I'm trying to reconcile yesterday's announcements with the rumors that have been reported. I and others have heard rumors of three events. Yesterday they reported on the event from 14-Sep-2015, and the paper LIGO-P1500217 titled "The Rate of Binary Black Hole Mergers Inferred from Advanced LIGO Observations Surrounding GW150914" at the LIGO DCC site refers to an event on 12-Oct-2015, but says that it has only an 84-91% chance of being of astrophysical origin. So this was presumably a weak event. Now, look at this article on New Scientist, where someone has been tracking LIGO's search for optical counterparts. The blue search that began in mid-September clearly corresponds to the event we heard about yesterday. But there is a new search that began in late December. So it looks like they saw another high-signifcance event in late December that we have yet to hear about. More to come!