Forty days after the Resurrection, while blessing His disciples (Gospel of Luke 24:50-51), Christ ascended into heaven, taking His place at the right hand of the Father (Gospel of Mark 16:19 and Nicene-Constantinopolitan Creed).
Troparion - Tone 4
O Christ God, You have ascended in Glory, Granting joy to Your disciples by the promise of the Holy Spirit. Through the blessing they were assured That You are the Son of God, The Redeemer of the world!
Kontakion - Tone 6
When You did fulfill the dispensation for our sake, And unite earth to Heaven: You did ascend in glory, O Christ our God, Not being parted from those who love You, But remaining with them and crying: I am with you and no one will be against you
taken from oca.org