easy question: when dst transition occurs at 00:00 hours...
many locales undergo DST transition at midnight - for instance - on Thu 21 Sept 2000 19:30 - DST will end in Tehran, and local time will go from 00:00->23:00 (actually, from 23:59 to 23:00). My question is whether this extra hour occurs (locally) on thursday or friday. I'd assume thursday, as 00:00 doesn't arrive before the transition. can anyone confirm? thanks tc
At 09:24 -0700 2000-08-15, Thomas Carey wrote:
many locales undergo DST transition at midnight - for instance - on Thu 21 Sept 2000 19:30 - DST will end in Tehran, and local time will go from 00:00->23:00 (actually, from 23:59 to 23:00).
If "00:00 to 23:00" seems odd, you can say "24:00 to 23:00" - the change doesn't take a minute, it happens instantaneously. But just what time is it at that instant? Is that defined anywhere?
My question is whether this extra hour occurs (locally) on thursday or friday. I'd assume thursday, as 00:00 doesn't arrive before the transition.
can anyone confirm?
I can't confirm, but to me it would seem far stranger and more confusing to have periods from 23:00 to 24:00 both at the beginning and the end of the same day, than to have two lots of 23:00 to 24:00 consecutively within the same day. (I'm ignoring the question of the inclusivity or otherwise of the beginning and end instants of these periods.) --Alex -- _______________ Alex LIVINGSTON Macintosh and Lotus Notes Support / Information Technology (IT) Australian Graduate School of Management (AGSM) UNSW SYDNEY NSW 2052 / Australia Facsimile: +61 2 9931-9349 / Telephone: +61 2 9931-9264 Time : UTC+11---[last Mar. Sun.---UTC+10---[last Aug. Sun.---UTC+11--- At midday today, Wednesday, August 16, time since epoch (1-1-1 at 00:00:00) is 730347.5 days = 1999.62353779 average Gregorian years time until 3rd millennium, 21st century, 201st decade, 2001st year is 137.5 days = .37646221 average Gregorian years
On Tue, 15 Aug 2000, Thomas Carey wrote:
many locales undergo DST transition at midnight - for instance - on Thu 21 Sept 2000 19:30 - DST will end in Tehran, and local time will go from 00:00->23:00 (actually, from 23:59 to 23:00). My question is whether this extra hour occurs (locally) on thursday or friday. I'd assume thursday, as 00:00 doesn't arrive before the transition.
Before 1999, Israel used to change back to standard time at 00:00 (usually on a Saturday night) and this caused massive confusion since there were two 23:00 - 00:00 hours that night. In 1999, at the request of the Airport Authority the time change took place at 02:00 old time to avoid this confusion and having people miss flights because of this.
From 2000 onwards, the change back is slated to take place at 01:00 (why this was changed from 02:00 is beyond me).
Ephraim ___________________________________________________________________________ Ephraim Silverberg, CSE System Group, Phone number: 972-2-6585521 Hebrew University, Jerusalem, Israel. Fax number: 972-2-6585439 WWW: http://www.cs.huji.ac.il/~ephraim E-mail: ephraim@cse.huji.ac.il
participants (3)
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Alex LIVINGSTON -
Ephraim Silverberg -
Thomas Carey