  Holz & Wheeler (\cite{hw}) have recently proposed that a Schwarzschild black
hole may act as a retro-lens which, if illuminated by a powerful light source,
deflects light ray paths to large bending angles and a series of luminous arcs
(or rings in the case of aligned objects) centered on the black hole may form.
Obviously, the most convenient geometry to get retro-lensing images would be
that of a very bright star close to a massive black hole, say the putative
$\sim 4\times 10^6$ M$_{\odot}$ black hole at the galactic center. Recent
observations of the galactic center region in the $K$-band have revealed the
presence of a very bright main sequence star (labelled S2) with mass $\sim 15$
M$_{\odot}$ orbiting at close distance (130-1900 AU) from Sgr A$^*$. The
relatively vicinity of S2 to the central massive black hole may offer a unique
laboratory to test the formation of retro-lensing images. The next generation
of space-based telescopes in the $K$-band (like NGST) may have high enough
limiting magnitude necessary to observe such retro-lensing images.
