  The perturbations of the Kerr metric and the miracle of their exact solutions
play a critical role in the comparison of predictions of general relativity
with astrophysical observations of compact massive objects. The differential
equations governing the late-time ring-down of the perturbations of the Kerr
metric, the Teukolsky Angular Equation and the Teukolsky Radial Equation, can
be solved analytically in terms of confluent Heun functions. In this article,
we solve numerically the spectral system formed by those exact solutions and we
obtain the electromagnetic (EM) spectra of the Kerr black hole.
  Because of the novel direct way of imposing the boundary conditions, one is
able to discern three different types of spectra: the well-known quasinormal
modes (QNM), the symmetric with respect to the real axis quasibound modes (QBM)
and a spurious spectrum who is radially unstable. This approach allows clearer
justification of the term "spurious" spectrum, which may be important
considering the recent interest in the spectra of the electromagnetic
counterparts of events producing gravitational waves.
