ISAAC LW Telluric Line Atlas

We present a status report on a project with the aim to enhance the wavelength calibration of ISAAC’s long wavelength spectroscopic mode. We measure telluric standard stars with high signal/noise and use the comparison with theoretical spectra of the telluric lines for the wavelength calibration. We show that calibrations done with arc-lines only can be wrong by up to 0.2 μm. The new atlas of telluric lines allows a spectral calibration with a precision of 0.003 μm.