A description of it can be found in the RS (Revised Statutes) in the chapter on the Liturgical Year; but, it would be worthwhile to signal some salient points. First of all, of course, we celebrate on the Thursday, rather than Sunday.

After Conventual Mass of the Feast, there takes place the only procession of the year, through the Great Cloister. The Prior bears the Sacrament, surrounded by four candlebearers and the incense. He does not lead the procession, however, but takes his place squarely in the middle of the community, so half are ahead and half behind. Familiars also take part in the procession, if the house has any. At each corner of the cloister (and in the middle of each, if the cloisters are very long), a small bell is rung, and the community faces the Blessed Sacrament from whichever direction, and an incensation takes place, followed by a profound bow. During the whole procession including the "stops" for incensation), the hymns of the day are sung from a small book called the Ritual (which also, for example, contains the chants for leading novices to their cells on the day of their clothing). If the cloisters are huge (as at Parkminster and the Grande Chartreuse, as opposed to Transfiguration), the singing begins with the "Te Deum", to be followed by the "Pange Lingua" from Vespers, the "Verbum Supernum" of Lauds, and the "Sacris Solemniis" of Matins.

Back in the church after the procession, the Blessed Sacrament is left exposed. At least one person is assigned to be in church for adoration at any one time throughout the day, including during refectory. There is no recreation, which is otherwise normally permitted on Solemnities. In many houses, especially the smaller ones such as Transfiguration, Exposition ends with Benediction after Vespers. The Statutes, however, allow that the Exposition can be continued for as long as a week, provided there is always someone present for adoration, and "provided the Exposition is not interruputed more than twice a day, as around midday or at night, because of an insufficiency of persons available to adore." ((RS 6.47.71: according to my early edition!) I do not know if any house actually does this, although I always imagined the Spanish houses doing it. At the Grande Chartreuse, with such a large community at the time I was there, adoration was continued at half-hour intervals throughout the night, and Exposition ended with morning Mass. Certainly it was impressive to be chanting Matins there, with the monstrance on the altar, and six enormous candles brightly shining in the darkness round about it!

As for the Office of the Feast itself, most everyone knows that St. Thomas Aquinas wrote the texts. The chant itself is therefore late, and quite decadent in our estimation, and extremely challenging to sing. As regards the style of chant, the same is also true of the Feasts of the Trinity and of the Sacred Heart in the Carthusian liturgy.