The Catechism in Questions & Answers

192. What does it mean to say that “Jesus Christ is seated at the right hand of God?”

Those who stood or sat at the right hand of a ruler in antiquity shared in the latter’s power and authority. The image that Jesus Christ sits at the right hand of God therefore points to the fact that He shares in the fullness of the power and glory of God, the Father. Jesus Christ desires to share this glory with His own in the future. It was for this reason that Jesus prayed as follows in the intercessory prayer: “Father, I desire that they also whom You gave Me may be with Me where I am, that they may behold My glory” (John 17: 24). This plea will be fulfilled when Jesus takes His own unto Himself from among the dead and the living, after which they will be with Him forever.

Rapture: see Questions 559. et seq.

“For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep. For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord.”
1 Thessalonians 4: 15-17