Simplify the following text for a Grade 7 native English-speaking person.
Original: On September 9 , 2008 , immediately following the band 's concert in Helsinki , Finland , Buck 's signature Rickenbacker guitar , used live and in the studio since Chronic Town in 1982 , was stolen from the stage .
Simplified: On September 9 , 2008 , after a concert in Helsinki , his famous black guitar was stolen .