Magnetar-driven explosions as power source of Gamma-ray Bursts and Supernovae

We present photometry and spectroscopy of SN 2011kl associated to GRB 111209A. Peculiarities arise from both the ultra-long GRB and the very luminous SN, brighter than any other GRB-associated SN observed to date. We present unequivocal evidence in favor of a scenario where a newly-formed magnetar powers both the GRB and the SN.