On-sky tests of sky-subtraction methods for fiber-fed spectrographs

TL;DR

This paper reports on on-sky tests of sky subtraction techniques for fiber-fed spectrographs, demonstrating that certain methods can achieve sub-1% accuracy, supporting their use for faint target observations.

Contribution

It provides empirical on-sky validation of sky subtraction methods, showing their effectiveness for fiber-fed spectrographs in faint object astronomy.

Findings

Cross beam-switching and dual stare methods reach under 1% accuracy.

Fiber-fed spectrographs are suitable for faint target observations.

Empirical validation challenges previous assumptions.

Abstract

We present preliminary results on on-sky test of sky subtraction methods for fiber-fed spectrograph. Using dedicated observation with FLAMES/VLT in I-band, we have tested the accuracy of the sky subtraction for 4 sky subtraction methods: mean sky, closest sky, dual stare and cross-beam switching. The cross beam-switching and dual stare method reach accuracy and precision of the sky subtraction under 1%. In contrast to the commonly held view in the literature, this result points out that fiber-fed spectrographs are adapted for the observations of faint targets.