Consider this, the public event with the Vanguard emblem beside it, this is a Vanguard generated public event. If we are awaiting for reports from the Vanguard, and that they are higher level players. It would seem that they would have the ability to be in a forward position to see or warn or report on conditions or events. The City must be able to know what is going on around itself on order to defend or attack enemies. This is probably one of many different public event.