In his Sixth Century guide to using the stars for monastic timekeeping, Bishop Gregory of Tours described a constellation which he called the Greater Cross, which can be identified with stars of the constellation Cygnus. Below the cross he placed lesser constellations which he called Alpha and Omega, which can be identified with part of Delphinus and Lyra. This reflects early medieval iconography, in which a cross is depicted with the letters Alpha and Omega below the arms of the cross.
