Regina Coeli

The Regina Cæli or Regina Cœli ("Queen of Heaven", pronounced [reˈdʒina ˈtʃeli] in Ecclesiastical Latin) is an ancient Latin Marian Hymn of the Christian Church.

It is one of the four seasonal Marian antiphons of the Blessed Virgin Mary, prescribed to be sung or recited in the Liturgy of the Hours at the conclusion of the last of the hours to be prayed in common that day, typically night prayer (Compline or Vespers). Any one of these four or of other suitable antiphons may now be sung at any time of the liturgical year. The Regina Coeli is sung or recited in place of the Angelus during the Easter season, from Holy Saturday until Pentecost.

As with many Roman Catholic prayers, it takes its name from its incipit or first word(s). The Latin word coelum, meaning "heaven" (whence the English word celestial), was a common medieval and early modern spelling of caelum, which was the only form in Classical Latin. In medieval Latin, ae and oe were both pronounced [eː]; the form was also influenced by an extremely dubious etymology from Greek koilos, "hollow".

While the authorship of the Regina Caeli is unknown, the hymn has been traced back to the 12th century. It was in Franciscan use, after Compline, in the first half of the following century. According to Catholic Tradition St Gregory the Great heard angels chanting the first three lines one Easter morning in Rome, while following barefoot in a great religious procession of the icon of the Virgin painted by Luke the Evangelist. He was thereupon inspired to add the fourth line.

...
Wikipedia