A sacrifice (yajña) requiring five priests; it may be performed three times a year on the full moon days at the beginning of spring, the rainy season, and autumn/winter as part of the duties of the Vedic śrauta sacrificer. Individually these sacrifices are known as Vaiśvadeva, Varuṇapraghāsa, and Sākamedha, each comprising a parvan or ‘part’ of the sequence as a whole. A fourth sacrifice, Śunāsīrīya, for which there is no fixed time, may also be performed at will. The cāturmāsyas may either be performed throughout the sacrificer's (yajamāna's) life or for one year only. Heaven is said to be the reward.