Contamination of spectroscopic observations by satellite constellations

Abstract This study focuses on the impact of satellite trails on spectroscopic observations in the visible and near-infrared, which represent a large fraction of the observing time on large professional telescopes. We simulate the number of observations affected using an hypothetical large set of low Earth orbit satellite constellations. We evaluate the effect of this contamination on various spectrographs. We also measure the contamination on actual data from the ESO archive for a set of representative objects, after adding a scaled solar analogue spectrum to represent the satellite. Even with a satellite population much larger than today’s, the fraction of contaminated spectra will remain low, essentially thanks to the typically small field of view of these instruments. Furthermore, high-resolution spectrographs, and medium-resolution ones on smaller telescopes, are essentially blind to satellites. However, for a range of instruments the contamination will be at a level comparable to that of the science signal, making its identification difficult, and potentially affecting the astrophysical measurements derived from the data.