Egypt transitions around Ramadan don't match timeanddate.com
Hi, In 2014e tzdata NEWS file stated:
Release 2014e - 2014-06-12 21:53:52 -0700
Changes affecting near-future time stamps
Egypt's 2014 Ramadan-based transitions are June 26 and July 31 at 24:00. (Thanks to Imed Chihi.) Guess that from 2015 on Egypt will temporarily switch to standard time at 24:00 the last Thursday before Ramadan, and back to DST at 00:00 the first Friday after Ramadan.
Since Ramadan appears to start on Thursday, June 18 this year: http://www.timeanddate.com/holidays/us/ramadan-begins I'm not sure if we should be transitioning on June 18 or June 11. tzdata is set to transition on the June 11. While timeanddate is expecting to transition on June 18. The end of Ramadan transition back to DST also differs between timeanddate and tzdata. Can someone please confirm the correct transition dates? Thanks! Patsy
AFAIK, there's no guarantee that the transitions will occur *exactly* at the same time as Ramadan. The Egyptian government may use the Ramadan dates to decide when DST will change, but my guess is that DST will end *before* Ramadan, and resume *after*. It could be +/- a few days on either side.
Date: Wed, 1 Apr 2015 12:45:49 -0400 From: pfrankli@redhat.com To: tz@iana.org Subject: [tz] Egypt transitions around Ramadan don't match timeanddate.com
Hi,
In 2014e tzdata NEWS file stated:
Release 2014e - 2014-06-12 21:53:52 -0700
Changes affecting near-future time stamps
Egypt's 2014 Ramadan-based transitions are June 26 and July 31 at 24:00. (Thanks to Imed Chihi.) Guess that from 2015 on Egypt will temporarily switch to standard time at 24:00 the last Thursday before Ramadan, and back to DST at 00:00 the first Friday after Ramadan.
Since Ramadan appears to start on Thursday, June 18 this year: http://www.timeanddate.com/holidays/us/ramadan-begins
I'm not sure if we should be transitioning on June 18 or June 11. tzdata is set to transition on the June 11. While timeanddate is expecting to transition on June 18.
The end of Ramadan transition back to DST also differs between timeanddate and tzdata.
Can someone please confirm the correct transition dates?
Thanks! Patsy
On 04/01/2015 11:26 AM, Matt Johnson wrote:
The Egyptian government may use the Ramadan dates to decide when DST will change, but my guess is that DST will end *before* Ramadan, and resume *after*.
Yes, that's the basis for the guess in the tz database; since Ramadan probably starts June 18, a clock transition at 24:00 on June 18 would mean the first day of Ramadan wouldn't be covered, so we guess that the clock transition will happen at 24:00 the previous Thursday (June 11). Admittedly the start of Ramadan observance is more complicated than this brief summary implies; still, this is the approximation that the tz database is currently documented to be using (for more info please see the GNU Emacs Lisp source code in the comments). We won't know if this guess is correct until the Egyptian authorities announce their plan. For lack of better info it's probably better to leave the tz database alone for now.
participants (3)
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Matt Johnson -
Patsy Franklin -
Paul Eggert