Wavelength calibration sources for instruments on extremely large telescopes

Extremely large telescopes (ELTs) and most of their instruments will be optimized for operating in the near infrared (IR) because of the wavelength dependent performance of adaptive optics. Few established sources for wavelength calibration exist in this wavelength domain. This project aims to provide the basic data to select the best calibration sources for instruments at the European ELT (E-ELT) as a function of wavelength range and spectral resolution. We have made use of the existing databases such as the NIST Atomic Spectra Database as well as first principle physics and practical considerations to select about 20 hollow cathode lamps for study. We are investigating their spectral and operational properties through laboratory measurements using a Fourier Transform spectrometer at the European Southern Observatory (ESO). The most interesting sources will then be studied at atomic physics laboratories, such as the US National Institute of Standards and Technology (NIST), in order to produce accurate wavelength standards and calibration reference data directly applicable to operations of E-ELT instruments. The resulting data archive will be used to recommend the best suited sources for the instruments proposed for the E-ELT.

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