[time-nuts] Loran-C & French Clocks

M. Warner Losh imp at bsdimp.com
Wed Mar 18 11:35:13 EDT 2009


And when people are asking about UTC vs GMT, it should be noted the
real question is "Is legal time defined to be UTC, or is it defined to
be mean solar time?"  GMT is mean solar time, except for all the silly
confusion caused by folks who think it is the same as UTC.  See recent
threads on LEAPSECONDS for perfectly reasonable people that still get
this distinction wrong...

Warner

In message: <E1LjiOr-0007z8-KY at meow.febo.com>
            "Arnold Tibus" <Arnold.Tibus at gmx.de> writes:
: 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:
: http://www.apparent-wind.com/gmt-explained.html 
: 
: 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...!
: 
: Arnold
: 
: 
: 
: 
: 
: On Tue, 17 Mar 2009 21:12:18 -0000, Jean-Louis Oneto wrote:
: 
: >Hello,
: >The French Legal Time Reference is defined since a 1978 decree by the 
: >UTC(OP) realisation of UTC, as stated here:
: >http://syrte.obspm.fr/index.php?prefix=temps&lang=en
: 
: >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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