Figure 6

Figure 6: Illustration of the exact lens map in spherically symmetric static spacetimes. The picture shows a spatial plane. The observation event (dot) is at r = rO, static light sources are distributed at r = r S. Q is the colatitude coordinate on the observer’s sky. It takes values between 0 and p. P(Q) is the angle swept out by the ray with initial direction Q on its way from rO to rS. It takes values between 0 and oo. In general, neither existence nor uniqueness of P(Q) is guaranteed for given Q. A similar picture is in [271].