Sky background accounting in spectral infrared observations of extended objects at the Caucasus Mountain Observatory of the SAI MSU

TL;DR

This paper presents a new technique for accurately accounting for variable atmospheric hydroxyl lines in near-infrared spectra of extended objects, improving spectral data quality at the Caucasus Mountain Observatory.

Contribution

The authors developed and validated a method to correct for atmospheric line variability in IR spectra of extended objects, addressing a key observational challenge.

Findings

The technique effectively isolates atmospheric line contributions in IR spectra.

Successful application demonstrated on the star-forming region NGC 7538.

Improves spectral analysis accuracy for extended objects in IR observations.

Abstract

The Caucasus Mountain Observatory of the Sternberg Astronomical Institute of Moscow State University is the only one in Russia and one of the few in the world where is possible to obtain spectral data in the near-infrared (IR) range at $\lambda$=1-2.5 $\mu$m. However, there is a problem of processing the spectra of extended objects, the angular dimensions of which exceed the length of the slit (4.5 arcmin). Obtaining additional spectra of the sky in the immediate vicinity of such objects does not solve the problem, since bright atmospheric hydroxyl lines at $\lambda$~2 $\mu$m change their intensity significantly over a time shorter than the exposure time of a single frame. We have developed a technique that allows us to correctly account for and exclude the contribution of variable atmospheric lines in the spectra of extended objects. This technique has been successfully tested in spectroscopic studies of the star-forming region NGC 7538 (S158) in our Galaxy.