LensMEM: A Gravitational Lens Inversion Algorithm Using the Maximum Entropy Method

We present a new algorithm for inverting poorly resolved gravitational lens systems using the maximum entropy method (MEM). We test the method with simulations and then apply it to an 8 GHz VLA map of the radio ring lens MG1654+134. We model the lens as a singular isothermal sphere embedded in an external shear field and find the critical radius of the lens is $b=0\parcs9820$, the dimensionless shear is $\gamma=0.0771$, and the position angle of the shear is $\theta=100\pdeg8$. These results are consistent with the results obtained by Kochanek (1995) using a complementary inversion algorithm based on Clean.