WASHINGTON (AP).- Jarring headlines from the Gulf Coast after Hurricane Katrina said it all: “Catastrophic,” ”Hitting Bottom,” ”Help Us, Please.” Five years later, the Newseum on Friday will open a special, one-year exhibit, “Covering Katrina,” that explores and explains how journalists reported on the disaster and its aftermath. The Newseum assembled the accounts and belongings of journalists, newspaper stories and artifacts from the Louisiana State Museum for what curators believe is the first major exhibit on news coverage of Katrina. About 80 front pages from around the world show how the story unfolded as the storm bore down on Louisiana and Mississippi — and what followed. At the time, newspapers and TV reporters were the only link between the people needing help and the government that could provide it. “It puts you right there in the middle of