WFC Science highlights - Gamma-ray burst 980519

GRB 980519 is the second brightest X-ray counterpart to a GRB measured by WFC. The richness in the data has enabled a more-than-usual thorough study of the X-ray emission of the burst. The X-ray emission is very interesting because it seems to start before the gamma-rays.

Photon count rates in a number of X-ray and gamma-ray bandpasses, using WFC and BATSE data. There is clearly X-ray activity before the gamma-ray event sets in

A detailed analysis of the X-ray spectral evolution, however, shows that the precursor X-ray emission is rather common to that during the gamma-ray phase and to the X-ray spectra of other GRBs. Therefore, this burst is probably nothing more than a rare (though not unprecedented) example of a soft-to-hard-to-soft evolution.

These results have been published by Jean in 't Zand, John Heise, Jan van Paradijs and Ed Fenimore (ApJL 1999, in press)

Jean in 't Zand, SRON, March 12, 1999