As I understand it, the magnetar is created during the supernova. The phys.org version of this story (http://phys.org/news/2015-07-biggest-explosions-universe-

As I understand it, the magnetar is created during the supernova. The phys.org version of this story (http://phys.org/news/2015-07-biggest-explosions-universe-powered-strongest.html http://phys.org/news/2015-07-biggest-explosions-universe-pow...) links to another article with more information: http://phys.org/news/2015-04-strange-supernova-link-gamma-ray.html#inlRlv http://phys.org/news/2015-04-strange-supernova-link-gamma-ra...