Light Echoes of Ancient Transients with the Blanco CTIO 4m Telescope
  For over a century, light echoes have been observed around variable stars and
transients. The discovery of centuries-old light echoes from supernovae in the
Large Magellanic Cloud has allowed the spectroscopic characterization of these
events using modern instrumentation, even in the complete absence of any visual
record of those events. Here we review the pivotal role the Blanco 4m telescope
played in these discoveries.
