The Octave Before Christmas
December 17-23"The O Antiphons refer to the seven antiphons that are recited (or chanted) preceding the Magnificat during Vespers of the Liturgy of the Hours. They cover the special period of Advent preparation known as the Octave before Christmas, Dec. 17-23, with Dec. 24 being Christmas Eve and Vespers for that evening being for the Christmas Vigil."
December 18
"O Leader of the House of Israel,
giver of the Law to Moses on Sinai:
come to rescue us with your mighty power!"