Copter alert: A federal helicopter will be flying low and fast over the area over the next couple weeks

The National Nuclear Security Administration reports residents shouldn't worry if they see a helicopter flying low and fast over their heads between now and April 15 - it's just there to measure background radiation.

Why? Well, you know, so government security experts can tell if somebody's doing something untoward with something that might release large amounts of radiation all at once in the area.

A twin-engine Bell 412 helicopter, operated by the Remote Sensing Laboratory Aerial Measuring System from Joint Base Andrews, will be equipped with radiation sensing technology. The helicopter will fly in a grid pattern over the area at 150 feet (or higher) above the ground surface, at a speed of approximately 80 miles per hour. Flyovers will occur only during daylight hours and are estimated to take about four days to complete. ...

The measurement of naturally occurring radiation to establish baseline levels is a normal part of security and emergency preparedness.