Broad-band burst spectra: Sharp breaks and GeV bursts

We have constructed 6 new combined spectra from 2 keV to 500 MeV from BATSE, EGRET, and Ginga data. This brings the total of such combined spectra to ten. The low energy slope of the spectra are all consistent with the strong prediction of the shocked synchrotron model that nu F-nu asymptotically approaches nu(4/3) for low energy. Three of the eight bursts selected for detection by EGRET have sharp spectral breaks from 1 - 2 MeV, so that the majority of all bursts are likely to have similar to MeV spectral breaks. Within a fireball scenario, the energy of the break in the emitter's rest frame will be of order a few keV, and we know of no physical mechanism that can cause a break at these energies. The sharpness of the breaks also begs for an explanation. Two of our new bursts show relatively flat spectra with no sign of a break or turnover. GRB950425 shows a rising spectrum which is still rising at 200 MeV, such that it is a 'GeV burst'.