The prompt X-ray emission of gamma-ray burst 980519

The prompt X-ray emission from gamma-ray burst (GRB) 980519, as measured wi th the Wide Field Cameras on board BeppoSAX, is characterized by a strong s oft-to-hard-to-soft evolution. An analysis of the evolution of the X-ray sp ectrum in terms of a single power-law model shows that the photon index evo lved from -2.0 to -1.1 to -2.4. The onset of the burst has such a soft spec trum that the 2-27 keV emission appears to precede the greater than or simi lar to 107 keV emission of GRB 980519 (as measured with the Burst and Trans ient Source Experiment) by about 70 s, Nevertheless, we show that this earl y spectral variation is part of a smooth evolution over the whole burst and that there is no convincing evidence that the early X-rays originate from a physical process that is different from that giving rise to the remainder of the burst.