An Etymological Dictionary of Astronomy and Astrophysics

The effect arising whenever a source star and lens star pass each other at an angular separation involving the → Einstein radius (R_E) of the lens. The time-scale for such an event is defined as t_E = R_E/v, where v is the magnitude of the relative transverse velocity between source and lens projected onto the lens plane.

See also: → microlensing; → event.