I need a reference. The orbits of pulsars PSR 1913+16 are shrinking. It seems that is because of the energy the pulsars are losing by emitting gravitational waves. General relativity predicts that. So far, so good; now the question. Is there an article where I can find the experimental/observational evidences of the structure, speed, and polarization of the gravitational waves? [According to general relativity, the structure is as if emanating from quadrupole source, the speed equals the speed of light, and polarization is 2 as of light.] By the way, I need some help re ellipses. Please give me an expression for the angle between the generatrix (the “radius” from a focus to a point on the ellipse) and the tangent at that point? I want to use the angle to calculate the values of some of the properties of gravitational waves.