This feast commemorates the appearing of our Lady on several occasions in 1858 at Lourdes in France.
Today is the 150th anniversary of the first apparition of our Lady of Lourdes to St. Bernadette. A plenary indulgance is available (click this link and scroll to the bottom of the page).
Although sadly eliminated in the creation of the Novus Ordo, in the traditional propers for today's Mass a passage from the Canticle of Canticles is selected for its reference to the "dove" appearing in a cleft of a rock; similarly, the Communion verse applies the words of Psalm 64 to the miraculous spring which Mary caused to appear in the Grotto.
Introit (Apoc. 21:2; Ps. 44:2)
I saw the holy city, the new Jerusalem, coming down out of heaven from God, prepared as a bride adorned for her Husband. (Psalm) My heart hath uttered a good word: I speak my works to the King. Glory be to the Father. I saw...
O God, Who by the Immaculate Conception of the Virgin didst prepare a worthy dwelling for Thy Son: we humbly beseech Thee, that we, who celebrate the Apparition of this same Blessed Virgin, may obtain health of soul and body. Through our Lord.
Epistle (Apoc. 11:19; 12:1, 10)
The vision of the Woman clothed with the sun
Gradual (Cant. 2:12,10,14)
The flowers have appeared in our land, the time of pruning is come, the voice of the turtle is heard in our land. Arise, My love, My beautiful one, and come; My dove in the cleft of the rock, in the hollow places of the wall.
Tract (Jud. 15:10)
Thou art the glory of Jerusalem, thou art the joy of Isreal, thou art the honor of our people. Thou art all fair, O Mary, and the original stain is not in thee. Truly happy art thou, O holy Virgin Mary, and most worthy of all praise; for with thy virginal foot thou hast crushed the serpent's head.
Gospel (Luke 1:26-31)
Gospel of the Annunciation by the Angel to the Blessed Virgin Mary
Offertory (Luke 1:28)
Hail, full of grace, the Lord is with thee; blessed art thou among women.
May this sacrifice of praise which we offer to Thee, O Lord, through the merits of the glorious and Immaculate Virgin, be to Thee as a sweet-smelling savor, and may it bring to us the health of soul and body which we desire. Through our Lord.
Communion (Ps. 64:10)
Thou has visited the earth, and hast plentifully watered it: thou has many ways enriched it.
O Lord, may the right hand of Thine Immaculate Mother uplift us whom Thou hast satisfied with heavenly food: that by her help we may win through to our eternal homeland. Who livest and reignest.