Integral: the International Gamma-ray Astrophysics Laboratory

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is dedicated to the ne spec-troscopy ((E: 2 keV FWHM @ 1 MeV) and ne imaging (angular resolution: 12 0 FWHM) of celestial gamma-ray sources in the energy range 15 keV to 10 MeV. The scientiic payload consists of two gamma-ray instruments and two monitors: the Ge spectrometer (SPI) and the CdTe/CsI imager (IBIS); the X-ray monitor (JEM-X) and optical monitor (OMC). INTEGRAL was selected by the ESA Science Programme Committee in 1993 as the next ESA medium-size scientiic mission (M2) to be launched in 2001. The mission is conceived as an observatory led by ESA with contributions from Russia and NASA. The INTEGRAL observatory will provide to the science community at large an unprecedented combination of imaging and spectroscopy over a wide range of X-ray and gamma-ray energies including the optical band. Most of the observing time will be open to the scientiic community interfacing with the INTEGRAL Science Data Centre. This paper summarises the key scientiic goals of the mission, the current status of the payload and spacecraft and it highlights elements of the science ground segment including data centre, science operations and the observing programme.