Letter to the Editor

INTEGRAL observations of the PSR B1259-63/SS2883 system after the 2004 periastron passage

¹ School of Physics and Astronomy, University of Southampton, SO17 1BJ, UK e-mail: simon.shaw@obs.unige.ch
² INTEGRAL Science Data Centre, 1290 Versoix, Switzerland
³ Observatoire de Genève, 51 chemin des Maillettes, 1290 Sauverny, Switzerland
⁴ CEA Saclay, DSM/DAPNIA/SAp (CNRS FRE 2591), 91191 Gif-Sur-Yvette Cedex, France
⁵ Max-Planck-Institut für Extraterrestrische Physik, 87548 Garching, Germany
⁶ Istituto di Astrofisica Spaziale e Fisica Cosmica, Sezione di Milano, via Bassini 15, 20133 Milano, Italy

Received: 6 July 2004
Accepted: 10 September 2004

Abstract

The millisecond pulsar PSR B1259-63 and the Be star SS2883 are situated in a highly eccentric binary system, with orbital period ~3.4 years. We report on hard X-ray observations obtained with the INTEGRAL satellite close to the 2004 periastron passage. These are the first imaging observations of this system in the hard X-ray range (>20 keV) and allow the emission of PSR B1259-63 to be separated from that of a nearby unidentified variable source which may have contaminated previous hard X-ray observations of this system. Using the IBIS/ISGRI instrument we measured a flux of ~2–6 mCrab in the 20–200 keV range, with a power law spectrum of photon index .