The BeppoSAX revolution in Gamma-Ray Burst science.pdf

a r X i v : a s t r o - p h / 0 4 0 5 3 2 0 v 2 1 8 M a y 2 0 0 4 Baltic Astronomy, vol.13, 193–200, 2004. THE BEPPOSAX REVOLUTION IN GAMMA–RAY BURST SCIENCE L.Amati Istituto di Astrofisica Spaziale e Fisica Cosmica - Sez. Bologna, CNR, via P. Gobetti 101, I-40129 Bologna, Italy Received October 15, 2003 Abstract. We review the BeppoSAX discoveries and studies in the field of Gamma-Ray Bursts, which allowed a huge step forward in the understanding of these still mysterious and highly interesting astrophys- ical sources. Key words: X–rays: general – gamma–rays: observations – gamma– rays: bursts 1. THE BEPPOSAX MISSION AND ITS SCIENTIFIC PAYLOAD BeppoSAX was a mission of the Italian Space Agency (ASI) with contribution of NIVR (Netherlands) launched in April 1996 and ended in April 2002. It was characterized by a Low Equatorial Orbit with 3.9? inclination and ～600 km altitude, resulting in a low and very stable background (few % variation along a single orbit). The scientific payload covered an unprecedented broad energy band (0.1–300 keV) and was composed by two set of instruments: the Narrow Field Instruments (NFI), pointing along the satellite Z axis, and two wide field instruments pointing in directions perpendicular to it. The NFI included (we report in parenthesis the energy band, the FOV and the angular resolution): the LECS (0.1–10 keV, 0.5?, ～3’), the MECS, composed by three units, (1.3–10 keV, 0.5?, ～1’), the HPGSPC (4–120 keV, 1.1?, collimated) and the PDS (15–300 keV, 1.3?, collimated). The wide field instruments were the Wide Field Cameras (WFC), two units pointing along the ±X axis (2–28 keV, 20? FOV, 3’ ang. res.), and the Gamma–Ray Burst Monitor, four units pointing along the ±X and ±Y directions (40–700 keV, 2 L.Amati open FOV, burst location capabilities of several degrees). See Boella et al. (1997) and references therein for more details. 2. THE DISCOVERY OF GAMMA-RAY BURSTS AFTERGLOW The possibility of detecting GRBs simultaneously with the G