regina coeli -2-

´Queen of Heaven´...

is a musical antiphon, addressed to the Blessed Virgin Mary...

that is used in the liturgy of the Roman Rite of the Catholic Church during the Easter season,
from Easter Sunday until Pentecost: during this season...

1. it takes the place of the [thrice-daily] Angelus prayer
2. and it is the antiphon that ends Compline [Night Prayer]

~wikipedia~