Deriving the redshift of distant galaxies with Gamma-Ray Burst transient   edges
  Cosmological Gamma-Ray Bursts (GRBs) offer a unique perspective to probe the evolution of distant galaxies. We discuss one of the multiple benefits of this approach, i.e. the detection of transient edges in the GRB prompt phase emission. These absorption features can be used to directly derive the redshift of GRBs and their host galaxies without the need of any optical spectroscopic follow-up. 
E. Le Floc'h, P.-A. Duc and I.F. Mirabel