Which South Indian poet and composer has a school of music where Sooryakantam  is called Chāyāvati ?
Muthuswami Dikshitar Muthuswami Dikshitar (March 24, 1775 – October 21, 1835) was a South Indian poet and composer and is one of the Musical Trinity of Carnatic music. His compositions, of which around 500 are commonly known, are noted for their contemplative nature and for capturing the essence of the raga forms through the vainika (veena) style that emphasises gamakas. They are typically in a slower speed (chowka kala). He is also known by his signature name of Guruguha which is also his mudra (can be found in every one of his songs). His compositions are widely sung and played in classical concerts of Carnatic music.
Chaitanya Mahaprabhu Chaitanya Mahaprabhu ((also transliterated Caitanya Mahāprabhu); 18 February 1486 – 14 June 1534) was a spiritual leader who founded Gaudiya Vaishnavism. He is believed by some of his devotees to be Krishna himself who appeared in the form of His own devotee in order to teach the people of this world the process of Bhakti and how to attain the perfection in life. He is considered as the most merciful manifestation of Krishna . Chaitanya was the proponent for the Vaishnava school of Bhakti yoga (meaning loving devotion to God), based on "Bhagavata Purana" and "Bhagavad Gita". Of various incarnations of Vishnu, he is revered as Krishna, popularised the chanting of the "Hare Krishna" mantra and composed the "Siksastakam" (eight devotional prayers) in Sanskrit. His followers, Gaudiya Vaishnavas, revere him as a Krishna with the mood and complexion of his source of inspiration Radha. His birthday is celebrated as Gaura-purnima.