28. February 2017 Location:  ZARM, University of Bremen, Room 1280  When:  14:30  Speaker:  Vittorio De Falco (ISSI, Bern, Switzerland)  Title:  Approximate analytical calculations of photon geodesics in the Schwarzschild metric  Topic:  In this talk, we show a method for deriving approximate analytical formulae. to integrate photon geodesics in a Schwarzschild spacetime. Based on this, we derive the approximate equations for light bending and propagation delay that have been introduced empirically already respectively by Beloborodov 2002 and Poutanen & Beloborodov 2006. We then derive for the first time an approximate analytical equation for the solid angle. We discuss the accuracy and range of applicability of the new equations and present a few simple applications of them to known astrophysical problems, that are: light curve from an emitting clump orbiting a black hole, emission line profile from an accretion disk around a black hole and light curve from a hot spot on the surface of a rotating neutron star. 
