Velocity Effects on the Deflection of Light by Gravitational Microlenses

We study the influence of general lens and source velocities on the gravitational deflection of light by single and two-point-mass microlenses with general axis orientation. We demonstrate that in all cases the lens equation preserves its form exactly. However, its parameters – the Einstein radius and the binary-lens separation – are influenced by the lens velocity. In Galactic microlensing settings the velocity mainly affects the inferred separation for wide binary-star or star+planet microlenses oriented close to the line of sight. We briefly discuss the case of lenses moving with highly relativistic velocities.