a) To undertake multi-colour imaging and broadband spectroscopy. Several systems will be targeted to compare the colours of the images and deduce extinction curves.
b) To look for radio propagation effects. Observations over a range of frequencies will be used to look for differences in image properties which are the tell-tail signs of scattering, absorption and Faraday depolarisation. We have the ambition to map the rotation measure round the B0218+357 Einstein ring to tell us about the magnetic field configuration in the lensing galaxy.
c) To use absorption line studies to tell us about the state of neutral, molecular and ionised gas. Absorption lines can also be used to study gas kinematics in the lens.