The coplanar n-body gravitational lens : a general theorem
arXiv:astro-ph/9909070
Abstract
Generalizing a result for the binary lens, similar alternative expressions are also given for the Jacobian determinant for a gravitational lens consisting of an arbitrary number of discrete lensing centres, with arbitrary masses and locations in a plane. The results for a binary lens are recovered, agreeing with some already known results, and correcting errors in others.
arXiv comment6 pages