The experimental results are in good agreement with the theoretical prediction. The dependences of its linewidth, slope and magnitude on the various experimental parameters are measured and fitted by the well-known theoretical expressions. We present the experimental study of modulation transfer spectroscopy of ytterbium atoms in a hollow cathode lamp. International Nuclear Information System (INIS) Modulation Transfer Spectroscopy of Ytterbium Atoms in a Hollow Cathode Lamp With these spectra we are measuring and calibrating the positions of these molecular lines in order to make them suitable for spectrograph calibration.In the near infrared region, U/Ne hollow cathode lamps give a higher density of calibration lines than Th/Ar lamps and will be implemented on the upgraded CRIRES+ spectrograph on ESOâ€™s Very Large This significantly exceeds the resolving power of most astronomical spectrographs and resolves many of the molecular lines of ThO. Second, we have measured the spectrum of a recent, contaminated Th/Ar hollow cathode lamp using a high-resolution Echelle spectrograph (Madison Wisconsin) at a resolving power (R~ 250,000). Interactive zooming and the ability to convolve any of the spectra with a Gaussian or uploaded instrument profile enable the user to see immediately what the spectrum would look like at the particular resolution of their spectrograph.

Spectra of hollow cathode lamps at up to 3 different currents can now be displayed simultaneously. First, we have expanded and improved the NIST Standard Reference Database 161, 'Spectrum of Th-Ar Hollow Cathode Lamps' to cover the region 272 nm to 5500 nm. In addition, recent changes in regulations regarding the handling of thorium have led to a degradation in the quality of Th/Ar calibration lamps, with contamination by molecular ThO lines that are strong enough to obscure the calibration lines of interest.We are pursuing two approaches to these problems. However, the high density of the spectrum that makes it attractive for calibrating high-resolution spectrographs is a detriment for lower resolution spectrographs and this is not obvious by examination of existing linelists. Thorium is an attractive element for calibration as it has a single isotope, has narrow spectral lines, and has a dense spectrum covering the whole of the visible region. Low-current Th/Ar hollow cathode lamps have long been used for calibration of astronomical spectrographs on ground-based telescopes.

Nave, Gillian Shlosberg, Ariel Kerber, Florian Den Hartog, Elizabeth Neureiter, Bianca Spectra of Th/Ar and U/Ne hollow cathode lamps for spectrograph calibration

Modulation of hollow cathode lamp