While October 28th is the Feast of Ss Simon and Jude, Apostles, October 27th is the Vigil of these two saints.
The Vigil of SS Simon and Jude is of simple rite and its liturgical colour is violet. This day was kept prior to the 1962 Missal so those Catholics still worshipping according to the 1954 Calendar, will observe today as the Vigil of Ss. Simon and Jude.Collect: Grant, we beseech Thee, almighty God, that even as we anticipate the glorious festival of Thy apostles Simon and Jude, so they, in imploring from Thy majesty thy blessings for us, may anticipate our prayers.
The Office is largely taken from the ferial Office of Monday but the lessons at Mattins and the collect are proper to the Vigil. At Mattins the ferial invitatory, Venite, Exsultemus Domino, is sung and the Office hymn is Somno refectis artubus. The nine antiphons and psalm divisions for Monday are sung followed by the versicle Psallite Domino etc and its response Et confitemini etc. As the lessons for the Vigil contain a Gospel after the Absolution, Exaudi, Domine etc., the first blessing is Evangelica lectio etc. The Gospel fragment is from St. John and the homily is taken from the writings of St. Gregory. The Te Deum is not sung. The second scheme of Lauds for Monday is sung beginning with the antiphon fragment Ecce veniet. After the antiphon on the Benedictus has been repeated the ferial preces are sung, with the choir kneeling. After the collect of the Vigil the Suffrage of the Saints is sung.
At Prime a fourth psalm is added, that displaced by the Miserere at Lauds, Psalm 46, Omnes Gentes. The chapter is that sung on ferial days, Pacem et veritatem etc. The Dominical and ferial preces are sung, both sets are sung with the choir kneeling. At the other Horae Minores the short set of ferial preces are sung, again the choir kneeling.
Mass is sung after None. Following the normal rules for Vigils four candles are placed on the altar, unlike two on ordinary ferial days. The deacon and sub-deacon wear violet dalmatic and tunicle, not folded chasubles. The chant for the Mass is ferial, the second collect is Concede nos, and the third for the Church. Being a 'kneeling day' all in choir kneel for the orations and from the Sanctus to the response after Pax Domini. As there is no Gloria , following the usual rule, Benedicamus Domino is sung as the dismissal.
Source: St. Lawrence Press
Saints Simon and Jude, pray for us!