The rapid advance in near-infrared (NIR) detector technology in the past decade has lead to a number of high-resolution astronomical spectrometers that are either in operation or in the planning stages. Precision wavelength calibration techniques traditionally used in the optical (e.g., thorium-argon lamps) are not as useful in the NIR due to lower line densities and fewer usable bright lines. The problem becomes particularly acute when using a small NIR array to observe a highly dispersed spectrum, or when attempting to achieve very high radial velocity precision with a calibration lamp. We present here an atlas of high resolution (R~ 50 000) spectra in the NIR of a uranium-neon (U/Ne) hollow cathode lamp. The large line density of stable uranium emission lines can mitigate many of the calibration challenges in the NIR. This spectral atlas was created with the Pennsylvania State University Pathfinder fiber-fed testbed instrument during a commissioning run at the Hobby-Eberly Telescope. We simultaneously observed both a U/Ne lamp and an H-band laser frequency comb through adjacent fibers, enabling us to independently wavelength-calibrate the U/Ne spectrum and compare the measured wavelengths with those from a recently-published uranium line list (derived from much higher- precision Fourier transform spectrometer measurements). This atlas of U/Ne spectra in the H band highlights the density of lines and the utility of hollow cathode lamps and laser frequency combs as calibration sources for precision NIR spectroscopy.
Citation: Astrophysical Journal Supplement Series
Pub Type: Journals
Extrasolar Planets, Frequency Comb, Hollow Cathode Lamps, Wavelength Calibration