1 J.. Larsson, C.. Fransson, G.. Östlin, P.. Gröningsson, A.. Jerkstrand, C.. Kozma, J.. Sollerman, P.M. Challis, R.. Kirshner, R.A. Chevalier, K.. Heng, R.A. McCray, N.B. Suntzeff, P.. Bouchet, A.. Crotts, J.I. Danziger, E.. Dwek, K.. France, P.. Garnavich, S.. Lawrence, B.. Leibundgut, P.. Lundqvist, N.. Panagia, C.S.J. Pun, N.. Smith, G.. Sonneborn, L.. Wang, and J.C. Wheeler, Nature 474, (2011).