  The accretion induced collapse (AIC) of a white dwarf to a neutron star has
long been suggested as a natural theoretical outcome in stellar evolution, but
there has never been a direct detection of such an event. This is not
surprising since the small amount of radioactive nickel synthesized
($\sim10^{-3}\,M_\odot$) implies a relatively dim optical transient. Here we
argue that a particularly strong signature of an AIC would occur for an
oxygen-neon-magnesium (ONeMg) white dwarf accreting from a star that is
experiencing Roche-lobe overflow as it becomes a red giant. In such cases, the
$\sim10^{50}\,{\rm erg}$ explosion from the AIC collides with and shock-heats
the surface of the extended companion, creating an X-ray flash lasting
$\sim1\,{\rm hr}$ followed by an optical signature that peaks at an absolute
magnitude of $\sim -16$ to $-18$ and lasts for a few days to a week. These
events would be especially striking in old stellar environments where
hydrogen-rich supernova-like, transients would not normally be expected.
Although the rate of such events is not currently known, we describe observing
strategies that could be utilized with high cadence surveys that should either
detect these events or place strong constraints on their rates.
