Antónia d'Astónaco was a Portuguese Carmelite nun who reported a private revelation by Saint Michael the Archangel.
Based on that revelation, the Archangel Michael had told in an apparition to the devoted Servant of God that he would like to be honored, and God glorified, by the praying of nine special invocations. These nine invocations correspond to invocations to the nine choirs of angels and origins the Chaplet of Saint Michael.
This private revelation and prayers were approved by Pope Pius IX in 1851.