Posh Sud Purnima, i.e. the fifteenth day of the Full Moon Day of month of Posh as per the Vikram Samvat year of Indian Hindu calendar, is religiously believed to be the Birthday of Mata Arasuri Ambaji . Hence it is celebrated with joy at the instance of Shri Arsuri Ambaji Devastan Trust by all the people and devotees of Ambaji, coming from all over the world. Mainly on this holy festival of Poshi Poonam, A big Satchandi Yagna is performed by the temple trust in a quite traditional manner with all the Vedic rituals and Mata Ambaji is worshiped with Om Havan and Annakoot, in which Mataji is offered with different kinds of Foods, Fruits and Pakvan and Prasad are distributed to all the devotees and the poor people. The Main Temple of Ambaji and the total Temple complex together with the surroundings area of Chachar Chowk is also nicely illuminated with colorful lightings from all corners, as it is so done during other Festivals of Ambaji Devasthan and all the devotees use to play, dance and enjoy Garba of Mata Ambaji in front of the main temple in this Chachar Chowk, during the whole period of this holy night, in the cool moon light of full moon night of Posh Month of each year. In the morning on Purnima, a huge colorful procession, together with the mass of the dancing people and devotees of Mata Ambaji, and the Silver Rath (Cart ) of Mata Arasuri Ambaji starts from the Northern Gate of the temple complex and reaches to the Main temple.