Gamma-ray bursts emission is strongly beamed into a small solid angle. So, although their equivalent isotropic energies (that is the energy that would be needed

Gamma-ray bursts emission is strongly beamed into a small solid angle. So, although their equivalent isotropic energies (that is the energy that would be needed to power gamma-ray bursts if the emission was isotropic) are huge, the actual energies released in gamma-ray bursts are more or less compatible with those of supernovae (~0.1% of a solar mass).