Hypernova Reveals Hidden Identity As Gamma-Ray Burst
An international research team, led by astronomers from the University of Tokyo, Hiroshima University, and the National Astronomical Observatory of Japan, used the Subaru telescope to obtain the spectrum of SN2003jd, a hypernova unaccompanied by a gamma-ray burst, and found the first evidence that it is a jet-like explosion viewed off-axis.
Hypernovae are hyper-energetic supernovas that are often associated with gamma-ray bursts. This result provides clear and firm evidence that all hypernovae may be associated with gamma-ray bursts, but that gamma-ray bursts are observable only when jets produced by the hypernova explosion point towards Earth.
More info: Subaru telescope web page