The Spectrum of Th-Ar Hollow Cathode Lamps in the 900 nm to 4500 nm Region: Establishing Wavelength Standards for the Calibration of VLT Spectrographs

Published

October 12, 2021

Author(s)

F Kerber, Gillian Nave, Craig J. Sansonetti

Abstract

We report new observations of the infra-red (IR) spectrum of low current Th-Ar hollow cathode lamps with the 2-m Fourier transform spectrometer (FTS) at the National Institute of Standards and Technology. These observations establish more than 2000 lines that are suitable for use as wavelength standards in the range 900 nm to 4500 nm. The line list is used as input for a physical instrument model that provides the wavelength calibration for the Cryogenic High-Resolution IR Echelle Spectrometer (CRIRES), the European Southern Observatory's new high resolution (R 100,000) IR spectrograph at the Very Large Telescope. We have also observed the variation of the spectrum of Th-Ar lamps as a function of operating current. The results allow us to optimize the spectral output in terms of relative intensity and line density for operation on the telescope.Our results should be generally useful for wavelength calibration in near IR astronomy providing a high density of sharp well-characterized emission lines with the ease and efficiency of operation of a commercial discharge lamp.

Citation

Astrophysical Journal

Pub Type

Journals

Keywords

atomic data, Fourier transform spectroscopy, infrared, wavelength standards

Citation

Kerber, F. , Nave, G. and Sansonetti, C. (2021), The Spectrum of Th-Ar Hollow Cathode Lamps in the 900 nm to 4500 nm Region: Establishing Wavelength Standards for the Calibration of VLT Spectrographs, Astrophysical Journal (Accessed October 14, 2025)