Laboratory reflectance spectra of several hydrated salts and sulfuric acic hydrates. They are possibly present on Ganymede according to previous near-infrared observations (Ligier et al. 2019; King & Fletcher 2022). The spectrum of Magnesium chloride (~250 µm, JB-JLB-G32-A) is from the NASA Reflectance Experiment LABoratory (RELAB) spectral database. Spectrum of Epsomite (GDS149) is from the USGS Spectral Library (Kokaly et al. 2017). Spectra of Bloedite (〜250 µm, Jim Crowley, USGS) and Hexahydrate (<45 µm, SPT143) are from the database of the Centre For Terrestrial and Planetary Exploration (C-TAPE) of University Winnipeg. The spectrum of sulfuric acid tetrahydrate at 160 K is from Loeffler et al. (2011). We note that this is a transmittance spectrum. A reflectance spectrum of Ganymede’s trailing side equatorial region (<30° latitude N/S, see Fig. 26) is scaled for comparison (black line). The vertical dotted lines indicate H₂O inter-band positions in NIRSpec spectrum, and the vertical dashed lines indicate the band positions in MIRI spectrum.