The Shadow of Black Holes

In this talk I present how to calculate the shadow of a Kerr-Newman-NUT black hole with a cosmological constant analytically. Here, the essential point is the existence of (unstable) spherical light rays in a region K because they determine the boundary of the shadow. After transformation to celestial coordinates on the observer’s sky, the shadow is viewed via stereographic projection as usual. Thereby, the observer is located at arbitrary Boyer-Lindquist coordinates outside of the horizon. Finally, I consider, how the shadow changes if the observer is moving. For a radial motion, one can recover the well known aberration formula.