Yesterday, today and tomorrow, Wednesday, are days within the Octave of the Epiphany. They are of semi-double rank.
Mattins has the normal structure, as was resumed on the 7th, with the opening verse Domine, labia, invitatory psalm and hymn. The antiphons and psalmody is as on the feast (but the antiphons are not doubled) but in the third nocturn the psalm Fundamenta replaces the special arrangement of psalm 94. Yesterday, the Incipit of the Epistle to the Corinthians was read in the first nocturn (displaced from the Sunday within the Octave by the feast of the Holy Family) with the first responsory Hodie. Corinthians continues to be read throughout the Octave but with Tria sunt as the first responsory. The second nocturn lessons are from St. Maximus (yesterday), St. Fulgentius today and from St. Leo tomorrow. In the third nocturn the homilies are from St. Jerome (yesterday), St. Ambrose, today, and St Augustine on Wednesday.
At Lauds the antiphon on the Benedictus is proper for each day. At the Hours the antiphons and psalmody is as on the feast, the hymns having the Doxology and melody of the Epiphany. Today a commemoration is sung at Lauds, and was sung at Vespers yesterday, of St. Hyginus. At Prime the versicle Qui apparuisti is sung in the short responsory and the lectio brevis is Omnes de Saba venient.
At Mass, today, the Gloria is sung, the second collect is of St. Hyginus, the third collect of the the BVM, Deus, qui salutis. The Credo is sung and the preface and communicantes are as on the feast. On other days within the Octave the second collect is of the BVM and the third for the Church.
Vespers are of the Octave with the antiphon on the Magnificat being proper to each day. Compline is festal.
In the 'liturgical books of 1962' these days after the Epiphany become IV class ferial days of Epiphanytide. Mattins has one nocturn and the psalmody is ferial. At the Hours the hymns do not have the Doxology in honour of the Epiphany and again have ferial psalmody. Despite the ferial psalmody the antiphons are doubled. At Mass the texts of the Sunday 'after' the Epiphany are sung, the Gloria is sung, the additional collects and Credo are omitted. St. Hyginus gets a commemoration at Low Mass only today. Vespers has ferial psalmody as does Compline.