The Department of Energy’s National Nuclear Security Administration said Monday it will dispatch a radiation-sniffing helicopter to the skies of Charlotte, N.C., ahead of the 2020 Republican National Convention scheduled there next week.

A twin-engine Bell [TXT] 412 helicopter, rigged with passive radiation-sensing instruments, “will conduct low-altitude helicopter flights over downtown Charlotte and areas in and around Yorkmount on August 20 and 21,” the semiautonomous Department of Energy agency said in a press release.

The helicopter

, operated from Joint Base Andrews in Maryland by the National Nuclear Security Administration’s (NNSA) Nuclear Emergency Support Team (NEST), will sweep a grid no lower than 150 feet above ground level, at about 80 mph. The agency routinely measures background radiation ahead of large public gatherings to create a base level against which the source of a radiological dispersal device — a dirty bomb — would pop out.

The agency usually lets residents know ahead of such operations, so nobody is alarmed by low-flying aircraft.

More than 300 Republican delegates, or 13% of the total party delegates, plan to travel to Charlotte to renominate President Trump to oppose Democratic Party nominee Joe Biden in the Nov. 3 election. The convention, which like this week’s Democratic convention has been downgraded to a mostly virtual event from the usual mass-gathering of pomp and celebration, is scheduled for Aug. 24-27.

Unlike Republicans, Democrats sent no delegates at all to their convention in Milwaukee. All the delegates to the Democratic National Convention voted remotely on Tuesday to nominate Biden to oppose Trump.

The NNSA wound up not sweeping Milwaukee for radiation ahead of the Democratic National Convention, owing to the decline in attendance.

“[D]ue to the severe reduction in planned events, the U.S. Secret Service released NEST from all DNC-related public safety tasking, including the planned flights over Milwaukee.” an NNSA spokesperson wrote Wednesday in an email.

Neither Biden nor his running mate, Sen. Kamala Harris (D-Calif.), attended their party’s convention, which until a few months ago was expected to draw 50,000 people to Milwaukee. Similarly, Trump has said he will accept his party’s nomination in a speech from the White House.

Like many planned mass gatherings this year, the conventions went virtual, or nearly so, because of the ongoing COVID-19 pandemic, which has killed more than 170,000 people in the U.S., and cratered the economy.