Supernova is a stellar explosion that is extremely luminous and cause burst of radiation that often is more energetic that entire galaxy. It then fades slowly over several weeks or months. During this period supernova can radiate as much energy as the Sun over its entire life span.
A few days ago (January, 21st) bright supernova SN2014J has been discovered in M82 galaxy (Ursa Major constellation) by Steve Fossey of University College London. First optical spectrum obtained showed that supernova is of type Ia. The supernova is expected to brighten within following days to be bright enough to be visible with binoculars.
Last night I was able to picture it:
First picture is composite of two 5 minutes exposures. Next one is one 60 seconds shot, so I was able to determine the supernova brightness:
Not exact visual brightness, but with Baaders luminance filter, but seems to be close to visual. At 10.8 magnitude you need instrument of 50-60mm aperture at least to try to view it under dark sky. But supernova may become brighter still, so may be a little bit easier to see.