The date of the martyrdom
Now, the blessed Polycarp suffered martyrdom on the second day of the month Xanthicus just begun, the seventh day before the Kalends of May, on the great Sabbath, at the eighth hour. He was taken by Herod, Philip the Trallian being high priest, Statius Quadratus being proconsul, but Jesus Christ being King for ever, to whom be glory, honour, majesty, and an everlasting throne, from generation to generation. Amen.
Source: The Martyrdom of Polycarp (New Advent)