Characterization in the Laboratory of VISIR, the mid-infrared imager and spectrometer for the VLT.

ABSTRACT In this paper, we present the status of VISIR, the mid-infrared instrument to be installed in 2003 at theCassegrain focus of MELIPAL, one of the four 8-meter telescopes of the European Very Large Telescope. Thiscryogenic instrument, optimized for diffraction-limited performance in both mid-infrared atmospheric windows(N and Q band), combines imaging capabilities over a field up to about 1x1 arcmin 2 , and long-slit (0.5 arcmin)grating spectroscopy with various spectral resolutions up to R=25000 at 10 m and 12500 at 20 m. Thecontract to design and build VISIR was signed in November 1996 between the European Southern Observatory(ESO) and a French-Dutch consortium of institutes led by Service d'Astrophysique of Commissariat a l'EnergieAtomique (CEA). A key step in the project has been passed in December 2001, with the first infrared images inthe laboratory and in April 2002 with the first infrared spectra in the laboratory. We present the results of thelaboratorytests of the instrument, which is scheduled to be shipped to Paranal at the end of 2002.Keywords : infrared, instrumentation, imager, spectrometer, VLT.