Israeli scientists recorded a supernova - in real time - with the Hubble Space Telescope. The scientists were able to "reach" the scene of the explosion while it was happening, and thus successfully map it at an unprecedented level of detail.
Supernovas cannot be predicted in advance, so scientists have no choice but to study it in retrospect. Innovations in telescopic means allow us to witness explosions not only in our own galaxy but also in distant galaxies, and to collect data that until recently could not be imagined at all.