a) To measure and refine time delays using both radio and optical monitoring. The VLA and MERLIN will be used for the radio work. Optical monitoring will be with the NOT and the Liverpool Telescope. Monitoring also gives microlensing light curves.
b) To quantify the contributions of random and systematic errors to the H0 error budget.
c) To refine mass models for time-delay lens systems. Various ANGLES deconvolution techniques, radio and optical, will be used to extract the best possible constraints.