Ascension
The Great Feast of the Ascension falls on the 40th day after Pascha (inclusive), always on a Thursday. The feast is celebrated with an All-Night Vigil starting on Wednesday evening. The Epitaphion (shroud), which had been on the Holy Table since the Paschal Vigil, is removed before the beginning of this service as an indication that the Ascension marked the end of Jesus' physical presence with his disciples after the Resurrection. The Afterfeast of Ascension lasts for eight days until the Apodosis on the following Friday.
Read more about this topic: Pentecostarion