Skymaps in equatorial coordinates of the visibility by the Pierre Auger Observatory during both BBH events. The colorscale indicates the fraction of a day each portion of the sky is visible by the Pierre Auger Observatory SD in the ES channel (top pannel) and the DG channel (bottom pannel). The white solid line represents the 90% CL position of GW150914, the dashed line is the 90% CL location of event GW151226 and the white star is the best-fit location of GW150914 obtained with data from the Fermi-GBM instrument. Taken from [48].