  We present the spectral analysis of duration-integrated broadband spectra (in
$\sim30 $keV$-200 $MeV) of 15 bright BATSE gamma-ray bursts (GRBs). Some GRB
spectra are very hard, with their spectral peak energies being above the BATSE
LAD passband limit of $\sim$2 MeV. In such cases, their high-energy spectral
parameters (peak energy and high-energy power-law indices) cannot be adequately
constrained by BATSE LAD data alone. A few dozen bright BATSE GRBs were also
observed with EGRET's calorimeter, TASC, in multi-MeV energy band, with a large
effective area and fine energy resolution. Combining the BATSE and TASC data,
therefore, affords spectra that span four decades of energy ($30 $keV$-200
$MeV), allowing for a broadband spectral analysis with good statistics.
Studying such broadband high-energy spectra of GRB prompt emission is crucial,
as they provide key clues to understanding its gamma-ray emission mechanism.
Among the 15 GRB spectra, we found two cases with a significant high-energy
excess, and another case with a extremely high peak energy (\epeak $\gtrsim$
170 MeV). There have been very limited number of GRBs observed at MeV energies
and above, and only a few instruments have been capable of observing GRBs in
this energy band with such high sensitivity. Thus, our analysis results
presented here should also help predict GRB observations with current and
future high-energy instruments such as AGILE and GLAST, as well as with
ground-based very-high-energy telescopes.
