A very luminous magnetar-powered supernova associated with an ultra-long γ-ray burst.

A new class of ultra-long-duration γ-ray bursts (GRBs) has recently been suggested, with durations in excess of 10,000 seconds, and now a supernova (SN 2011kl) has been found to be associated with the ultra-long-duration GRB 111209A, allowing a physical understanding of the nature of ultra-long-duration GRBs.