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 compute the deflection angle and demonstrate that in all cases the lens equation preserves its form exactly. However, the Einstein radius and the separation of the two lenses depend on the lens velocity. In Galactic microlensing settings the velocity mainly affects the inferred separation for tangentially moving 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.