Thanks for the correction. From what you write, it appears that we
misread the sources for that transition, and made the common mistake of
thinking it was a transition at 24:00 when it was really a transition at
00:00. To fix this, I installed the attached patch on the development
repository on GitHub.From 7f78d3fd8ba7bbd3f5dc2ae1b16dac1845edd293 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Mon, 27 Jul 2026 10:46:11 -0700
Subject: [PROPOSED] =?UTF-8?q?Iran=E2=80=99s=201989-05-26=20spring=20forwa?=
=?UTF-8?q?rd=20was=20at=2000:00?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
(Thanks to N.F. Hase.)
* NEWS: Mention this.
* asia (Iran): Change 1979 May date from 26 to 25.
---
NEWS | 3 +++
asia | 20 ++++++++++++++++----
2 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/NEWS b/NEWS
index 35816c2f..99b58d09 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,9 @@ Unreleased, experimental changes
Colombia’s 1992-05-02 spring forward was at 00:00, not 24:00.
+ Iran’s 1989-05-26 spring forward was at 00:00, not 24:00.
+ (Thanks to N.F. Hase.)
+
The backward-compatibility names EST5EDT, CST6CDT, MST7MDT, and
PST8PDT now conform better to POSIX. For example, EST5EDT now
always uses the abbreviation "EST" for standard time (now always 5
diff --git a/asia b/asia
index dd76bdfc..4d41d09e 100644
--- a/asia
+++ b/asia
@@ -1544,9 +1544,21 @@ Zone Asia/Jayapura 9:22:48 - LMT 1932 Nov
# leap year calculation involved. There has never been any serious
# plan to change that law....
#
-# From Paul Eggert (2022-06-30):
-# Go with Pournader for 1935 through spring 1979, and for timestamps
-# after August 1991; go with with Shanks & Pottenger for other timestamps.
+# From N.F. Hase (2026-07-26):
+# Ettela'at (Tehran daily) printed a daily panel headed "taqvim-e
+# Ettela'at / sa'at-ha-ye shar'i", attributed to Dr. Riyazi Kermani.
+# Each panel gives today's maghrib followed by fajr, sunrise, solar noon
+# and maghrib for the next day, together with the Iranian, Hijri and
+# Gregorian dates.... 26 May 1979 (1358-03-05)
+# https://mashruteh.org/wiki/index.php/%D9%BE%D8%B1%D9%88%D9%86%D8%AF%D9%87:Ettelaat13580305.pdf
+# ... That also matches Movahedi's wording, that the government
+# returned to DST on 26 May, and the note in the 2022 thread that the
+# change was announced one day in advance on 25 May.
+#
+# From Paul Eggert (2026-07-26):
+# Go with Pournader for 1935 through spring 1979 (with the last
+# transition clarified by Hase), and for timestamps after August 1991;
+# go with Shanks & Pottenger for other timestamps.
# Go with Santoni's citation of the UIT for fall 1977, as 20 October 1977
# is 28 Mehr 1356, consistent with the "Mehr" in Pournader's source.
# Assume that the UIT's "1930" is UTC, i.e., 24:00 local time.
@@ -1597,7 +1609,7 @@ Rule Iran 1977 only - Mar 21 23:00 1:00 -
Rule Iran 1977 only - Oct 20 24:00 0 -
Rule Iran 1978 only - Mar 24 24:00 1:00 -
Rule Iran 1978 only - Aug 5 01:00 0 -
-Rule Iran 1979 only - May 26 24:00 1:00 -
+Rule Iran 1979 only - May 25 24:00 1:00 -
Rule Iran 1979 only - Sep 18 24:00 0 -
Rule Iran 1980 only - Mar 20 24:00 1:00 -
Rule Iran 1980 only - Sep 22 24:00 0 -
--
2.53.0
