Obtaining mass parameters of compact objects from red-blue shifts   emitted by geodesic particles around them
  The mass parameters of compact objects such as Boson Stars, Schwarzschild, Reissner Nordstrom and Kerr black holes are computed in terms of the measurable redshift-blueshift (zred, zblue) of photons emitted by particles moving along circular geodesics around these objects and the radius of their orbits. We found bounds for the values of (zred, zblue) that may be observed. For the case of Kerr black hole, recent observational estimates of SrgA\* mass and rotation parameter are employed to determine the corresponding values of these red-blue shifts. 
Ricardo Becerril, Susana Valdez-Alvarado and Ulises Nucamendi
gr-qc