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Entertainment Tonight -- Robert Pattinson partied with one of his 'New Moon' castmates on her birthday yesterday in Vancouver! Read on for the details.

Rob and fellow movie-vampire Jackson Rathbone helped Kristen Stewart celebrate her 19th b-day at a local Vancouver eatery, says OK! Magazine.

'New Moon' rises in theaters on Nov. 20. Click here for info on a new addition to the cast of the highly anticipated 'Twilight' sequel!