Titan ESPRESSO and UVES spectra

We identified 6195 absorption features in the ESPRESSO spectra potentially associated with CH_4_, of which 5436 are newly reported. ESPRESSO detected twice as many features as UVES in overlapping regions, highlighting the advantage of higher-resolution data. Most detected lines remained unresolved, so our reported features are primarily blended absorption structures.

We estimated the detection limit for feature identification to correspond to a CH_4_ absorption coefficient of approximately 0.02km/am. Comparison of our results with a previous analysis of Titan UVES spectra and with experimental CH_4_ data at a similar temperature showed good agreement, while some discrepancies were observed when compared with data acquired at a different temperature. We provide a comprehensive list of Titan absorption features with key reliability metrics, along with Titan's intrinsic spectra, to support future studies.