After the Resurrection we get various accounts of the appearances of Jesus. The most significant difference appears to be at the end of John where Jesus appears to the disciples after they have returned to Galilee.
In Luke’s account the ascension occured in Bethany, a short distance from Jerusalem. Then they returned to the upper room; perhaps they were huddled together there more in fear than in joy; they knew it was not healthy to be a follower of Jesus in Jerusalem.
Very likely their prayer was for their physical safety, much like that of the seamen in Shakespeare’s Tempest. (That seems to be the primary time that most people pray– in an extremity.)
The hopeful sign of their gathering was that they were together; this theme is emphasized repeatedly in Luke in connection with the original community: “they had all things in common”.
We’re given to understand that Jesus ascended 40 days after the Resurrection, and the disciples were secluded together 40 days before the day of Pentecost. This term deserves some reflection: recall that the children of Israel spent 400 years in Egypt; Moses spent 40 years in the wilderness; Jesus spent 40 days in the wilderness at the beginning of his ministry. There are other examples of the use of this figure: it seems to denote a complete period of time.
In general the metaphoric significance of the events we’re studying are at least as worthy of consideration as considering them a detailed factual record.