Supplement: Localization and broadband follow-up of the   gravitational-wave transient GW150914
  This Supplement provides supporting material for arXiv:1602.08492 . We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands. 
B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese,   K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhi...
astro-ph.HE gr-qc