Agnicayana
The Agnicayana (ati-rātra agni-cayana; lit. 'over-night piling up of the fire') or Athirathram (Malayalam: അതിരാത്രം) is a category of advanced Śrauta rituals. After one has established the routine of the twice-daily Agnihotra offerings and fortnightly darśa-pūrṇa-māsa offerings (Full and New Moon rites), one is eligible to perform the Agnistoma, the simplest soma rite.