SIMBAD references

We discuss the prompt emission of the γ-ray burst GRB 990510 and its subsequent X-ray afterglow from 8.0 to 44.3 hr after the prompt emission, using observations with the Gamma-Ray Burst Monitor and Narrow Field Instruments on BeppoSAX. In the 40-700 keV band, GRB 990510 had a fluence of ∼1.9x10^–5 ergs.cm^–2, whereas it reached a peak flux of ∼2.4x10^–6 ergs.cm^–2.s^–1. The X-ray afterglow decay light curve can be satisfactorily described by a single power law with an index of -1.42±0.07. Both the X-ray and optical behavior of the afterglow can be explained by γ-ray burst debris expanding as a jet; we find that the cooling frequency is (fixed) between the optical and X-ray wavelength bands.