netherland timezone UTC offset (0:19:32.13) history
(I am not currently subscribed, please keep me CCed) Hi all, I'm interested in some specific timezone history. Specifically I'm curious about the origin of 'STDOFF 0:19:32.13'. Does anyone have an authoritative source for where this is derived from? Below is what I found so far: 1. In "NEWS" there is this entry: === zic now accepts subsecond precision in expressions like 00:19:32.13, which is approximately the legal time of the Netherlands from 1835 to 1937... === 2. Wikipedia here https://en.wikipedia.org/wiki/UTC%2B00:20 says === The reason for the specific offset of +0h 19m 32.13s was that the time zone was centered on the mean solar time of the Westertoren (4° 53' 01.95" E Longitude), the tower of the Westerkerk church in Amsterdam. === but I can't find any reference to this specific offset in any of the sources listed on Wikipedia. It is possible I missed the reference though. https://articles.adsabs.harvard.edu/pdf/1909Obs....32..297. https://books.google.com/books?id=MbA-AQAAIAAJ&pg=PA75&printsec=frontcover&n... 3. I've seen several references that cite *to* wikipedia or tzdata, but I haven't been able to find anything older. (if this is off topic for the mailing list I apologize, this is the best place I could find) -- Eitan Adler
On Mon, 5 Aug 2024 at 12:09, Eitan Adler via tz <tz@iana.org> wrote:
I'm interested in some specific timezone history. Specifically I'm curious about the origin of 'STDOFF 0:19:32.13'. Does anyone have an authoritative source for where this is derived from?
For one example, the backzone entry for Europe/Amsterdam contains the following comment: # The data entries before 1945 are taken from # https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm Section III of that webpage (in Dutch) has a subsection entitled "Eenheid van tijd in Nederland" ("Unit of time in the Netherlands") which states that, though the law did not specify the Amsterdam meridian, there was a general understanding to use "the meridian of the Westertoren (4° 53' 01.95" east longitude), corresponding to a time difference of 19 minutes 32.13 seconds with UT. However, for the sake of convenience, a rounded value of exactly 20 minutes was usually used." That page is the responsibility of Robert Harry van Gent and is hosted by the Faculty of Science at Universiteit Utrecht. -- Tim Parenti
On 2024-08-05 09:22, Tim Parenti via tz wrote:
That page is the responsibility of Robert Harry van Gent and is hosted by the Faculty of Science at Universiteit Utrecht.
Van Gent cites many sources for Amsterdam time (mostly in Dutch) here: https://webspace.science.uu.nl/~gent0113/wettijd/wt_text6b.htm Many of his sources are contemporaneous. It's an impressive list. Although it's not clear whether the ".32.13" is van Gent's calculation or is copied verbatim from one of those sources, it's surely close to the correct value insofar as that can be determined.
On Mon, 5 Aug 2024 at 09:53, Paul Eggert <eggert@cs.ucla.edu> wrote:
On 2024-08-05 09:22, Tim Parenti via tz wrote:
That page is the responsibility of Robert Harry van Gent and is hosted by the Faculty of Science at Universiteit Utrecht.
Van Gent cites many sources for Amsterdam time (mostly in Dutch) here:
https://webspace.science.uu.nl/~gent0113/wettijd/wt_text6b.htm
Many of his sources are contemporaneous. It's an impressive list.
Although it's not clear whether the ".32.13" is van Gent's calculation or is copied verbatim from one of those sources, it's surely close to the correct value insofar as that can be determined.
Wow! Thank you both. The Van Gent site in particular certainly seems complete - though I don't speak dutch. -- Eitan Adler
Hi, The origin of the non-standard time zone known as Amsterdam Time has a long and interesting history but to save you the trouble of wading through the website mentioned in earlier postings, the following will probably suffice. The adopted value of 0h 19m 32.13s was obtained by comparing the longitude of Leiden Observatory with the central meridian of the Topographische Kaart van het Koninkrijk der Nederlanden ("Topographical Map of the Kingdom of the Netherlands") which ran exactly through the Westertoren in Amsteradm and the longitude difference between Leiden Observatory and Greenwich Observatory as listed in the <i>Nautical Almanac</i>. Details can be found in this paper Hk. J. Heuvelink, "Amsterdamsche tijd", <i>De Ingenieur</i>, vol. 23 (1908), pp. 895-896, online here https://resolver.kb.nl/resolve?urn=dts:2951065:mpeg21:pdf See also p. 301 of https://ui.adsabs.harvard.edu/abs/1909Obs....32..297./abstract rvg From: tz <tz-bounces@iana.org> On Behalf Of Eitan Adler via tz Sent: Tuesday, August 6, 2024 12:19 AM To: Paul Eggert <eggert@cs.ucla.edu> Cc: Time zone mailing list <tz@iana.org> Subject: Re: [tz] netherland timezone UTC offset (0:19:32.13) history CAUTION: This email originated from outside of Utrecht University. Do not click links or open attachments unless you recognize the sender and know the content is safe. On Mon, 5 Aug 2024 at 09:53, Paul Eggert <eggert@cs.ucla.edu<mailto:eggert@cs.ucla.edu>> wrote:
On 2024-08-05 09:22, Tim Parenti via tz wrote:
That page is the responsibility of Robert Harry van Gent and is hosted by the Faculty of Science at Universiteit Utrecht.
Van Gent cites many sources for Amsterdam time (mostly in Dutch) here:
https://webspace.science.uu.nl/~gent0113/wettijd/wt_text6b.htm
Many of his sources are contemporaneous. It's an impressive list.
Although it's not clear whether the ".32.13" is van Gent's calculation or is copied verbatim from one of those sources, it's surely close to the correct value insofar as that can be determined.
Wow! Thank you both. The Van Gent site in particular certainly seems complete - though I don't speak dutch. -- Eitan Adler
participants (4)
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Eitan Adler -
Gent, R.H. van (Rob) -
Paul Eggert -
Tim Parenti