 
>> each
>> countries latest laws might be found at:
>> http://www.twinsun.com/tz/tz-link.htm
>
> As far as I can see, it works under assumption that GMT = UTC. Thus, it
> fails on my lackmus test of GMT+1h for Denmark.
>
> While it is a great resource, if fails this fine distinction that I was
> asking about.
>
> Cheers,
> Magnus

Magnus,
On that same page was a link to an older archive, tzarchive.gz 
ftp://elsie.nci.nih.gov/pub/tzarchive.gz

You will find references to actual laws and links imbedded in that for 
various countries. Your assumption that that GMT = UTC I would say is true 
from 1970 on.

GMT was the first internationally accepted international/global standard 
with various "legally" defined offsets. It was only after the advent of the 
cesium and the gps system that UTC became the standard, again with the legal 
offsets. Most older law, pre 1970 I've seen references to gmt, but when laws 
are appended for example saving time, reference is often or sometimes made 
to utc, though the old legal definition may still reference gmt.

Perhaps most lawmakers accept them (gmt, utc) to be the same with their 
local/regional offsets now that you can get standardized utc off satellites 
world wide.

Other than the "flying clock" how else can all countries of the world 
synchronize their time? I think a lot of small countries have a single 
cesium, if that, tied to gps and vend their countries "official" time based 
on that. In that case they are based on UTC regardless of the wording of 
their prior law.

I know in North Carolina, USA a law was still on the books a few years ago 
that it was illegal to look at your wife naked. Law is often slow to catch 
up with society and technology. The various countries definitions of time 
referencing GMT may too be laws that have not come into the twentieth 
century though utc (with offsets) is now the accepted standard.

Phil 





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