One of the most recently detected (Cline et al., 1980) Gamma Ray Bursts (GRB) appears to have very unusual properties.
We recall here briefly the main features of the time history and of the spectral data, as given by Cline (19 79). The time history has a very fast initial rise, less than 200 usee , a smooth, large but very short initial peak, with a maximum intensity of several × 10−3 ergs cm−2 sec−1 and a 150 msec duration, followed by an oscillating decay phase, with at least 22 compound 8 second pulses. The spectrum of the initial phase of the event; corresponds to a steep power law with possibly a line at 420 keV. The total spectrum of the decay phase is even steeper and shows no lines (Mazets and Golenetskii, 1979), The location of the wait (Evans et al., 1980) corresponds to N49, a supernova remnant in the Large Magellanic Cloud, which gives a total (isotropic) emission of ≈ 1045 erg, one half of it in the initial spike, the rest in the decay phase. Three later events, apparently with no special properties, are attributed to the same source (Mazets and Golenetskii, 1979), with increasing delays (0.6, 29 and 50 days) and decreasing peak intensities (3%, 1% and 0.5% of the first event), because their locations are all consistent with the much smaller March 5 error box.