Using our semi-linear inversion method , we measure the mass profile of the lens galaxy in the Einstein ring system 0047 - 2808 .
The lens is modelled as a baryonic component following the observed light , embedded in a dark matter generalised NFW halo .
The semi-linear method makes full use of the information content in the ring image .
We determine an unevolved B-band mass to light ratio for the baryons of 3.05 ^ { +0.45 } _ { -0.86 } h _ { 65 } M _ { \odot } / L _ { B \odot } ( 95 % CL ) , accounting for 65 % of the total projected mass within the radius of 1.16 ^ { \prime \prime } traced by the ring .
This result is obtained without need of dynamical measurements .
The inner logarithmic slope of the halo is found to be 0.87 ^ { +0.69 } _ { -0.61 } ( 95 % CL ) .
We find that the halo is fairly well aligned with the light but has only half the ellipticity .