The 2021 outburst of RS Oph. A pictorial atlas of the spectroscopic evolution: the first 18 days

TL;DR

This paper provides a detailed visual and spectral analysis of the first 18 days of the 2021 RS Oph outburst, documenting its optical spectroscopic evolution before high ionization lines appeared.

Contribution

It offers the first comprehensive pictorial atlas of the early spectroscopic evolution of RS Oph during its 2021 outburst, with daily calibrated spectra from multiple telescopes.

Findings

Spectroscopic features observed before high ionization lines emerged.

High-resolution spectra captured the evolution of emission lines.

The dataset enables detailed temporal analysis of the outburst.

Abstract

A pictorial atlas of the spectroscopic evolution at optical wavelengths is presented for the first 18 days of the 2021 outburst of the recurrent nova RS Oph, prior to the emergence of high ionization emission lines. The spectra presented here have been obtained at daily cadence with the Asiago 1.22m + B&C (3200-7900 Ang, 2.3 \AA/pix) and Varese 0.84m + Echelle telescopes (4250-8900 \AA, resolving power 18,000). The spectra have been fully calibrated in IRAF, absolutely fluxed, and heliocentric corrected. The Echelle spectra have been also corrected for telluric absorptions.