Spatial and temporal distribution of all the ACS MIR observations covered in this analysis. Squares represent observations made by ACS using grating position 9 (sensitive to SO₂), diamonds using grating position 5 (H₂S), and triangles using grating position 11 (OCS). The colour of each symbol represents the time, in units of solar longitude (L_s) over Martian years (MY) 34 and 35, at which the observation was obtained. The relative concentration of observations made closer to the poles is due to the TGO orbital geometry. Latitude values are planetocentric. The background image of Mars is based on topography data from the Mars Orbiter Laser Altimeter (MOLA) instrument on board Mars Global Surveyor (Smith et al. 2001).