  It is proposed that the gamma ray burst photons near the peak of the spectrum
at several hundred KeV are produced on very compact scales, where photon
production is limited by blackbody effects and/or the requirement of energetic
quanta ($E>2m_e c^2$) for efficient further production. The fast variation of
order milliseconds in the time profile is then a natural expectation, given the
other observed GRB parameters. Analytic calculations are presented to show that
the escape of non-thermal, energetic gamma rays can emerge within a second of
the thermal photons from a gammasphere of below $10^{12}$ cm. The minimum
asymptotic bulk Lorentz factor in this model is found to be of order several
hundred if the photosphere is of order $3 \times 10^{11}$ cm and greater for
larger or smaller photospheric radii. It is suggested that prompt UHE gamma
rays might provide a new constraint on the asymptotic Lorentz factor of the
outflow.
