Proper Antiphons for the Baptism of the Lord, Dominican Rite

The Dominican Rite is often more Roman than the Roman, retaining older usages, as well as many items quite common in the medieval West, but not used in Rome itself, and so not taken into the Tridentine Missal and Breviary that swept away most local uses.  

In the Breviarium S.O.P., unlike in the Breviarium Romanum (which repeats the Epiphany Office with proper lessons and collect only), proper antiphons are provided for the Feast of the Baptism of the Lord on the Octave Day of the Epiphany; they have a Byzantine flavour about them, were apparently used elsewhere in the West, especially in France (cf. Guéranger), and may well come from the Greek (phrases like "Christ our God" are a dead giveaway):

1st Vespers, Magnificat Antiphon:

Baptizat miles Regem, servus Dominum suum, Joannes Salvatorem: aqua Jordanis stupuit: columba protestata est: paterna vox audita est: Hic est Filius meus.

Lauds, Antiphons for the psalms:

1.  Veterem hominem renovans Salvator, venit ad baptismum: ut naturam, quæ corrupta erat, per aquam recuperaret, incorruptibili veste circumamictans nos.

2.  Te, qui in Spiritu, et igne purificas humana contagia, Deum, ac Redemptorem omnes glorificamus.

3.  Baptista contremuit, et non audet tangere sanctum Dei verticem, sed clamat cum tremore: Sanctifica me, Salvator.

4.  Caput draconis Salvator contrivit in Jordanis flumine: et ab ejus potestate omnes eripuit.

5.  Magnum mysterium declaratur hodie: quia Creator omnium in Jordane expurgat nostra facinora.

Benedictus Antiphon:

Præcursor Joannes exultat cum Jordane: baptizato Domino facta est orbis terrarum exultatio, facta est peccatorum nostrorum remissio.  Sanctificans aquas, ipsi omnes clamemus: Miserere nobis.

2nd Vespers, Magnificat Antiphon:

Fontes aquarum sanctificati sunt, Christo apparente in gloria: orbis terrarum, haurite aquas de fontibus Salvatoris: sanctificavit enim nunc omnem creaturam Christus Deus noster.

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The current Liturgia Horarum, as usual, has picked over the various traditional antiphons and the like from the various Western uses, and redistributed them, taking on variant readings from different recensions:  Veterem hominem becomes the Magnificat antiphon at 1st Vespers (reading circumiciens not circumamictans), exchanging places with Baptizat miles regem, which is now the 1st antiphon to the psalms at Lauds (with a few verbal differences – suum dropt, protestata est becoming protestatur); Fontes aquarum moves to be the 2nd antiphon to the psalms of Lauds (reading orbi instead of orbis); Te qui in Spiritu is now the 3rd antiphon to the psalms of Lauds (replacing ac with et); Caput draconis (conteruit, not contrivit; Jordane, not Jordanis; omitting et) and Magnum mysterium (unchanged) appear as the 2nd and 3rd psalm antiphons at 2nd Vespers.

The other antiphons in the modern Divine Office (at 1st Vespers, Office of Readings and the Little Hours) are fairly obviously drawn from Scripture, as is the new Magnificat antiphon at 2nd Vespers, Christus Jesus dilexit nos (Apoc. i, 5-6).

The modern rite Benedictus antiphon, however, also seems "Byzantine":

Baptizatur Christus, et sanctificatur omnis mundus; et tribuit nobis remissionem peccatorum; aqua et Spiritu omnes purificemur.