Extended Data Fig. 1: A sequence of transmittance spectra measured with the ACS MIR channel.
From: No detection of methane on Mars from early ExoMars Trace Gas Orbiter observations
The spectra are for an example orbit (Lsolar = 180.9°) obtained using the secondary grating position 12 (ref. 17). Different diffraction orders (top axis) are denoted by the changing colour of the transmission curves, and their numbers are indicated on the upper scale. Diffraction orders used in this study are 178 (for CO2), 180 (the CH4 Q-branch), and 182 (the CH4 R-branch). Enhanced extinction on the short wavelength edge of the spectra is due to H2O ice absorption.
