[time-nuts] Loran-C & French Clocks

Arnold Tibus Arnold.Tibus at gmx.de
Tue Mar 17 23:07:39 UTC 2009

Magnus and all,

interestlingly the discussion about GMT seem to be a never ending 
story, all over the world. As I know GMT was already renamed  in 
the year 1925 ( or 1928 acc. other source ) to UT and 
"universal time coordinated" (U T C) (that) is standard since 
January 1, 1972. acc. "About the Time" :

http://www.fai.org/astronautics/time.asp ,
look into the short overview to this history. 

"Does anyone know the exact difference between GMT and UTC?" 
- this question seem to be already very old, Magnus. 

Richard B. Langley wrote a summary trying to give the right 
answer with "A Few Facts Concerning GMT, UT, and the RGO ". 

His article can be found here:

It summarizes:
"The Greenwich mean time, GMT, has today only an historical 
interest. It has been abandoned since the thirties for successively
 the T U 1, the T U 2 and finally, in 1972, for the much more regular 
universal time coordinated, U T C, that must be used 
for all present use." ! 

That is what I thought as well quite a while. 
But I had to change ever so often all kind of scientific and 
technical units, and I see the need to adopt it, I am sure we have 
to be open for more steps into the future. Learning will never end...!


On Tue, 17 Mar 2009 21:12:18 -0000, Jean-Louis Oneto wrote:

>The French Legal Time Reference is defined since a 1978 decree by the 
>UTC(OP) realisation of UTC, as stated here:

>Furthermore, the International Earth Rotation Service at Paris Observatory 
>is responsible for the leapseconds insertion in UTC...
>Have a nice day,
>Jean-Louis Oneto
>Grasse - France

>----- Original Message ----- 
>From: "Magnus Danielson" <magnus at rubidium.dyndns.org>
>To: "Discussion of precise time and frequency measurement" 
><time-nuts at febo.com>
>Sent: Tuesday, March 17, 2009 7:27 PM
>Subject: Re: [time-nuts] Loran-C & French Clocks

>> Arnold,
>>> I therefore cannot see any problem is with France,
>>> but we have the need to define more precise and stable
>>> reference time from where we can then measure and add
>>> the Earth and Solar instabilities for our daily used standard
>>> watches, in order to be enabled still to continue living and
>>> travelling sun synchronously....
>>> I hope not having been informed wrong so far,
>>> kind regards and always precise time
>> Please recall that just because the TAI and UTC clocks is being
>> maintained by BIPM just outside of Paris does not mean the same as being
>> legally accepted basis of time within France.
>> Citing relevant law stating that the time of France shall be UTC + 1h
>> for normal time and UTC + 2h for summer time is providing the piece of
>> the puzzle that I was asking for.
>> I have read Swedish and Danish law in this respect, as well as most
>> translations of the EC directive on summertime.
>> It should be noted that I do not assume UTC = GMT.
>> Cheers,
>> Magnus

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