What time does the encounter happen?
Impact will occur between 05:49 and 5:55 UT July 4th or 5:52 +/- 3 minutes. We selected this time to be sure three conditions were covered. First we need to have two Deep Space Network (DSN) stations able to receive data from the spacecraft. Secondly, we wanted a good ground-based observing site in darkness to observe the comet, and third, we want the Hubble Space Telescope in a position to observe the impact. We have been monitoring the predicted times of Hubble orbits to set the time and coordinate with engineers who execute trajectory correction maneuvers.
