A High-Resolution Atlas of Uranium-Neon in the H Band

TL;DR

This paper provides a high-resolution uranium-neon spectrum atlas in the H-band, calibrated with a laser frequency comb and uranium line list, to improve wavelength calibration for near-infrared spectrographs.

Contribution

It introduces a detailed high-resolution U/Ne spectrum atlas calibrated with two methods, enhancing the precision and usability of calibration lamps in the H-band.

Findings

U/Ne spectrum calibrated with laser comb and uranium line list

Comparison of calibration precision between laser comb and U/Ne lamp

U/Ne lamps are effective for high-precision near-infrared calibration

Abstract

We present a high-resolution (R ~ 50 000) atlas of a uranium-neon (U/Ne) hollow-cathode spectrum in the H-band (1454 nm to 1638 nm) for the calibration of near-infrared spectrographs. We obtained this U/Ne spectrum simultaneously with a laser-frequency comb spectrum, which we used to provide a first-order calibration to the U/Ne spectrum. We then calibrated the U/Ne spectrum using the recently-published uranium line list of Redman et al. (2011), which is derived from high-resolution Fourier transform spectrometer measurements. These two independent calibrations allowed us to easily identify emission lines in the hollow cathode lamp that do not correspond to known (classified) lines of either uranium or neon, and to compare the achievable precision of each source. Our frequency comb precision was limited by modal noise and detector effects, while the U/Ne precision was limited primarily by the signal-to-noise ratio (S/N) of the observed emission lines and our ability to model blended lines. The standard deviation in the dispersion solution residuals from the S/N-limited U/Ne hollow cathode lamp were 50% larger than the standard deviation of the dispersion solution residuals from the modal-noise-limited laser frequency comb. We advocate the use of U/Ne lamps for precision calibration of near-infrared spectrographs, and this H-band atlas makes these lamps significantly easier to use for wavelength calibration.