The Dixson Gradual
A thirteenth-century Cistercian gradual of 200 folios from the Abbey of San Stephano al Corno, Lodi, Italy. This manuscript is now in the Dixson Collection, State Library of New South Wales. It contains a Temporal Cycle, a Sanctoral Cycle, some Commons and a Hymnal.
The Poissy Antiphonal
A certified Dominican antiphonal of 428 folios from Poissy, written 1335-1345, with a complete annual cycle of chants for the Divine Office (Temporal, Sanctoral and Commons) and a hymnal. The manuscript also contains rules for copying chant and 23 historiated initials: it is in the State Libary of Victoria
The Rimini Antiphonal
A Franciscan Common of the Saints of 155 folios from Rimini, written 1328 and palimpsested on 40 folios with new texts and altered melodies sometime after 1582. The manuscript was decorated by Neri da Rimini with 8 historiated and 21 decorated letters: it is in the Richardson Collection of the State Library of New South Wales.
The Adelaide Antiphonal
A 13th century Italian antiphonal of 180 folios from Christmas to the Saturday after Epiphany held by the State Library of South Australia. This site includes a transcription, translation of the text and rubrics into English and sound recordings of selected works. The manuscript has one historiated and 13 illuminated letters and other noteworthy features
The MMDB is a wonderful thing; it lists the Annual cycle of feasts by both The Temporal Cycle and by The Sanctoral Cycle - and most entries have single or multiple instances of chant scores of introits, graduals, antiphons and etc.
Here's more about the MMDB; I believe the changes they refer to have already been included. At least, we know the manuscripts have been.
La Trobe University closed its Music Department at the end of 1999. This site has not been updated since February 2004. A new and updated version of the Medieval Music Database is currently under construction and should be available early in 2008: in the meantime we welcome your comments, corrections and additions.
The main features of the new version are a much expanded repertoire of works in addition to the melodic incipits of liturgical works. Four complete manuscripts, a gradual and three antiphonals, have been added. Browse by Liturgical Feast is entirely new. This displays the melodic incipit of each liturgical chant for each feast, analyses related melodies and displays colour images of source manuscripts. The Browse by Composers, by Genre and by Manuscripts remain the same as they were is the earlier versions.
Note to Howard: I didn't think to tell you, but all the antiphons for all the days of Lent are listed at the Temporal Cycle page. It may not have the one you were looking for, though, which I think you said was new?