243 -- Deflection of Light in the Equatorial Plane of a Kerr Black Hole

Series expansions for the bending angle of light in the equatorial plane of a Kerr black hole are given for the strong and weak deflection limits with various values of the spin parameter ranging from low to high spin. From the exact bending angle expression, with no known analytical solution, we get series approximations for the bending angle in terms of the impact parameter of the incident light ray. Analytical expressions allow us to derive and connect to other results relating to images formed due to gravitational lensing. Specifically, the asymmetry that arises in the spin-dependent shifts in image positions can be predicted by the analytical expansions. We apply our results for the case of a galactic supermassive black hole to predict asymmetric angular positions of relativistic images on either side of the lens. The possible observation of the asymmetric image shifts with telescopes can only be predicted with the perturbative expansions in the strong deflection regime.