  Considering the spacetime around a rotating massif body it is seen that the
time of flight of a light ray is different whether it travels on one side of
the source or on the other. The difference is proportional to the angular
momentum of the body. In the case that a compact rapidly rotating object is the
source of a gravitational lensing effect, the contribution coming from the
above mentioned gravitational Aharonov-Bohm effect should be added to the other
causes of phase difference between light rays coming from different images of
the same object.
