Time history, energy spectrum, and localization of an unusual gamma-ray burst

A ..gamma..-ray burst lasting approx.48 ms was observed on 1979 June 13 by four instruments in the interplanetary network. The event is unusual not only by virtue of its extremely short duration, but also by the presence of rise and fall times at the 2 ms level in the time history, and because the energy spectrum is hard, extending to 2 MeV. The 0.7 arcmin/sup 2/ error box contains no optical counterpart on the POSS plate (limiting magnitude approx.21). The spectral characteristics measured by experiments in the interplanetary network are substantially different from those previously reported for this burst.