what was the last recorded supernova event
In 1604 there was a supernova that is commonly called Kepler's Supernova. That is the last one that was definitely observed (there may have been others since then that were obscured by dust in our own galaxy). The telescope was first used by Galileo in 1609 to observe the heavens (he didn't invent the telescope, however) and we haven't observed a supernova in our galaxy since before then!