Achyuta Pisharati

Acyuta Piṣāraṭi (c. 1550 at Thrikkandiyur (aka Kundapura), Tirur, Kerala, India – 7 July 1621 in Kerala), also known as Achyuta Pisharati or Achyutha Pisharadi, was a Sanskrit grammarian, astrologer, astronomer and mathematician who studied under Jyeṣṭhadeva and was a member of Madhava of Sangamagrama's Kerala school of astronomy and mathematics.

Works He discovered the techniques of 'the reduction of the ecliptic'. He authored Sphuta-nirnaya, Raasi-gola-sphuta-neeti (raasi meaning zodiac, gola meaning sphere and neeti roughly meaning rule), Karanottama (1593) and a four- chapter treatise Uparagakriyakrama on lunar and solar eclipses.

The book of slokas written by Narayana were named Narayaneeyam. The day on which Narayana dedicated his Narayaneeyam to Sri Guruvayurappan is celebrated as "Narayaneeyam Dinam" every year at Guruvayur.