HOUSTON -- Concerned KHOU 11 viewers have a question: "Why did that helicopter just fly by my office building so low!?"
Several viewers shared videos of a helicopter flying very low around the Galleria area on Monday, including Henri Dubiton.
The chopper zoomed by his office tower window at Sage Road and San Felipe at around lunch time Monday.
"It turned around little bit further south on San Felipe and heads right back toward us," said Dubiton, who works on the 13th floor.
At times the chopper appeared to be only about 10 stories off the ground.
On Wednesday, the chopper was spotted again in downtown and near NRG Stadium.
The Department of Energy was doing a radiation test. KHOU 11 News is still waiting for official word on that but the tail number on the helicopter confirms it belongs to that government agency.
"I was just about able to see the pilot's face and his head gear on and to be honest I wasn't thinking too much other than there's a helicopter 30 feet from me right now," Dubiton said.
Others in the Galleria area did the same thing he did, pulling out their phones to capture the sight.
In April, the Department of Energy did one of these low-altitude flights around Boston before the marathon to measure naturally occurring background radiation, using the same twin-engine Bell helicopter it used Monday.
"There's going to be all sorts of odd things going on in our city that we don't normally see so it's kind of what we chalked it up to," Dubiton added.
The DOE says they do this to establish baseline levels and that it's a normal part of emergency preparedness.
Houston Police tells us the chopper is part of security operations, adding that the public should not be alarmed.