Coletta, AlessandroAlessandroColettaGiommi, PaoloPaoloGiommiCosta, E.E.CostaFrontera, F.F.FronteraHeise, J.J.Heise2020-09-172020-09-171997-06-01https://hdl.handle.net/20.500.13025/385Here we report the discovery in the X-ray band of the first afterglow of a gamma-ray burst. It was detected and quickly positioned by the Beppo-SAX satellite on 1997 February 28 (GRB970228). The X-ray afterglow source was detected with the X-ray telescopes aboard the same satellite about eight hours after the burst and faded away in a few days with a power law decay function. The energetic content of the X-ray afterglow results to be a significant fraction of gamma-ray burst energetics. The Beppo-SAX detection and fast imaging of GRB970228 started a multiwavelength campaign that lead to the identification of a fading optical source in a position consistent with the X-ray source.Article Journalhttp://arxiv.org/pdf/astro-ph/9706065v1.pdf54dcce078580fe1368eeaea7