According to the Internet source given below, Sebastian Aguilera de Heredia was a Spanish organist. He was organist at the cathedral of Huesca (Aragon) from 1585 until 1603, when he moved on to Saragossa. His fine and austere Magnificats à 4 - 8, published in 1618, remained long in use, and his tientos in various styles are among the best Spanish organ music of the period. He was one of the Spanish composers whose music was exported to Mexico.
||Sebastian Aguilera de Heredia
||Brief biography by www.hoasm.org