Letter to the Editor

JEM–X: The X-ray monitor aboard INTEGRAL^*

¹ Danish Space Research Institute, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
² Metorex International Oy, Nihtisillankuja 5, PO Box 85, 02631 Espoo, Finland
³ Observatory, PO Box 14, 00014, University of Helsinki, Finland
⁴ Space Research Center, Bartycka 18A 00-716, Warsaw, Poland
⁵ Instituto de Astrofisica CNR, via del Fosso del Cavaliere 100, 00133 Rome, Italy
⁶ ENEA-Frascati UTS-Fusione, via Enrico Fermi 45, 00045 Frascati, Italy
⁷ IASF-Bologna, via Gobetti 101, 40129, Bologna, Italy
⁸ Dipartimento di Fisica, University of Ferrara, via del Paradiso 12, 44100 Ferrara, Italy
⁹ GACE, University of Valencia, PO Box 20085, 46071 Valencia, Spain
¹⁰ Stockholm University, Roslagstullgatan 21, Stockholm, Sweden
¹¹ Copernicus Astronomical Center, Bartycka 18, 00-716, Warsaw, Poland
¹² Instituto de Astrofísica de Andalucía (IAA-CSIC), PO Box 03004, 18080 Granada, Spain
¹³ Alenia Spazio, Space Division, Corso Marche 41, 10146 Torino, Italy
¹⁴ ESOC, Robert-Bosch Str. 5, 64293 Darmstadt, Germany
¹⁵ ESTEC, Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, The Netherlands
¹⁶ MPI Extraterr. Physik, Gießenbachstr., 85748 Garching and ISDC, Chemin d'Écogia 16, Versoix, Switzerland
¹⁷ Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, MA 02138, USA

Corresponding author: N. Lund, nl@dsri.dk

Received: 15 July 2003
Accepted: 3 September 2003

Abstract

The JEM–X monitor provides X-ray spectra and imaging with arcminute angular resolution in the 3 to 35 keV band. The good angular resolution and the low energy response of JEM–X plays an important role in the identification of gamma ray sources and in the analysis and scientific interpretation of the combined X-ray and gamma ray data. JEM–X is a coded aperture instrument consisting of two identical, coaligned telescopes. Each of the detectors has a sensitive area of 500 cm², and views the sky through its own coded aperture mask. The two coded masks are inverted with respect to each other and provides an angular resolution of 3' across an effective field of view of about 10° diameter.