GAMMA-RAY-BURST SPECTRAL SHAPES FROM 2 KEV TO 500 MEV

We present three gamma-ray-burst spectra for bright bursts over very w ide energy ranges. These were created from BATSE, COMPTEL, and OSSE da ta. The three spectra are for GRB 910503 (from 20 keV to 300 MeV), GRB 910601 (from 28 keV to 10.5 MeV), and GRB 910814 (from 103 keV to 500 MeV). A composite spectrum of 19 bright bursts is presented from 41 k eV to 1.9 MeV (with no weak lines visible) for use in calculating aver age redshift corrections in cosmological models. Expanding fireball mo dels with shocked synchrotron emission are predicted to have low-energ y spectral slope (vF(v) proportional to v(alpha)) that asymptotically approaches alpha = 4/3 such that alpha should never exceed 4/3. This p rediction is tested with more than 100 bright bursts with BATSE and Gi nga data. Over 90% of the bursts have spectral slopes in agreement wit h this prediction. For only one burst (GRB 870303, which has reported cyclotron lines) can a strong case be made that the slope violates the model limit, and then only from 2-5 keV.