The feast of the Ascension
The chants for the feast of the Ascension can be found in full in the Liber Responsorialis (available online at CC Watershed), starting at page 94.
A version of the Office for the feast including all of the texts and chants needed (including psalms) can be found on the Gregofacsimil website, but note that many of the responsories use verses that are not the same as those in the breviary.
Sunday after the Ascension
The invitatory, hymn and responsories for the Sunday after Ascension are the same as for the feast.
You can also find a nicely laid out version of the chants and texts as one document over at Gregofacsimil (it is labelled as being Sunday within the Octave, but is the same as for the feast), but note that many of the responsories verses are not the same as those in the breviary.
Divinum Officium as usual gives the correct psalms and antiphons, but the Roman version of the readings and responsories; for the correct set, see the Lectio Divina Notes blog.
Links for translations, sources for the responsories and recordings available online provided on this blog can be found below:
Feast of the Ascension
Short responsory for Ascensiontide (ferias)
The 'Ordinary' of Ascensiontide
Once upon a time, the feast of the Ascension warranted an Octave. This was, alas abolished, but many of the texts used are preserved in the 'Ordinary of Ascensiontide'. For Matins:
- the invitatory antiphon is as for the rest of Eastertide, viz Alleluia, alleluia, alleluia, alleluia;
- the hymn (when not displaced by a feast) is Aeterne Rex Altissime;
- the versicles after the psalms in the first Nocturn are of Ascensiontide (in the psalter);
- the one reading becomes Hebrews 6:18-30 with short responsory 'Dominus in caelo' (not on Divinum Officium); and
- the chapter verse is Revelation 5:12 with versicle 'Exaltare Domine'.