Persian dating rules
For a succession of Iranian solar calendars, see Iranian calendars.
or Shamsi Hijri calendar, and abbreviated as SH, is the official calendar of Iran and Afghanistan.
The Solar Hijri calendar produces a five-year leap year interval after about every seven four-year leap year intervals.
It usually follows a 33-year cycle with occasional interruptions by single 29-year or 37-year subcycles.
It revived the ancient Persian names, which are still used.It begins on the vernal equinox (Nowruz) as determined by astronomical calculation for the Iran Standard Time meridian (52.5°E or GMT 3.5h).This determination of starting moment is more accurate than the Gregorian calendar for predicting the date of the vernal equinox, because it uses astronomical observations rather than mathematical rules.The names are in fact the Arabic names for signs of Zodiac, please see دائرة البروج.In the Iranian calendar, every week begins on Saturday and ends on Friday.