A γ-ray burst at a redshift of zåisebox-0.5ex 8.2


Long-duration γ-ray bursts (GRBs) are thought to result from the explosions of certain massive stars, and some are bright enough that they should be observable out to redshifts of z>20 using current technology. Hitherto, the highest redshift measured for any object was z = 6.96, for a Lyman-α emitting galaxy. Here we report that GRB090423 lies at a redshift of zåisebox-0.5ex 8.2, implying that massive stars were being produced and dying as GRBs i̊sebox-0.5ex 630Myr after the Big Bang. The burst also pinpoints the location of its host galaxy.