A fast and portable reimplementation of piskunov and valenti's optimal-extraction algorithm with improved cosmic-ray removal and optimal sky subtraction

Abstract

We present a fast and portable reimplementation of Piskunov and Valenti's optimal-extraction algorithm (Piskunov & Valenti 2002) in C/C++ together with full uncertainty propagation, improved cosmicray removal, and an optimal background-subtraction algorithm. This reimplementation can be used with IRAF and most existing data-reduction packages and leads to signal-to-noise ratios close to the Poisson limit. The algorithm is very stable, operates on spectra from a wide range of instruments (slit spectra and fibre feeds), and has been extensively tested for VLT/UVES, ESO/CES, ESO/FEROS, NTT/EMMI, NOT/ALFOSC, STELLA/SES, SSO/ WiFeS, and finally, P60/SEDM-IFU data. © 2014. The Astronomical Society of the Pacific. All rights reserved.