  We calculate the expected envelope of emission for relativistic shells under
the assumption of local spherical symmetry. Gamma-Ray Burst envelopes rarely
conform to the expected shape, which is similar to a FRED; a fast rise and
exponential decay. The fast rise is determined by the time that the
relativistic shell prodcues gamma rays. The decay has the form of a power law
and arises from the curvature of the shell. The amount of curvature comes from
the overall size of the shell so the duration of the decay phase is related to
the time the shell expands before converting its energy to gamma rays. From the
envelope of emission, one can estimate when the central explosion occurred and,
thus, the energy required for the shell to sweep up the ISM. The energy greatly
exceeds 10^{53} erg unless the bulk Lorentz factor is less than 75. This puts
extreme limits on the "external" shock models. However, the alternative,
"internal" shocks from a central engine, has a problem: the entire long complex
time history lasting hundreds of seconds must be postulated at the central
site.
