Letter to the Editor

IBIS performances during the Galactic Plane Scan^*

I. The Cygnus region

¹ IASF-CNR, via del Fosso del Cavaliere 100, 00133 Roma, Italy
² CEA Saclay, DSM/DAPNIA/SAp, CNRS FRE 2591, 91191 Gif-sur-Yvette Cedex, France
³ Integral Science Data Center, Chemin d'Écogia 16, 1290 Versoix, Switzerland
⁴ School of Physics and Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
⁵ IASF/CNR, sezione di Bologna, via P. Gobetti 101, 40129 Bologna, Italy
⁶ CEA Saclay, DSM/DAPNIA/SAp, 91191 Gif-sur-Yvette Cedex, France
⁷ IASF/CNR, sezione di Milano, via Bassini 15, 20133 Milano, Italy
⁸ IASF/CNR, sezione di Palermo, via Ugo La Malfa 153, 90146 Palermo, Italy

Corresponding author: M. Del Santo, delsanto@rm.iasf.cnr.it

Received: 14 July 2003
Accepted: 8 August 2003

Abstract

The Plane of our Galaxy is regularly observed by the INTEGRAL satellite by means of scheduled scans. We present here results from the IBIS/ISGRI instrument using data from the first two Galactic Plane Scans performed at the end of the Performance Verification phase, while INTEGRAL was pointed towards the Cygnus region.
Considering the predicted IBIS sensitivity, we expected three persistent sources to be detectable: Cyg X-1, Cyg X-3, Cyg X-2, in order of decreasing intensity in the hard-X energy range (>15 keV). In addition to these sources, our analysis revealed two more transient sources, confirming the unprecedented IBIS sensitivity. For each exposure (~2200 s) of the two scans, we report on detected source fluxes, variabilities and localisation accuracies.