  By integrating the relativistic hydrodynamic equations introduced by Taub we
have determined the exact EQuiTemporal Surfaces (EQTSs) for the Gamma-Ray Burst
(GRB) afterglows. These surfaces are compared and contrasted to the ones
obtained, using approximate methods, by Panaitescu & Meszaros (1998), Sari
(1998), Granot et al. (1999).
