Last year's biggest news story - the death of Osama bin Laden - is now a key to understanding just how deeply Twitter has affected the news universe. The Georgia Institute of Technology will release a study today about coverage of bin Laden's killing that may be the most comprehensive yet in showing how news spreads on Twitter.

Researchers at Georgia Tech worked with researchers at Microsoft Research Asia and University of California-Davis to analyze more than 600,000 tweets sent in a two-hour period, stretching from minutes before the first rumor of Osama bin Laden's death to tweets surrounding confirmation of his killing by U.S. forces. Among the key findings: The majority of people reading the early tweets believed they were true, even before they were confirmed by mainstream media, and celebrities played a key role in disseminating the news.

That second part may have lasting effects beyond simply analyzing the news: Two of the lead researchers are now working on software that could help analyze the mood of celebrities on social media to help marketing companies unveil products and find celebrity endorsers.

“Rumors spreading on Twitter is one thing,” said Mengdie Hu, a Ph.D. candidate in Georgia Tech's School of Interactive Computing, who led the study. “Determining if they are true is another, especially in this era of social media and the rush to break news.”

Keith Urbahn (@keithurbahn), an aide to former Secretary of Defense Donald Rumsfeld, is credited in the study with confirming reports of bin Laden’s death at 10:24 p.m. on May 1 of last year. By that point, 50% of the tweets discussing the news had been written as fact or in “very confident” terms. CBS producer Jill Jackson (@jacksonjk) tweeted her own confirmation eight minutes after Urbahn. The news began to spread rapidly after New York Times reporter Brian Stelter (@brianstelter) retweeted both reports.

By the time network news broke into programming 21 minutes after Urbahn’s initial tweet, 80% of tweets discussing bin Laden’s death had been written as fact or in certain terms, according to the study.

“We believe Twitter was so quick to trust the rumors because of who sent the first few tweets,” Hu said. “They came from reputable sources. It’s unlikely that a CBS News producer or a New York Times reporter would spread rumors of something so important and risk jeopardizing their reputation. Twitter saw their credentials and quickly believed the news was true.”

After the initial reports and confirmations, however, something interesting happened: Celebrities became the key connectors in spreading news about bin Laden’s death. Within a half-hour of the first television reports, a group of 100 “elite users,” including comedian Steve Martin and reality stars Kim Kardashian and Paul “DJ Pauly D” DelVecchio of MTV's “Jersey Shore,” had surpassed the traditional media's reach in spreading the news by Twitter.

“The celebrities weren’t the first people to arrive at the party,” said John Stasko, Hu’s advisor and professor in the School of Interactive Computing. “But they stayed the longest and brought the most guests.”

The first anniversary of bin Laden’s death is Tuesday, May 1.