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We present a complete treatment in the strong field limit of gravitational retrolensing by a static spherically symmetric compact object having a photon sphere. The results are compared with those corresponding to ordinary lensing in similar strong field situations. As examples of the application of the formalism, a supermassive black hole at the Galactic center and a stellar mass black hole in the Galactic halo are studied as retrolenses, in both cases using Schwarzschild and Reissner-Nordstr\"om geometries.
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Eiroa et al. (2004) studied this question.
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