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Astron. Astrophys. 332, L29-L32 (1998)

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Letter to the Editor

BeppoSAX follow-up search for the X-ray afterglow of GRB970111

M. , Feroci 1, L.A. , Antonelli 2, M. , Guainazzi 2, J.M. , Muller 2, 3, E. , Costa 1, L. , Piro 1, J. , Heise 3, J.J.M. , in 't Zand 3, F. , Frontera 4, 5, D. , Dal Fiume 4, L. , Nicastro 4, M. Orlandini 4, E. , Palazzi 4, G. , Zavattini 5, P. , Giommi 2, A.N. Parmar 6, A. , Owens 6, A.J. , Castro-Tirado 7, M.C. , Maccarone 8, R.C. and Butler 9

1 Istituto di Astrofisica Spaziale, CNR, Via Fosso del Cavaliere, I-00133 Roma, Italy
2 BeppoSAX Scientific Data Center, Via Corcolle 19, I-00131 Roma, Italy
3 Space Research Organization in the Netherlands, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands
4 Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Via Gobetti 101, I-40129 Bologna, Italy
5 Dipartimento di Fisica, Università di Ferrara, Via Paradiso 11, I-44100 Ferrara, Italy
6 Astrophysics Division, Space Science Department of ESA, ESTEC, P.O. Box 299, 2200 AG, Noordwijk, The Netherlands
7 Laboratorio de Astrofisica Espacial y Fisica Fundamental, INTA, Madrid, Spain
8 Istituto Fisica Cosmica e Applicazioni Informatica, CNR, Via U. La Malfa 153, I-90146 Palermo, Italy
9 Agenzia Spaziale Italiana, Viale Regina Margherita 202, I-00162 Roma, Italy

Received 6 January 1998 / Accepted 3 March 1998


The BeppoSAX satellite has recently opened a new way towards the solution of the long standing gamma-ray bursts' (GRBs) enigma, providing accurate coordinates few hours after the event thus allowing for multiwavelength follow-up observational campaigns.

The BeppoSAX Narrow Field Instruments observed the region of sky containing GRB970111 16 hours after the burst. In contrast to other GRBs observed by BeppoSAX no bright afterglow was unambiguously observed. A faint source (1SAXJ1528.1+1937) is detected in a position consistent with the BeppoSAX Wide Field Camera position, but unconsistent with the IPN annulus. Whether 1SAXJ1528.1+1937 is associated with GRB970111 or not, the X-ray intensity of the afterglow is significantly lower than expected, based on the properties of the other BeppoSAX GRB afterglows. Given that GRB970111 is one of the brightest GRBs observed, this implies that there is no obvious relation between the GRB gamma-ray peak flux and the intensity of the X-ray afterglow.

Key words: Gamma rays: bursts – X-rays: bursts

Send offprint requests to: feroci@saturn.ias.rm.cnr.it

© European Southern Observatory (ESO) 1998

Online publication: March 30, 1998