The UVES Spectral Quasar Absorption Database (SQUAD) Data Release 1: The first 10 million seconds

TL;DR

This paper introduces the first data release of the SQUAD, a comprehensive high-resolution quasar spectral database from UVES, enabling large-scale statistical studies of quasar absorption systems with fully reproducible data and tools.

Contribution

The paper provides the first public release of a large, high-quality quasar spectral database with open-source processing tools and detailed documentation for reproducibility and specific scientific applications.

Findings

Release includes 467 spectra with high S/N ratios.

Catalog of 155 DLAs, 18 newly reported, with measured HI column densities.

Spectra cover redshifts 0-5, enabling diverse absorption studies.

Abstract

We present the first data release (DR1) of the UVES Spectral Quasar Absorption Database (SQUAD), comprising 467 fully reduced, continuum-fitted high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph (UVES) on the European Southern Observatory's Very Large Telescope. The quasars have redshifts $z=0$-5, and a total exposure time of 10 million seconds provides continuum-to-noise ratios of 4-342 (median 20) per 2.5-km/s pixel at 5500 \AA. The SQUAD spectra are fully reproducible from the raw, archival UVES exposures with open-source software, including our UVES_popler tool for combining multiple extracted echelle exposures which we document here. All processing steps are completely transparent and can be improved upon or modified for specific applications. A primary goal of SQUAD is to enable statistical studies of large quasar and absorber samples, and we provide tools and basic information to assist three broad scientific uses: studies of damped Lyman-$\alpha$ systems (DLAs), absorption-line surveys and time-variable absorption lines. For example, we provide a catalogue of 155 DLAs whose Lyman-$\alpha$ lines are covered by the DR1 spectra, 18 of which are reported for the first time. The HI column densities of these new DLAs are measured from the DR1 spectra. DR1 is publicly available and includes all reduced data and information to reproduce the final spectra.