Today is the Octave Day of the Ascension of the LORD. The Octave Day is of greater double rite. The semi-double feast of St. Bernardine of Siena is simplified and is commemorated at both Vespers, Lauds and Mass.
The Office began with first Vespers yesterday afternoon. The antiphons Viri Galilaei etc are sung with the psalms, chapter and hymn that were used at first Vespers on the feast. A commemoration is sung of St. Bernardine and of the preceding Office of St. Peter Caelestine.
At Mattins all is sung as on the feast except the lessons. In the first nocturn the lessons are from the fourth chapter of St. Paul's Epistle to the Ephesians. In the second nocturn the lessons are taken from a sermon of St. Augustine on the Ascension and St. Gregory provides the homily on St. Mark's Gospel in the third nocturn. At Lauds the antiphons Viri Galilaei etc are sung with the Dominical psalms, a commemoration is sung of St. Bernardine.
At the Hours the Doxology of the Ascension is sung at the conclusion of the hymns. At Prime the festals psalms are sung.
Mass is sung after Terce. The Gloria is sung, the second collect is of St. Bernardine. The Creed is sung, the preface and communicantes are of the Ascension.
At second Vespers a commemoration is sung of St. Bernardine.
Tomorrow is rather a curiosity, from a liturigcal perspective. Friday after the Octave Day of the Ascension is of semi-double rite and in some ways is treated like another day within the Octave. The Office is that of the previous Sunday. The psalms and antiphons at Mattins are those used on the Ascension. Mattins has three nocturns. At Lauds the antiphons Viri Galilaei are sung with the Dominical psalms. Although of semi-double rite the Commemoration of the Cross is not sung.
At Prime the festal psalms are sung, the Dominical preces are omitted. At the other Hours the Sunday psalms are sung. Mass is sung after Terce. The Mass is Exaudi, Domine as sung on the previous Sunday. The Gloria is sung, the second collect is Concede nos, the third collect Ecclesiae or for the pope. The preface is of the Ascension. At Vespers the Commemoration of the Cross is omitted and at Compline the preces are not sung. When a feast of nine lessons occurs the Friday after the Ascension is commorated in the Office and at Mass.
In 'the liturgical books of 1962' the Octave has of course been abolished. St. Bernardine of Siena becomes a third class feast of one nocturn. The Friday is a fourth class ferial day, the Mass is of the Ascension without the communicantes and with only one collect.