GRB 030131: a long Gamma-Ray Burst detected with INTEGRAL during a satellite slew D. G¨ otz a , S. Mereghetti a , K. Hurley b , S. Deluit c , M. Feroci d , F. Frontera e , A. Fruchter f , J. Gorosabel f , g , D.H. Hartmann h , J. Hjorth i , R. Hudec j , I.F. Mirabel k, l , E. Pian m , G. Pizzichini n , P. Ubertini d , C. Winkler o a Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF) – CNR, Milano, Via Bassini 15, I-20133 b UC Berkeley Space Sciences Laboratory, Berkeley CA 94720-7450, USA c Integral Science Data Centre, Chemin d’ ´ Ecogia 16, CH-1290 Versoix, Switzerland d IASF – CNR, Sezione di Roma ,via Fosso del Cavaliere 100, I-00133 Roma, Italy e Dipartimento di Fisica, Universit` a di Ferrara, Via Paradiso 12, I-44100 Ferrara, Italy f Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA g Instituto de Astrof´ ısica de Andaluc´ ıa (IAA-CSIC), P.O. Box 03004, E–18080 Granada, Spain h Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978, USA i Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, DK j Astronomical Institute, Academy of Sciences of the Czech Republic, CZ-251 65 Ondrejov, CZ k Service d’Astrophysique, CEA/Saclay, Orme des Merisiers Bˆ at. 709, F-91191 Gif-sur-Yvette, France l Instituto de Astronomia y Fisica del Espacio / CONICET, cc67, suc 28. 1428 Buenos Aires, Argentina m Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste, Italy n IASF – CNR, Sezione di Bologna, via Piero Gobetti 101, I-40129 Bologna, Italy o ESA-ESTEC, RSSD, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands A long Gamma-Ray Burst (GRB) was detected with the instruments on board the INTEGRAL satellite on January 31 2003. Although most of the GRB, which lasted ∼150 seconds, occurred during a satellite slew, the automatic software of the INTEGRAL Burst Alert System was able to detect it in near-real time. Here we report the results obtained with the IBIS instrument, which detected GRB 030131 in the 15 keV - 200 keV energy range, The burst displays a complex time profile with numerous peaks. The peak spectrum can be described by a single power law with photon index Γ ≃1.7 and has a flux of ∼2 photons cm -2 s -1 in the 20-200 keV energy band. The high sensitivity of IBIS has made it possible for the first time to perform detailed time-resolved spectroscopy of a GRB with a fluence of 7×10 -6 erg cm -2 (20-200 keV). 1. INTRODUCTION Ever since their discovery [1], Gamma-Ray Bursts (GRBs) have been a puzzling mystery, mostly because of their short durations and the apparent lack of counterparts at other wave- lengths. A breakthrough in this field came thanks Nuclear Physics B (Proc. Suppl.) 132 (2004) 316–319 0920-5632/$ – see front matter © 2004 Elsevier B.V. All rights reserved. www.elsevierphysics.com doi:10.1016/j.nuclphysbps.2004.04.056