Letter to the Editor

Simultaneous observations of the quasar 3C 273 with INTEGRAL, XMM-Newton and RXTE^*,**

¹ Science Data Centre, Chemin d'Écogia 16, 1290 Versoix, Switzerland
² Geneva Observatory, Chemin des Maillettes 51, 1290 Sauverny, Switzerland
³ Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
⁴ Danish Space Research Institute, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138, USA
⁶ Department of Physics and Astronomy, University of Leicester, University road, Leicester LE1 7RH, UK
⁷ N. Copernicus Astronomical Ctr, Bartycka 18, 00716 Warsaw, Poland

Corresponding author: T. Courvoisier (ISDC), Thierry.Courvoisier@obs.unige.ch

Received: 15 July 2003
Accepted: 1 August 2003

Abstract

INTEGRAL has observed the bright quasar 3C 273 on 3 epochs in January 2003 as one of the first observations of the open programme. The observation on January 5 was simultaneous with RXTE and XMM-Newton observations. We present here a first analysis of the continuum emission as observed by these 3 satellites in the band from 3 keV to 500 keV. The continuum spectral energy distribution of 3C 273 was observed to be weak and steep in the high energies during this campaign. We present the actual status of the cross calibrations between the instruments on the three platforms using the calibrations available in June 2003.