If you notice some helicopters in D.C. flying lower than usual, there’s no reason to be worried — the U.S. Department of Energy is running some tests tied to the upcoming inauguration.

The agency’s National Nuclear Security Administration will be conducting some low-altitude chopper flights over downtown until Dec. 13.

At the core, is the Nuclear Emergency Support Team. It wants to “measure expected background radiation as part of standard preparations to protect public health and safety during the event.”

What you’re likely to see, according to the agency, is a Leonardo AW-139 helicopter.

Precisely how low the aircraft will fly was not specified.