A NASA team that investigates unidentified flying objects has collected about 800 mysterious reports — but researchers say only a small fraction are truly unexplained.

The agency set up a panel last year to explain its work, called Unidentified Abnormal Events (UAP).

UAP is defined as “unrecognizable as natural phenomena known from an aeronautical or scientific perspective.”

The panel, which will issue a report later this year, held its first public meeting on Wednesday.

Here are some revealing moments.

“Every month we have 50 to 100-ish new reports,” said Sean Kirkpatrick, director of NASA’s All-Domain Anomaly Resolution Office (AARO).

But he said the number of those views that are “truly anomalous” is between 2% and 5% of the total database.

At one point during the investigation, video taken by Navy aircraft over the western United States showed a series of dots moving across the night sky. The military aircraft was unable to intercept the object, which turned out to be a commercial airliner heading towards a major airport.

Other scenes are more mysterious.

Mr Kirkpatrick also noted that privacy concerns limit the agency’s investigations.

“We can point to the world’s largest collection of instruments any time we want,” he said.

“What we have is around the continental United States,” he added. “Most people…wouldn’t like our entire collection tool pointed in your backyard.”

Data related to UAP are often difficult to interpret and can be easily skewed.

David Spergel, head of NASA’s UAP team, noted the burst of radio waves picked up by researchers in Australia.

“They had a very strange set-up. People couldn’t figure out what was going on. At lunch time they started to notice a lot of them clustered together,” he said.

The sensors used by the researchers turned out to pick up signals from the microwave used to heat their lunch.

Scott Kelly, a former astronaut and pilot with decades of experience, told a story about an optical illusion.

He and his co-pilot were flying near Virginia Beach and his colleague believed “we were flown by a UFO.”

“I didn’t see it and we turned around and went to look at it and it was Bart Simpson – a balloon.”

Because of the stigma surrounding flying saucers, commercial pilots are more reluctant to report sightings, Mr Spergel said.

“One of our goals is to remove the stigma,” he said, “because we need high-quality data to address important questions about UAPs.”

And some scientists have faced online harassment for their work in the area.

“The harassment further stigmatizes the UAB field, significantly hinders the scientific process and discourages others from studying this important subject,” said NASA Science Chief Nicola Fox.

One reason Wednesday’s meeting was so significant was NASA’s shift in approach. The space agency has been debunking UFO sightings for decades.

At the end of the hearing, the panel asked questions from the public. One is “What is NASA hiding?”

NASA’s Dan Evans responded that the agency is committed to transparency. “That’s why we’re live on TV today,” he said.