Wikipedia
Byrgius (crater)
Byrgius is a lunar crater located in the western part of the Moon, near the limb. As a result, Byrgius appears strongly oval in form due to foreshortening. To the northwest is the nearly ruined crater Lamarck. The rim of Byrgius is worn and eroded, with Byrgius A overlying the eastern rim and Byrgius D lying across the northwest. The floor is relatively flat and undistinguished by significant craterlets. Byrgius A possesses its own ray system that extends for over 400 kilometres.