1. n. [Geophysics]

A marine seismic data acquisition method that uses one or more vessels to tow source arrays and streamers to record seismic signals, along with one or more source-only vessels sailing parallel to, but at some specified distance from, the recording vessel(s). The source-only vessels provide offset sources that generate reflections from a wide range of azimuths; these reflections are received by streamers towed by the recording vessel(s).