Very low flying helicopters continue to buzz over Wellesley and the rest of the Boston Marathon route as part of the U.S. Department of Energy’s National Nuclear Security Administration public health and safety preparations. The flights began on April 11 and will continue into Monday, April 15, race day.

The Nuclear Emergency Support Team aircraft, which fly at 150 feet or higher at about 80mph, measure for expected background radiation. The copters fly in a grid pattern.

We caught the copters over Wellesley College on Saturday, then again in the Cedar Street area on Sunday morning.