Ultralong GRBs: a nearby laboratory for PopIII openPar-likeclosePar star explosions

Swift observations of gammaray bursts recently highlighted the existence ofrare highenergy transients, characterized by extremely long durations (fromhours to days). The origin of these enigmatic events, dubbed ultralong GRBs,remains uncertain with the prime model being the collapse of a lowmetallicityBlue Supergiant star. In this scenario ultralong GRBs could represent the localanalogues of pop III GRBs, thus providing a nearby laboratory to investigateprimordial star explosions. Here we propose a ToO program to observe a newlydiscovered ultralong GRB. The requested Xray observations will be complementedby an extensive followup campaign through our ongoing radio, optical, and IRprograms. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]