Blue blip

The blue blip seen at left is the false lightning report, which could be a meteor flash.

Like many across southern New Hampshire, including the Monadnock Region, Lisa Rigopoulos heard a loud boom late Sunday morning.

Rigopoulos, 57, was upstairs at her home in Jaffrey at the time. A production manager at the damage-restoration firm ServiceMaster Elite in Merrimack, she said the noise reminded her of a dumpster being dropped onto pavement.

“It was really bizarre,” she said. “... That’s all I could associate it with.”

In fact, the boom — which people as far south as central Massachusetts reported on social media that they’d heard — may have been caused by a meteor entering Earth’s atmosphere, according to the National Weather Service.

Meteorologists noticed Monday that a satellite tracking lightning activity had registered a blip around 11:20 a.m. Sunday near Hillsboro, said Greg Cornwell with the agency’s Gray, Maine, office.

Cornwell said a single flash would be consistent with the light produced by a meteor, or bolide, as it enters the atmosphere and explodes. With no lightning in the area Sunday, he said there is “reason to believe” the incident was due to a meteor.

Such an event would have likely produced a loud boom as it entered the atmosphere, and the resulting flash of light would’ve been difficult to see in the daytime, according to Cornwell.

William J. Cooke, head of NASA’s Meteoroid Environment Office, said Tuesday that sound-wave data suggest a fireball may have entered upper atmosphere above New Hampshire on Sunday morning.

Known as “infrasound,” which humans cannot hear, those waves indicate the unknown event had a total energy equal to detonating between one and 20 tons of TNT, Cooke told The Sentinel. The resulting pressure wave would have caused the noise and shaking that some on social media said they also felt, he said.

“This is not certain, but fits the data we currently have in hand,” he said.

Cooke had said Monday the satellite reading “is not characteristic of a fireball” and more closely resembles lightning. After reviewing the infrasound data Tuesday, however, he said it’s more plausible that a fireball caused the loud boom.

As animals have been known to do before an earthquake, Rigopoulos said her dog, Carlos, had been “going nuts” about 30 seconds before the loud boom, running from window to window and barking loudly.

“Thinking back, it was like he had a sixth sense,” she said.

But neither the U.S. Geological Survey nor Boston College’s Weston Observatory in Weston, Mass., reported a quake in New Hampshire on Sunday. Officials with both organizations told WMUR their instruments hadn’t registered any seismic activity.

The Federal Aviation Administration told state officials Sunday that no military planes flew over the state that morning, WMUR also reported.

NWS hadn’t received any reports of a meteorite impact as of Monday afternoon, according to Cornwell, though he said its entry over Hillsboro is an estimated location. Meteors often burn up completely while entering the atmosphere, leaving nothing to collide with Earth.

“A lot of these will be totally consumed by re-entry,” he said.

New Hampshire’s 9-1-1 call center received just one report of a loud boom around 11:30 a.m. Sunday from a caller in Lyndeborough, N.H. Department of Safety spokesman Paul Raymond said that night. No calls came in to the state police dispatch center, he said.

This report has been updated with new information from William J. Cooke, head of NASA’s Meteoroid Environment Office. Staff writer Mia Summerson contributed reporting.

Caleb Symons can be reached at 352-1234, extension 1420, or csymons@keenesentinel.com. Follow him on Twitter @CalebSymonsKS.