Happy Feast Day!

Dei mater Virgo
absque casu stella
pulchra tamquam luna
utque sol electa

Nostras audi preces
tu,quae captivorum
miserata questus
conteris catenas

O ter fausta dies
flamine qua tuo
sedulum pro votis
recreasti petrum!

O nimis profundius
caritatis ardor!
sic a culpa solve
quos a iugo solvis

Agit iste grates
Ordo, quem benigna
voce demonstrasti
consecrandum tibi

Tuo, diva parens
gratos reple zelo
ut sequamur corde
ore quod vovemus

Ei laus qui simplex
Personisque Trinus
contulit Mariam
nobis in Parentem.Amen.

-hymn of Vespers, solemnity of Our Lady of Mercy.
Interestingly,I found this site, which gives the mass for the day, which includes the sequence I posted a while ago.
It seems it passed over into the new missal.