Velocity Dispersion of the Gravitational Lens 0957+561
Velocity Dispersion of the Gravitational Lens 0957+561
0957+561 is the first gravitational lens system to be discovered and first for which a time delay was measured. Because the system is unusually rich in observables such as image positions, fluxes, VLBI structure, and polarization it has been modelled quite extensively. However, since it resides in a cluster providing …