  There is now good evidence linking short-hard GRBs with both elliptical and
spiral galaxies at relatively low redshifts, redshift of about 0.2. This
contrasts with the average redshift of about 2 of long-duration events, which
also occur only in star-forming galaxies. The diversity of hosts is reminiscent
of type Ia supernovae, which are widely (but not universally) believed to
originate from the coalescence of white dwarfs. By analogy, it has been
postulated that short-hard bursts originate from neutron star mergers. Mergers,
as well as stellar core-collapse events (type II SNe and long-duration GRBs)
are accompanied by long-lived sub-relativistic components powered by
radioactive decay of unstable elements produced in the explosion. It is
therefore interesting to explore whether short duration events also have ejecta
powered by radioactivity (i.e. that are supernova-like). Observations already
inform us that any supernova like component in the first few well studied short
hard bursts must be fainter than those typical of type Ia or core-collapse
supernovae. Rather than refer to weaker supernova-like component as
``mini-super nova'', an etymologically indefensible term, I use the term {\it
macronova}. I investigate the observability of macronovae powered by neutron
decay and by radioactive Nickel. Separately, I note that a macronova will
reprocess energetic emission arising from a long lived central source. I find
that surprisingly interesting limits on the basic parameters of macronovae can
be obtained provided observations are obtained with current 10-m class
telescopes over a range of one hour to one day following the burst.
