Solar Hijri calendar
The Solar Hijri calendar is a solar calendar and one of the various Iranian calendars. It begins on the March equinox as determined by the astronomical calculation for the Iran Standard Time meridian (52.5°E, UTC+03:30) and has years of 365 or 366 days. It is the modern principal calendar in Iran and is sometimes also called the Shamsi calendar and Khorshidi calendar. It is abbreviated as SH, HS or, by analogy with AH, AHSh. The ancient Iranian Solar calendar is one of the oldest calendars in the world, as well as the most accurate solar calendar in use today.