BeppoSAX Observations of GRB980425: Detection of the Prompt Event and Monitoring of the Error Box

E. Pian; L. Amati; L. A. Antonelli; R. C. Butler; E. Costa; G. Cusumano; J. Danziger; M. Feroci; F. Fiore; F. Frontera; P. Giommi; N. Masetti; J. M. Muller; L. Nicastro; T. Oosterbroek; M. Orlandini; A. Owens; E. Palazzi; A. Parmar; L. Piro; J. J. M. in 't Zand; A. Castro-Tirado; A. Coletta; D. Dal Fiume; S. Del Sordo; J. Heise; P. Soffitta; V. Torroni

doi:10.1086/308978

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arXiv · astro-ph/9910235

BeppoSAX Observations of GRB980425: Detection of the Prompt Event and Monitoring of the Error Box

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Abstract

We present BeppoSAX follow-up observations of GRB980425 obtained with the Narrow Field Instruments (NFI) in April, May, and November 1998. The first NFI observation has detected within the 8' radius error box of the GRB an X-ray source positionally consistent with the supernova 1998bw, which exploded within a day of GRB980425, and a fainter X-ray source, not consistent with the position of the supernova. The former source is detected in the following NFI pointings and exhibits a decline of a factor of two in six months. If it is associated with SN 1998bw, this is the first detection of X-ray emission from a Type I supernova above 2 keV. The latter source exhibits only marginally significant variability. The X-ray spectra and variability of the supernova are compared with thermal and non-thermal models of supernova high energy emission. Based on the BeppoSAX data, it is not possible to firmly establish which of the two detected sources is the GRB X-ray counterpart, although probability considerations favor the supernova.

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E. Pian, L. Amati, L. A. Antonelli, R. C. Butler, E. Costa, G. Cusumano, J. Danziger, M. Feroci, F. Fiore, F. Frontera, P. Giommi, N. Masetti, J. M. Muller, L. Nicastro, T. Oosterbroek, M. Orlandini, A. Owens, E. Palazzi, A. Parmar, L. Piro, J. J. M. in 't Zand, A. Castro-Tirado, A. Coletta, D. Dal Fiume, S. Del Sordo, J. Heise, P. Soffitta, V. Torroni. 1999-10-13. BeppoSAX Observations of GRB980425: Detection of the Prompt Event and Monitoring of the Error Box. https://doi.org/10.1086/308978

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