Using raytracing to derive the expected performance of STELLA's SES-VIS spectrograph

TL;DR

This paper uses raytracing simulations to predict the performance of the SES-VIS spectrograph, focusing on calibration sources and environmental effects to ensure precise radial velocity measurements.

Contribution

It introduces a ZEMAX-based simulation tool for SES-VIS, enabling performance prediction and calibration analysis before actual deployment.

Findings

Simulation of calibration spectra using the new software.

Assessment of environmental impacts on wavelength calibration.

Preparation for future commissioning data analysis.

Abstract

The visual STELLA echelle spectrograph (SES-VIS) is a new instrument for the STELLA-II telescope at the Iza\~na observatory on Tenerife. Together with the original SES spectrograph - which will still be used in the near IR - and a new H&K-optimized spectrograph, which is currently in the design phase, it will extend the capabilities of STELLA with the follow up of planetary candidates from space missions (TESS, PLATO2). SES-VIS is optimized for precise radial velocity determinations and long term stability. We have developed a ZEMAX based software package to create simulated spectra, which are then extracted using our new data reduction package developed for the PEPSI spectrograph. The focus in this paper has been put on calibration spectra, and the full range of available calibration sources (flat field, Th-Ar, and Fabry-Perot etalon), which can be compared to actual commissioning data once they are available. Furthermore we tested for the effect of changes of the environmental parameters to the wavelength calibration precision.