Original: It was discovered by the Cassini Imaging Science Team in images taken by the Cassini-Huygens probe on June 21, 2004 and announced on September 9, 2004.
Simplified: It was first seen by Carl Murray of the Cassini Imaging Science Team in pictures taken by the Cassini-Huygens probe on June 21, 2004, and announced on September 9, 2004.