Shortly after that, Athar, known on Twitter as @ReallyVirtual, reported the helicopter had crashed.
"[S]eems like my giant swatter worked!" he wrote.
Athar did not know the import of the event and wouldn't connect the dots until seeing another tweet.
"Osama Bin Laden killed in Abbottabad, Pakistan.: ISI has confirmed it," it read.
"Uh oh, there goes the neighborhood :-/" said Athar after seeing a tweet at 10:45.
The first official hint that big news was afoot was cryptic, perfectly suited for social media.
At 9:45 p.m., Obama's director of communications, Dan Pfeiffer, tweeted a terse 61 characters: "POTUS to address the nation tonight at 10:30 PM Eastern Time."
There was little in it to indicate that Sunday would become a day the world would never forget. A late night presidential news conference is a rare event. And there were no other details.
Philadelphia Daily News columnist Will Bunch fired off a blog item at 10:11 p.m. and followed with an e-mail to his editors three minutes later: "This is big: Obama to give mystery speech in 15 minutes," Bunch wrote.
In the Twitterverse, speculation exploded. Was Libyan strongman Moammar Gadhafi dead? Or had the World's Most Wanted Man, Osama bin Laden, been captured?
In a note that scooped all other news outlets, a former aide to Donald Rumsfeld wrote at 10:45: "So I'm told by a reputable person they have killed Osama bin Laden. Hot damn."
It was a swift poke to the beehive, and journalists raced to confirm. CNN's Anderson Cooper was among the first of the mainstream media stars to pick up on the news: "Ed henry of cnn reporting osama killed in mansion outside islamabad. Wow, if true that is stunning, and Pakistan has some explaining to do," Cooper tweeted.
Numerous celebrities chimed in before Obama strode to the lectern.
"Go USA," tweeted Lindsay Lohan.
"Need to sleep. Too excited. About Bin Ladan and the cover story of how it happened. He probably Choked on a macaroon," quipped comedian Judd Apatow.
Hundreds of thousands of other folks joined in, too. Just before 11 p.m., more than 5,106 tweets per second were being posted, according to Twitter. In contrast, there were 4,064 tweets per second at the end of Super Bowl XLV in February.
People immediately sought to share the experience with others, and couldn't wait for Monday's water cooler to do it.
"At one time, they all would have had to go the White House or Ground Zero or a baseball game," said Mandy Jenkins, D.C. social news editor for the Huffington Post. "But now people could stay at their houses and be part of this outpouring of emotion and the conversation."
Celebratory crowds began to amass at sites as disparate as the White House, Ground Zero in New York City, State College, and Bridesburg.
All this before a single word from the president. Obama's suddenly anticlimactic announcement, delayed for an hour, came about 11:30.
"Twitter basically had an entire news cycle before the president even spoke," said the Huffington Post's Jenkins. "It scooped real life."
Contact staff writer Sam Wood at 215-854-2796 or firstname.lastname@example.org.
Contact Daniel Victor at 215-854-2499 or email@example.com.