The Agnicayana (ati-rātra agni-cayana; lit. 'over-night piling up of the fire')[1] or Athirathram (Malayalam: അതിരാത്രം) is a category of advanced Śrauta rituals.
After one has established the routine of the twice-daily routine of Agnihotra offerings and biweekly darśa-purna-masa offerings (Full and New Moon rites), one is eligible to perform the Agnistoma, the simplest soma rite.[2] After the agnistoma, one is eligible to perform more extensive soma rites and Agnicayana rites.[3] There are various varieties of Agnicayana.[4]
Agnicayana continues to be performed in Kerala and Andhra Pradesh.[5]