The recalibration of the UVES-POP stellar spectral library

TL;DR

This paper presents a comprehensive re-reduction and calibration of the UVES-POP stellar spectral library, improving spectral quality and continuity through advanced data processing and synthetic spectrum integration.

Contribution

It introduces a new pipeline-based method for ripple removal and a synthetic spectrum approach for merging spectral segments, enhancing the library's flux calibration accuracy.

Findings

Achieved flux calibration accuracy of 2% or better for 85% of spectra.

Successfully removed ripples caused by order stitching issues.

Enhanced spectral coverage and quality of the UVES-POP library.

Abstract

We have re-reduced all spectra from the UVES-POP stellar spectral library using the version 5.5.7 of the UVES pipeline and an algorithm we designed, which allows us to remove ripples in regions where echelle orders are stitched. These ripples are caused by the offset of a flat field with respect to a science frame and under- or oversubtraction of scattered light. We have also developed an approach to merge 6 UVES spectral chunks divided by gaps in the spectral coverage by using synthetic stellar atmospheres to predict the flux difference between the segments. At the end, we improved the flux calibration quality to 2% or better for 85% of 430 spectra in the library.