Characterization of the HCl-HBr-HI gas absorption cell for GIANO-TNG

GIANO is an high resolution cross-dispersed spectrometer operating at near IR wavelengths (0.9-2.5 microns) which will be soon commissioned at the 3.6m TNG Italian telescope in La Palma. One of its most ambitious aims is searching for earth-like planets with habitable conditions around very cool main sequence stars. This requires measurements of radial velocities with accuracies of a few m/s which can be achieved by means of a gas absorption cell containing a mixture of the halogen-hydrates HCl, HBr and HI. We present here the results of the laboratory work for the construction and characterization of such cell.