That's today, the last day of Epiphanytide. The "daft days", so called in ancient Scotland due to all the merry-making, ended with Hogmanay. The 12 days of Christmas ended on 6 January, the proper feast of the Epiphany. The Pauline Rite ends Christmas and Epiphany on 13 January, the feast of the Baptism of the Lord. And the last real liturgical day counted from Christmas is Candlemas which is 2 February. Everything else in the traditional Roman Rite is counted as weeks after Epiphany until Septuagesima.
And tomorrow is Septuagesima Sunday, which makes today the very last day of Epiphanytide.
Septuagesima begins the pre-Lenten period. We won't hear the Alleluia in the traditional rite again until the Easter vigil. A farewell to the Alleluia hymn used to be sung at Vespers on this Saturday but nothing so florid remains even in the traditional rite. Here's one of those hymns taken from Dom Gueranger's The Liturgical Year
with the translation of Dom Laurence Shephard, O.S.B.
And from 13th century France:
Alleluia dulce carmen,
Vox perennis gaudii,
Alleluia laus suavis
Est choris coelestibus,
Quam canunt Dei manentes
In domo per saecula.
Alleluia laeta mater
Concivis Jerusalem :
Alleluia vox tuorum
Civium gaudentium :
Exsules nos flere cogunt
Alleluia non meremur
In perenne psallere ;
Alleluia vo reatus
Cogit intermittere ;
Tempus instat quo peracta
Unde laudando precamur
Te beata Trinitas,
Ut tuum nobis videre
Pascha des in aethere,
Quo tibi laeti canamus
The sweet Alleluia-song, the
word of endless joy, is the melody
of heaven's choir, chanted by them
that dwell for ever in the house
O joyful mother, O Jerusalem our
city, Alleluia is the language of thy
happy citizens. The rivers of
Babylon, where we poor exiles live,
force us to weep.
We are unworthy to sing a ceaseless
Alleluia. Our sins bid us interrupt our
Alleluia. They time is at hand when
it behoves us to bewail our crimes.
We, therefore, beseech thee whilst
we praise thee, O blessed Trinity!
that thou grant us to come to that
Easter of heaven, where we shall
sing to thee our joyful everlasting