IPN supplement to the 2nd Fermi GBM catalog

Of the 462 bursts in that catalog between 2010 July 12 and 2012 July 11, 428, or 93%, were observed by at least 1 other instrument in the 9-spacecraft IPN. Of the 428, the localizations of 165 could be improved by triangulation.

For these bursts, triangulation gives one or more annuli whose half-widths vary between about 2'.3{deg} and 16{deg}, depending on the peak flux, fluence, time history, arrival direction, and the distance between the spacecraft. We compare the IPN localizations with the GBM 1{sigma}, 2{sigma}, and 3{sigma} error contours and find good agreement between them. The IPN 3{sigma} error boxes have areas between about 8 square arcminutes and 380 square degrees, and are an average of 2500 times smaller than the corresponding GBM 3{sigma} localizations.