Letter to the Editor

Time resolved spectroscopy of GRB 030501 using INTEGRAL^*

¹ Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
² INTEGRAL Science Data Centre, Chemin d'Écogia 16, 1290 Versoix, Switzerland
³ Geneva Observatory, 51 chemin des Maillettes, 1290 Sauverny, Switzerland
⁴ Istituto di Astrofisica Spaziale e Fisica Cosmica, CNR v. Bassini 15, 20133 Milano, Italy
⁵ Astronomical Institute, Academy of Sciences of the Czech Republic, 25165 Ondrejov, Czech Republic
⁶ Danish Space Research Institute, Juliane Maries Vej 30, 2100, Copenhagen, Denmark
⁷ School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, UK
⁸ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
⁹ Paul Scherrer Institut, 5232 Villingen, Switzerland

Corresponding author: V. Beckmann, Volker.Beckmann@obs.unige.ch

Received: 28 May 2003
Accepted: 26 June 2003

Abstract

The gamma-ray instruments on-board INTEGRAL offer an unique opportunity to perform time resolved analysis on GRBs. The imager IBIS allows accurate positioning of GRBs and broad band spectral analysis, while SPI provides high resolution spectroscopy. GRB 030501 was discovered by the INTEGRAL Burst Alert System in the ISGRI field of view. Although the burst was fairly weak (fluence it was possible to perform time resolved spectroscopy with a resolution of a few seconds. The GRB shows a spectrum in the 20–400 keV range which is consistent with a spectral index . No emission line or spectral break was detectable in the spectrum. Although the flux seems to be correlated with the hardness of the GRB spectrum, there is no clear soft to hard evolution seen over the duration of the burst. The INTEGRAL data have been compared with results from the Ulysses and RHESSI experiments.