2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194408We calculate the vorticity of world--lines of observers at rest in a Bondi--Sachs frame, produced by gravitational radiation, in a general Sachs metric. We claim that such an effect is related to the super--Poynting vector, in a similar way as the existence of the electromagnetic Poynting vector is related to the vorticity in stationary electrovacum spacetimes.9 pages; to appear in Classical and Quantum GravityGeneral Relativity and Quantum Cosmologytext