A helicopter is flying low and in circles over the area this morning. It could be a federal radiation chopper, or it could be a training exercise by the FBI and State Police.
Teman reports it circled his Chelsea neighborhood three times. In Charlestown, Samantha Hammar reports it was flying lower than the top of the Bunker Hill Monument. On Beacon Hill, Megz McClaff says it was so low, "I thought it was going to land on my roof!"
The National Nuclear Security Administration said it is flying a copter over the area to soak in all those good good background-radiation levels with which to use as baselines should somebody try to sneak in a bomb or something.
You may recall how they did something similar before the Marathon in April.
But the Chelsea Fire Department tweets it's a joint training exercise between the FBI and State Police.
So take your pick.
H/t The BeanReport617 for the link to the NNSA press release.