Oh, you better believe DCist is still on the case of the mysterious noise which woke the District this morning. (We’ve got stick-to-itiveness, what can I say.) Tamika Wright, a spokesperson at Fort Myer, tells DCist that the cannon blasts “weren’t coming from” the base as we previously suspected, but instead were being fired at Arlington Cemetery as part of an installation. So we dialed up Arlington National Cemetery spokesperson Steve Satkowski, who tells DCist that there was indeed some blasts being fired at the Cemetery this morning.

“Yes, the Old Guard was doing a training mission,” Satkowski confirmed. When I asked Satkowski how much noise such an exercises can produce, he said that couldn’t cite a decibel level, but that “there’s noise ordinances between certain times that I know they can’t fire,” and that “they are following any regulations out there for Arlington” between the hours of 10 p.m. and 6 a.m.

The Old Guard — otherwise known as the 3rd United States Infantry Regiment or the Escort to the President — is the Army’s oldest active Infantry and conducts memorial affairs for fallen service members at Arlington as wells as “special events to represent the Army, communicating its story to our Nation’s citizens and the world.” (You know, like the kind of event during which cannons might be fired.) We’ve got a phone call in with the Old Guard’s public information office and will share whatever information we receive with you.