That occasionally new sources ("Stella Nova") would pop up in the
heavens was noted more than a thousand years ago. The earnest study
of cosmic explosions began in earnest less than a hundred years
ago. Over time we have come to appreciate the central role
of supernovae in synthesizing new elements (and making life
as we know possible).
The Palomar Transient Factory (PTF), an innovative 2-telescope
system, was designed to explicitly to chart the transient sky with
a particular focus on events which lie in the nova-supernova gap.
PTF is now finding an extragalactic transient every 20 minutes and
a Galactic (strong) variable every 10 minutes. The results so far:
classification of 2000 supernovae, identification of an emerging
class of ultra-luminous supernovae, the earliest discovery of a Ia
supernovae, discovery luminous red novae, the most comprehensive
UV spectroscopy of Ia supernovae, discovery low energy budget
supernovae, clarification of sub-classes of core collapse and
thermo-nuclear explosions, mapping of the systematics of core
collapse supernovae, identification of a trove of eclipsing binaries
and the curious AM CVns.