Sizdah-bedar (National day to end Noruz) Friday April 2 2010 (the date changes according to the year)
*The thirteenth day of the Persian New Year marks the end of the Noruz break. This tradition is called Sizdah Bedar (sizdah means thirteen) which in English translates to "getting rid of thirteen". The concept of avoiding the number thirteen is mainly to symbolize the will and power to deal with all evil in the new year. ***http://www.farhangsara.com/13bedar.htm