THE SPHERE IFS AT WORK

SPHERE is an extrasolar planet imager whose goal is to detect giant extrasolar planets in the vicinity of bright stars and to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made of an extreme-Adaptive Optics (AO) turbulence correction, a pupil tracker and NIR and Visible coronagraph devices. At its back end, a differential dual imaging camera and an integral field spectrograph (IFS) work in the Near Infrared (NIR) (0.95 <= lambda <= 2.32 mu m) and a high resolution polarization camera covers the visible (0.6 <= lambda <= 0.9 mu m). The IFS is a low resolution spectrograph (R similar to 50) operates in the near IR (0.95 <= lambda <= 1.6 mu m), an ideal wavelength range for the detection of planetary features, over a field of view of about 1.7 x 1.7 square arcsecs. Form spectra it is possible to reconstruct monochromatic images with high contrast (10(-7)) and high spatial resolution, well inside the star PSF. In this paper we describe the IFS, its calibration and the results of several performance which IFS underwent. Furthermore, using the IFS characteristics we give a forecast on the planetary detection rate.