  eta Telescopii is a ~23 Myr old A-type star surrounded by an edge-on debris
disc hypothesised to harbour gas. Recent analysis of far- and near-ultraviolet
spectroscopic observations of eta Tel found absorption features at ~-23 km/s
and ~-18 km/s in several atomic lines, attributed to circumstellar and
interstellar gas, respectively. In this work, we put the circumstellar origin
of the gas to a test by analysing high resolution optical spectroscopy of eta
Tel and of three other stars with a similar line of sight as eta Tel: HD
181327, HD 180575, and rho Tel. We found absorption features at ~-23 km/s and
~-18 km/s in the Ca ii H&K lines, and at ~-23 km/s in the Na i D1&D2 doublet in
eta Tel, in agreement with previous findings in the ultraviolet. However, we
also found absorption features at ~-23 km/s in the Ca ii K lines of the three
other stars analysed. This strongly implies that the absorption lines
previously attributed to circumstellar gas are more likely due to an
interstellar cloud traversing the line of sight of eta Tel instead.
