Full text: 
Astra polorum super ascendit Christus ad patris dexteram sedens victor et auctor noster ubique
Fulltext source: 
CZ-Pu (Praha) XII E 15c, fol. 44r;
if the text is given only in incipit, be careful since the second stanza of another hymn has the text "Astra polorum cuncta hominum gens (...)"