Hello, The current rule for Iran's 1979 DST start
Rule Iran 1979 only - May 26 24:00 1:00 - was introduced in 2022b on the basis of a single sentence in Movahedi (1985), quoted by Roozbeh Pournader on 2022-05-31. I have found contemporary newspaper evidence that bears on it, and it suggests the rule is one day late. SOURCE 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. The same heading and the same attribution appear in all four issues below, so the compiler and the method are unchanged across the period examined. Scanned facsimiles are public domain in Iran and are available from the Mashruteh archive. File names encode the Iranian date as Ettelaat<YYYY><MM><DD>: 1 Apr 1979 (1358-01-12) https://mashruteh.org/wiki/index.php/%D9%BE%D8%B1%D9%88%D9%86%D8%AF%D9%87:Ettelaat13580112.pdf 22 May 1979 (1358-03-01) https://mashruteh.org/wiki/index.php/%D9%BE%D8%B1%D9%88%D9%86%D8%AF%D9%87:Ettelaat13580301.pdf 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 27 May 1979 (1358-03-06) https://mashruteh.org/wiki/index.php/%D9%BE%D8%B1%D9%88%D9%86%D8%AF%D9%87:Ettelaat13580306.pdf The 1 April and 22 May issues also have copies on Wikimedia Commons: https://commons.wikimedia.org/wiki/File:Ettelaat13580112.pdf https://commons.wikimedia.org/wiki/File:Ettelaat13580301.pdf OBSERVED VALUES Issue Gregorian Today's maghrib Next day's solar noon 1358-01-12 1 Apr 1979 6:43 p.m. 12:10 1358-03-01 22 May 1979 7:26 p.m. 12:02 1358-03-05 26 May 1979 8:28 p.m. 1:02 p.m. 1358-03-06 27 May 1979 8:29 p.m. 1:03 p.m. COMPUTED VALUES (Tehran, 35.6893N 51.3896E, Swiss Ephemeris) sunset solar noon (next day) +03:30 +03:30 +04:30 1 Apr 1979 18:23 12:08 13:08 22 May 1979 19:05 12:01 13:01 26 May 1979 20:08* 12:01 13:01 27 May 1979 20:09* 12:01 13:01 (* computed at +04:30) The panel is internally consistent throughout: maghrib is always sunset plus 20-21 minutes, printed sunrise runs 4-6 minutes early, and printed solar noon runs 1-2 minutes late. The method therefore does not change across the four issues; only the clock does. Solar noon in particular cannot shift by 53 minutes between 1 April and 27 May, since the equation of time accounts for only about seven minutes over that interval. CONCLUSION On 1 April and 22 May 1979 the printed times correspond to UTC+03:30. On 26 May 1979 they correspond to UTC+04:30, and this includes that issue's own same-day maghrib, so the change was already in effect during 26 May. The present rule places the transition at 24:00 on 26 May, which makes 26 May a standard-time day. The newspaper contradicts this. A start of Rule Iran 1979 only - May 25 24:00 1:00 - would make 26 May the first DST day. 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. CAVEAT The archive lacks the issues of 23 and 24 May, and 25 May was a Friday with no publication, so the newspapers alone cannot exclude a transition on 23 or 24 May. They do, however, exclude 26 May as a standard-time day. I can supply page crops for any of the four issues. Best regards, N. F. Hase
