Near-infrared wavelength calibration of astrophysical spectrographs with the emission spectrum of the CN molecule

摘要

Many astrophysical applications require precise wavelength calibration of high resolution spectra. Calibration sources for this purpose at near-infrared wavelengths are sparse. We present an experimental setup for an elec-trodeless microwave discharge lamp that produces molecular band emission spectra. The discharge is sustained inside a glass cell filled with a combination of different gases producing CN molecules with many spectral lines in the wavelength range between 1 μm and 2.5 μm. We investigate this lamp in terms of its usability for wavelength calibration in high resolution spectroscopy. In this conference contribution, we present the experimental setup and the characterization of the calibration source in terms of line identification, line intensities, and line density. We find approximately 20,000 lines in the spectral region of 1 - 2 μm with relative peak intensities in a range of two orders of magnitude. The results from a first endurance test show that the durability of the spectrum requires careful attention in the course of further development.