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Britney Spears is set to make her big announcement this month on "Good Morning America."  The ABC morning show announced on Thursday that the pop star will be appearing on the show on September 17th, which is also the day that the "All Eyes On Me" countdown timer on her website comes to an end. 

"E! News" is reporting that Spears will be doing a live performance.  "GMA" tweeted the news, adding that they've booked both Katy Perry and Lady Gaga as performers.  The show is calling the line-up its "Pop Icons Exclusive."  

Speculation has been brewing about Britney's announcement since she posted this countdown timer on her site last month.  Not only has Britney been working on a new album, but fans are also expecting to hear more about the Las Vegas residency long-rumored to be in the works.