Constraints on galaxy density profiles from strong gravitational lensing: The case of B1933+503

We consider a wide range of parametric mass models for B1933+503, a 10-imag e radio lens, and identify shared properties of the models with the best fi ts. The approximate rotation curves vary by less than 8.5% from the average value between the innermost and the outermost image (1.5-4.1 h(-1) kpc) fo r models within 1 sigma of the best fit, and the radial dependence of the s hear strength and angle also have common behavior for the best models. The time delay between images 1 and 6, the longest delay between the radio core s, is Deltat = 10.6(-1.1)(+2.4) days (Omega (0) = 0.3, lambda (0) = 0.7) da ys including all the modeling uncertainties Deeper infrared observations, t o more precisely register the lens galaxy with the radio images and to meas ure the properties of the Einstein ring image of the radio source's host ga laxy, would significantly improve the model constraints and further reduce the uncertainties in the mass distribution and time delay.