Letter to the Editor

SPI/INTEGRAL observation of the Cygnus region

¹ Centre d'Étude Spatiale des Rayonnements, CNRS/UPS, BP 4346, 31028 Toulouse, France
² Space Science Laboratory, University of California, Berkeley, CA 94720, USA
³ IASF, via Bassini 15, 20133 Milano, Italy
⁴ DSM/DAPNIA/Sap, CEA-Saclay, 91191 Gif-sur-Yvette, France
⁵ Max-Planck-Institut für Extraterrestrische Physik, Postfach 1603, 85740 Garching, Germany
⁶ IFIC, University of Valencia, 50 avenida Dr. Moliner, 46100 Burjassot, Spain
⁷ UCSD/CASS, 9500 Gilman Drive, La Jolla, CA 92093-0111, USA
⁸ Laboratory for High Energy Astrophysics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA

Corresponding author: L. Bouchet, bouchet@cesr.fr

Received: 17 July 2003
Accepted: 27 August 2003

Abstract

We present the analysis of the first observations of the Cygnus region by the SPI spectrometer onboard the Integral Gamma Ray Observatory, encompassing 600 ks of data. Three sources namely Cyg X-1, Cyg X-3 and EXO 2030+375 were clearly detected. Our data illustrate the temporal variability of Cyg X-1 in the energy range from 20 keV to 300 keV. The spectral analysis shows a remarkable stability of the Cyg X-1 spectra when averaged over one day timescale. The other goal of these observations is SPI inflight calibration and performance verification. The latest objective has been achieved as demonstrated by the results presented in this paper.