Thiruvannamalai Maha Deepam will be lit at around 6 pm at the top of 2668 ft high holy mountain. The entire Mountain is shiva Linga. Maha Deepam will be lit using nearly 3500 kg of Ghee. Sri Arthanareeshwara will bless devotees in the temple at the time of lighting the Maha Deepam. The Maha Deepam will be visible around the Holy Mountain in a radius of 35 km. Lakhs of devotees will perform 16 km Girivalam (circumambulation of the holy mountain).
The Moist Black Ash (what they call as 'Mai' in Tamil) that remains after the lighting of the ghee & Cotton Wick will be distributed as Prasadam to devotees on the Marghazhi Arudra Darisanam day.
As in Tiruvannamalai, tamilnadu, Karthigai festival is also famous in Koneshwaram, Trincomakee, Srilanka. The festival is celebrated for three days. The first day is called Appa Karthigai, the second Vadai Karthigai and the final day is called Thiru Karthigai, widely considered as the Karthigai day, when the main pooja is performed. On Karthigai day, a huge fire lamp is lit up on the hill(in both temples), visible for several kilometers around. The fire (deepam) is called Mahadeepam. hindu devotees visit the place, to pray and make offerings to lord Shiva.