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Astron. Astrophys. 334, L69-L72 (1998)

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Letter to the Editor

High resolution imaging of the X-ray afterglow of GRB970228 with ROSAT

F. Frontera 1, 2, J. Greiner 3, L.A. Antonelli 4, E. Costa 5, F. Fiore 4, A.N. Parmar 6, L. Piro 5, T. Boller 7 and W. Voges 7

1 Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Via Gobetti, 101, I-40129 Bologna, Italy
2 Dipartimento di Fisica, Università di Ferrara, Via Paradiso, 11, I-44100 Ferrara, Italy
3 Astrophysikalisches Institut Potsdam, D-14482 Potsdam, Germany
4 BeppoSAX Scientific Data Centre, c/o Nuova Telespazio, Via Corcolle 19, I-00131 Roma, Italy
5 Istituto di Astrofisica Spaziale, CNR, Via E. Fermi, I-00044 Frascati, Italy
6 Astrophysics Division, Space Science Department of ESA, ESTEC, 2200 AG Noordwijk, The Netherlands
7 Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching, Germany

Received 6 January 1998 / Accepted 7 April 1998


We report results of a ROSAT High-Resolution Imager (HRI) observation of the X-ray error box given by the BeppoSAX Wide Field Camera for the gamma-ray burst that occurred on 1997 February 28. The observation started 10 days after the burst and ended three days later, with a total exposure of 34.3 ks. An X-ray source was detected within the [FORMULA] WFC error box and its position determined with a [FORMULA] radius accuracy. The source position is in the BeppoSAX Narrow Field Instrument source error box and is coincident (to within [FORMULA]) with the optical transient associated with GRB970228. This is the most precise position obtained for an X-ray afterglow and confirms that the X-ray and optical afterglows have the same origin. We present the 0.1-2.4 keV combined HRI and BeppoSAX Low-Energy Concentrator Spectrometer decay light curve which can be well fit with a power-law. The decay is consistent with that measured at higher energies (2-10 keV) with the BeppoSAX Medium-Energy Concentrator Spectrometer.

Key words: gamma-rays: bursts – gamma-rays: observations – X-rays: observation – X-rays: sources

Send offprint requests to: F. Frontera (e-mail: filippo@tesre.bo.cnr.it)

© European Southern Observatory (ESO) 1998

Online publication: June 2, 1998