Asia/Tehran

... the exact time of Iran's transition from +0400 to +0330 ... was Friday 1357/8/19 AP=1978-11-10. Here's a newspaper clip from the Ettela'at newspaper, dated 1357/8/14 AP=1978-11-05, translated from Persian (at Following the government's decision about returning the official time to the previous status, the spokesperson for the Ministry of Energy announced today: At the hour 24 of Friday 19th of Aban (=1978-11-10), the country's time will be pulled back half an hour. This is an English translation of what I just found (originally in Persian). The Gregorian dates in brackets are mine: Official Newspaper No. 13548-1370/6/25 [1991-09-16] No. 16760/T233 H 1370/6/10 [1991-09-01] The Rule About Change of the Official Time of the Country The Board of Ministers, in the meeting dated 1370/5/23 [1991-08-14], based on the suggestion number 2221/D dated 1370/4/22 [1991-07-13] of the Country's Organization for Official and Employment Affairs, and referring to the law for equating the working hours of workers and officers in the whole country dated 1359/4/23 [1980-07-14], and for synchronizing the official times of the country, agreed that: The official time of the country will should move forward one hour at the 24[:00] hours of the first day of Farvardin and should return to its previous state at the 24[:00] hours of the 30th day of Shahrivar. First Deputy to the President - Hassan Habibi From personal experience, that agrees with what has been followed for at least the last 5 years. Before that, for a few years, the date used was the first Thursday night of Farvardin and the last Thursday night of Shahrivar, but I can't give exact dates.... The text of the Iranian law, in effect since 1925, clearly mentions that the true solar year is the measure, and there is no arithmetic leap year calculation involved. There has never been any serious plan to change that law.... Go with Pournader for 1935 through spring 1979, and for timestamps after August 1991; go with 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. From Oscar van Vlijmen (2005-03-30), writing about future discrepancies between cal-persia and the Iranian calendar: For 2091 solar-longitude-after yields 2091-03-20 08:40:07.7 UT for the vernal equinox and that gets so close to 12:00 some local Iranian time that the definition of the correct location needs to be known exactly, amongst other factors. 2157 is even closer: 2157-03-20 08:37:15.5 UT. But the Gregorian year 2025 should give no interpretation problem whatsoever. By the way, another instant in the near future where there will be a discrepancy between arithmetical and astronomical Iranian calendars will be in 2058: vernal equinox on 2058-03-20 09:03:05.9 UT. The Java version of Reingold's/Dershowitz' calculator gives correctly the Gregorian date 2058-03-21 for 1 Farvardin 1437 (astronomical). Several of my users have reported that Iran will not observe DST anymore: From Reuters (2007-09-16), with a heads-up from Jesper Nørgaard Welen: ... the Guardian Council ... approved a law on Sunday to re-introduce daylight saving time ... This is quoted from Official Gazette of the Islamic Republic of Iran, Volume 63, No. 18242, dated Tuesday 1386/6/24 [2007-10-16]. I am doing the best translation I can:... The official time of the country will be moved forward for one hour on the 24 hours of the first day of the month of Farvardin and will be changed back to its previous state on the 24 hours of the thirtieth day of Shahrivar. Official IR News Agency announcement: irna.ir/xjJ3TT ... Highlights: DST will be cancelled for the next Iranian year 1402 (i.e 2023-March-21) and forthcoming years. Work around a bug in zic 2022a and earlier.