## 2. Point-mass lens and point source
For a lens at a distance from the observer, a
source at a distance from the observer, and
the lens-source distance, the Einstein radius
for a lens of mass Let the lens move on a straight line with a velocity
transverse to the line-of-sight observer-source,
so that it moves one Einstein radius in the lens plane in the time
.
where The light amplification for a point source and a point-mass lens is given by © European Southern Observatory (ESO) 1998 Online publication: April 28, 1998 |