The list of tantalum lines for wavelengths calibration of the Hamilton echelle-spectrograph

TL;DR

This paper identifies tantalum lines in a thorium-argon lamp spectrum used for wavelength calibration of the Hamilton Echelle spectrograph, providing a comprehensive line list and discussing calibration accuracy limitations.

Contribution

It presents the first detailed list of tantalum lines for wavelength calibration and estimates the lamp's gas temperature, improving calibration precision.

Findings

Identified tantalum lines in the lamp spectrum.

Compiled a line list for spectral calibration.

Discussed hyperfine splitting effects on accuracy.

Abstract

We present solution of the problem of wavelength calibration for Hamilton Echelle spectrograph using hollow cathode lamp, which was operated at Lick Observatory Shane telescope before June 9, 2011. The spectrum of the lamp claimed to be thorium-argon, contains, in addition to the lines of thorium and argon, a number of the unrecognized lines identified by us with tantalum. Using atomic data for measured lines of tantalum and thorium, we estimated the temperature of the gas in the lamp as T=3120+/-60 K. From the atomic line database VALD3 we selected all lines of TaI and TaII which can be seen in the spectrum of the lamp and compiled a list for the use in the processing of spectral observations. We note a limitation of the accuracy of calibration due to the influence of the hyperfine line splitting.