Rihanna is sending Katy Perry off to marriage with a bang. The R&B singer threw the pop star a fabulous bachelorette party in Las Vegas Saturday night and Breaking Celebrity News has the pictures.

Now we know why Katy Perry and fiancé Russell Brand were headed to Vegas Friday when he got arrested for tangling with a photographer at LAX.  Rihanna was throwing the bride-to-be a Sin City bash!

Fortunately Katy still got there in time, and the girls plus 25 of their closest friends started Saturday night by seeing a performance of KÀ by Cirque du Soleil at MGM Grand.