This is the Marian Antiphon for Compline during the seasons of Advent and Christmas. It is used from the First Sunday of Advent until the Feast of the Purification of the Blessed Virgin Mary (February 2).
Mother of Christ! hear thou thy people’s cry,
Star of the deep, and Portal of the sky!
Mother of Him who thee from nothing made,
Sinking we strive, and call to thee for aid:
Oh, by that joy which Gabriel brought to thee,
Thou Virgin first and last, let us thy mercy see.
Words: Herman Contractus, 11th C.; tr. Fr. Edward Caswall, 1849.
Simple Tone: “Alma Redemptoris Mater (Simplex)” Gregorian Chant, Mode V, traditional.
Solemn Tone:“Alma Redemptoris Mater (Solemnis)” Gregorian Chant, Mode V, traditional.
The original Latin text may be found here.